TWI766760B - Reactor system coupled to an energy emitter control circuit - Google Patents

Abstract

A microwave energy source that generates a microwave energy is disclosed. The microwave energy source has an on-state and an off-state. A control circuit is coupled to the microwave energy source and includes an output to generate a control signal that adjusts a pulse frequency of the microwave energy. A voltage generator applies a non-zero voltage to the microwave energy source during the off-state. A frequency and a duty cycle of the non-zero voltage is based on a frequency and a duty cycle of the control signal. A waveguide is coupled to the microwave energy source. The waveguide has a supply gas inlet that receives a supply gas, a reaction zone that generates a plasma, a process inlet that injects a raw material into the reaction zone, and an outlet that outputs a powder based on a mixture of the supply gas and the raw material within the plasma.

Description

Reactor system coupled to energy transmitter control circuit Field of Invention

The present disclosure relates generally to reactors for producing carbon particles, and more particularly, to reactors coupled to circuits configured to propagate microwave energy to the reaction at a defined pulse frequency or duty cycle in the device for the output of carbon particles.

Background of the Invention

For example, microwave emitting devices such as magnetrons or klystrons can be configured to output electromagnetic (EM) radiation in the form of microwave energy. To carefully control the output power level of the output microwave energy, an integrated circuit can be coupled to such a microwave transmitter to control the microwave energy source to output microwave energy in discrete pulses and duty cycles with various frequencies. This circuit can be designed for a specific range of pulse frequencies, duty cycles, shapes, and output power levels; however, challenges encountered in conventional microwave launcher and reactor designs actually limit the overall operating range. The observed rise and fall times of pulsed signals may be observed instance limitations, given that relatively slow rise or fall times may negatively affect the rate of switchable signals. Also, the power that the circuit can deliver to the magnetron can also affect the output power level of the magnetron. Careful control and consideration of optimization of circuit design and its integration with various reactor designs can provide benefits with regard to reactor product output.

Summary of Invention

The systems, methods, and devices of the present disclosure each have several innovative aspects, no single one of which is solely responsible for the desired attributes disclosed herein.

One novel aspect of the subject matter described in this disclosure can be implemented in a reactor system including a microwave energy source configured to generate microwave energy. The microwave energy source has an on state and an off state. A control circuit is coupled to the microwave energy source and includes an output to generate a control signal configured to at least partially adjust the pulse frequency of the microwave energy. The voltage generator is configured to apply a non-zero voltage to the microwave energy source during the off state, wherein the frequency and duty cycle of the non-zero voltage is based on the frequency and duty cycle of the control signal. A field enhancement waveguide (FEWG) is coupled to the microwave energy source and includes a field enhancement region having a decreasing cross-sectional area along the length of the FEWG. The field enhancement zone includes a supply gas inlet configured to receive a supply gas, a reaction zone configured to generate a plasma in response to excitation of the supply gas by microwave energy, and a process configured to inject raw materials into the reaction zone An inlet, and an outlet configured to output a carbonaceous powder based on a mixture of a portion of the supply gas and raw materials within the plasma.

In some implementations, the reactor system can include a collector configured to collect the carbonaceous powder. Field enhancement regions can be configured to concentrate microwave energy. The reaction zone can be configured to self-ignite the plasma in response to excitation of the supply gas by concentrated microwave energy. One or more of the physical or chemical properties of the carbonaceous powder may be based, at least in part, on the pulse frequency. In some aspects, the non-zero voltage can have a rise time in a range between about 20 nanoseconds and 50 nanoseconds, and the non-zero voltage can have a rise time in a range between about 20 nanoseconds and about 50 nanoseconds the fall time.

In some implementations, the pulse frequency of the microwave energy can be further based, at least in part, on a non-zero voltage. The control circuit may also include a filament configured to adjust the dissociation of the supply gas. The power level of the microwave energy can be based, at least in part, on a non-zero voltage. The microwave energy source includes any one or more of a magnetron, a klystron, or a traveling wave tube amplifier (TWTA). The control circuit may include a pulse switch including a series connection A first bipolar active switch and a second bipolar active switch are coupled between the voltage supply and ground potential. In some aspects, the supply gas can include hydrocarbons. The carbonaceous powder may include any one or more of carbonaceous particles, a colloidal dispersion, or a plurality of solid particles.

In some implementations, the reactor system can include a gas/solid separator configured to separate gas phase and solid phase materials from carbonaceous powders. The FEWG can be configured to generate one or more conditional measurements of a microwave energy source. The carbonaceous powder may include a plurality of graphene sheets. The FEWG can be assembled to fuse multiple graphene sheets with each other at substantially orthogonal angles. The FEWG is configured to adjust the length of the plasma generated within the FEWG by selectively flowing the supply gas into the reaction zone. The reaction zone can be configured to contain the mixture at a pressure of about 1 atm. In some aspects, the reactor system can include a temperature control unit configured to control the temperature within the FEWG.

Another novel aspect of the subject matter described in this disclosure can be implemented as a method that can include: generating microwave energy from a microwave energy source; generating a control signal configured to adjust a pulse frequency of the microwave energy to Control the microwave energy source; apply a non-zero voltage to the microwave energy source during the off state of the microwave energy source, the non-zero voltage is configured to adjust the frequency and duty cycle of the control signal; in response to excitation of the supply gas by the microwave energy A plasma is generated; a raw material is injected into the plasma; a mixture is formed based on the combination of a supply gas within the plasma and a portion of the raw material; and a carbonaceous powder is output based on excitation of the mixture by microwave energy. In some aspects, the method may include pulsing the non-zero voltage, the pulsed non-zero voltage having a rise time between about 20 nanoseconds and 50 nanoseconds.

Another novel aspect of the subject matter described in this disclosure can be implemented as a method that can include: controlling the temperature and pressure of any one or more of a hydrocarbon species and a raw material; generating microwaves by a microwave energy source energy, the microwave energy source includes an output to generate a control signal; ignites the plasma by exciting hydrocarbon species by the propagated microwave energy; cracks the hydrocarbon species in the plasma into a plurality of smaller carbonaceous species based on the propagated microwave energy species; and based on a mixture of a plurality of smaller carbon-containing species with raw materials carbon powder. In some aspects, the method can include performing one or more post-processing operations on any one or more of the smaller carbon-containing species.

The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects and advantages will become apparent from the description, drawings and claims. It should be noted that the relative dimensions of the following figures may not be drawn to scale.

122: Known Low Frequency Switching Circuit Mechanism

124: conventional low power switching circuit

126: High power and high frequency switching mechanism

140: Microwave transmitter control circuit

141,804,904,1004: Microwave Energy Sources

142: High voltage control circuit

143: Filament control circuit

144: Pulsed high voltage output

145: Components

200:Characteristics

201: Hatrey curve, characteristic curve

202: Haar cutoff curve, characteristic curve

203: Deadline

204: Conductive area or mode

205: Oscillation Zone

206: "On" operating point

207: "Disconnect" operating point

208, 209: Dimensions

300: Control signal trace

301: Second trace, output current or power trace

400: Prior Art Control Voltage Trace

401: Second trace, prior art output current or power trace

402: Response lag

500: Schematic, Microwave Transmitter Control Circuit

501: Voltage input

502: Power Supply Circuit

503: Pulse Generator

504: High Voltage Controller

505: High Voltage Power Supply (HVPS) Transformers

506: Voltage Doubler

507: Pulse switch

508: Filament Controller

509: Filament Isolation Transformer

510: Main control switch

511: High Voltage Control Switch

512: Filament control switch

513: Pump/Fan Control Switch

514: Cooling Pump or Fan

515: Transformer

516: Relay

517: Relay Controller

518: Potentiometer

519,520: Capacitors

521, 522, 529, 530, 603: Diodes

523: High side resistor

524: Low Side Resistor

525: High-voltage side bipolar active switch

526: Low-voltage side bipolar active switch

527, 528: Switch Drivers

531: Reactance Components

600: Rise time adjustment network

601: Inductor

602, 604: Resistors

700A, 700B, 1800A, 1800B: Operation

Blocks

800: Conventional Microwave Chemical Processing System

801: Reaction Chamber

802: Gas inlet

803, 903, 1003, 1103, 1205, 1303: Export

805: Waveguide

806, 906, 1006: Microwave Plasma

807, 1307, 1407: Microwave Transmitter Circuits

808, 908b, 1011a, 1011b: Process Materials

809, 909, 1009, 1201, 1409: Microwave energy

900, 1000, 1500: Reactor Systems

901, 1001: Reaction Zone

902: Supply gas and/or process material inlet

905, 1005, 1102, 1305, 1405, 1505: Field Enhanced Waveguide (FEWG)

907, 1007: Microwave Circuits

908a: Supply Gases and/or Process Materials

910, 911: Pressure Barrier

912: Pressure blow out port

1002, 1302, 1402, 1502: Supply gas inlets

1008a, 1008b: Supply gas

1010, 1310, 1410: Process material entry

1101, 1304, 1404, 1504: Microwave Energy Generators

1202: Manifold Waveguide, Network Waveguide

1203: FEWG Field Enhancement Zone

1204: Smaller cross-sectional area reaction zone of FEWG

1300: Microwave Gas Handling Systems

1320: Precursor Gas

1330: First isolated components

1332: Second Separated Components

1340: Catheter

1400: Microwave Processing System

1420: Metal Filament

1506: Plasma

1509: General Orientation

1520: Electron Source

1530: Energy Source, Electrode

1600: Flowchart

1702: Multi-Walled Spherical Fullerene (MWSF)

1704: Graphene Layer

1706, 1710, 1714, 1720: Mass-Based Cumulative Particle Size Distribution

1708, 1716, 1722: Mass particle size distribution

1712: Mass Benchmark Particle Size Distribution

1718, 1724: Number-Based Cumulative Particle Size Distribution

1730: 3D Carbon Materials, 3D Carbon Growth

1731, 1732: Fiber

1734: Edge Plane

1735: Fiber Surface

1736: basal plane

a,b: size

L: length

L _A , L _B , L ₀ : length, part

L ₁ : length, section, plasma area

L ₂ : length, section, reaction length, reaction zone

+out: DC drive voltage

G: Ground

L: Voltage line

N: neutral pole, neutral potential

1A depicts various domains in which control circuit (such as filament) power can be switched over a range of delivered power and/or a range of switching frequencies, according to some implementations.

IB shows a simplified schematic diagram of an example circuit, such as a microwave transmitter control circuit, according to some implementations.

2 shows a simplified diagram of a comparative comparison of operating voltage and magnetic field produced by a magnetron, according to some implementations.

3 shows a simplified graph of test results for the example microwave transmitter control circuit shown in FIG. IB, according to some implementations.

4 shows a simplified graph of test results of a prior art microwave transmitter control circuit according to some implementations.

5 shows a diagram of the example circuit shown in FIG. IB, according to some implementations.

6 shows a diagram of a rise time adjustment network circuit suitable for incorporation and/or use with the example circuits shown in FIGS. 1B and 5, according to some implementations.

7A is a flowchart of a method of generating pulsed microwave radiation by an electrical circuit, according to some implementations.

7B is a flowchart of a method of alternately connecting pulsed voltage outputs in accordance with some implementations.

8A shows a vertical cross-section of a conventional microwave chemical processing system according to some implementations.

8B and 8C show example geometries and dimensions of waveguides, such as field enhancement waveguides, FEWGs, according to some implementations.

9 shows a vertical cross-section of a reactor, such as a reactor coupled to a microwave energy source, according to some implementations.

10 shows a simplified vertical cross-section of a microwave gas processing system according to other implementations.

11A, 11B, 11C, and 11D show block diagrams of a microwave chemical processing system with multiple field enhancement waveguides and multiple microwave energy sources, according to some implementations.

12A and 12B show simplified diagrams of a microwave chemical processing system in which multiple field-enhancing waveguides are coupled to a microwave energy generator, according to some implementations.

13 shows a vertical cross-section of a microwave gas processing system with precursor gas input, according to some implementations.

14 shows a vertical cross-section of a reactor with a filament, such as a reactor coupled to a microwave energy source, according to some implementations.

15 shows a vertical cross-section of a reactor including an electron source and any one or more of a pair of electrodes, such as a reactor coupled to a microwave energy source, according to some implementations.

16 shows an example flow diagram of an example method for supplying microwave radiation, such as microwave energy, to excite and/or excite a supply gas and generate plasma based on the excited supply gas, according to some implementations.

17A-17Y depict structured carbon, various carbon nanoparticles, various carbon-based aggregates, and various three-dimensional carbon-containing aggregates grown over other materials, according to some implementations.

18A is a flow diagram of a method of outputting carbonaceous powder, according to some implementations.

18B is a flowchart of a method of pulsing a non-zero voltage according to some implementations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made to implementations of the disclosed invention, one or more examples of which are illustrated in the accompanying drawings. The examples are provided by way of explanation of the techniques of the present invention, and not as limitations of the techniques of the present invention. Indeed, it will be apparent to those skilled in the art that modifications and variations of the present technology can be made without departing from the scope of the present technology. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield yet another embodiment. Accordingly, the inventive subject matter is intended to cover all such modifications and variations as come within the scope of the appended claims and their equivalents.

Embodiments of the systems and methods of the present invention may be used to provide pulsed microwave energy, such as by a circuit-controlled microwave energy source, for generating particles including carbon from raw materials using the microwave plasma chemical processing techniques disclosed herein. In some implementations, the starting material can be a gaseous, liquid, or colloidal dispersion. In some other implementations, the starting material can be or include any one or more of carbon-containing particles, a colloidal dispersion, or a plurality of solid particles. In some aspects, the raw material can be processed into separate components in the reactive region of the waveguide. In some implementations, the waveguides can be field-enhanced waveguides that not only allow relatively large quantities of raw materials to be processed, but also serve as reaction chambers in which plasma (also known as plasma) can be generated in response to excitation of a supply gas by microwave energy. called the plasma environment).

This is in contrast to conventional systems, which may not provide pulsed microwave energy controlled by electrical circuits and/or use a separate and distinct quartz chamber from the waveguide to concentrate the pulsed microwave energy for excitation within a plasma environment A mixture of carbon-containing supply gas and raw materials. In conventional systems, particle buildup on the walls of the quartz chamber can prevent microwave energy from passing through the walls of the quartz chamber, thereby reducing the efficiency with which such conventional systems can process raw materials. More specifically, the circuit can be coupled to a microwave energy source, wherein the circuit can generate a pulsed voltage output that can control the microwave energy source. For example, a pulsed voltage output may cause a microwave energy source to generate pulsed microwave energy that propagates along a graded waveguide where the concentration of pulsed microwave energy in the waveguide is proportional to the degree of cross-section grade. The waveguide also acts as a reaction chamber where an input carbon-containing supply gas (such as methane, _CH4 ) can be combined with additional raw materials such as silicon or other metals and excited after exposure to concentrated and pulsed microwave energy, which also Some of the supply gases are ignited and a plasma is generated. The mixture of supply gas and raw material is excited within a plasma environment by concentrated and pulsed microwave energy. As a result, the efficiency with which the reactor systems disclosed herein can process a mixture of supply gas and raw materials within a plasma to output carbonaceous powders is enhanced. Furthermore, the waveguide itself is not necessarily susceptible to particle buildup on the inward facing surfaces of its chamber walls, which is but one example of the advantages realized by the various aspects of the subject matter disclosed herein.

As used herein, the term "field-enhanced waveguide" (FEWG) refers to a waveguide having a first cross-sectional area and a second cross-sectional area, wherein the second cross-sectional area is smaller than the first cross-sectional area and compared to the first cross-sectional area. The cross-sectional area is farther away from the microwave energy source. The reduction in cross-sectional area enhances the field by concentrating microwave energy, where the waveguide is sized to maintain propagation at the particular microwave frequency being used. The second cross-sectional area of the FEWG extends along the reaction length of the reaction zone forming the FEWG. There is a field enhancement region between the first cross-sectional area and the second cross-sectional area of the FEWG. In some aspects, the field enhancement region may vary in cross-sectional area in a continuous manner (such as linearly or non-linearly) or abruptly (such as via one or more discrete steps). In some aspects, the pressure within the FEWG is from 0.1 atm to 10 atm, or from 0.5 atm to 10 atm, or from 0.9 atm to 10 atm, or greater than 0.1 atm, or greater than 0.5 atm, or greater than 0.9 atm.

