RU2326512C9 - Method for plasma formation (variants) - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention relates to methods of ignition, formation and retention of plasma consisting of gases, using catalyst. In an example of invention realisation, plasma is ignited by the gas exposed to electromagnetic radiation (in a multimode treatment cavity) with frequency between 1 MHz and 333 GHz at the presence of plasma catalyst, which can be active or passive. Passive plasma catalyst can include, for example, any object able to induce plasma by deformation of local electric field. Active plasma catalyst can include any particle or high-energy wave packet, able to transfer sufficient energy to gaseous atom or molecule in order to remove, at least, one electron from the gaseous atom or molecule at the presence of electromagnetic radiation.

EFFECT: reduction of energy cost and enhancement of thermal treatment efficiency.

48 cl, 9 dwg

Description

Link to related applications

Priority is claimed on US patent application No. 60/378,693, filed May 8, 2002, 60 / 430,677, filed December 4, 2002, and No. 60 / 435,278, filed December 23, 2002, all of which are incorporated herein by reference in their entirety.

Field of Invention

This invention relates to methods for igniting, forming and retaining plasma from gases using plasma catalysts.

BACKGROUND OF THE INVENTION

It is known that plasma can be ignited by exposing the gas to a sufficient amount of microwave radiation. Plasma ignition, however, is usually easier at gas pressures well below atmospheric pressure. However, the vacuum equipment that is required to reduce gas pressure can be expensive, as well as slow and consuming a lot of energy. Moreover, the use of such equipment may limit production flexibility.

SUMMARY OF SOME ASPECTS OF THE INVENTION

Plasma catalysts may be provided for igniting, forming and retaining the plasma. The plasma catalyst may be passive or active. A passive plasma catalyst may include any object capable of inducing plasma by deforming the electric field (e.g., electromagnetic field) of the present invention without adding additional energy. An active plasma catalyst, on the other hand, is any packet of particles or a high-energy wave that can transfer enough energy to a gaseous atom or molecule to remove at least one electron from a gaseous atom or molecule in the presence of electromagnetic radiation. In both cases, the plasma catalyst can improve or attenuate the environmental conditions necessary to ignite the plasma.

A method and apparatus for plasma formation are presented.

A plasma forming method includes passing gas into a multimode processing cavity; and igniting the plasma by exposing the gas in the cavity to electromagnetic radiation having a frequency of less than 333 GHz in the presence of at least one passive plasma catalyst comprising a material that is at least electrically semiconductor.

The material includes at least one metal, inorganic substance, carbon, carbon-based alloy, carbon-based composite, conductive polymer, conductive silicone elastomer, polymer nanocomposite, organic-inorganic composite, and any combination thereof.

In addition, the material is presented in at least one of the forms: nanoparticles, nanotubes, powder, dust, flakes, fibers, sheet, needles, threads, strands, hair, yarn, twine, beard hair, shard, slivers, woven material , tape, fiber crystal, or any combination thereof.

The material may also include carbon fiber.

In another embodiment, the material includes carbon and is presented in at least one of the forms: nanoparticles, nanotubes, powder, dust, flakes, fibers, sheet, needles, threads, strands, hair, yarn, twine, beard hair, splinter , wood chips, woven material, tape, fiber crystal, or any combination thereof.

The material may include at least one nanotube.

The material can at least partially be coated with a second material.

At least one passive plasma catalyst includes a plurality of elongated electrically conductive positions distributed at different places in the cavity.

The radiation has electric field lines, each of the elongated positions has a longitudinal axis, while the longitudinal axes are not significantly centered with the electric field lines.

The plasma catalyst includes at least one electrically conductive component and at least one additive in the ratio, the method further comprising confining the plasma, the confinement comprising: directing additional electromagnetic radiation into the cavity; and allowing the catalyst to be absorbed by the plasma, so that the plasma contains at least one additive.

The ratio is different for different portions of the catalyst, wherein enabling includes enabling various parts of the catalyst to be absorbed by the plasma at different times so that the plasma contains a varying ratio of the electrically conductive component to at least one additive.

The multimode cavity is configured to maintain at least the first mode and the second radiation mode, each mode having a maximum electric field vector in the cavity, and each vector has a magnitude, the ratio between the magnitude of the first mode and the magnitude of the second mode being less than 1:10, in another embodiment, the ratio may be less than 1: 5 or less than 1: 2.

In this case, the multimode cavity can be configured to maintain at least the first mode and the second radiation mode, while each of the modes has a maximum electric field vector in the cavity at the position, and the method further moves each of the positions using mode mixing.

Ignition involves igniting a plurality of plasma catalysts at various locations in the cavity.

The cavity is a radiation chamber, and the catalyst is placed completely in the chamber in such a way that the catalyst practically does not conduct electric current to the chamber or to any electrically conductive object located outside the chamber.

The catalyst may be located at the top of a practically non-conductive extension, which passes through the ignition hole in the radiation chamber. It includes a plurality of discontinuous segments separated and mechanically connected to a plurality of electrically non-conductive segments, wherein during ignition, the catalyst passes through the ignition hole in the cavity between a place inside the cavity and another place outside the cavity.

Ignition involves igniting a plasma with a catalyst suspended in a cavity.

A plasma forming method involves igniting a plasma by exposing the gas to electromagnetic radiation having a frequency of less than 333 GHz in the presence of a plasma catalyst including a powder. Exposure may occur in the chamber, and the method further includes passing gas into the chamber.

In another embodiment, exposure may occur in a cavity located in the chamber. In this case, the camera is a multimode camera.

The method also includes introducing the powder into the radiation using a carrier gas.