Microwave plasma chemical processing reactors of the present disclosure may include a supply gas flow to one or more supply gas inlets and an input material flow to one or more process inlets, or may be combined with the one or more supply gas inlets An entry is associated with one or more process entries. A supply gas and a process inlet are located in or upstream of the reaction zone, and the supply gas is used to generate a plasma in the reaction zone. The supply gas flow can be from 1 slm (standard liters per minute) to 1000 slm, or from 2 slm to 1000 slm, or from 5 slm to 1000 slm, or greater than 1 slm, or greater than 2 slm, or greater than 5 slm. The process material is a gas, and The flow rate is from 1 slm (standard liters per minute) to 1000 slm, or from 2 slm to 1000 slm, or from 5 slm to 1000 slm, or greater than 1 slm, or greater than 2 slm, or greater than 5 slm. The process material is a liquid, or a colloidal dispersion, and the flow rate is less than 1% to greater than 100% of the flow rate of the supplied gas.

The microwave plasma chemical processing reactor of the present disclosure may have a single microwave energy generator, which is a microwave energy source coupled to one or more than one FEWG. The disclosed reactor can have more than one microwave energy generator coupled to more than one FEWG. The microwave energy is continuous wave or pulsed microwave energy. The microwave energy generator power is from 1 kW to 100 kW. The disclosed reactors may have more than one reaction zone connected together and having one or more outlets from which the separated components are collected. The disclosed reactors can include multiple FEWGs with different geometries including manifold configurations and network configurations. These geometries are described more fully herein.

The disclosed reactors of the present disclosure have a reaction zone with walls, and supply gas and process inlets provide supply gas (for microwave plasma generation) and input materials to the reaction zone through the walls. There may be multiple supply gas and process inlets that provide supply gas and input materials to the reaction zone at controlled mass fractions through the wall. Providing supply gas and input materials to the reaction zone at controlled mass fractions across the walls can mitigate deposition of separated components on the walls of the reaction zone.

Various techniques can be used for microwave plasma chemical treatment of hydrocarbon gases, including pulsing microwave energy to control the energy of the plasma. The ability to control the plasma energy enables the selection of one or more reaction paths in the conversion of hydrocarbon gases into specific separated components. Pulsed microwave energy can be used to control the energy of the plasma because the short-lived energetic species produced when the plasma ignites can be regenerated at the beginning of each new pulse. The plasma energy is controlled to have a lower average ion energy than the prior art, but at a sufficiently high level to enable the target chemical reaction to occur at high gas flow and high pressure.

Microwave plasma chemical processing systems using pulsed microwave energy have been developed, which control the energy of the plasma and have a very high pyrolysis efficiency of over 90%. However, these conventional systems use With low flow rates below 1 standard liter per minute (slm) and smaller gas volumes, the result is lower production rates and higher production costs. These conventional systems cannot increase the gas flow rate and gas volume within the plasma when using high frequency microwave pulses (such as above about 100 Hz) because the plasma cannot increase the gas flow rate and gas volume within the plasma when using larger volumes and high gas flow rates Fire fast enough to keep up with the pulse.

Energy Transmitter Control Circuit

Microwave generating magnetrons provide utility in a variety of applications. In general, a magnetron generates a tuned microwave signal by directing electrons emitted from a filament after excitation from a direct current. The electrons are guided using a magnetic "B" field that vortexes the emitted electrons over the cavity in the magnetron ring. As the electrons swirl over the opening in the cavity, a microwave signal can be emitted. The frequency of the microwave signal can be tuned over a range by varying the shape and size and positioning and orientation of the cavity within the magnetron.

Thus, the transmitted microwave signal can be tuned (such as tuned for power level, tuned for frequency, tuned for signal shape) to suit applications in many different fields. For example, an emitted microwave signal tuned to the resonant frequency of water molecules can be used to heat water in food placed in a microwave oven. In microwave oven applications, the energy in the microwave signal is used to heat food or beverages, and the power consumed by heating water is in the range of several hundred watts. Controlled heating of the food is accomplished by pulsing the microwave energy of the microwave signal. This pulse is accomplished by, for example, (1) switching on the direct current to the magnetron for a first controlled duration to apply energy to the food; then (2) switching off to the magnetron for a second controlled duration Direct current to the tube to allow the food to absorb (such as distribute) energy via molecular vibration and rotation promotes slow and uniform heating (such as without drying out or burning the food), thus transferring heat into the heated food.

Microwave magnetrons are used in many other applications, some of which require higher power and higher on/off rates. In some cases, these other applications require extremely high power and extremely high on/off rates. When a microwave magnetron is used to apply energy to a sample of the material to be annealed, the The magnetron power required to heat the sample for an amount of time (such as a few minutes or less) can be much higher than the power used to heat food (such as in the range of several kilowatts), and the on/off rate is fast Much more (such as in the range of 10KHz to 25KHz).

In one example, when a microwave magnetron is used to generate a plasma in a microwave plasma reactor, depending on various factors, the energy required to dissociate the process gas into ions is even higher than the energy used to anneal the material (such as in the range of tens of thousands of watts), and the on/off rate required to control the temperature of the electrons is even faster (such as in the range of 25KHz to 100KHz). The stable plasma plume that produces the dissociated components of the process gas is extremely sensitive to on/off rates and duty cycles. Furthermore, the need to perform dissociation in an atmospheric (such as low cost) environment further complicates the generation of stable plasma plumes in process gas reactors.

Unfortunately, power supplies that can deliver tens of thousands of watts of power do not switch from "on" to "off" (or from "off" to "on") as quickly. This inability to quickly switch from a high power "on" state to a low or zero power "off" limits the ability to finely tune or control the microwave signal. In turn, the inability to control the microwave signal limits the ability to control the annealing and/or the ability to control the kinetics of dissociation of the process gas. Techniques for controlling high power current to the filament are needed so that the high power and high frequency switching capabilities required for controlling the annealing process and/or for controlling the kinetics of dissociation of the process gases can be achieved. It should be noted that although the embodiment of the electronic control circuit should be described as being used with a microwave energy source, the electronic circuit may be used at other frequencies, such as a magnetron of any frequency.

Figure 1A presents various mechanisms in which the filament power is switched on and off over a wide range of powers and in which the filament power is switched over a wide range of switching frequencies. The abscissa of the graph covers the switching frequency range from about 2KHz to about 30KHz. The ordinate of the graph covers the range from several watts to greater than 30 kilowatts. In addition, the vacuum environment mechanism and the atmospheric environment mechanism are superimposed on the left and right sides of the figure, respectively. Determining the mechanism used to conduct the process, such as selecting a vacuum or atmospheric environment, is based on a particular process or application. For example, a vacuum environment may be preferred for gas dissociation, material annealing, material deposition, etching, and various functionalization purposes, while Atmospheric mechanisms may be preferred for generating plasma or plasma radicals, or pyrolysis, or sintering, or annealing.

As can be seen, the conventional low frequency switching circuit mechanism 122 only extends to about 10KHz, and only in the vacuum mechanism. Also, as can be seen, the conventional low power switching circuit 124 shown extends only to about 20KHz, while the high power and high frequency switching mechanism 126 covers the switching range from about 20KHz and above. As indicated above, there is a need to control the high power current to the filament in a manner such that high power and high frequency switching capabilities for controlling the kinetics of annealing and/or for controlling dissociation of process gases can be achieved.

Microwave signal generating devices generally include magnetrons or klystrons, or traveling waveguides, or another source of microwave energy. Electronic circuitry controls the delivery of electrical power, such as direct current, to the microwave signal generating device. This electronic circuit can be assembled into two components: (1) a component to control the high voltage power, and (2) a component to control the pulsed delivery of power to the filament.

As shown in FIG. 1B , according to some embodiments, microwave transmitter control circuit 140 includes a magnetron or klystron, traveling waveguide, or other microwave energy source 141 , high voltage control circuit 142 , and filament control circuit 143 , and Other possible circuit components not shown for simplicity. Microwave transmitter control circuit 140 is a relatively low cost, low complexity design that allows relatively fast rise and fall times for pulsing microwave energy source 141 with a relatively wide range of output power levels. In addition, the microwave transmitter control circuit 140 provides fine control over the pulse frequency and pulse duty cycle of the pulsed microwave radiation generated by the microwave energy source. High voltage control circuit 142 generally includes high voltage power electronics (high voltage generators) for generating high voltages and pulse switches for generating pulsed high voltage outputs 144 from the generated high voltages (as described below with reference to FIG. 5 . describe). Filament control circuit 143 generally includes a filament isolation transformer for generating filament current at 145 and an optional filament controller (as described below with reference to FIG. 5). Pulsed high voltage output 144 is applied to the high voltage components of microwave energy source 141, and filament current at 145 is applied to the filament of microwave energy source 141; thereby causing microwave energy source 141 to generate or emit microwave radiation (such as at about 915MHz, or at or about 2.45GHz, or at or at at about 5.8GHz). Additionally, the pulsing nature of the pulsed high voltage output 144 pulses or switches the microwave energy source 141 on and off, or pulses or switches it between high and low power levels; The energy source 141 intermittently generates or emits microwave radiation when pulsed on and off.

The on/off pulsing of the microwave energy source 141 (and thus the emitted microwave radiation) is performed at operating power levels, pulse frequencies, and pulse duty cycles that generally depend on the particular application of the microwave transmitter control circuit 140 . Additionally, the on/off pulsing of the microwave energy source 141 (and thus the emitted microwave radiation) is to allow for a relatively wide variety of combinations of different ranges of operating power levels, pulse frequencies and pulse duty cycles (thereby allowing Relatively fast use of microwave transmitter control circuit 140 in a variety of different applications (such as for generating plasma or plasma radicals, or for pyrolysis, sintering, annealing, etc.) and/or involving various types of materials rise and fall times. The rise and fall times may be slowed, tuned or adjusted for specific applications by the rise time adjustment network circuit with the output of the high voltage control circuit 142, as described below with respect to FIG. 6 .

In general, microwave transmitter control circuit 140 allows microwave radiation power levels of about 100 watts to 250 kW or from 250 kW to about 500 kW or from about 500 kW to 1 megawatt, pulse frequencies of about 5 Hz to 100 kHz, and About 5% to 100% pulse duty cycle. More specific operating parameters generally depend on the specific application in which the microwave transmitter control circuit 140 is being used. A non-limiting list of such applications may include pyrolysis, cracking or transformation of various types of gases or molecules, annealing of various types of materials, sintering of various types of materials, formation of nanodiamonds, formation of carbon nanoonions , and plasma-based material synthesis, etc. The particular operating parameters also generally depend on the type of magnetron, klystron, traveling waveguide, or other microwave generation or other source of microwave energy controlled by the microwave transmitter control circuit 140 .

FIG. 2 shows a generalized characteristic graph 200 of operating voltage versus magnetic field and its correspondence with electron cloud behavior for a typical magnetron. The characteristic diagram 200 may illustrate the control circuit of the microwave transmitter of FIG. 1B How the circuit 140 can achieve the above-mentioned range of operating parameters. The lower line represents the "Hartree curve" 201 and the upper line represents the "Hull cutoff curve" 202. These characteristic curves 201 and 202 have different values for the different magnetrons, so the absolute values for the cells are not shown. However, the operating mode of any given magnetron generally depends on the operating voltage of the magnetron and the general position of the magnetic field relative to the characteristic curves 201 and 202 . For example, below the Hartree curve 201 , the magnetron is generally in the cutoff region 203 , where the magnetron neither conducts nor oscillates, so it does not generate microwave radiation in the cutoff region 203 . Above or to the left of the Haar cutoff curve 202 , the magnetron is generally in a conduction region or mode 204 , where current flows through the magnetron, but it is not oscillating, so it does not generate microwave radiation in this region 204 . Between the Hartree curve 201 and the Haar cutoff curve 202, the magnetron is generally in the oscillation region 205, where the magnetron has current flow and is oscillating, so it is in this oscillation region also known as the Hartree region 205 produces microwave radiation. At different operating locations or points within the oscillation region 205, the magnetrons generally operate at different power outputs and/or different efficiencies. For example, within the oscillation region 205 but close to the operating point of the Hatrey curve 201, the magnetron is oscillating, but hardly producing any microwave radiation. On the other hand, going further into the middle of the oscillating region 205, the magnetron produces significant levels of microwave radiation, generally depending on the total operating power level.

The microwave transmitter control circuit 140 of FIG. 1B operates in a manner such that an on/off cycle or pulse of the microwave energy source 141 causes the microwave energy source 141 to be at the "on" operating point during the on time and the off time, respectively. Cycles between 206 and the "off" operating point 207. The "on" point 206 is just above the Hatrey curve 201 and substantially within the oscillation region 205, as generally indicated by the dimension 208 relative to the Hatrey curve 201, such that the microwave energy source 141 is at a significant power level and with Relatively high efficiency oscillates and generates microwave radiation. On the other hand, the "off" point 207 is only slightly below the Hatrey curve 201 at a non-zero voltage level and barely within the cutoff region 203, as generally indicated by the dimension 209 relative to the Hatrey curve 201, such that The microwave energy source 141 is not oscillating or generating microwave radiation.

However, even though the microwave energy source 141 output power is turned off at this time, the power to the microwave energy source 141 is not completely turned off at the "off" point 207 due to maintaining a non-zero voltage level of the operating voltage. In fact, some non-zero level of power or voltage is still being applied to the microwave energy source 141 at the "off" point 207 during the off time. That is, when the pulsed microwave radiation is turned off, the method includes maintaining the microwave energy source at a non-zero voltage level below the oscillating region.

Maintaining this low level of power or voltage during the off time allows the magnetron to quickly return to fully on operating power, such as "on" within a very short period of time, such as a rise time of about 20 to about 50 nanoseconds ” at point 206. This concept of maintaining or maintaining the microwave energy source 141 only slightly outside and below the oscillation region 205 (such as slightly below the Hartree curve 201 or slightly within the cut-off region 203 ) is referred to herein as "brewing", where the microwave The energy source 141 is "brewed" at a power or voltage level that is only outside the "on" condition and from which the microwave energy source can transition very quickly to a fully on level. This technique can be used in some embodiments for pulse shaping of pulsed microwave radiation. For example, the pulse shape may be triangular, trapezoidal, or smoothed versions of triangular, trapezoidal or square pulses. The pulse shape can be controlled to a fine degree by the microwave transmitter control circuit 140 . For example, the pulse shape can be based on a set of desired properties of the plasma plume, which in turn are based on tuning for a particular application (such as for pyrolysis, sintering, annealing, etc.).

Maintaining the brewing power level of the microwave energy source during the off time is different from a process or system that converts the power to the microwave energy source completely to off, as compared to when the microwave energy source must be completely disconnected from the lower point Initially, when the microwave energy source can start from the brewing power level, the time and power required to transition to the "on" point is significantly less. The ability to rapidly transition from the brewing point to the "on" point allows high frequency pulses of the microwave energy source. Additionally, this incubation technique differs from a process or system that maintains a source of microwave energy within the oscillating region 205 . Furthermore, the faster rise times possible when using the incubation techniques discussed herein and the faster fall times possible when using the abort techniques discussed herein help prevent arcing or instability in the plasma.

FIG. 3 illustrates test results for an example of the microwave transmitter control circuit 140 . Control signal trace 300 shows operation with a relatively high pulsed control voltage applied to the microwave energy source, and second trace 301 shows the efficacy of the resulting output current or power of the microwave energy source. The rise and fall times for the transitions of the control signal trace 300 are about 40 nanoseconds. The fast response of the output current or power trace 301 shows a large initial spike at the rise/fall transition, but it is insignificant at the time interval involved, and the rise/fall time of the output current or power trace 301 The rise/fall times of the control signal traces 300 are in a similar order (such as about 100 nanoseconds or less).

4 illustrates test results of an example prior art microwave transmitter control circuit. Trace 400 shows operation with a relatively high pulsed control voltage applied to the magnetron, and second trace 401 shows the performance of the resulting output current or power of the magnetron. The rise and fall times for the control voltage trace 400 are about 4 milliseconds.

The traces 300 and 301 provided in FIG. 3 are shown at a much finer horizontal resolution than the traces 400 and 401 of FIG. 4, but the vertical resolution is about the same. If traces 300 and 301 of Figure 3 were presented at the horizontal resolution of Figure 4, the initial rise/fall transition spikes of the output current or power trace 301 of the microwave energy source would not be visible. In effect, the output current or power trace 301 will appear as a near-perfect square wave, such as without significant rise/fall times, spikes or ringing. In contrast, however, the prior art output current or power trace 401 exhibits significant response lag 402 and noticeable ringing. Additionally, the prior art control voltage trace 400 exhibits significant ringing. In contrast, the control signal trace 300 for the microwave energy source of an embodiment of the present invention has little visible ringing, even at the much finer horizontal resolution of FIG. 3 .

FIG. 5 shows an example schematic diagram 500 that may be one example of the microwave transmitter control circuit 140 of FIG. 1B in accordance with some embodiments. Microwave transmitter control circuit 500 is shown including microwave energy source 141 , high voltage control circuit 142 , filament control circuit 143 , voltage input 501 , power supply circuit 502 and pulse generator 503, as well as other possible circuit components not described below or shown in this schematic diagram for simplicity. The high voltage control circuit 142 generally includes a high voltage controller 504, a high voltage power supply (HVPS) transformer 505, a voltage doubler 506, and a pulse switch 507, as well as other possible circuit components described below or not shown for simplicity. Filament control circuit 143 generally includes optional filament controller 508 and filament isolation transformer 509, among other possible circuit components not shown for simplicity. Other embodiments may include other components or configurations of components to achieve similar results in the operation of microwave energy source 141 (such as a microprocessor may be used in place of high voltage controller 504 to control the waveform provided to pulse switch 507).

Microwave transmitter control circuit 500 receives an appropriate input AC voltage (such as 120 volts AC) at voltage input 501 via voltage line L, neutral N, and ground G (such as ground potential). The main control switch 510 is connected to the voltage line L to control turning on and off the input AC voltage to the microwave transmitter control circuit 500 . The main control switch 510 provides the input AC voltage from the voltage line L to the power supply circuit 502 . Main control switch 510 provides input AC voltage from voltage line L via additional control switches such as high voltage control switch 511, filament control switch 512, pump/fan control switch 513. When the control switches 510 , 511 , 512 and 513 are closed, the AC voltage from the voltage line L is supplied to the high voltage controller 504 , the filament control circuit 143 and the cooling pump or fan 514 . The neutral potential N is directly applied to the high voltage controller 504 , the HVPS transformer 505 , the power supply circuit 502 and the filament control circuit 143 .

High voltage controller 504 generally includes transformer 515, relay 516, relay controller 517, and potentiometer 518, among other possible circuit components not shown for simplicity. The high voltage controller 504 generally controls the voltage provided to the HVPS transformer 505 . To generate the voltage for the HVPS transformer 505, a relay 516, such as a solid state zero-crossing relay, receives the input AC voltage via the high voltage control switch 511 and, under the control of the relay controller 517, scales down or cuts the input AC voltage to the original waveform a percentage (such as 5% to 10% of a sine wave) to form a reduced or clipped Sinusoidal AC voltage. The reduced waveform can be as low as 0% and as high as 100% of the original waveform, but in some embodiments the actual duty cycle range generally depends on the properties of the HVPS transformer 505 and the voltage at which the microwave energy source 141 operates. The setting of potentiometer 518 determines the percentage of the original waveform of the input AC voltage across relay 516 . Transformer 515 receives the input AC voltage and neutral N to generate a voltage, such as 24 volts, to power relay controller 517 .

A HVPS transformer 505, such as a step-up transformer, receives the neutral N and clipped AC voltage. From this voltage, the HVPS transformer 505 produces an intermediate high voltage (such as from about zero volts to about 10,000 volts). The level of the mid-high voltage is based on the percentage of the original sine wave of the input AC voltage through relay 516 , which is adjusted by setting potentiometer 518 . The waveform of the intermediate high voltage is averaged by the HVPS transformer 505 .

As shown, voltage doubler 506 generally includes capacitor 519, capacitor 520, and diodes 521 and 522 connected to each other and to ground. Voltage doubler 506 receives the intermediate high voltage generated by HVPS transformer 505 and multiplies it to form a high voltage (such as about 3 to 15 kilovolts, depending on the output power requirements for microwave energy source 141). The high voltage passes through the high side resistor 523 to the high side input or high voltage connection point of the pulse switch 507 to be supplied to the microwave energy source 141 on a per pulse basis.

Power supply circuit 502 is any suitable AC-DC power converter that receives an input AC voltage, neutral N, and ground. The power supply circuit 502 generates a DC drive voltage (+out). Pulse generator 503 provides a signal to pulse switch 507 .

Pulse generator 503 is any suitable internal or external function generator capable of generating a variable pulse control signal. The pulse control signal is at the desired frequency and duty cycle mentioned above to generate microwave power at the pulse frequency, duty cycle, shape and output power level suitable for the particular application. In some embodiments, the pulse generator 503 is manually controlled by a computer, analog input, or by other suitable control techniques to set the frequency and duty cycle of the pulse control signal.

The pulse switch 507 is connected to the power supply circuit 502 to receive the DC drive voltage (+out), and to the pulse generator 503 to receive the pulse control signal. The pulse switch 507 is also connected to the high side resistor 523 to receive the high voltage provided by the voltage doubler 506 and is further connected to the ground path via the low side resistor 524 . Pulse switch 507 is any suitable switching device, and may include vacuum relays, power MOSFETs, IGBTs, or other switching components. For example, the HTS-GSM switching module series available from Behlke Power Electronics, Kronberg, Germany, or other suitable push-pull circuits can be used for pulse switch 507 .

The pulse switch 507 generally includes a high side bipolar active switch 525 and a low side bipolar active switch 526 and corresponding switch drivers (such as switch driver 527 and switch driver 528). In some embodiments, bipolar active switches are relatively sensitive semiconductor or vacuum tube switches with relatively consistent hysteresis to the switch point. In some embodiments, both bipolar active switch 525 and bipolar active switch 526 are connected in series between a high voltage connection and a ground connection, such as a high voltage conductor and a ground conductor. The pulsed high voltage output 144 is generated from the node between the bipolar active switches such that the bipolar active switch 525 provides a positive power supply to the microwave energy source 141 while the bipolar active switch 526 quickly shunts the power back to lower level.

The DC drive voltage (+out) powers switch drivers 527 and 528. Switch drivers 527 and 528 drive bipolar active switches 525 and 526, respectively. Bipolar active switches 525 and 526 are turned on and off according to the frequency and duty cycle of the pulse control signal received from pulse generator 503 . The high-side switch driver 527 generates a drive signal that is inverted compared to the drive signal of the low-side switch driver 528, so that the bipolar active switches 525 and 526 are activated and deactivated in a complementary manner. Diode 529 (connected from the high voltage side high voltage input to the pulsed high voltage output of pulse switch 507) and diode 530 (connected from the pulsed high voltage output to the low voltage side or ground connection via resistor 524) are pulse switches 507 provides electrical protection.

When bipolar active switch 525 is closed, bipolar active switch 526 is open, and a high voltage is rapidly applied to microwave energy source 141 as described above at a pulsed high voltage output such as pulsed high voltage output 144, so that the microwave energy source 141 begins to oscillate and generate microwave radiation. Applying a high voltage directly to the microwave energy source 141 induces a rapid rise in the current or power output of the microwave energy source 141 described above with respect to FIG. 3 (such as in the range of about 20 to 50 nanoseconds, or about 40 nanoseconds). value). Due to the corresponding adjustment of the high voltage level, the set potentiometer 518 will adjust the current or power output level.

When bipolar active switch 526 is closed, bipolar active switch 525 is open, and the pulsed high voltage output of pulse switch 507 is connected to the ground connection via resistor 524 directly to ground. In this way, the output voltage is quickly shunted to a low voltage level (as determined by resistor 524 and reactive component 531). The effect of this rapid shunting of the output voltage and its corresponding rapid cessation on the circulating electron cloud is referred to herein as the "stop technique." In some embodiments, the aforementioned "suspend technique" is implemented using reactive components 531 that introduce capacitive sinks (such as charge sinks) and/or inductive loads across resistors 524 . Alternatively, in some embodiments, reactive component 531 is placed directly across the outputs of bipolar active switches 525 and 526 . In some embodiments, a relatively small power supply component is used in addition to or instead of reactive component 531 to maintain the voltage at the node between bipolar active switches 525 and 526 at a brewing level.

The microwave energy source 141 still has potential power within it in the form of a circulating electron cloud as it generates microwaves. This latent power is shunted to a low level to rapidly terminate the circulating electron cloud, thereby causing a rapid dip response (such as in the range of about 20 to 50 nanoseconds) in the current or power output of the microwave energy source 141 described above with respect to FIG. 3 , or a value of about 40 nanoseconds). Thus, when the bipolar active switches 525 and 526 are repeatedly pulsed on and off to alternately connect the pulsed high voltage output back and forth between the high voltage connection and the relatively lower voltage level, the pulsed high voltage output A pulsed high voltage is generated at 144. That is, the pulsed voltage output is shunted to ground via the second bipolar active switch, the pulsed voltage output is The discovery could collapse the circulating electron cloud in the cavity of the magnetron ring, thus interrupting the generation of microwave energy. The pulsed high voltage has a frequency and duty cycle based on the frequency and duty cycle of the pulse control signal received from the pulse generator 503 .

Filament isolation transformer 509 provides power to the filaments of microwave energy source 141 . For embodiments without filament controller 508 , filament isolation transformer 509 is driven directly by the input AC voltage received from voltage input 501 . As described above, the output current or power level of microwave energy source 141 is dependent on or controlled by the high voltage (and its pulse frequency and pulse duty cycle) received through pulse switch 507 and the filament current . Therefore, without the filament controller 508, the output current or power level of the microwave energy source 141 is controlled only by the high voltage received through the pulse switch 507, since the filament current is constant. For implementations with filament controller 508 , the AC voltage applied to filament isolation transformer 509 may be regulated or controlled by filament controller 508 . In this case, filament controller 508 controls the amount of current or voltage to the filament of microwave energy source 141, thereby providing additional, relatively coarse control over the output current or power level of microwave energy source 141. Control of the filament current can shift the position of the "on" point 206 in FIG. 2 .

The electronic circuit includes a high voltage generator that generates a high voltage, a pulse generator and a pulse switch that generate a pulse control signal with frequency and duty cycle. Electronic circuits can be used with energy sources that generate energy at various frequencies, such as microwave energy sources. In implementations relating to microwave energy, the electronic circuit acts as a microwave transmitter control circuit for a microwave energy source that generates pulsed microwave radiation upon receiving a pulsed high voltage, and wherein the power level of the pulsed microwave radiation depends on Voltage level, frequency and duty cycle of pulsed high voltage. The pulse switch may have a first bipolar active switch, a second bipolar active switch, a high voltage connection, a ground connection, a pulse input, and a pulsed voltage output. The first bipolar active switch and the second bipolar active switch are connected in series between the high voltage connection and the ground connection. The high voltage connection is connected to the high voltage generator to receive the high voltage. The ground connection is connected to ground potential. pulsed voltage The output is connected between the first bipolar active switch and the second bipolar active switch. The pulse input is connected to the pulse generator to receive the pulse control signal. When the first bipolar active switch and the second bipolar active switch are repeatedly pulsed on and off to alternately connect the pulsed voltage output back and forth between the high voltage connection and the ground connection, at the pulsed voltage output Generates pulsed high voltage. The frequency and duty cycle of the pulsed high voltage are based on the frequency and duty cycle of the pulsed control signal.

The microwave transmitter control circuit includes a microwave energy source, a high voltage generator for generating high voltage, a pulse generator for generating a pulse control signal with frequency and duty cycle, and a pulse switch. The microwave energy source generates pulsed microwave radiation when receiving the pulsed high voltage, wherein the power level of the pulsed microwave radiation depends on the voltage level, frequency and duty cycle of the pulsed high voltage. The pulse switch has a first bipolar active switch, a second bipolar active switch, a high voltage connection, a ground connection, a pulse input and a pulsed voltage output. The first bipolar active switch and the second bipolar active switch are connected in series between the high voltage connection and the ground connection. The high voltage connection is connected to the high voltage generator to receive the high voltage. The ground connection is connected to ground potential. The pulsed voltage output is connected between the first bipolar active switch and the second bipolar active switch. The pulse input is connected to the pulse generator to receive the pulse control signal. When the first bipolar active switch and the second bipolar active switch are repeatedly pulsed on and off to alternately connect the pulsed voltage output back and forth between the high voltage connection and the ground connection, at the pulsed voltage output with 20 A pulsed high voltage is generated with rise and fall times of up to 50 nanoseconds. The frequency and duty cycle of the pulsed high voltage are based on the frequency and duty cycle of the pulsed control signal. When the pulsed microwave radiation is pulsed off, the microwave energy source is maintained at a non-zero voltage level below the oscillating region. The pulsed voltage output is shunted to ground potential via a second bipolar active switch, and the pulsed voltage output can collapse the circulating electron cloud.

The apparatus includes electronic circuits configured to generate high voltages with voltage levels and to generate pulsed control signals with frequency and duty cycle. The electronic circuit is also configured to generate a pulsed high voltage from a high voltage and a pulsed control signal by means of a pulse switch. The pulsed high voltage has voltage level, frequency and power In a cycle, the pulse switch has a first bipolar active switch, a second bipolar active switch, a high voltage connection, a ground connection, a pulse input and a pulsed voltage output, wherein the first bipolar active switch and the second bipolar active switch are connected in series Connected between the high voltage connection and the ground connection, the high voltage connection receives the high voltage, the ground connection is connected to the ground potential, the pulsed voltage output is connected between the first bipolar active switch and the second bipolar active switch, the pulse The input receives a pulsed control signal and when the first bipolar active switch and the second bipolar active switch are repeatedly pulsed on and off to alternately connect the pulsed voltage output back and forth between the high voltage connection and the ground connection A pulsed high voltage is generated at the pulsed voltage output. The electronic circuits are also configured to generate pulsed microwave radiation with a power level that depends on the voltage level, frequency and duty cycle.

The equipment includes an energy source, a high voltage generator to generate high voltage on the high voltage connection, a pulse generator to generate a pulse control signal with a pulse control frequency and a pulse control duty cycle, and a pulse switch. The energy source may be, for example, a microwave energy source. The energy source generates pulsed radiation (such as microwave radiation) when receiving a pulsed high voltage, wherein the power level of the pulsed radiation depends on the voltage level, frequency and duty cycle of the pulsed high voltage. The pulse switch has a first bipolar active switch, a second bipolar active switch, a high voltage connection, a ground connection, a pulse input and a pulsed voltage output. When the voltage at the high voltage connection transitions from the higher voltage to the lower voltage, the power level of the pulsed microwave radiation transitions from the higher power level to the lower power in the range of about 20 nanoseconds to about 50 nanoseconds level (such as a transition from a first power level to a second power level lower than the first power level).

FIG. 6 shows an optional rise time adjustment network 600 for tuning the rise and fall times of the pulsed high voltage output 144 for applications of the microwave transmitter control circuit 140 with, for example, requiring some additional rise time reactors or chemicals. Rise time adjustment network 600 generally includes a parallel arrangement of inductor 601 , resistor 602 and series diode/resistor ( 603 / 604 ), which slows the rise and fall times of pulsed high voltage output 144 . Therefore, the rise time Adjustment network 600 may be placed between pulse switch 507 and the microwave energy source to create a more controllable slope in the transition of the square wave of control signal trace 300 in order to smooth or reduce spikes or ringing, and in Curves are formed in the transitions of the output current or power trace 301 shown in FIG. 3 . In this manner, rise time adjustment network 600 smoothes ringing, or provides a controlled rise time in output current or power trace 301 to smooth or otherwise shape the overall waveform.

7A shows an illustrative flowchart depicting example operations 700A of a method for generating pulsed microwave radiation. In some implementations, operation 700A can be an example of one or more of the operations that can be performed by any one or more of the circuits disclosed herein, such as microwave transmitter control circuit 140 shown generally as including FIG. 5 Microwave energy source 141 presented in . At block 702A, the microwave transmitter control circuit 140 may apply a high voltage having a voltage level. At block 704A, the microwave transmitter control circuit 140 may generate a pulsed control signal having a frequency and duty cycle. At block 706A, the microwave transmitter control circuit 140 may generate a pulsed high voltage from the high voltage and the pulsed control signal by pulsing the switch. At block 708A, the microwave transmitter control circuit 140 may connect the first bipolar active switch and the second bipolar active switch in series between the high voltage connection and the ground connection. At block 710A, the microwave transmitter control circuit 140 may connect a pulsed voltage output between the first bipolar active switch and the second bipolar active switch, where the pulsed input receives a pulsed control signal. At block 712A, the microwave transmitter control circuit 140 may generate pulsed microwave radiation with a power level that depends on the voltage level, frequency, and duty cycle.

7B shows an illustrative flowchart depicting example operations 700B of a method for alternately connecting a pulsed voltage output between a high voltage connection and a ground connection. In some implementations, operation 700B may be part of operation 700A and/or an instance of one or more of the operations performed by any one or more of the circuits disclosed herein, such as microwave transmitter control circuit 140 in general Shown above as including the microwave energy source 141 presented in FIG. 5 . At block 702B, the microwave transmitter control circuit 140 receives pulses when the pulsed voltage output is connected between the first bipolar active switch and the second bipolar active switch control signal. At block 704B, the microwave transmitter control circuit 140 generates a pulsed high voltage at the pulsed voltage output. At block 706B, the microwave transmitter control circuit 140 repeatedly pulses the first bipolar active switch and the second bipolar active switch on and off. At block 708B, the microwave transmitter control circuit 140 alternately connects the pulsed voltage output between the high voltage connection and the ground connection.