In another embodiment, the method may include introducing the powder into the radiation using a sequence of operations, where the powder at least temporarily hangs in the cavity, while these operations consist of at least a feed, gravity feed, transfer, spray, spray and blowing.

The introduction of powder into the cavity can be carried out through many ignition holes.

Ignition involves igniting the plasma while the powder is suspended.

The plasma catalyst includes a non-combustible material or is at least one of a metal, carbon, carbon-based alloy, an electrically conductive polymer, a conductive silicone elastomer, a polymer nanocomposite, and an organic - inorganic composite.

A method of forming a plasma includes exposing a gas in a cavity to electromagnetic radiation having a frequency of less than 333 GHz in the presence of an active plasma catalyst comprising at least one ionizing particle.

In this case, at least one ionizing particle includes a particle beam; or the particle is at least one X-ray particle, alpha particle, beta particle, neutron and proton.

At least one ionizing particle may be a charged particle.

In addition, the ionizing particle includes a radioactive fission product.

The cavity is formed in the vessel, which at least partially passes the fission product, the method further includes positioning the fission source outside the cavity so that the source directs the fission product through the vessel into the cavity.

The vessel and the fission source are located inside the radiation chamber, while the chamber includes material that practically prevents product leakage from the chamber.

The method may further include positioning the source of radioactive fission in the cavity, wherein the source generates at least one fission product.

The ionizing particle is a free electron, the method further comprising generating an electron by supplying energy to an electron source. Energy supply includes heating an electron source.

The particle may include a free proton, the method further comprising generating a free proton by ionizing hydrogen.

The cavity may be at least partially open, allowing gas to flow through it.

One of the options for the method of plasma formation in the system also assumes that the system has at least one ignition cavity and a second cavity in fluid communication with the first cavity, the method comprising: exposing the gas in the first ignition cavity to electromagnetic radiation having a frequency of less than 333 GHz, so that the plasma in the first cavity causes the formation of plasma in the second cavity; and holding the second plasma by exposing it to additional electromagnetic radiation.

Exposure includes exposing the gas to radiation in the presence of a plasma catalyst.

The first cavity may be smaller than the second cavity.

The first cavity can practically be a single-mode cavity, and the second cavity can also be a multimode or high-mode cavity.

Plasma catalyst includes carbon fiber.

In one embodiment of the invention, the method includes directing gas into a multimode processing cavity and igniting the gas by exposing the gas in the cavity to electromagnetic radiation having a frequency of less than 333 GHz in the presence of at least one passive plasma catalyst including at least electrically semiconductor.

In another embodiment of the invention, methods and apparatus for igniting a plasma by exposing a gas to electromagnetic radiation having a frequency of less than about 333 GHz in the presence of a plasma catalyst including a powder are provided.

In yet another embodiment, additional methods and apparatus for plasma formation using a dual cavity system are provided. The system may include a first ignition cavity and a second cavity having fluid communication with each other. The method may include: (i) exposing the gas in the first ignition cavity to electromagnetic radiation with a frequency of less than about 333 GHz, so that the plasma in the first cavity causes the formation of plasma in the second cavity, and (ii) holding the second plasma in the second cavity by exposing it exposure to additional electromagnetic radiation.

Additional plasma catalysts and methods for ignition, formation and retention of plasma in accordance with this invention are provided.

Brief Description of the Drawings

Further aspects of the invention will be apparent after consideration of the following detailed description in conjunction with the accompanying drawings in which like items refer to like items throughout the text and in which:

figure 1 is a schematic diagram of an illustrative plasma system corresponding to this invention;

1A is an illustrative embodiment of a portion of a plasma system for adding a powder plasma catalyst to a plasma cavity for igniting, forming, or retaining plasma in a cavity in accordance with this invention;

Figure 2 shows an illustrative example of a plasma catalyst fiber with at least one component having a concentration gradient along its length according to this invention;

Figure 3 shows an illustrative example of a plasma catalyst fiber with many components with a ratio that varies the length of its length in accordance with this invention;

Figure 4 shows another illustrative example of a plasma catalyst fiber, which includes a core sublayer and a coating in accordance with this invention;

Figure 5 shows a cross section of the plasma catalyst fiber of figure 4, taken along line 5-5 of figure 4, corresponding to this invention;

FIG. 6 shows an illustrative example of another part of a plasma system, including an elongated plasma catalyst that extends through a burning hole in accordance with the present invention;

Figure 7 shows an illustrative example of an elongated plasma catalyst that can be used in the system of figure 6, corresponding to this invention;

On Fig shows another illustrative example of an elongated plasma catalyst that can be used in the system of Fig.6, corresponding to this invention; and

Fig. 9 shows an illustrative example of a portion of a plasma system for directing radiation into a radiation chamber in accordance with this invention;

Detailed Description of Embodiments

This invention may relate to methods and apparatus for igniting, forming and retaining plasma for a variety of applications, including heat treatment, synthesis and deposition of carbides, nitrides, borides, oxides and other substances, alloying, carburization, nitration and carbonitriding, agglomeration, multi-link processing, compound , decrystallization, manufacture and operation of furnaces, treatment of exhaust gases, wastewater treatment, calcination, cleaning, ashing, growing carbon structures, generating odoroda and other gases forming electrodeless plasma torches, plasma treatment on production lines, sterilization, cleaning, etc.

The present invention can be used for controlled heat generation and for plasma-assisted treatment to reduce energy costs and increase heat-treatment efficiency and flexibility in plasma-assisted production.