Microwave Chemical Processing System

Microwave transmitter control circuit 140 is generally shown to include microwave energy source 141 presented in FIG. 5, which may be coupled with any one or more of the waveguides and/or reactor systems disclosed herein for control throughout the waveguide Pulsed and/or propagated microwave energy to output the carbonaceous powder. With regard to waveguide and/or reactor systems, microwave plasma can be generated in the supply gas and/or process material, and the energy in the plasma is sufficient to form separate components from the process material molecules. A microwave energy source is coupled to the FEWG, plasma is generated along the plasma region of the FEWG, and process materials are separated into components by the plasma along the reaction length in the FEWG. As in conventional methods, the microwave energy is coupled directly into the plasma without coupling through the dielectric walls. The microwave plasma can be generated in the supply gas and/or process material, and the energy in the plasma is sufficient to form separate components from the molecules of the process material. A microwave energy source is coupled to the FEWG, plasma is generated along the plasma region of the FEWG, and process materials are separated into components by the plasma along the reaction length in the FEWG. As in conventional methods, the microwave energy is coupled directly into the plasma without coupling through the dielectric walls.

FIG. 8A illustrates a conventional microwave chemical processing system 800 . As shown, microwave chemical processing system 800 generally includes a reaction chamber 801, one or more gas inlets 802 configured to receive process material 808 flowing into the reaction chamber, and configured to collect gas from the reaction chamber One or more outlets 803 for the separated product of 801, and a microwave energy source 804 coupled to the reaction chamber via a waveguide 805, and other elements not shown for simplicity. Microwave energy 809 generates microwave plasma 806 in reaction chamber 801 and provides energy for the reaction to occur. Microwave transmitter circuit 807 can control microwave energy 809 emitted from microwave energy source 804 as continuous wave or pulsed microwave energy. Given the correct conditions, the plasma The energy in it will be sufficient to form separate components from the molecules of the process material.

Microwave Chemical Processing Reactor with Field Enhanced Waveguide (FEWG)

As shown in Figure 8B, the widest dimension of the waveguide is referred to as the "a" dimension and determines the range of operating frequencies. The narrowest dimension determines the power handling capability of the waveguide and is referred to as the "b" dimension. The FEWGs of the present disclosure efficiently transfer microwave frequency electromagnetic energy. The FEWGs of the present disclosure are composed of conductive materials and can be rectangular, circular, or oval in cross-section.

8C shows an example of a field enhancement region of a FEWG where the widest dimension "a" remains constant to efficiently transmit microwave energy at selected frequencies, and the narrower dimension "b" is reduced along the length of the FEWG to concentrate the microwave energy density. Figure 8C depicts a linear decrease in dimension "b"; however, the decrease in dimension "b" may be non-linear (such as parabolic, hyperbolic, etc.) with different rates of decrease along the length (such as linear decrease, a region Linear in one segment and nonlinear in another segment), or include abrupt steps that reduce the length of dimension "b". The disclosed arrangements or implementations are applicable to both standing wave systems (in which the peaks remain at the same location) and traveling wave systems (in which the peaks can move).

9 shows a reactor system 900 in which the FEWG is coupled to a microwave energy generator (such as a microwave energy source), plasma is generated from a supply gas in the plasma region of the FEWG, and the reaction length of the FEWG acts as a reaction region to transfer process materials separated into separate components. 10 shows another reactor system 1000 in which the FEWG is coupled to a microwave energy generator (such as a microwave energy source), plasma is generated from a supply gas in the plasma region of the FEWG, and the reaction length of the FEWG acts as the reaction region to Process materials are separated into separate components. The reactor system 900 of Figure 9 and the reactor system 1000 of Figure 10, respectively, do not have a dielectric barrier between the field enhancement region and the reaction region of the field enhancement waveguide. In contrast, the reaction zone of the conventional system is enclosed within a dielectric barrier such as a quartz chamber as explained previously. The propagation direction of the microwave energy flows parallel to the bulk of the supply gas and/or process material, and the microwave energy enters the waveguide upstream of the portion of the FEWG that produces the separated components.

As shown in FIG. 9, reactor system 900 includes FEWG 905, one or more inlets 902 configured to receive supply gas and/or process material 908a flowing into FEWG 905, and microwave energy coupled to FEWG 905 Source 904, and other elements not shown for simplicity. Microwave circuit 907 , which may be equivalent or similar to microwave transmitter control circuit 140 , is shown generally to include microwave energy source 141 presented in FIG. 5 that controls the pulse frequency at which microwave energy 909 from microwave energy source 904 is pulsed. The microwave energy 909 from the microwave energy source 904 is a continuous wave.

FEWG 905 has length L. The portion of the _FEWG 905 having length LA (shown in Figures 9 and 10) is closer to the microwave energy generator than the portion of the _FEWG having length LB (shown in Figures 9 and 10). Throughout this disclosure, different parts of the FEWG will be described by a capital letter L with a subscript (such as L _A , L ₀ , L _B , L ₁ , L ₂ ) denoting a certain part of the FEWG, and synonymously, The lengths of different parts of the FEWG will also be described by a subscripted capital letter L (such as L _A , L ₀ , LB , L ₁ , L _{2 )} representing the length of a certain part of the FEWG.

The cross-sectional area of the _FEWG in the length LB is less than the cross-sectional area of the _FEWG in the length LA. The length of _{FEWG L 0} lies between the lengths LA and LB of the FEWG and has a reduced cross-sectional area along the path of microwave energy propagation. The cross-sectional area of the FEWG along the length L ₀ may decrease in a continuous manner. _The cross _- sectional area of the _FEWG along length Lo decreases linearly between lengths LA and LB. The cross-sectional area of the _FEWG along length L ₀ may decrease non _- linearly, such as parabolically, hyperbolically, exponentially, or logarithmically, between lengths LA and LB. The cross-sectional area of the _FEWG along length _{L 0} decreases in a sharp manner between lengths LA and LB, such as through one or more discrete steps.

The cross-sectional area is reduced to concentrate the electric field, thus increasing the microwave energy density, while still providing a large area in which plasma can be formed compared to conventional systems. When using a microwave energy frequency of 2.45 GHz, the portion of the _FEWG having length LB (shown in Figures 9 and 10) may have a rectangular cross-section measuring 0.75 inches by 3.4 inches. This cross-sectional area is much larger than conventional systems where the plasma generation area is substantially less than one square inch. The different parts of the FEWG 905 are sized according to the microwave frequency in order to function properly as a waveguide. For example, for elliptical waveguides, for 2.1 to 2.7 GHz, the cross-sectional dimensions may be 5.02 inches by 2.83 inches.

In conventional gas processing systems, a limited area, such as less than one square inch, from which a plasma can form, confines the volume in which gas reactions can occur, such as described above. Also, in conventional systems, microwave energy enters the reaction chamber through a window (usually quartz). In these systems, a dielectric material, such as particulate carbon, is coated on the window during processing, resulting in reduced power delivery over time. This can be highly problematic if these separated components absorb microwave energy because it prevents the coupling of microwave energy into the reaction chamber to generate plasma.

As a result, a rapid build-up of by-products such as carbon particles from gaseous reactions occurs and limits the operating time of the processing equipment. Microwave chemical processing reactor 900 can be designed without the use of windows in the reaction zone; that is, a parallel propagation/gas flow system using energy entering upstream from the reaction. As a result, more energy and power can be coupled into the plasma from the microwave energy source. Compared to the limited reaction chamber volume in conventional systems, the lack of windows and larger volume in the waveguide greatly reduces the particle build-up problem that causes limited run time, thus improving the productivity of the microwave processing system.

Microwave energy 909 in FIG. 9 produces microwave plasma 906 in the supply gas and/or process materials in the plasma region of length L ₁ (shown in FIGS. 9 and 10 ) of the length of FEWG 905 . _A plasma region of length _{L 1} is located within the portion of FEWG LB where the cross-sectional area is smaller and the microwave energy density is higher than the length LA . Supply gases other than process materials are used to generate microwave plasma 906 . The supply gas can be, for example, hydrogen, helium, a noble gas such as argon, or a mixture of more than one type of gas. The supply gas can be the same as the process material, where the process material is the material from which the separate components are generated.

The supply gas and/or process material inlet 902 may be located upstream of the portion of _FEWG LB, or within the portion of _FEWG LO, or within the portion of _FEWG LA, or upstream of the portion of _FEWG LA. _The portion of FEWG L1 extends from the location of the supply gas and/or process material 908a downstream from the location where the supply gas and/or process material 908a enters the FEWG along the location of the FEWG to the end of the FEWG, or to the point between the inlet of the supply gas and/or process material and the end of the FEWG 905. Location. _A portion of FEWG L1 extends from where the supply gas and/or process material 908a enters the FEWG to the end of the FEWG, or to a location between the inlet of the supply gas and/or process material and the end of the FEWG.

The generated plasma 906 provides energy for reaction to take place in the process material 908b within the reaction zone 901 of the _FEWG 905 having a reaction length L2. Reaction zone L2 extends from the point where process material 908a enters _FEWG 905 to the end of FEWG 905, or to a position between the inlet of the process material and the end of FEWG 905. Given the correct conditions, the energy in the plasma 906 will be sufficient to form separate components from the molecules of the process material. One or more outlets 903 are configured to collect the separated product from the FEWG 905 downstream of the portion of the reaction zone of the FEWG where the reaction takes place in the process material 908b. In the example shown in Figure 9, the propagation direction of microwave energy 909 is parallel to most of the supply gas and/or process material flow 908b, and the microwave energy 909 enters the FEWG 905 upstream of the reaction zone 901 of the FEWG that produces the separated components .

The pressure barrier 910 transparent to microwave energy can be located within the microwave energy source 904 near the outlet of the microwave energy source, or at other locations between the microwave energy source 904 and the plasma 906 produced in the FEWG. This pressure barrier 910 can act as a safety measure to prevent potential backflow of plasma into the microwave energy source 904 . The plasma does not form at the pressure barrier itself; in fact, the pressure barrier is merely a mechanical barrier. Some examples of materials from which pressure barriers can be made are quartz, ethylene tetrafluoroethylene (ETFE), other plastics, or ceramics. There may be two pressure barriers 910 and 911, one or both of which are located within the microwave energy source 904 near the outlet of the microwave energy source, or between the microwave energy source 904 and the plasma 906 produced in the FEWG. other locations in the room. The pressure barrier 911 may be closer to the plasma 906 in the FEWG than the pressure barrier 910, and in the event that the pressure barrier 911 fails, the pressure barriers 910 and 911 There is a pressure blow-out port 912 therebetween.

A plasma backstop (not shown) may be included in the system to prevent the propagation of plasma to the microwave energy source 904 or the supply gas and/or process material inlet 902 . The plasma backstop can be a ceramic or metal filter with holes to allow microwave energy to pass through the plasma backstop but prevent most plasma species from passing through. Most of the plasma species will not be able to pass through the plasma backstop because the hole will have a high aspect ratio and the plasma species will recombine when hitting the side walls of the hole. The plasma backstop is located between sections L ₀ and L ₁ , or upstream of section L ₁ and section L ₀ downstream of inlet 902 (in embodiments where inlet 902 is within section L ₀ ) and microwave energy source 904 Inside.

Referring again to FIG. 10, the reactor system 1000 generally includes a FEWG 1005, one or more supply gas inlets 1002 configured to receive a supply gas 1008a flowing into the FEWG 1005, one or more of the process materials 1011a configured to receive, or A plurality of process material inlets 1010, and a microwave energy source 1004 coupled to the FEWG 1005, and other elements not shown for simplicity. The location of the process material inlet 1010 is downstream of the location of the supply gas inlet 1002, where downstream is defined in the direction of microwave energy propagation.

Microwave circuit 1007 can control the pulse frequency at which microwave energy 1009 from microwave energy source 1004 is pulsed. The microwave energy from microwave energy source 1004 may be a continuous wave. Similar to the embodiment shown in FIG. 9, the _FEWG 1005 in FIG. ₁₀ has portions LA, _L0 , LB, L1, L2, wherein portion _LB has _a cross _- sectional area less than the cross _- sectional area of LA , portion L ₀ has a reduced cross-sectional area between portions LA and _{LB, L 1 is the portion that generates the plasma, and L 2 is the portion} that is the reaction zone.

Microwave energy 1009 produces microwave plasma 1006 in supply gas _1008b within plasma region L1 of length L of FEWG 1005. Portion L1 may extend from the location _of the FEWG 1005 downstream from the location where the supply gas 1008a enters the FEWG 1005 to the end of the FEWG 1005, or to a location between the inlet of the supply gas and the end of the FEWG 1005. Portion L1 may extend from where the supply gas 1008a enters the _FEWG 1005 to the end of the FEWG 1005, or to a location between the inlet of the supply gas and the end of the FEWG 1005. One or more additional process material inlets 1010 are configured to receive process material flowing into the FEWG at a second set of locations downstream of the supply gas inlets 1002 . The generated plasma 1006 provides energy for the reaction to take place within the reaction zone 1001 of the FEWG 1005 having a reaction length L ₂ .

Portion L2 may extend from where the process material 1011a enters the _FEWG 1005 to the end of the FEWG 1005, or to a location between the entry of the process material and the end of the FEWG 1005. Given the correct conditions, the energy in the plasma will be sufficient to form separate components from the molecules of the process material. One or more outlets 1003 are configured to collect the separated product from the FEWG 1005 downstream of the portion 1001 where the reaction occurs. In the example system 1000 shown in Figure 10, the propagation direction of microwave energy 1009 is parallel to most of the supply gas stream 1008b and process material flow 1011b, and the microwave energy 1009 enters the FEWG upstream of the reactive portion 1001 of the FEWG that produces the separated components 1005.

One or more pressure barriers that are transparent to microwave energy can be located within microwave energy source 1004 near the outlet of the microwave energy source, or at other locations between microwave energy source 1004 and the plasma 1006 generated in the FEWG (similar to the above). described herein and depicted in Figure 9). There may be two pressure barriers, and in the case of failure of the barrier closer to the plasma 1006 in the FEWG, there may be a pressure blow-out port between the pressure barriers.

_The walls of the reaction zone L2 can be configured such that the supply gas inlet and the process material inlet pass through the walls of the FEWG to supply the reaction zone with the supply gas and process materials. For example, the wall may have a series of holes that act as secondary supply gas inlets through which supply gas and/or process material may be inserted into the FEWG, or the supply and/or process material may be permeable through the wall, or the wall may be porous of. Providing the supply gas and input material to the reaction zone through the walls can alleviate deposition of the separated components on the reaction zone walls by forming a reactive plasma close to the walls that etch away the deposited material.

There may be multiple supply gas and process inlets that provide supply gas and input materials to reaction zone L2 through the walls of the _FEWG . There may be multiple supply gas and process inlets configured to provide controlled mass fractions of supply gas and input materials to reaction zone L2 through the _FEWG walls. Introducing the supply gas and process materials into the FEWG at controlled mass fractions can more efficiently etch away any material deposited on the walls of the FEWG in the reaction zone.

As described above, a FEWG (such as 905 in FIG. 9 and 1005 in FIG. 10 ) has an overall length _L , _a portion of the overall length LA, and a portion LB, where the cross _- sectional area of LB is less than the cross _- sectional area of LA , the portion L ₁ along which the plasma is generated, and the portion L ₂ along which the process material is converted into the total length of the separated components. The total length L of the waveguide can be from 1 cm to 1000 cm. The length L ₀ of the waveguide can be from 1 cm to 100 cm. The length L1 of the waveguide can be from ₁ cm to 100 cm. The length L ₂ of the waveguide can be from 1 cm to 1000 cm. The length L of the waveguide can be from 30 cm to 60 cm. The length L ₀ of the waveguide can be from 10 cm to 40 cm. The length L1 _of the waveguide can be from 10 cm to 30 cm. The length L ₂ of the waveguide can be from 5 cm to 20 cm. For a microwave frequency of 2.45 GHz, the portion of the _FEWG length LA is from, for example, 0 inches to 10 inches, but the length can vary depending on the microwave frequency used. The portion of the _FEWG length LB is from, for example, 10 inches to 20 inches, which will depend on factors such as gas flow velocity and microwave power.

For example, higher gas flow rates will extend the length of the reaction zone. The length L ₁ is more than 10%, or more than 20%, or more than 30%, or more than 40%, or more than 50%, or more than 60%, or more than 70%, or more than 80%, or more than 10% of the length L of the waveguide to 90%, or from 20% to 80%, or from 30% to 70%, the length L ₂ is more than 5% of the length L of the waveguide, or more than 10%, or more than 15% or more than 20%, or more than 25% % or more than 30%, or more than 35%, or more than 40%, or more than 45%, or more than 50%, or more than 55%, or more than 60%, or from 1% to 90%, or from 1% to 70% %, or from 1% to 50%, or from 10% to 50%, or from 10% to 40%, or from 20% to 40%.