Therefore, a plasma catalyst is proposed for ignition, formation and retention of plasma. The catalyst may be passive or active. A passive plasma catalyst may include any object capable of inducing plasma by deforming a local electric field (e.g., an electromagnetic field) in accordance with this invention without the need to add additional energy through the catalyst, similar to applying voltage to create a spark. On the other hand, the active plasma catalyst may be any particle or high-energy wave packet capable of transferring a sufficient amount of energy to a gaseous atom or ion to remove at least one electron from a gaseous atom or molecule in the presence of electromagnetic radiation.

Illustrative Plasma System

1 illustrates an exemplary plasma system 10 in accordance with one aspect of the invention. In this embodiment, a cavity 12 is formed in a vessel that is placed inside the radiation chamber 14, (i.e., an applicator). In another embodiment (not shown), the vessel 12 and the radiation chamber 14 are one and the same, thereby eliminating the need for two additional components. The vessel in which the cavity 12 is formed may include one or more radiation transmitting layers to improve its thermal insulation properties without significantly closing the cavity 12 from the radiation.

In one embodiment, a cavity 12 is formed in a vessel made of ceramic. Due to the extremely high temperatures that can be obtained from the plasmas of this invention, ceramics operating at about 3000 ° F (1648.9 ° C) can be used. Ceramic material may include 29.8% by weight silica, 68.2% alumina, 0.4 iron oxide, 1% titanium, 0.1% lime, 0.1% magnesium, 0.4% alkali, which are sold under the model No.LW-30 by New Castle Refactors, New Castle, PA. Specialists in this field, however, will understand that other materials, such as quartz and other than those described above, may also be consistent with this invention.

In one successful experiment, plasma formed in a partially open cavity inside the first brick, on which the second brick was on top. The cavity was about: 2 inches × 2 inches × 1.5 inches (about 50.78 mm × 50.78 mm × 38.085 mm). At least two holes were made in the brick in connection with the cavity: one for inspection of the plasma and at least one hole for gas supply. The size of the cavity may depend on the desired plasma process being performed. Also, the cavity must be configured in such a way as to prevent the rise of the plasma and its removal from the primary treatment area.

The cavity 12 can be connected to one or more gas sources 24 (for example, a source of argon, nitrogen, hydrogen, xenon, krypton) through line 20 and a control valve 22, which can be powered by power source 28. Line 20 can be a tube (for example , between about 1/16 inch (1.586875 mm) and about 1/4 inch (6.3475 mm), i.e. on the order of 1/8 inch (3.17175 mm)). Also, if desired, a vacuum pump can be connected to the chamber to remove the vapors that can be generated during the plasma treatment. In one embodiment, gas may flow into and / or from cavity 12 through one or more gaps in the composite vessel. Thus, the gas openings of the present invention do not have to be clear openings and can also take other forms, such as numerous small distributed openings.

A radiation leak detector (not shown) was installed near source 26 and waveguide 30 and connected to a safety lock to automatically turn off the radiation power source (for example, a microwave) if a leak was detected above a predetermined safety level similar to that defined by the Federal Communications Commission and the Administration occupational safety and health (e.g. 5 mV / cm ² ).

A radiation source 26, which can be powered by an electric power source 28, directs the radiation energy into the chamber 14 through one or more waveguides 30. Those skilled in the art will understand that the source 26 can be connected directly to the cavity 12, thereby eliminating the waveguide 30. Energy radiation entering the cavity 12 is used to ignite the plasma inside the cavity. This plasma can be significantly retained and limited in the cavity by attaching additional radiation to the catalyst. Also, the frequency of radiation (e.g., microwave radiation) is considered uncritical in many applications.

The radiation energy can be supplied through the circulator 32 and the tuner 34 (for example, a 3-loop tuner). Tuner 34 can be used to minimize reflected energy as a function of changing initiation or processing conditions, especially after plasma formation, because microwave power, for example, will be strongly absorbed by the plasma.

As explained more fully below, the location of the radiation-transmitting cavity 12 in the chamber 14 may not be critical if the chamber 14 supports multiple modes, and especially when the modes are continuously or intermittently mixed. As also more fully explained below, the engine 36 can be connected to the mixer operating modes 38 in order to make the time-averaged distribution of radiation energy almost uniform over the chamber 14. Further, the window 14 (for example, a quartz window) can be located in one of the walls of the chamber 14 adjacent to the cavity 12, which allows the temperature sensor 42 (for example, an optical pyrometer) to be used to view the process inside the cavity 12. In one embodiment, the output of the optical pyrometer can be l is increased from zero volts as the temperature rises to the captured range.

The sensor 42 may generate output signals as a function of temperature or any other controlled condition associated with the workpiece (not shown) inside the cavity 12, and provide signals to the controller 44. Dual temperature sensing and heating, as well as automated cooling rate control and gas stream. The controller 44, in turn, can be used to control the operation of the power source 28, one output of which is connected to the source 26, as described above, and the other output is connected to the valve 22 to control the flow of gas into the cavity 12.

The invention was used with equal success when using microwave sources at both 915 MHz and 2.45 GHz provided by the communications and energy (CPI) industry, although radiation having any frequency of less than about 333 GHz can be used. The 2.45 GHz system provided continuous variable microwave energy from about 0.5 kW to about 5.0 kW. A 3-loop tuner made it possible to match impedance for maximum energy transfer, and a bi-directional combiner was used to measure directional and reflected energy. Optical pyrometers were also used for remote sensing of the temperature sample.

As mentioned above, radiation having any frequency lower than about 333 GHz can be used according to this invention. For example, frequencies such as linear supply frequencies (about 50 to about 60 Hz) can be used, although the pressure of the gas from which the plasma is formed can be lowered to help ignite the plasma. Also, any radio frequency or microwave frequency can be used according to this invention, including frequencies greater than about 100 kHz. In most cases, the gas pressure for such relatively high frequencies should be lowered to ignite, form, or hold the plasma, thereby allowing many plasma processes to occur at atmospheric pressures and above.

The equipment was controlled by a computer using LabView 6i software, which made it possible to control temperature in real time and control microwave energy. Noise was reduced by using averaging of an acceptable number of data points. Also, to improve the speed and efficiency of calculations, the number of data points stored in the buffer array was limited by using shift registers and setting the buffer size.

The pyrometer measured the temperature of the sensitive area of about 1 cm ² , which was used to calculate the average temperature. The pyrometer perceived radiation intensities at two wavelengths and adjusted these intensities using Planck's law to determine the temperature. However, it should be appreciated that other devices and methods for controlling and controlling the temperature are also available and they can be used according to the present invention.

The chamber 14 has several glass-covered inspection openings with radiation screens and one quartz window for pyrometer access. There are also several openings for connecting to a vacuum pump and a gas source, although they are not necessarily used.

The system 10 also included a closed cooling system with deionized water (not shown), while the external heat exchanger is cooled by tap water. During operation, deionized water first cooled the magnetron, then the load was released in the circulator (used to protect the magnetron) and ultimately the radiation chamber through the water channels welded to the outer surface of the chamber.

Plasma catalysts

The plasma catalyst of this invention may include one or more different substances and may be either passive or active. A plasma catalyst can be used, inter alia, to ignite, form and / or hold plasma at a gas pressure less than or equal to or greater than atmospheric pressure.

One plasma forming method of this invention may include exposing the gas in the cavity to electromagnetic radiation having a frequency of less than about 333 GHz in the presence of a passive plasma catalyst. The passive plasma catalyst of this invention may include any object capable of inducing plasma by deforming a local electric field (e.g., an electromagnetic field) in accordance with this invention, without the need to add additional energy through the catalyst, such as applying an electrical voltage to create a spark.

The passive plasma catalyst in accordance with this invention may also be a nanoparticle or nanotube. As used herein, the term “nanoparticle” can include any particle having a maximum physical size of less than about 100 nm, which is at least electrically semiconductor. As single-walled and multi-walled carbon nanotubes, alloyed and undoped, can be especially effective for igniting the plasma according to this invention due to their exceptional electrical conductivity and elongated shape. Nanotubes can be of any convenient length and can be powder fixed to the substrate. If they are fixed, then the nanotubes can be randomly oriented on the surface of the substrate or fixed to the substrate (for example, in some given orientation), while the plasma is ignited or held.

The passive plasma catalyst may also be a powder in accordance with this invention, and there is no need for a compromise between nanoparticles or nanotubes. It can be formed, for example, from fibers, dust particles, flakes, sheets, etc. When it is in powder form, the catalyst may be suspended, at least temporarily, in the gas. By suspending the powder in a gas, the powder can be rapidly dispersed throughout the cavity and, if desired, more easily consumed.

In one embodiment of the invention, the powder catalyst may be introduced into the cavity and at least temporarily suspended in a carrier gas. The carrier gas may be the same or different from the gas that forms the plasma. Also, the powder may be added to the gas prior to introduction into the cavity. For example, as shown in FIG. 1A, the radiation source 52 may supply radiation to the radiation cavity 55 in which the plasma cavity 60 is located. The powder source 65 provides the catalytic powder 70 to the gas stream 75. In an alternative embodiment, the powder 70 is first added to the cavity 60 in bulk (for example, bales) and then distributed in the cavity by any of the paths, including passing gas through or over the dusted powder. In addition, the powder can be added to the gas to ignite, form, or hold the plasma by moving, transferring, spraying, spraying, blowing, or otherwise, feeding the powder into and inside the cavity.

In one embodiment, the plasma was ignited in the cavity by placing a bale of carbon fiber powder in a copper pipe that passed through the cavity. Although sufficient radiation was directed into the cavity, the copper tube shielded the powder from the radiation, and plasma ignition did not occur. However, as soon as the carrier gas began to pass through the tube, forcing the powder to move from the tube into the cavity and thereby exposing the powder to radiation, the plasma ignited almost instantly in the cavity.

The powder plasma catalyst of the present invention can be substantially non-combustible, so that it should not contain oxygen or burn in the presence of oxygen. Thus, the catalyst may include metal, carbon, carbon alloys, carbon-based composite materials, an electrically conductive polymer, a conductive silicone elastomer, a polymer nanocomposite, an organic-inorganic composite, and any combination thereof.

Also, powder catalysts can be almost uniformly distributed in the plasma cavity (for example, when suspended in a gas), and the initiation of the plasma can be precisely controlled inside the cavity. Uniform initiation may be important in some applications, including applications requiring a short plasma exposure, such as in the form of one or more bursts. Anyway, a certain amount of time may be required for the powder catalyst to be distributed throughout the cavity, especially in complex, multi-chamber cavities. Therefore, in accordance with another aspect of the present invention, a powder catalyst can be introduced into the cavity through a plurality of ignition holes in order to more quickly obtain a more uniform distribution of the catalyst in it (see below).

In addition to the powder, the passive plasma catalyst of this invention may include, for example, one or more microscopic or macroscopic fibers, sheets, needles, threads, strands, hairs, yarn, twine, shavings, chips, chips, woven material, tape, beard hair or any combination thereof. In these cases, the plasma catalyst may have at least one portion with one physical size that is significantly larger than the other physical size. For example, the ratio between at least two orthogonal dimensions should be at least about 1: 2, but it can also be more than about 1: 5, or even more than about 1:10.