FEWG 905 and 1005 can be configured to maintain pressures from 0.1 atm to 10 atm, or from 0.5 atm to 10 atm, or from 0.9 atm to 10 atm, or greater than 0.1 atm, or greater than 0.5 atm, or greater than 0.9 atm. In many conventional systems, microwave chemical processing is operated under vacuum. However, in In embodiments of the invention where the plasma is generated within the FEWG, operating in a positive pressure environment helps prevent the generated plasma from feeding back into the microwave energy source, such as depicted in FIGS. 9 and 10 .

_FEWG 905 and 1005 may have a rectangular cross-section with dimensions of 0.75 inches by 3.4 inches within length LB to correspond to a microwave energy frequency of 2.45 GHz. For other microwave frequencies, other dimensions of _LB are possible, and depending on the waveguide mode, these cross-sectional dimensions can be from 3 to 6 inches. _FEWG 905 and 1005 may have a rectangular cross-section within length LA with dimensions of 1.7 inches by 3.4 inches to correspond, for example, to a microwave energy frequency of 2.45 GHz. Other dimensions of LA are possible for other microwave frequencies _. FEWG 905 and 1005 can be made of any inherently conductive material or material with a sufficiently conductive coating to transmit greater than 90% of the incoming power. Some examples of FEWG materials are metallic materials, metallic materials with conductive coatings, ceramic materials, ceramic materials with conductive coatings, stainless steel, stainless steel coated with conductive layers such as Al, Ni, Au or Ni/Au alloys , Stainless steel with aluminum lining, or ceramic material coated with conductive layer.

Notably, FEWGs 905 and 1005 can act as chambers where plasma is generated and process material reactions occur, rather than having separate waveguide and quartz reaction chambers as in conventional systems. Having FEWGs 905 and 1005 serve as reactor chambers provides much larger volumes (such as up to 1000 L) in which gaseous reactions can take place. This enables the handling of high flow rates of process materials, but is not limited by the build-up of carbon particles as occurs in conventional systems. For example, process material flow rates through inlets 902 and 1010 into respective FEWGs 905, 1005 may be from 1 slm (standard liters per minute) to 1000 slm, or from 2 slm to 1000 slm, or from 5 slm to 1000 slm, or greater than 1 slm, or greater than 2slm, or greater than 5slm. The supply gas flow rate through inlets 902 and 1002 into respective FEWGs 905 and 1005 may be, for example, from 1 slm to 1000 slm, or from 2 slm to 1000 slm, or from 5 slm to 1000 slm, or greater than 1 slm, or greater than 2 slm, or greater than 5 slm . The flow rate can be from 1 slm to 1000 slm and the pressure up to 14 atm, depending on the plasma properties of the gas resulting in sufficient plasma density, such as secondary electron emission coefficient.

Process materials (alternatively referred to as raw materials) may be liquids provided into the FEWGs 905 and 1005 through the process material inlets. Some examples of liquids that can be used as process materials are water, alkanes, alkenes, alkynes, aromatic hydrocarbons, saturated and unsaturated hydrocarbons (such as alkanes, alkenes, alkynes or aromatic hydrocarbons), ethanol, methanol, isopropyl Alcohol (such as isopropanol) or a mixture thereof (such as a 50/50 mixture of ethanol/methanol). The liquid process materials listed above can produce separate components of carbon and hydrogen. The flow rate of the liquid can be a percentage of the supply gas flow entering the reactor, such as from 0.001% to 1000%, or from 0.001% to 100%, or from 0.001% to 10%, or from 0.001% to 1%, or from 0.001% to 0.1%, or from 0.01% to 1000%, or from 0.01% to 100%, or from 0.01% to 10%, or from 0.01% to 1%, or from 0.01% to 0.1%.

The process material can be a colloidal dispersion (such as a mixture of solid particles suspended in a liquid or gas) that is provided into the FEWG 905 and 1005 through the process material inlet. For example, the colloidal dispersion may include carbon-containing particles. Some examples of colloidal dispersions that can be used as process materials are solids from Group 16, Group 14, Group 10, Group 9, Group 5, Group 2, Group 1 mixed with a liquid or gas Particles, their alloys and their mixtures. The solid particles listed above may be mixed with liquids such as water, alkanes, alkenes, alkynes, aromatic hydrocarbons, saturated and unsaturated hydrocarbons (such as alkanes, alkenes, alkynes or aromatic hydrocarbons), ethanol, methanol, Isopropanol or a mixture thereof (such as a 50/50 mixture of ethanol/methanol).

Examples of gases are Groups 1 and 15-18, and inorganic compounds such as Group 14 hydrides. Some examples of isolated components that can result from the colloidal dispersion process materials listed above are solid inorganic materials (such as graphene-coated silicon) coated with organic materials, and those with interlayers of organic/inorganic materials. Composite materials (such as silicon cores with carbon layers encapsulating silicon coated with additional inorganic layers). The flow rate of the colloidal dispersion can be a percentage of the supply gas flow entering the reactor, such as from 0.001% to 1000%, or from 0.001% to 100%, or from 0.001% to 10%, or from 0.001% to 1% , or from 0.001% to 0.1%, or from 0.01% to 1000%, or from 0.01% to 100%, or from 0.01% to 10%, Or from 0.01% to 1%, or from 0.01% to 0.1%.

The process material can be a gas. Process materials may be hydrocarbon _gases such as _C2H2 , _{C2H4 , C2H6 .} The process material can be methane, and the separated components are hydrogen and nanoparticle carbon. The process material may be carbon dioxide with water, and the separated components are oxygen, carbon and water. _The process material is H2S, and the separated components may include hydrogen and sulfur. Process materials do not contain carbon dioxide. Process materials may be gas-based composites such as _SiH4 , trimethylaluminum (TMA), trimethylgallium (TMG), glycidyl methacrylate (GMA), _SF6 , and in the semiconductor industry for deposition and other materials for etching metals and dielectrics.

One of the isolated components is nanoparticulate carbon such as, but not limited to, carbon black, carbon nanoonion (CNO), necked CNO, carbon nanospheres, graphite, pyrolytic graphite, graphene, graphene nanospheres Rice particles, graphene sheets, fullerenes, hybrid fullerenes, single-wall nanotubes, and multi-wall nanotubes. One or more of these nanoparticulate carbons may be produced during a particular process run. The isolated components may comprise agglomerated nanoparticulate carbon, which may also be described as aggregated particles. In some cases, the agglomerated or aggregated particles comprise many nanoparticulate carbon particles. Agglomerated or aggregated particles may comprise nanoparticulate carbon particles and have an average diameter greater than 50 microns, or greater than 100 microns, or greater than 200 microns, or greater than 300 microns, or greater than 500 microns, or greater than 1000 microns, or from 1 to 1000 microns, or from 10 microns to 1000 microns, or from 100 microns to 1000 microns, or from 100 microns to 500 microns.

Tuning Microwave Energy in Microwave Chemical Processing Systems

Different process materials require different amounts of energy to react into different discrete components. In the present disclosure, the available reaction paths can be selected by changing the average energy of the plasma. The microwave energy coupled to the plasma can be pulsed, and the average energy of the plasma, and thus the reaction path, is selected by controlling the microwave energy pulse duration and frequency, duty cycle, shape, and time-averaged output power level. Additional details of tuning microwave energy in microwave chemical processing systems are disclosed in US Patent 9,812,295, which is owned by the assignee of the present application and is incorporated herein by reference in its entirety.

The average energy in the plasma can be controlled by varying the pulse period, by selecting the pulse frequency to achieve the desired plasma energy. In addition, the average energy of the plasma can be controlled by controlling the duty cycle. This can be understood by considering the case where both the time-averaged input power and the pulse period are kept constant and the duty cycle varies. Shorter duty cycles will increase the amount of power coupled into the chamber when the microwave energy is turned on. This is advantageous because a relatively low amount of power, such as time-averaged power, can be used to generate reaction products from the reaction path, it would not be possible to promote this generation at the same power in a continuous wave.

The reaction path can be selected by controlling the time-averaged power input into the plasma. For example, if the duty cycle and pulse frequency are kept constant and the power input to the microwave generator is increased, the energy of the plasma will increase. By way of another example, if the duty cycle and pulse frequency are kept constant, and the power is more efficiently coupled into the reaction chamber, the energy of the plasma will increase.

The reaction path can be selected by controlling the shape of the microwave energy pulse. The microwave pulses may be rectangular waves, where the power is constant for the duration of the pulse period when the microwaves are on. When the microwave power is on, the pulse power may not be constant during the duration of the pulse period. Microwave pulses are triangular waves, or trapezoidal waves, or different wave profiles. Plasma may be referred to as diffusing during periods of time in which high energy species are present in higher fractions, such as at the beginning of a pulse before the plasma reaches equilibrium. The microwave energy can increase over the time period of plasma diffusion, which increases the time-averaged fraction of high energy species in the plasma. As described above, tuning the pulse frequency, duty cycle, and pulse shape can enable the generation of a higher fraction of higher energy species within the plasma for a given time-averaged input power. Higher energy species may allow additional reaction pathways that would otherwise be energetically disadvantaged.

The above techniques can be further understood by using methane ( _CH4 ) as an example process material to be separated into hydrogen and nanoparticulate carbon. Typically, 4 to 6 eV is required to dissociate methane (CH ₄ ); however, the plasma energy typically stabilizes at about 1.5 eV after the initial ignition energy spike. By pulsing the microwaves, the average plasma energy, such as the time-averaged plasma energy, is maintained at a higher level, where the frequency and duration of the pulses control the average plasma energy. In particular, pulse parameters such as frequency and duty cycle can be controlled to provide an average plasma energy of 4 to 6 eV to select specific dissociation reactions of methane. Another advantage of pulsing microwave energy is that the energy is more distributed in the chamber into which the microwaves are input.

In conventional systems, at equilibrium, the plasma forms a dense layer of ionized species in the chamber towards the location of the microwave input, which absorbs incoming microwave energy and thus prevents other microwave energy from penetrating deeper into the chamber. The high frequency pulses of the present disclosure maintain the plasma in a non-equilibrium state for a larger time fraction and a dense layer of ionized species exists for a smaller time fraction, which allows the microwave energy to penetrate deeper into the chamber and the plasma Produced in a larger volume within the chamber. More generally, in various embodiments of the present disclosure, the average energy of the plasma over the entire duration of the pulse period may be from 0.9 eV to 20 eV, or from 0.9 eV to 10 eV, or from 1.5 eV to 20 eV , or from 1.5eV to 10eV, or greater than 0.9eV, or greater than 1.5eV. The particular value to which the plasma energy is tuned will depend on the type of process material being utilized.

In the microwave processing system described above, the microwave energy source is controlled by a microwave transmitter circuit (such as 907 in FIG. 9 and 1007 in FIG. 10 ), which can control the microwave energy emitted from the source as Continuous wave or pulsed microwave energy. Microwave transmitter circuits can generate microwave energy via the use of magnetrons, such as at 915MHz, 2.45GHz, or 5.8GHz. In order to control the pulsed output power of the microwave energy, the microwave transmitter circuit can pulse the magnetron at various frequencies and duty cycles. Each microwave transmitter circuit is designed for a specific range of pulse frequencies, duty cycles, shapes, and pulse output power levels, wherein the selection of specific values for these parameters is used to tune the chemical reaction paths in the process materials.

The microwave control circuit can realize the pulse frequency from 500Hz to 1000kHz, or from 1kHz to 1000kHz, or from 10kHz to 1000kHz, or from 40kHz to 80kHz, or from 60kHz to 70kHz, or more than 10kHz, or more than 50kHz, or more than 100kHz. The microwave emission source can be from 1 to 100kW, or from 1kW to 500kW, or from 1kW to 1MW, or from 10kW to 5 MW, or greater than 10kW, or greater than 100kW, or greater than 500kW, or greater than 1MW, or greater than 2MW of time-averaged power to transmit continuous wave or pulsed microwave energy. The pulse period has a first duration in which the microwave power is on, and a second duration in which the microwave energy is off or at a lower power than during the first duration. The second duration may be longer than the first duration. The optimal duty cycle for a given system depends on many factors, including microwave power, pulse frequency, and pulse shape. The duty cycle (fraction of the pulse period such as microwave energy on, expressed as a percentage) can be from 1% to 99%, or from 1% to 95%, or from 10% to 95%, or from 20% to 80% %, or from 50% to 95%, or from 1% to 50%, or from 1% to 40%, or from 1% to 30%, or from 1% to 20%, or from 1% to 10%, or less than 99%, or less than 95%, or less than 80%, or less than 60%, or less than 50%, or less than 40%, or less than 30%, or less than 20%, or less than 10%.

Microwave Chemical Processing Reactor with Multiple Field Enhanced Waveguides

11A-11D show block diagrams representing embodiments of microwave chemical processing systems of the present disclosure in which multiple FEWGs are coupled to one or more microwave energy generators, such as microwave energy sources. The FEWGs in these embodiments may share some or all of the features of the systems described above. Supply gas and process material inputs in these embodiments may also share some or all of the features described above. Each FEWG may have a reaction zone. Plasma can be generated from a supply gas in a plasma region in each of the FEWGs, and the reaction length of each of the FEWGs acts as a reaction region to separate process materials into separate components. The reaction zones can be connected together, and the microwave chemical processing system has one outlet for the separated components. The reaction zones can be connected together and the microwave chemical processing system has more than one outlet for the separated components. Each reaction zone may have its own outlet for the separated components.

Figure 11A shows an embodiment in which there is one microwave energy generator 1101 coupled to one of multiple FEWGs 1102, and the reaction zones of the FEWGs are all connected together such that there is a single outlet 1103 that collects the separated components. FIG. 11B shows the presence of a microwave energy generator coupled to one of the FEWGs 1102 1101, and embodiments where the reaction zones of some FEWGs are connected together such that there is more than one outlet 1103 to collect the separated components. 11C shows an embodiment where there is more than one microwave energy generator 1101 coupled to multiple FEWGs 1102, and the reaction zones of the FEWGs are all connected together such that there is a single outlet 1103 that collects the separated components. Figure 1 ID shows an embodiment where there is more than one microwave energy generator 1101 coupled to multiple FEWGs 1102, and the reaction zones of some FEWGs are connected together such that there is more than one outlet 1103 that collects the separated components.

11A-11D depict 6 FEWGs for illustrative purposes, but may be less or more than 6 FEWGs in an actual implementation. For example, there may be 1 to 10 FEWGs coupled to each microwave energy generator. Microwave energy from more than one microwave generator can be combined using a power combiner, and then the combined microwave energy can be coupled into more than one FEWG. The microwave energy emitted from this power combiner can be very large and can be coupled into many FEWGs (such as more than 10). Multiplexing can be used to couple microwave energy into multiple FEWGs from a single microwave energy source.

In one example, multiplexing is time division multiplexing, which means that energy is coupled from a microwave energy source into a set of FEWGs at one time, and switches are used to direct energy into a different set of FEWGs at a later time. The switch may be used to cycle energy over time between sets of FEWGs (such as more than 2, or more than 5, or more than 10) from a single microwave energy source, where each set of FEWGs may contain multiple FEWGs (such as more than 2 , or more than 5, or from 1 to 10). Figure 11B depicts two outlets, and Figure 11D depicts three outlets, but there may be more than two or three outlets in other FEWG array configurations, where, for example, each FEWG may have its own collection of separated components the export. There are 1 to 10 outlets for collecting the separated components. 11B and 11D depict 3 FEWGs connected to each outlet, but fewer or more than 3 FEWGs may be connected to each outlet, and each FEWG may have its own outlet that collects the separated components. 11C and 11D depict two microwave energy generators, but there are more than two microwave energy generators. There may be 1 of each outlet connected together to collect the separated components FEWG to 10 FEWG.

12A and 12B show embodiments of the microwave chemical processing system of the present disclosure in which FEWGs are coupled to a microwave energy generator (such as a microwave energy source) using different geometries. The FEWGs in these embodiments may share some or all of the features of the systems described above. Supply gas and process material inputs in these embodiments may also share some or all of the features described above. Each FEWG may have a reaction zone. Plasma can be generated from a supply gas in a plasma region in each of the FEWGs, and the reaction length of each of the FEWGs acts as a reaction region to separate process materials into separate components. The reaction zones can be connected together, and the microwave chemical processing system has one outlet for the separated components. The reaction zones can be connected together and the microwave chemical processing system has more than one outlet for the separated components. Each reaction zone may have its own outlet for the separated components.