Thus, a passive plasma catalyst may include at least one part of a material that is relatively thin compared to its length. A bundle of catalysts (e.g. fibers) may also be used and may include, for example, a section of graphite tape. In one experiment, a section of tape was successfully used, having approximately thirty thousand strands of graphite fiber, each with a diameter of about 2-3 microns. The number of fibers and the length of the bundle are not critical for ignition, formation and retention of plasma. For example, satisfactory results were obtained using a graphite tape section about one quarter of an inch long (about 6.3475 mm). One type of carbon fiber that has been used successfully in this invention is marketed under the trademark Magnamite ^® Model No. AS4C-GP3K, Hexel Corporation, from Anderson, South Carolina, USA. Silicon carbide fibers have also been used successfully.

A passive plasma catalyst in accordance with another aspect of the present invention may include one or two parts that are, for example, substantially spherical, annular, pyramidal, cubic, planar, rectangular or elongated.

Passive plasma catalysts discussed above include at least one material that is at least electrically semiconductor. In one embodiment, the material may have high conductivity. For example, the passive plasma catalyst of the present invention may include metal, inorganic matter, carbon, carbon alloy, carbon composite, conductive polymer, conductive silicone elastomer, polymer nanocomposite, organic-inorganic composite, and any combination thereof. Some possible inorganic substances that can be included in a plasma catalyst include carbon, silicon carbide, molybdenum, platinum, tantalum, tungsten, carbon nitride and aluminum, although there are reasons to believe that other electrically conductive inorganic substances also work well.

In addition to one or more electrically conductive materials, the passive plasma catalyst of the present invention may include one or more additives (which should not be electrically conductive). When used in this invention, the additive may include any substance that the user wants to add to the plasma. For example, when doping semiconductors and other materials, one or more dopants can be added to the plasma via a catalyst. The catalyst may include the dopant itself, or it can include a precursor material which, after decomposition, can form a dopant. Thus, the plasma catalyst may include one or more additives and one or more electrically conductive materials in any desired ratio, depending on the desired final plasma composition and plasma-using process.

The ratio of electrically conductive components to additives in a passive plasma catalyst may vary with time during consumption. For example, during ignition, a plasma catalyst could desirably include a relatively large percentage of electrically conductive components to improve ignition conditions. On the other hand, if it is used in plasma confinement, the catalyst could include a relatively large percentage of additives. Specialists in this field will understand that the ratio of the components of the plasma catalyst used to initiate and maintain plasma can be the same.

A predetermined ratio profile can be used to simplify many plasma processes. In many conventional plasma processes, components are added to the plasma as needed, but such an addition requires programmable equipment to add the components according to a predetermined schedule. However, in accordance with this invention, the ratio of components in the catalyst may vary, and thus the ratio of components in the plasma itself may automatically vary. That is, the ratio of the components in the plasma at any given time depends on what portions of the catalyst are currently consumed by the plasma. Thus, the ratio of the components of the catalyst can be different in different places inside the catalyst. And the current ratio of the components in the plasma may depend on the proportions of the catalyst that was used now and / or earlier, especially when the rate of gas flow through the plasma chamber is relatively slow.

The passive plasma catalyst of this invention may be uniform, heterogeneous, or differentiated. Also, the ratio of the components of the plasma catalyst can vary continuously or intermittently in the catalyst. For example, in FIG. 2, the ratio can vary smoothly, forming a gradient along the length of the catalyst 100. The catalyst 100 may include a bundle of material that contains a relatively low concentration of components in section 105 and continuously increases the concentration towards section 110.

Alternatively, as shown in FIG. 3, the ratio may vary intermittently in each part of the catalyst 120, which includes, for example, alternating sections 125 and 130 having different concentrations. It should be noted that the catalyst 120 may have more than two types of sections. Thus, the ratio of the components of the catalyst consumed by the plasma can vary in any predetermined manner. In one embodiment of the invention, when a specific additive is monitored and detected in the plasma, further processing can be automatically started or completed.

Another way to change the ratio of the components in the retained plasma is to introduce a plurality of catalysts having different component ratios at different times or at different speeds. For example, a multiple catalyst may be introduced at approximately the same place or at different places within the cavity. When it is introduced in various places, the plasma formed in the cavity may have a concentration gradient of the components determined by the location of the various catalysts. Thus, the automated system may include a device by which the consumed plasma catalyst is mechanically inserted before and / or during ignition, formation and / or retention of the plasma.

The plasma catalyst of this invention may also be coated. In one embodiment, the catalyst may include a substantially non-conductive coating applied to the surface of the substantially conductive material. Alternatively, the catalyst may include a substantially conductive coating deposited on the surface of a substantially non-conductive material. For example, FIGS. 4 and 5 show a fiber 140 that includes an underlying layer 145 and a coating 150. In one embodiment, a plasma catalyst comprising a carbon core is coated with nickel to prevent carbon oxidation.

A single plasma catalyst may also include multiple coatings. If the coatings are consumed during contact with the plasma, the coatings could be introduced into the plasma sequentially, from the outer coating to the innermost coating, thereby creating a delay mechanism. Thus, a coated plasma catalyst may include any number of materials, as long as the portion of the catalyst is at least electrically semiconductor.