12A shows a manifold geometry in which there is a microwave energy generator coupled to one of the FEWGs. Microwave energy 1201 is coupled into manifold waveguide 1202, and then into multiple FEWGs. Microwave energy enters the larger cross-sectional area section of each FEWG, then enters the field enhancement region 1203 of the FEWG, and then couples into the smaller cross-sectional area reaction region 1204 of the FEWG. In the embodiment depicted in Figure 12A, all the FEWGs are connected together such that there is a single outlet 1205 that collects the separated components.

Figure 12B shows a network geometry with one microwave energy generator coupled to one of the FEWGs. Microwave energy 1201 is coupled into network waveguides 1202, and then into multiple FEWGs. The specific network waveguide size depends on the microwave frequency being used. Microwave energy enters the larger cross-sectional area section of each FEWG, then enters the field enhancement region 1203 of the FEWG, and then couples into the smaller cross-sectional area reaction region 1204 of the FEWG. In the implementation depicted in Figure 12B, all FEWGs are connected together such that there is a single outlet 1205 to collect the separated components.

Although Figures 12A and 12B depict a manifold or network geometry coupled to five One microwave energy generator for the FEWG, but in other implementations there may be other suitable numbers or instances of microwave energy generators. Microwave energy from more than one microwave generator can be combined using a power combiner, and then the combined microwave energy can be coupled into more than one FEWG in a manifold or network geometry. The microwave energy emitted from this power combiner can be extremely large and can be coupled into many FEWGs (such as more than 10) in a manifold or network geometry. There may be 1 to 10 FEWGs coupled to each microwave energy generator in a manifold or network geometry.

Similarly, although Figures 12A and 12B depict one outlet, in other implementations, other suitable numbers or instances of outlets may be present. There may be 1 to 10 outlets collecting the separated components from the FEWG coupled to the microwave energy generator in manifold or grid geometry. Similarly, although FIGS. 12A and 12B depict one microwave energy generator coupled to one of a plurality of FEWGs, in other implementations, other suitable numbers or instances of microwave energy generators may be present. There may be 1 FEWG to 10 FEWGs connected together in each outlet that collects the separated components from the FEWG coupled to the microwave energy generator in a manifold or network geometry.

In some implementations, there may be voids between the manifold or mesh geometry waveguide 1202 and the field enhancement region 1203 of the FEWG. The dimensions of these apertures are adapted to efficiently couple microwave energy from the manifold or mesh geometry waveguide 1202 to the field enhancement region 1203 of the FEWG. These apertures are sized differently to balance microwave energy transmission from the manifold or network geometry waveguides 1202 between all coupled field enhancement regions 1203 of the FEWG.

In some implementations, the dimensions of the manifold or mesh geometry waveguide 1202 can be adapted such that it forms a resonant cavity and a standing wave of microwave energy exists within the manifold or mesh geometry waveguide 1202. The standing wave of microwave energy can be tuned to efficiently couple microwave energy into each of the coupling field enhancement regions 1203 of the FEWG.

In some implementations, there may be waveguides 1202 from the manifold or mesh geometry to the FEWG Controlled leakage of the field enhancement regions 1203 to effectively distribute the amount of microwave energy coupled into each of the reaction regions 1204 of the FEWG. Some design examples for controlling leakage from the manifold or network geometry waveguides 1202 to the field enhancement regions 1203 of the FEWG and efficiently distributing the amount of microwave energy coupled into each of the reaction regions 1204 of the FEWG are: varying the waveguide cross section and/or length; use apertures between the manifold or mesh geometry waveguide 1202 and the field enhancement region 1203 of the FEWG; change the distance between the manifold or mesh geometry waveguide 1202 and the field enhancement region 1203 of the FEWG the angle of orientation; the use of filaments, point sources, electrodes, and/or magnets (as will be discussed in further detail below) within the manifold or network geometry waveguide or within the FEWG; and two or more of these design features combination.

Additional Features in Microwave Chemical Processing Reactors with Field Enhanced Waveguides

In addition to the above features of microwave processing systems with FEWGs, other features that may be used in the systems described above will now be discussed. 6 illustrates a microwave processing system with a FEWG in which a plasma is generated in one or more precursor gases inserted upstream of where the process material flows into the reaction zone of the FEWG. The precursor gas improves the cracking efficiency by adding species with various free potentials. That is, different gases have different ionization energies, which is the amount of energy required to remove electrons from atoms or molecules. In addition, various gases have different opposite (how many electrons can be generated per ion) and secondary electron emission properties (electron emission when charged particles bombard the surface). Thus, in the present disclosure, the use of precursor gases may be utilized to affect the energy of the plasma.

13 shows a microwave gas processing system 1300 including a microwave energy generator (such as a microwave energy source) 1304, a FEWG 1305, and a microwave transmitter circuit 1307, which may be similar or equivalent to generally shown including microwaves presented in FIG. 5 Microwave transmitter control circuit 140 of energy source 141 . For clarity, the drawing of FIG. 13 is a simplified drawing compared to the previous figures. Supply gas inlet 1302 receives supplemental supply gas (not shown) to generate a plasma precursor gas 1320 in the waveguide. In various embodiments, the precursor gas 1320 may include one or more of hydrogen, argon, helium, or various noble gases. Process material Inlet 1310 is configured to receive process materials to be reacted.

One or more of the separated components of the process material may be recycled back into the supply gas and/or process material entering the FEWG 1305. For precursor gases that are not the intended output product of the system (such as the argon precursor gas when processing methane), the precursor gases are removed from the separated components 1330 and 1332 output from outlet 1303 in a work-up step. As shown in Figure 13, the gaseous reaction in the FEWG 1305 produces separate components 1330 and 1332. For example, for methane as the process material, the first separated component 1330 may be carbon, and the second separated component 1332 may be _H2 gas (which is reconstituted from atomic hydrogen H+ before being collected at outlet 1303).

Alternatively, the first separated component 1330 may be _CH2 and the second separated component 1332 may be hydrogen _H2 . The separated components 1332 are recycled back into the FEWG 1305 via conduit 1340 returning to the supply gas inlet 1302. The recycled separated components 1332 are thus used as precursor gas 1320. Although returning the resulting separated components to the reaction system may seem abnormal, the recycling of these components adds energy to the plasma and can also aid in thermal cracking of process materials because the recycling The components have been heated during the gas treatment. For example, for a process that produces a total of 150 to 200 slm H ₂ , the separated component 1332 may be 2 to 10 slm H ₂ that is recycled back into the FEWG 1305. Other amounts or portions of the separated components 1332 may be recycled as determined by factors such as the flow rate of the process materials and/or the amount of energy that needs to be added to the process to initiate the target chemical pathway.

To initiate the aforementioned chemical pathways, one or more microwave energy sources can be configured to initiate chemical reactions within the microwave chemical treatment reactor.

Some or all of the supply gas contains one or more of the recycled separated components of the process material. For example, the supply gas can be hydrogen, and the process material can be methane that is reacted to form hydrogen and carbon, and at least a portion of the hydrogen produced from the methane can be recycled and used as the supply gas. Recycling the hydrogen produced beneficially improves the efficiency of the overall gas treatment because the plasma formed from the hydrogen is highly efficient in cracking the hydrocarbon bonds in the molecules of the process material. Additionally, the recycled _H2 is already at high temperature, and thus requires less energy input to achieve thermal cracking energy. The supply gas is _H2 provided by an external source to which recycled _H2 is added. The generated plasma may be hydrogen plasma.

Figure 14 illustrates a microwave processing system 1400 with FEWG and filament. In some implementations, microwave processing system 1400 includes a microwave energy generator (such as a microwave energy source) 1404 , FEWG 1405 , and microwave transmitter circuitry 1407 . Microwave energy 1409 is supplied by microwave energy source 1404 to propagate in the downward direction of length L of FEWG 1405. In this embodiment, the supply gas inlet 1402 is placed near the inlet of the portion L ₀ , rather than at the inlet of the portion L ₁ , such as the plasma region. One or more metal filaments 1420 are placed within the FEWG 1405 to facilitate ignition of the plasma and/or excitation of higher energy species within the plasma. In this implementation, the metal filament 1420 is downstream of the supply gas inlet 1402, near the inlet _of the plasma region portion of FEWG L1 (having a smaller cross-sectional area relatively close to the FEWG of the microwave energy generator).

Filament 1420 may be located elsewhere within portion L1 _of the overall length L of _FEWG 1405, where L1 is the region in the waveguide where the plasma is formed as described with respect to previous embodiments. Filament 1420 is located within portion L ₁ of the FEWG and upstream of process material inlet 1410 such that it will be outside of portion L ₂ (such as length L ₂ shown in FIG. 9 ) where the reaction occurs and can be coated with reactive species. The presence of the filament 1420 can reduce the plasma ignition voltage by focusing the electric field of the microwave energy 1409 by providing an ignition site. Additionally, the filament 1420 can become heated and emit electrons via thermionic emission, which further helps reduce the plasma ignition voltage. Although the filament 1420 is illustrated as a single wire in this embodiment, other configurations of the filament 1420 may be employed, such as a coil or multiple filaments. Filament 1420 may be tungsten. The filament may be actively energized (powered) or may be passive. Filament 1420 may be an osmium filament adjacent to the heater coil (such as assembled as a plate or coil or other shape). Filament 1420 may be a ferrous material in the field of inductor coils. Filament 1420 is actively heated with an active component, such as a heat source component, located outside of FEWG 1405 and the filament material being heated is inside FEWG 1405.

15 shows a reactor system 1500 in which the energy source 1530 extends generally along the sides of the FEWG 1505 and/or may be similarly positioned with any one or more of the FEWGs disclosed herein. In some implementations, the energy source 1530 may be embodied as one or more electrodes, or one or a pair of coplanar electrodes oriented along a common vertical axis extending longitudinally through the center of the FEWG 1505 . Each pair of electrodes may include a positive electrode (referred to as a "cathode") and a negative electrode (referred to as an "anode"). As generally understood and referred to herein, an "electrode" means an electrical conductor used to make contact with a non-metallic portion of an electrical circuit. In lieu of or in addition to the combination of energy sources 1530 incorporating one or more electrodes, the energy sources may be embodied as (or otherwise incorporated into) electron guns that generate narrower collimated particles with precise kinetic energy in some vacuum tubes. The electrical components of the electron beam. Such an electron gun assembly may include several components, such as a hot cathode, which is heated to generate a flow of electrons via thermionic emission; an electrode, which generates an electric field to focus the electron beam (such as a Vénett cylinder); and one or more anodes electrodes, which accelerate and further focus the beam.

Furthermore, in addition to or in lieu of the configurations discussed, the energy source can be configured to provide the transfer of thermal energy (as heat) for liquid and viscous fluid materials such as the supply gas provided by the supply gas inlet 1502 and/or process input material, which in some implementations may also flow through an overheated flow heater and/or reactor of the supply gas inlet 1502). In some implementations, the energy source 1530 can be used independently of the recycled precursor gas 1320 of Figure 13, the filament 1420 of Figure 14, or the electron source 1520 of Figure 15, or with any combination of the foregoing. The system 1500 can include one or more sets of energy sources 1530, wherein any one or more of the energy sources 1530 can be configured to supply energy, such as in the form of thermal and/or electromagnetic energy, as well as other forms of energy, to electricity. Slurry 1506. The energy source 1530, when embodied as flanking one pair of oppositely charged coplanar electrodes (such as the coplanar electrodes shown in FIG. 15) flanking one of the FEWG 1505, may be configured to be generated within the portion L1 _of the overall length L of the FEWG 1505 electric field. L1 refers to the region where the plasma is formed in the _FEWG as described above. The energy source 1530 (when embodied as a pair of oppositely charged coplanar electrodes flanking one of the FEWG 1505) can be energized to a specific voltage to energize gaseous and/or plasma-based species within the plasma 1506 that are receiving energy from the plasma 1506. The energy of the source 1530 becomes charged) is accelerated to the desired level, thus allowing precise control of the energy level of the plasma 1506 (measured as temperature or some other type of energy measurement).

The energy source 1530 of this implementation can be configured to function with continuous wave microwave energy input (as provided, for example, by microwave processing system 1500), and is also effective when used in combination with pulsed microwave input. For example, in a conventional system having electrodes and using continuously provided microwave energy, the plasma 1506 located between the energy sources 1530 would tend to locate there in an equilibrium state. The plasma 1506 can shield (meaning at least partially block or otherwise hinder) exposure to the electric field generated by the energy source 1530 (such as when embodied as a pair of coplanar electrodes), which in turn can limit the energy source 1530 to the plasma 1506 The ability to add energy. In contrast, when the supplied microwaves are pulsed microwaves, the plasma 1506 can exist in a non-equilibrium state (meaning a plasma that is not in thermodynamic equilibrium) for a large portion of the entire processing time, since electrons are warmer than those in, for example, ions and The temperature of the heavier species is much hotter). As a result, the plasma 1506 can exist in equilibrium for the remainder of the entire processing time, and thus will shield the electric field generated by the energy source 1530 for a small fraction of the entire processing time.

As shown in Figure 15, the energy source 1530 may be used independently of or in combination with the recycled precursor gas 1320 of Figure 13, the filament 1420 of Figure 14, or the electron source 1520 of Figure 15. System 1500 includes one or more sets of electrodes 1530 for adding energy to the plasma. The electrodes are configured to generate an electric field within a portion L1 _of the overall length L of the FEWG 1505, where L1 is the region in the _FEWG where the plasma is formed as described above. Energy source 1530 is shown in FIG. 15 as a pair of oppositely charged coplanar electrodes on the outside and on opposite sides of the portion of FEWG 1505 that generates plasma 1506, but other energy source types are possible (such as including the thermal energy of the heater). The electrodes can be energized to specific voltages to accelerate charged species within the plasma to a desired degree, thus controlling the plasma energy. The electrodes of this embodiment can be used with continuous wave microwave energy, such as microwave energy applied in general direction 1509 from microwave energy generator 1504, and are particularly effective when combined with pulsed microwave input. In conventional systems with electrodes and continuous microwave energy, the plasma between the electrodes will be positioned in equilibrium (such as near the electrodes) and shield the electric field from the electrodes, which limits the ability of the electrodes to add energy to the plasma. However, when the microwaves are pulsed, the plasma will exist in a non-equilibrium state for a larger time fraction and will shield the electric field of the electrode for a smaller time fraction.

The microwave processing system of the present disclosure will include magnets (not shown) to confine the plasma in the reaction zone and reduce the ignition voltage for generating the plasma. Magnets are permanent or electromagnets. The magnets can be positioned such that the plasma density distribution can be controlled. _The magnets will increase the plasma density in portion L1, which will improve the efficiency of separation of process materials by plasma. The local impedance within the FEWG is adapted using filaments, point sources, electrodes and/or magnets. Filaments, point sources, electrodes, and/or magnets are used to increase the density plasma within the reaction zone of the FEWG.

As previously described, a microwave energy generator coupled to the FEWG containing the reaction zone and pulsed microwave energy, high gas flow (such as greater than 5 slm), larger plasma volume (such as up to 1000 L), high pressure (such as greater than 0.1 atm or Greater than 0.9 atm, or greater than 2 atm), a filament or electron source to aid in the ignition of the plasma at the beginning of each pulse, and/or electrodes to further add energy to the plasma can be cost-effective at low energy input requirements High productivity chemical gas treatment system.

A microwave processing system with the above features is configured in such a way that a plasma is generated within the FEWG itself and the process material is separated into components, such as Figures 9, 10, 11A-11D, 12A, and 12A Examples depicted in 12B, 13, 14, and 15. In such systems, the microwave energy enters the system upstream of the reaction that produces the separated components, and thus the problem of the separated components building up on the microwave entry window of the reactor and absorbing the microwave energy before it can generate a plasma is solved ease. The portion of the FEWG that produces the separated components acts as a reaction chamber, and the supply gas flow and/or process material flow through the reaction chamber is parallel to the direction of propagation of microwave energy in the FEWG. Charging of microwave energy in FEWG When the portion of the reaction chamber that produces the separated components enters the FEWG upstream.

Gas recirculation, filament and electron sources can be used in microwave gas processing systems with FEWGs utilizing continuous wave (CW) microwave energy. In a configuration with CW microwave energy, the gas recirculation, filament and electron source will still be beneficial to improve the gas processing efficiency of the system, reduce the ignition voltage of the plasma and control the density distribution of the plasma. Despite the larger volume of the reaction zone in the FEWG, the separated components can still adhere to the walls of the FEWG downstream of the reactions that produce the separated components. Although this does not prevent plasma generation, it still represents a loss of production and a source of contamination in the system. Therefore, the gas flow of the supply gas and process materials can be designed to generate a plasma near the deposition area to remove separate products deposited on the waveguide walls (or reaction chamber walls). In some implementations, additional inlets supplying gases and/or process materials can be configured to direct the gases to the deposition area to remove separated products deposited on the waveguide walls (or reaction chamber walls).