According to another embodiment of the present invention, the plasma catalyst can be completely located inside the radiation cavity to significantly reduce or prevent leakage of radiation energy. Thus, the plasma catalyst is not electrically or magnetically coupled to the vessel containing the cavity, or to any electrically conductive object outside the cavity. This prevents the formation of a spark at the ignition window and prevents leakage of radiation outside the cavity during ignition and possibly later when the plasma is held. In one embodiment, the catalyst may be located at the top of a substantially electrically non-conductive extension cable that extends through the ignition hole.

6, for example, a radiation chamber 160 is shown in which a plasma cavity 165 is placed. The plasma catalyst 170 is elongated and extends through the ignition hole 175. As shown in FIG. 7, and in accordance with the invention, the catalyst 170 may include an electrically conductive distal portion 180 (which is placed in the chamber 160) and an electrically non-conductive part 185 (which is placed practically outside the chamber 160). This configuration prevents electrical connection (e.g., arcing) between the distal portion 180 and the chamber 160.

In another embodiment shown in FIG. 8, the catalyst may be formed of a plurality of electrically conductive segments 190 separated from and mechanically connected to a plurality of electrically non-conductive segments 195. In this embodiment, the catalyst can propagate through an ignition hole between a point inside the cavity and another point outside the cavity, but an electrically intermittent profile significantly prevents sparking and energy leakage.

Another plasma forming method of this invention involves exposing the gas in the cavity to electromagnetic radiation having a frequency of less than about 333 GHz in the presence of an active plasma catalyst that generates or includes at least one ionizing particle.

The active plasma catalyst of this invention can be any particle or high-energy wave packet capable of transferring a significant amount of energy to a gaseous atom or molecule to remove at least one electron from a gaseous atom or molecule in the presence of electromagnetic radiation.

Depending on the source, the ionizing particles can be directed into the cavity in the form of a focused or collimated beam, or they can be sprayed, squeezed out, sprayed or introduced differently.

For example, FIG. 9 shows a radiation source 200 directing radiation to a radiation chamber 205. Plasma cavity 210 is located inside chamber 205 and may allow gas to flow through openings 215 and 216. Source 220 directs ionizing particles 225 to cavity 210. Source 220 may be protected, for example, by a metal shield that allows ionizing particles to pass through, but shields the source 220 from radiation. If necessary, source 220 may be water cooled.

Examples of ionizing particles of this invention may include x-ray particles, gamma-ray particles, alpha particles, beta particles, neutrons, protons, and any combination thereof. Thus, the catalyst on ionizing particles can be charged (for example, an ion from an ion source) or discharged and may be the product of a nuclear fission process. In one embodiment of the invention, the vessel in which the plasma cavity is formed can completely or partially pass the ionizing particle catalyst. The source of radioactive fission can be located inside the radiation chamber and practically prevent fission products (for example, a catalyst based on ionizing particles) from creating a security risk.

In another embodiment, the ionizing particle may be a free electron, but it should not be emitted during the fission process. For example, an electron can be introduced into a cavity by exciting an electron source (like a metal) so that the electrons have enough energy to escape from the source. The electron source can be placed inside the cavity, next to the cavity, or even in the wall of the cavity. Ordinary specialists in this field will understand that any combination of electron sources is possible. The usual way to produce electrons is by heating a metal, and these electrons can be further accelerated by applying an electric field.

In addition to electrons, free energy protons can also be used to catalyze plasma. In one embodiment, a free proton can be generated by ionization of hydrogen and, optionally, be accelerated by an electric field.

One advantage of the active and passive catalyst of this invention is that they can catalyze plasma almost continuously. A spark device, for example, can only catalyze plasma when a spark is present. A spark, however, is usually generated by applying a voltage between two electrodes. Usually sparks are generated periodically and separated by periods in which a spark is not generated. During such sparkless periods, plasma is not catalyzed. Also, spark devices, for example, typically require electrical energy to operate, although the active and passive plasma catalysts of this invention do not require electrical energy to operate.

Multimode radiation cavities

A radiation waveguide, cavity or chamber may be designed to maintain or facilitate the propagation of at least one mode of electromagnetic radiation. As used herein, the term “mode” refers to a specific pattern of any standing or propagating electromagnetic wave that satisfies the Maxwell equations and acceptable boundary conditions (eg, “cavity”). In a waveguide or cavity, a mode can be any one of various propagation or standing patterns of electromagnetic fields. Each mode is characterized by its frequency and polarization of the vectors of the electric and / or magnetic field. The scheme of the electromagnetic field of the mode depends on the frequency, reflection coefficients or dielectric constants, and the geometry of the waveguide or cavity.

A transverse electric mode (TE) is a mode (of electromagnetic waves) in which the electric field vector is normal (perpendicular) to the direction of propagation (of electromagnetic waves). Similarly, the transverse magnetic (TM) mode is a mode in which the magnetic field vector is normal to the direction of propagation. A transverse electric and magnetic (TEM) mode is a mode in which both vectors of both electric and magnetic fields are normal to the direction of propagation. A hollow metal waveguide usually does not support the normal mode (TEM) of radiation propagation. Even though the impression is that the radiation moves along the length of the waveguide, it can do this only by reflecting from the internal walls of the waveguide at a certain angle. Therefore, depending on the propagation mode, the radiation (for example, microwave) can have either some component of the electric field or some component of the magnetic field along the waveguide axis (part called the z axis).

The actual distribution of the field inside the cavity or waveguide is a superposition (superposition) of modes in it. Each mode can be identified by one or more subscripts (for example, TE ₁₀ ("t e one zero")). These subscripts usually indicate how many "half-waves" along the length of the waveguide are contained in the x and y directions. Specialists in this field will understand that the wavelength may differ from the wavelength of free space, because the radiation propagates inside the waveguide by reflection at a certain angle from the inner walls of the waveguide. In some cases, a third subscript may be added to determine the number of half-waves in the standing wave pattern along the z axis.

For a given radiation frequency, a sufficiently small waveguide size can be chosen so that it can support a single propagation mode. In such a case, the system is called a “single-mode system” (ie, a single-mode applicator). The TE ₁₀ mode usually prevails in a rectangular single-mode waveguide.

As the size of the waveguide (or the cavity to which the waveguide is connected) increases, the waveguide or applicator can sometimes support additional higher-order modes, forming a multimode system. When many modes can be supported at the same time, the system is often called high-mod.

A simple, single-mode system has a field distribution that includes at least one maximum and / or minimum. The magnitude of the maximum largely depends on the magnitude of the radiation supplied to the system. Thus, the field distribution of a single-mode system fluctuates strongly and is largely inhomogeneous.

Unlike a single-mode cavity, a multimode cavity can support several propagation modes simultaneously, which, when superimposed, lead to a complex field distribution scheme. In such a scheme, the fields tend to spatially diffuse, and thus the field distribution usually does not show the same types of strong minimum and maximum field values inside the cavity. In addition, as explained more fully below, a mode mixer (for example, a mechanically moving radiation reflector) can be used to “shake” or “redistribute” the modes. This redistribution desirably provides a more uniform time-averaged field distribution within the cavity.

The multimode cavity in accordance with this invention can support at least two modes and can support significantly more than two modes. Each mode has a maximum electric field vector. Although there can be two or more modes and one mode can be dominant and has a maximum electric field vector that is larger than other modes. When used here, a multimode cavity can be any cavity in which the ratio between the values of the first and second modes is less than about 1:10 or less than about 1: 5 or even less than about 1: 2. Ordinary specialists in this field will understand that the smaller the ratio, the more distributed will be the energy of the electric field between the modes and, therefore, the more distributed will be the radiation energy in the cavity.

The distribution of the plasma inside the treatment cavity can greatly depend on the distribution of the applied radiation. For example, in a purely single-mode system, there can only be one place in which the electric field reaches a maximum. Consequently, a strong plasma can form only in this single place. In many applications, such a strongly localized plasma can undesirably lead to inhomogeneous plasma treatment or heating (i.e., localized overheating and underheating).

Regardless of whether a single-mode or multi-mode cavity is used in accordance with this invention, ordinary specialists in this field will understand that the cavity in which the plasma is formed can be completely closed or partially open. For example, in some applications, such as plasma-stimulated furnaces, the cavity may be completely closed. However, in other applications it may be desirable to purge the gas through the cavity and, therefore, the cavity should be somewhat open. Thus, the flow, type and pressure of the flowing gas can change over time. This may be desirable because some gases that facilitate the formation of plasma, such as argon, are more easily ignited, but they may not be needed during subsequent plasma treatment.

Mixer mod

For many applications, a cavity containing a uniform plasma is desirable. However, because microwave radiation can have a relatively long wavelength (for example, a few tenths of a centimeter), it can be difficult to achieve a uniform distribution. As a result, in accordance with one aspect of the present invention, radiation modes in a multimode cavity can be mixed or redistributed over a period of time. Since the distribution of the field inside the cavity must satisfy all the boundary conditions imposed by the inner surface of the cavity (if it is metal), it is possible to change these field distributions by changing the position of any part of this inner surface.

In one embodiment of the invention, a movable reflective surface may be placed inside the radiation cavity. The shape and movement of the reflective surface when combined should change the internal surface of the cavity during movement. For example, an L-shaped metal object (ie, “mode mixer”), when rotated around any axis, will change the location and orientation of the reflecting surfaces in the cavity and, therefore, will change the distribution of radiation in it. Any other asymmetric object can also be used (when rotating), but symmetrical objects can also be used to the extent that their relative motion (for example, rotation, translational motion, or a combination of both) causes some change in the location or orientation of the reflecting surfaces . In one embodiment, the mode mixer may be a cylinder that rotates around an axis that is not the longitudinal axis of the cylinder.

Each mode of a multimode cavity can have at least one maximum electric field vector, but each of these vectors can occur periodically according to the internal size of the cavity. Usually these maxima are fixed, assuming that the radiation frequency does not change. However, by moving the mode mixer in such a way that it interacts with the radiation, one can move the positions of the maxima. For example, a mod mixer 38 can be used to optimize the distribution of the field inside the cavity 14 so that the conditions for ignition of the plasma and / or confinement of the plasma are optimized. Therefore, as soon as the plasma is excited, the position of the mode mixer can be changed and moved to the maximum position for a homogeneous time-averaged plasma process (for example, heating).

Thus, in accordance with the present invention, mode mixing can be useful during plasma ignition. For example, when an electrically conductive fiber is used as a plasma catalyst, it is known that the orientation of the fiber can greatly affect the minimum ignition conditions of the plasma. For example, it was noted that when such a fiber is oriented at an angle of more than 60 ° to the electric field, the catalyst does little to improve or weaken these conditions. However, by moving the reflective surface either inside or near the cavity, the distribution of the electric field can be significantly changed.

Mode mixing can also be obtained by triggering radiation into the applicator chamber through, for example, the rotating articulation of the waveguide, which can be mounted inside the applicator chamber. The rotating joint can be mechanically moved (for example, rotated) to effectively start radiation in different directions in the radiation chamber. As a result, a changing field pattern can be generated inside the applicator chamber.