Method of microwave gas treatment

16 is an example flow diagram 1600 illustrating a method for microwave processing of gases using chemical control in high efficiency gas reactions by FEWG. In block 1602, microwave energy is supplied through the FEWG having a length where the microwave energy propagates in a direction along the FEWG. The microwave energy can be pulsed microwave energy or continuous wave. Microwave energy is less than 100kW, or from 1kW to 100kW, or from 1kW to 500kW, or from 1kW to 1kW, or from 10kW to 5kW, or more than 10kW, or more than 100kW, or more than 500kW, or more than 1MW, or more than 2MW The time-averaged power is supplied to the FEWG. The pressure within the FEWG is at least 0.1 atmosphere, such as from 0.9 atm to 10 atm. In block 1604, supply gas is provided into the FEWG at a first location along the length of the FEWG, with the majority of the supply gas flowing in the direction of microwave energy propagation. In block 1606, a plasma is generated in the supply gas in at least a portion of the length of the FEWG. Process material may be added to the FEWG at a second location downstream of the first location. Most process materials can flow in the direction of microwave propagation at flow rates greater than 5 slm.

Optionally, in block 1608, the average energy of the plasma is controlled to convert process materials into separate components. The average energy may be, for example, 0.8 eV to 20 eV. The pulse frequency can be controlled, wherein the pulse frequency is greater than 500Hz. For example, the pulse frequency of microwave energy can be from 500 Hz to 1000 kHz. In addition to or instead of the pulse frequency, the duty cycle of the pulsed microwave energy can be controlled, wherein the duty cycle is less than 50%.

It should be noted that the operations of Figure 16 may be performed in sequences other than those shown. For example, the process gas may be added at the same point as block 1604; that is, the process gas may be added in block 1604 prior to the block where the plasma is generated. In another example, plasma energy control in block 1606 may be performed in conjunction with plasma generation in block 1608. Conditions in the afterglow can be controlled by different forms of energy input. As a specific example, afterglow conditions can be controlled by microwave energy. This microwave energy can be used directly to expand the plasma plume or particles in the heating zone. This feature expands the plasma, thereby accommodating tuning of the time the particles spend in the plasma. This feature further aids in controlling the gas phase chemical reaction, particle charging and particle heating processes of the particles throughout this region. Control over these parameters leads to control over particle morphology. Alternatively, the energy source in this zone can be selected such that no plasma is formed, and instead the particles are heated, resulting in direct control of the particle temperature. This in turn allows control of the growth kinetics and thus the morphology of the particles. One implementation of the juxtaposition and use of energy sources positioned along the length of the FEWG is as shown and discussed with respect to FIG. 15 .

Structured carbon, various carbon nanoparticles, various carbon-containing aggregates

17A-17Y depict structured carbon, various carbon nanoparticles, various carbon-containing aggregates, and various three-dimensional carbon-containing structures grown over other materials. Carbon nanoparticles and aggregates can be characterized by high "uniformity", such as desired carbon isotopes, in contrast to the less uniform, more irregular, and less pure particles achievable by conventional systems and methods High mass fraction of isoforms; high "regularity", such as low concentrations of defects; and/or high "purity", such as low concentrations of elemental impurities.

Nanoparticles produced using the methods described herein can comprise multi-wall spherical fullerenes (MWSF) or linked MWSF and have high homogeneity, such as graphene to MWSF ratios from 20% to 80%; highly regular Properties, such as Raman signatures with ID/IG ratios from 0.95 to 1.05; and high purity, such as carbon to elements other than hydrogen ratios greater than 99.9%. Nanoparticles produced using the methods described herein may comprise MWSF or linked MWSF, and the MWSF does not comprise a core composed of impurity elements other than carbon. In some cases, the particles produced using the methods described herein are aggregates comprising the nanoparticles described above, the nanoparticles having larger diameters, such as greater than 10 μm.

Conventional methods have been used to produce particles comprising multiwall spherical fullerenes with a high degree of regularity, but conventional methods produce carbon products with various disadvantages. For example, high temperature synthesis techniques result in particles having a mixture of many carbon allotropes, and thus low homogeneity, such as a ratio of fullerenes to other carbon allotropes of less than 20%, and/or smaller particle sizes, such as in In some cases less than 1 μm or less than 100 nm. Processes using catalysts produce products that include catalyst elements, and are therefore also of low purity, such as a carbon to other element ratio of less than 95%. These improper properties also often lead to improper electrical properties of the resulting carbon particles, such as electrical conductivity of less than 1000 S/m.

The carbon nanoparticles and aggregates described herein are characterized by Raman spectroscopy that indicates a high degree of regularity and uniformity of structure. The uniform regular and/or pure carbon nanoparticles and aggregated systems described herein are produced using the reactors and methods described below. Additional advantages and/or improvements will also become apparent from the following disclosure.

definition

The term "graphene" means an allotrope of carbon in the form of a two-dimensional atomic-scale hexagonal lattice with one atom forming each vertex. The carbon atoms in graphene are bonded by sp ² . In addition, graphene has a Raman spectrum with two main peaks: a G mode at about 1580 cm-1 and a D mode at about 1350 cm-1 when a 532 nm excitation laser is used.

The term "fullerene" means a molecule of carbon in the form of a hollow sphere, ellipsoid, tube or other shape. Spherical fullerenes are also known as buckminster fullerenes or buckyballs. Cylindrical fullerenes can also be called carbon nanotubes. Fullerenes are structurally similar to graphite, which consists of stacked graphene sheets linked by hexagonal rings. Fullerenes may also contain pentagonal (or sometimes heptagonal) rings.

The term "multi-walled fullerene" refers to a fullerene having multiple concentric layers. For example, multi-wall nanotubes (MWNTs) contain multiple rolled layers of graphene (concentric tubes). Multiwall spherical fullerenes (MWSFs) contain multiple concentric fullerene spheres.

The term "nanoparticle" refers to particles measuring from 1 nm to 989 nm. Nanoparticles can include one or more structural features, such as crystal structure, defect concentration, etc., and one or more types of atoms. Nanoparticles can be of any shape, including but not limited to spherical shapes, spheroid-like shapes, dumbbell shapes, cylindrical shapes, elongated cylindrical type shapes, rectangular prism shapes, disc shapes, wire shapes, irregular shapes, dense shapes ( such as having few voids), porous shapes such as having many voids, and the like.

The term "aggregate" refers to a plurality of nanoparticles linked together by Van der Waals forces, by covalent bonds, by ionic bonds, by metallic bonds, or by other physical or chemical interactions. The size of the aggregates can vary considerably, but is generally greater than about 500 nm.

As described herein, carbon nanoparticles include two or more than two linked multi-wall spherical fullerenes (MWSFs) and graphene layers coated with linked MWSFs. As described herein, carbon nanoparticles include two or more than two linked multi-wall spherical fullerenes (MWSFs) and graphene layers coated with linked MWSFs, wherein the MWSFs do not contain any material other than carbon. The core composed of impurity elements. As described herein, the carbon nanoparticle includes two or more than two linked multi-wall spherical fullerenes (MWSF) and a graphene layer coating the linked MWSF, wherein the MWSF does not contain voids at the center, Such as greater than about 0.5 nm, or greater than about 1 nm of carbon-free space. As contrasted to spheres of more irregular, non-uniform, amorphous carbon particles, linked MWSFs can be formed from concentric regular spheres of _sp2 mixed carbon atoms.

Nanoparticles comprising linked MWSF can have an average diameter ranging from 5 to 500 nm, or from 5 to 250 nm, or from 5 to 100 nm, or from 5 to 50 nm, or from 10 to 500 nm, or from 10 to 250 nm, or from 10 to 100 nm, or from 10 to 50 nm, or from 170 to 500 nm, or from 170 to 250 nm, or from 170 to 100 nm, or from 50 to 500 nm, or from 50 to 250 nm, or from 50 to 100 nm.

The carbon nanoparticles described herein can form aggregates, in which many nanoparticles are aggregated together to form larger units. The carbon aggregates can include a plurality of carbon nanoparticles. The diameter across the carbon aggregates can range from 10 to 500 μm, or from 50 to 500 μm, or from 100 to 500 μm, or from 250 to 500 μm, or from 10 to 250 μm, or from 10 to 100 μm, or from 10 to 50 μm Inside. As defined above, aggregates may be formed from a plurality of carbon nanoparticles. Aggregates may comprise linked MWSFs. Aggregates comprise linked MWSFs with high homogeneity measures, such as graphene to MWSF ratios ranging from 20% to 80%; high regularity, such as Raman signatures with ID/IG ratios ranging from 0.95 to 1.05; and high Purity, such as greater than 99.9% carbon.

One benefit of producing aggregates of carbon nanoparticles, especially with diameters in the ranges described above, is that particle aggregates larger than 10 μm are easier to collect than particles or particle aggregates smaller than 500 nm. Ease of collection reduces the cost of manufacturing equipment used in the production of carbon nanoparticles and increases the yield of carbon nanoparticles. In addition, particles larger than 10 μm in size pose fewer safety concerns than the risks of handling smaller nanoparticles, such as potential health and safety risks due to inhalation of smaller nanoparticles. Thus, lower health and safety risks further reduce manufacturing costs.

The ratio of graphene to MWSF of carbon nanoparticle can be from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 170%, or from 10% to 20% %, or from 20% to 170%, or from 20% to 90%, or from 170% to 90%, or from 60% to 90%, or from 80% to 90%. The ratio of graphene to MWSF of the carbon aggregate is from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 170%, or from 10% to 20%, or from 20% to 170%, or from 20% to 90%, or from 170% to 90%, or from 60% to 90%, or from 80% to 90%. The ratio of graphene to linked MWSF of carbon nanoparticle is from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 170%, or from 10% to 20%, or from 20% to 170%, or from 20% to 90%, or from 170% to 90%, or from 60% to 90%, or from 80% to 90%. The ratio of graphene to linked MWSF of carbon aggregates is from 10% to 90%, or from 10% to 80%, or from 10% to 60%, or from 10% to 170%, or from 10% to 20% %, or from 20% to 170%, or from 20% to 90%, or from 170% to 90%, or from 60% to 90%, or from 80% to 90%.

Raman spectroscopy can be used to characterize carbon allotropes used to differentiate their molecular structures. For example, Raman spectroscopy can be used to characterize graphene to determine information such as regularity/irregularity, edges and grain boundaries, thickness, number of layers, doping, strain, and thermal conductivity. The MWSF has also been characterized using Raman spectroscopy to determine the regularity of the MWSF.

Raman spectroscopy can be used to characterize the structure of MWSF or linked MWSF. The main peaks in the Raman spectrum are G mode and D mode. The G mode is ascribed to the vibrations of carbon atoms in the sp ² mixed carbon network, and the D mode is associated with the respiration of defective hexagonal carbon rings. In some cases, defects may be present but not detectable in Raman spectroscopy. For example, if the presented crystalline structure is orthogonal with respect to the plane of the substrate, the D peak will exhibit an increase. Alternatively, if a perfectly planar surface parallel to the plane of the substrate is present, the D peak will be zero.

When using 532 nm incident light, the Raman G mode is typically at 1582 cm-1 for planar graphite, but can be shifted downward (such as down to 1565 cm-1 or down to 1580 cm-1) for MWSF or linked MWSF. The D mode is observed at approximately 1350 cm-1 in the Raman spectrum of MWSF or linked MWSF. The ratio of the intensity of the D-mode peak to the G-mode peak, such as ID/IG, is related to the regularity of the MWSF, with lower ID/IG indicating higher regularity. ID/IG indication phase near or below 1 For a higher degree of regularity, an ID/IG greater than 1.1 indicates a lower degree of regularity.

As described herein, carbon nanoparticles or carbon aggregates comprising MWSF or linked MWSF have a Raman spectrum with a first Raman peak at about 1350 cm and a second Raman peak when 532 nm incident light is used At about 1580cm 1. The ratio (such as ID/IG) of the intensity of the first Raman peak to the intensity of the second Raman peak of the nanoparticles or aggregates described herein is from 0.95 to 1.05, or from 0.9 to 1.1, or from 0.8 to 1.2, or from 0.9 to 1.2, or from 0.8 to 1.1, or from 0.5 to 1.5, or less than 1.5, or less than 1.2, or less than 1.1, or less than 1, or less than 0.95, or less than 0.9, or less than 0.8 Inside.

As defined above, carbon aggregates comprising MWSF or linked MWSF are of high purity. The carbon-to-metal ratio of carbon aggregates comprising MWSF or linked MWSF is greater than 99.99%, or greater than 99.95%, or greater than 99.9%, or greater than 99.8%, or greater than 99.5%, or greater than 99%. The ratio of carbon to other elements in carbon aggregates is greater than 99.99%, or greater than 99.95%, or greater than 99.9%, or greater than 99.5%, or greater than 99%, or greater than 90%, or greater than 80%, or greater than 70%, or greater than 60%. The ratio of carbon to other elements (other than hydrogen) of carbon aggregates is greater than 99.99%, or greater than 99.95%, or greater than 99.9%, or greater than 99.8%, or greater than 99.5%, or greater than 99%, or greater than 90%, or More than 80%, or more than 70%, or more than 60%.

As defined above, carbon aggregates comprising MWSF or linked MWSF have a high specific surface area. The Beuett (BET) specific surface area of carbon aggregates is from 10 to 200m2/g, or from 10 to 100m2/g, or from 10 to 50m2/g, or from 50 to 200m2/g, or from 50 to 100m2/ g, or from 10 to 1000m2/g.

As defined above, carbon aggregates comprising MWSF or linked MWSF have high electrical conductivity. As defined above, carbon aggregates comprising MWSF or linked MWSF are compressed into agglomerates, and the agglomerates have greater than 500 S/m, or greater than 1000 S/m, or greater than 2000 S/m, or greater than 3000S/m, or more than 17000S/m, or more than 5000S/m, or more than 10000S/m, or more than 20000S/m, or more than 30000S/m, or more than 170000S/m, or more than 50000S/m, or more than 60000S/ m, or greater than 70000S/m, or from 500S/m to 100000S/m, or from 500S/m to 1000S/m, or from 500S/m to 10000S/m, or from 500S/m to 20000S/m, or from 500S/m to 100000S/m, or from 1000S/m to 10000S/m, or from 1000S/m to 20000S/m, or from 10000 to 100000S/m, or from 10000S/m to 80000S/m, or from 500S/ Conductivity from m to 10000S/m.

In some cases, the agglomerates have a density of about 1 g/cm3, or about 1.2 g/cm3, or about 1.5 g/cm3, or about 2 g/cm3, or about 2.2 g/cm3, or about 2.5 g/cm3, or About 3g/cm3. Additionally, tests have been performed in which compressed agglomerates of carbon aggregate material have been formed at compressions of 2000 psi and 12000 psi and annealing temperatures of 800°C and 1000°C. Higher degrees of compression and/or higher annealing temperatures generally produce agglomerated grains with higher degrees of electrical conductivity, including electrical conductivities in the range of 121710.0 S/m to 13173.3 S/m.

Before or after post-processing, the carbon nanoparticles and aggregates described herein are used in various applications. Such applications include, but are not limited to, transportation applications (such as car and truck tires, couplings, mounts, elastic o-rings, hoses, sealants, grommets, etc.) and industrial applications (such as rubber additives, functional chemical additives, epoxy resin additives, etc.).

17A and 17B show transmission electron microscopy (TEM) images of arsenic-synthesized carbon nanoparticles. The carbon nanoparticles of Figures 17A (at first magnification) and 17B (at second magnification) comprise linked multi-wall spherical fullerenes 1702 (MWSF) with graphene layer 1704 coating linked MWSF . In this example, the ratio of MWSF to graphene allotropes is about 80% due to the relatively short resonance time. The MWSFs in Figure 17A are approximately 5 nm to 10 nm in diameter, and may be 5 nm to 500 nm in diameter using the conditions described above. The average diameter across the MWSF is 5nm to 500nm, or from 5nm to 250nm, or from 5nm to 100nm, or from 5nm to 50nm, or from 10nm to 500nm, or from 10nm to 250nm, or from 10nm to 100nm, or from 10nm to 50nm, or from 40nm to 500nm, or from 40nm to 250nm, or from 40nm to 100nm, or from 50nm to 500nm, or from 50nm to 250nm, or from 50nm to 100nm. No catalyst is used in this process, and therefore there are no central seeds containing contaminants. The particle size of the aggregated particles produced in this example is about 10 μm to 100 μm, or about 10 μm to 500 μm.

Figure 17C shows the Raman spectrum obtained with incident light at 532 nm for the arsenic-synthesized aggregates in this example. The ID/IG of the aggregates produced in this example was about 0.99 to 1.03, indicating that the aggregated system was composed of carbon allotropes with a high degree of regularity.

17D and 17E show example TEM images of carbon nanoparticles after size reduction by milling in a ball mill. Ball milling was performed in a cycle of a 3 minute counterclockwise grinding step, followed by a 6 minute idle step, followed by a 3 minute clockwise grinding step, followed by a 6 minute idle step. The grinding step was performed using a rotational speed of 1700 rpm. The grinding media was zirconia and ranged in size from 0.1 mm to 10 mm. The total size reduction processing time was 60 minutes to 120 minutes. After size reduction, the aggregated particles produced in this example had a particle size of about 1 μm to 5 μm. The carbon nanoparticle after size reduction is a linked MWSF, wherein the graphene layer coats the linked MWSF.

Figure 17F shows the Raman spectra obtained from these aggregates with incident light at 532 nm after size reduction. The ID/IG of the aggregated particles in this example after size reduction was about 1.017. In addition, the particles after size reduction have a Beuett (BET) specific surface area of about 40 m2/g to 50 m2/g.

The purity of the aggregates produced in this sample was measured using mass spectrometry and x-ray fluorescence (XRF) spectroscopy. Carbon and elements other than hydrogen measured in 16 different batches The ratio is 99.86% to 99.98%, with an average of 99.917% carbon.

In this example, the precursor material is methane, which flows at 1 slm to 5 slm. At these flow rates and tool geometries, the resonance time of the gas in the reaction chamber was about 20 to 30 seconds, and the carbon particle generation rate was about 20 g/hr. Additional details regarding this processing system can be found in the previously mentioned US Patent 9,862,602 entitled "CRACKING OF A PROCESS GAS".

17G, 17H, and 17I show TEM images of arsenic-synthesized carbon nanoparticles of this example. The carbon nanoparticles comprise linked multi-wall spherical fullerenes (MWSFs) with a graphene layer coating the linked MWSFs. Since the relatively long resonance time allows thicker or more graphene layers to coat the MWSF, the ratio of multi-wall fullerenes to graphene allotropes in this example is about 30%. No catalyst is used in this process, and therefore there are no central seeds containing contaminants. The particle size of the arsenic-synthesized aggregated particles produced in this example was about 10 μm to 500 μm. Figure 17J shows the Raman spectrum of the aggregate from this example. The Raman signature of the arsenic-synthesized particles in this example indicates a thicker graphene layer coating the MWSF in the arsenic-synthesized material. In addition, the arsenic-synthesized particles have a Beuett (BET) specific surface area of about 90 m2/g to 100 m2/g.

17K and 17L show TEM images of carbon nanoparticles of this example. Specifically, the images depict carbon nanoparticles after size reduction by milling in a ball mill. The size reduction process conditions are the same as those described with respect to Figures 17G-17J previously. After size reduction, the aggregated particles produced in this example had a particle size of about 1 μm to 5 μm. TEM images show that connected MWSFs embedded in the graphene coating can be observed after size reduction. Figure 17M shows the Raman spectrum obtained from the aggregate of this example with 532 nm incident light after size reduction. After size reduction, the ID/IG of the aggregated particles in this example is about 1, indicating that the connected MWSF embedded in the arsenic-synthesized graphene coating becomes detectable in Raman after size reduction , and the regularity is good. The particles after size reduction have a Beuett (BET) specific surface area of about 90 m2/g to 100 m2/g.

Figure 17N is a scanning electron microscope (SEM) image at first magnification showing carbon aggregates of graphite and graphene allotropes. Figure 17O is an SEM image at a second magnification showing carbon aggregates of graphite and graphene allotropes. Layered graphene is clearly displayed within the deformations (folds) of the carbon. The 3D structure of the carbon allotropes is also visible.

The particle size distributions of the carbon particles of Figures 17N and 17O are shown in Figure 17P. The mass-based cumulative particle size distribution 1706 corresponds to the left y-axis (Q3(x)[%]) in the graph. The histogram of the mass particle size distribution 1708 corresponds to the right axis (dQ3(x)[%]) in the graph. The median particle size is approximately 33 μm. The 10th percentile particle size is about 9 μm and the 90th percentile particle size is about 103 μm. The mass density of the particles was about 10 g/L.

The particle size distribution of carbon particles captured from the multistage reactor is shown in Figure 17Q. The mass-based cumulative particle size distribution 1714 corresponds to the left y-axis (Q3(x)[%]) in the graph. The histogram of the mass particle size distribution 1716 corresponds to the right axis (dQ3(x)[%]) in the graph. The captured median particle size was approximately 11 μm. The 10th percentile particle size is about 3.5 μm and the 90th percentile particle size is about 21 μm. The graph in Figure 17Q also shows a number-based cumulative particle size distribution 1718 corresponding to the left y-axis of the graph (Q0(x)[%]). The median particle size on a number basis is from about 0.1 μm to about 0.2 μm. The mass density of the collected particles was about 22 g/L.

Returning to the discussion of Figure 17P, the figure also shows a second set of example results. Specifically, in this example, the size of the particles is reduced by mechanical milling, and then the size-reduced particles are processed using a cyclone. The mass-based cumulative particle size distribution 1710 of the size-reduced carbon particles captured in this example corresponds to the left y-axis (Q3(x)[%]) of the graph. The histogram of the mass reference particle size distribution 1712 corresponds to the right axis (dQ3(x)[%]) in the graph. The median particle size of the size-reduced carbon particles captured in this example was approximately 6 μm. The 10th percentile particle size is from 1 μm to 2 μm, and the 90th percentile particle size is from 10 μm to 20 μm.

Additional details regarding the manufacture and use of cyclones can be found in US Patent Application Serial No. 15/725,928, entitled "MICROWAVE REACTOR SYSTEM WITH GAS-SOLIDS SEPARATION," filed October 5, 2017, which is incorporated by reference in its entirety. Incorporated herein.

High Purity Carbon Allotropes Produced Using a Microwave Reactor System

Carbon particles and aggregates comprising graphite, graphene and amorphous carbon can be produced using a microwave plasma reactor system using precursor materials comprising methane or comprising isopropanol (IPA) or comprising ethanol or comprising condensed hydrocarbons such as hexane body. In some other examples, the carbon-containing precursor is optionally mixed with a supply gas, such as argon. The particles produced in this example comprise graphite, graphene, amorphous carbon, and no seed particles. The ratio of carbon to other elements (other than hydrogen) for the particles in this example is about 99.5% or greater.

In one particular example, the hydrocarbons are the input material of the microwave plasma reactor, and the separated output of the reactor includes hydrogen gas and carbon particles including graphite, graphene, and amorphous carbon. Carbon particles are separated from hydrogen in a multistage gas-solid separation system. The solids loading from the separated output of the reactor was from 0.001 g/L to 2.5 g/L.

Figures 17R, 17S, and 17T are TEM images of arsenic-synthesized carbon nanoparticles. The images show examples of graphite, graphene, and amorphous carbon allotropes. Layers of graphene and other carbon materials can be clearly seen in the image.

The particle size distribution of the captured carbon particles is shown in Figure 17U. The mass-based cumulative particle size distribution 1720 corresponds to the left y-axis (Q3(x)[%]) in the graph. The histogram of the mass particle size distribution 1722 corresponds to the right axis (dQ3(x)[%]) in the graph. The median particle size captured in the cyclone in this example was about 14 μm. The 10th percentile particle size is about 5 μm and the 90th percentile particle size is about 28 μm. The graph in Figure 17U also shows a number-based cumulative particle size distribution 1724 corresponding to the left y-axis (Q0(x)[%]) of the graph. The median particle size on a number basis in this example is about 0.1 μm to about 0.2 μm.

17V, 17W, and 17X and 17Y are images showing three-dimensional carbon-containing structures grown onto other three-dimensional structures. Figure 17V is a 100X magnification of a three-dimensional carbon structure grown on carbon fiber, and Figure 17W is a 200X magnification of a three-dimensional carbon structure grown on carbon fiber. Figure 17X is a 1601X magnification of a three-dimensional carbon structure grown onto a carbon fiber. Three-dimensional carbon growth above the fiber surface is shown. Figure 17Y is a 10000X magnification of a three-dimensional carbon structure grown onto carbon fibers. The images depict growth in the basal plane as well as in the marginal plane.

More specifically, Figures 17V-17Y show example SEM images of 3D carbon materials grown onto fibers using plasma energy from a microwave plasma reactor. Figure 17V shows an SEM image of intersecting fibers 1731 and 1732 of 3D carbon material 1730 grown on the fiber surface. FIG. 17W is a higher magnification image showing 3D carbon growth 1730 on fiber 1732 (scale bar is 300 μm compared to 500 μm in FIG. 17V). Figure 17X is another magnified view showing 3D carbon growth 1730 on fiber surface 1735 (scale bar is 40 [mu]m), where the 3D nature of carbon growth 1730 can be clearly seen. Figure 17Y shows only a close-up view of the carbon (scale bar is 500 nm) showing the interconnection between the basal plane 1736 and the edge plane 1734 of the sub-particles of the 3D carbon material grown on the fiber. 17V-17Y demonstrate the ability to grow 3D carbon on 3D fiber structures, such as 3D carbon growth on 3D carbon fibers, according to some embodiments.

3D carbon growth on fibers can be achieved by introducing multiple fibers into a klystron powered ionization reactor and etching the fibers using plasma in the microwave reactor. Etching creates condensation nucleation sites such that the growth of 3D carbon structures is initiated at these condensation nucleation sites as carbon particles and daughter particles are produced by dissociation of hydrocarbons in the reactor. The 3D carbon structure in itself provides a highly integrated 3D structure with pores, into which the resin can penetrate, for direct growth on fibers in three dimensions. This 3D reinforcement matrix for resin composites, including 3D carbon structures integrated with high aspect ratio reinforcement fibers, produces reinforced material properties such as Tensile strength and shear.

18A shows an illustrative flow chart depicting example operations 1800A of a method for outputting carbonaceous powder. Operation 1800A may be performed by any one or more of the assembly and/or coupling of the presented FEWGs and circuits, such as microwave transmitter control circuit 140 shown generally to include microwave energy source 141 presented in FIG. 5 , the circuit Collectively referred to as the reactor system. At block 1802A, the reactor system generates microwave energy from a microwave energy source. At block 1804A, the reactor system generates control signals that are configured to adjust the pulse frequency of the microwave energy to control the microwave energy source. At block 1806A, the reactor system applies a non-zero voltage to the microwave energy source during the off state of the microwave energy source, the non-zero voltage configured to adjust the frequency and duty cycle of the control signal. At block 1808A, the reactor system generates plasma in response to excitation of the supply gas by microwave energy. At block 1810A, the reactor system injects the raw material into the plasma. At block 1812A, the reactor system forms a mixture based on the combination of portions of the supply gas and raw materials within the plasma. At block 1814A, the reactor system outputs carbonaceous powder based on excitation of the mixture by microwave energy.

18B shows an illustrative flowchart depicting example operations 1800B of a method for pulsing a non-zero voltage. Operation 1800B may be performed by any one or more of the arrangement and/or coupling of the presented FEWGs and circuits, such as microwave transmitter control circuit 140 shown generally to include microwave energy source 141 presented in FIG. 5 , the circuit Collectively referred to as the reactor system. At block 1802B, the reactor system pulses a non-zero voltage.

functionalized carbon

Carbon materials such as the 3D carbon materials described herein can be functionalized to promote adhesion and/or add elements such as oxygen, nitrogen, carbon, silicon, or hardeners. The carbon material can be functionalized in situ, that is, within the same reactor where the carbon material is produced. The carbon material can be functionalized in post-processing. For example, the surface of fullerenes or graphene may be available with oxygen- or nitrogen-containing species that form bonds with the polymer of the resin matrix Functionalized, thus improving adhesion and providing strong bonds to enhance the strength of the composite.

Embodiments include functionalized surface treatment of carbon (such as CNT, CNO, graphene, 3D carbon materials such as 3D graphene) using a plasma reactor described herein, such as a klystron powered ionization reactor. Various embodiments may include in-situ surface treatment during the creation of carbon materials, which may be combined with binders or polymers in the composite material. Various embodiments may include surface treatment after producing the carbon material while the carbon material is still within the reactor.

Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to others without departing from the spirit or scope of this disclosure implement. Therefore, the scope of the claims is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the disclosure, principles and novel features disclosed herein.

141: Microwave Energy Source 142: High voltage control circuit 143: Filament control circuit 144: Pulsed high voltage output 145: Components 500: Schematic diagram, microwave transmitter control circuit 501: Voltage input 502: Power Supply Circuit 503: Pulse Generator 504: High Voltage Controller 505: High Voltage Power Supply (HVPS) Transformers 506: Voltage Doubler 507: Pulse switch 508: Filament Controller 509: Filament Isolation Transformer 510: Main control switch 511: High Voltage Control Switch 512: Filament control switch 513: Pump/Fan Control Switch 514: Cooling Pump or Fan 515: Transformer 516: Relay 517: Relay Controller 518: Potentiometer 519,520: Capacitors 521, 522, 529, 530: Diodes 523: High side resistor 524: Low Side Resistor 525: High-voltage side bipolar active switch 526: Low-voltage side bipolar active switch 527, 528: Switch Drivers 531: Reactance Components

Claims (24)

A reactor system comprising: a microwave energy source configured to generate a microwave energy, the microwave energy source having an operating power level including an on state and an off state; a control circuit, which coupled to the microwave energy source and including an output to generate a control signal configured to maintain the operating power level of the microwave energy within a proximity defined by one of the on-states; a voltage generating a device configured to apply a non-zero voltage to the microwave energy source during the off state, wherein a frequency and a duty cycle of the non-zero voltage are based on a frequency and a duty cycle of the control signal; and a waveguide configured to act as a reactor and coupled to the microwave energy source, the waveguide comprising: a reaction zone configured to generate a plasma in response to the microwave energy; an inlet configured configured to inject a raw material into the reaction zone; and an outlet configured to output a powder based on the raw material. The system of claim 1, further comprising a collector configured to collect the powder. The system of claim 1, wherein the waveguide is configured to concentrate the microwave energy. The system of claim 3, wherein the reaction zone is configured to self-ignite the plasma in response to at least excitation of the raw material by concentrated microwave energy. The system of claim 4, wherein one or more of a physical property or a chemical property of the powder is based, at least in part, on the concentrated microwave energy. The system of claim 1, wherein the non-zero voltage has a rise time in a range between about 20 nanoseconds and 50 nanoseconds. The system of claim 1, wherein the non-zero voltage has a fall time in a range between about 20 nanoseconds and about 50 nanoseconds. The system of claim 1, wherein a pulse frequency of the microwave energy is further based at least in part on the non-zero voltage. The system of claim 1, wherein the control circuit further comprises a filament configured to adjust a dissociation of the plasma. The system of claim 1, wherein a power level of the microwave energy is based at least in part on the non-zero voltage. The system of claim 1, wherein the microwave energy source comprises any one or more of a magnetron, a klystron, or a traveling wave tube amplifier (TWTA). The system of claim 1, wherein the control circuit includes a pulse switch including a first bipolar active switch and a second bipolar active switch coupled in series between a voltage supply and ground potential. The system of claim 1, wherein the plasma contains a carbonaceous species. The system of claim 1, wherein the powder comprises any one or more of carbon-containing particles, a colloidal dispersion, or a plurality of solid particles. The system of claim 1, further comprising a gas/solid separator configured to separate gas phase material and solid phase material from the powder. The system of claim 1, wherein the waveguide is configured to generate one or more conditional measurements of the microwave energy source. The system of claim 1, wherein the powder includes a plurality of graphene sheets. The system of claim 17, wherein the waveguides are assembled to fuse the plurality of graphene sheets with each other at substantially orthogonal angles. The system of claim 1, wherein the waveguide is configured to adjust a length of the plasma generated within the waveguide by selectively flowing a supply gas into the reaction zone. The system of claim 1, wherein the reaction zone is configured to contain the plasma at a pressure of about 1 atm. The system of claim 1, further comprising a temperature control unit configured to control a temperature within the waveguide. A method for outputting powder, comprising: generating a microwave energy from a microwave energy source; generating a control signal, the control signal is configured to adjust a pulse frequency of the microwave energy; in an off state of the microwave energy source during which a non-zero voltage is applied to the microwave energy source, the non-zero voltage is configured to adjust a frequency and a duty cycle of the control signal; a plasma is generated in response to exciting a supply gas by the microwave energy; the A raw material is injected into the plasma; a mixture is formed based on a combination of the supply gas within the plasma and one or more portions of the raw material; and output is based on an excitation of the mixture by the microwave energy a powder. The method of claim 22, further comprising pulsing the non-zero voltage. The method of claim 23, wherein the pulsed non-zero voltage has a rise time between about 20 nanoseconds and 50 nanoseconds.

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