Mode mixing can also be obtained by triggering radiation into the applicator chamber through a flexible waveguide. In one embodiment, the waveguide may extend into the chamber. The position of the end part of the flexible waveguide can be continuously or periodically moved (for example, bent) in any suitable way to trigger radiation (for example, microwave radiation) into the chamber in various directions and / or places. This movement can also lead to mode mixing and facilitate more uniform plasma processing (e.g., heating) on a time-averaged basis. Alternatively, this motion can be used to optimize the location of the plasma for ignition or other plasma processes.

If the flexible waveguide is rectangular, simply twisting the open end of the waveguide will invert the orientation of the vectors of the electric and magnetic fields in the radiation inside the applicator chamber. Then, periodic twisting of the waveguide can lead to mixing of the modes, as well as to the rotation of the electric field, which can be used to assist in ignition, formation or retention of the plasma.

Thus, even if the initial orientation of the catalyst is perpendicular to the electric field, redirection of the electric field vectors can change the ineffective orientation to a more effective one. Those skilled in the art will understand that mode mixing can be continuous, batch, or reprogrammable.

In addition to plasma ignition, mode mixing can be useful during subsequent plasma processing to reduce or create (for example, adjust) hot spots in the chamber. When the microwave cavity supports only a small number of modes (for example, less than 5), one or more localized field maxima can lead to “hot spots” (for example, inside the cavity 12). In one embodiment of the invention, these hot spots may be configured to coincide with one or more separate but simultaneous plasma ignitions or processing events. Thus, the plasma catalyst can be located at one of these positions of ignition or subsequent processing.

Multiple ignition

Plasma can be ignited by using multiple plasma catalysts in various places. In one embodiment, multiple fibers could be used to ignite the plasma at various points within the cavity. Such multi-point ignition can be especially useful when uniform plasma ignition is desired. For example, when a plasma is formed at a high frequency (for example, tens of Hz and above) or is ignited in a relatively large volume, or both, an almost uniform instantaneous ignition and re-ignition of the plasma can be improved. Alternatively, when plasma catalysts are used at a plurality of points, they can be used to sequentially ignite the plasma at various locations within the plasma chamber by selectively introducing the catalyst at those various locations. Thus, inside the cavity, if desired, a plasma ignition gradient can be formed in a controlled manner.

Also in a multimode cavity, an arbitrary distribution of the catalyst over multiple locations in the cavity increases the likelihood that at least one of the fibers or any other passive plasma catalyst of the present invention will be optimally oriented in the electric field lines. Still, even when the catalyst is not optimally oriented (not centered on the electric field lines), the ignition conditions are improved.

Moreover, since the catalyst powder can be suspended in a gas, it is believed that each powder particle can have the effect of being placed in a different physical location within the cavity, thereby improving the uniformity of ignition within the cavity.

Two-sheet ignition / plasma retention

The two-cavity arrangement can be used to ignite and hold the plasma of this invention. In one embodiment, the system includes at least a first ignition chamber and a second ignition chamber in fluid communication with the first cavity. To ignite the plasma, the gas in the first ignition chamber must be exposed to electromagnetic radiation with a frequency of less than 333 GHz, with the possibility of the presence of a plasma catalyst. Thus, the proximity of the first and second cavities can allow the plasma formed in the first cavity to ignite the plasma in the second cavity, which can be retained by additional electromagnetic radiation.

In one embodiment of the invention, the first cavity may be very small and is intended primarily or exclusively for igniting the plasma. In this way, very little microwave energy may be required to ignite the plasma, which makes it easier to ignite, especially when the plasma catalyst is used in accordance with this invention.

In one embodiment of the invention, the first cavity may be a substantially single-mode cavity, and the second cavity a multi-mode cavity. When the first ignition cavity supports a single mode, the distribution of the electric field can vary greatly inside the cavity, forming one or more precisely located maxima of the electric field. Peaks like these are usually the first places in which the plasma is ignited, making them ideal points for placing plasma catalysts. However, it should be understood that when a plasma catalyst is used, it should not be placed at the maximum of the electric current and in many cases should not be oriented in any particular direction.

In the preceding embodiments, various features are grouped together into one embodiment for the purpose of simplifying the disclosure. This method of disclosure should not be interpreted as a reflection of the intention that the claimed invention requires a greater number of features, in addition to explicitly reflected in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all the features of the particular disclosed exemplary embodiment above. Therefore, the following claims are included in the detailed description of embodiments of the invention, with each claim being independent and considered as a separate preferred embodiment of the invention.

Claims (48)

1. A method of forming a plasma, including: passing gas into a multimode processing cavity and igniting a plasma by exposing the gas in the cavity to electromagnetic radiation having a frequency of less than 333 GHz in the presence of at least one passive plasma catalyst comprising a material that is at least electrically semiconductor. 2. The method according to claim 1, characterized in that the material includes at least one metal, inorganic substance, carbon, carbon-based alloy, carbon-based composite, conductive polymer, conductive silicone elastomer, polymer nanocomposite, organic-inorganic composite and any combination thereof. 3. The method according to claim 2, characterized in that the material is presented in at least one of the forms: nanoparticles, nanotubes, powder, dust, flakes, fibers, sheet, needles, threads, strands, hair, yarn, twine, hair beards, splinter, slivers, woven material, tape, fiber crystal, or any combination thereof. 4. The method according to claim 3, characterized in that the material includes carbon fiber. 5. The method according to claim 1, characterized in that the material includes carbon and is presented in at least one of the forms: nanoparticles, nanotubes, powder, dust, flakes, fibers, sheet, needles, threads, strands, hair, yarn , twine, beard hair, shard, slivers, woven material, tape, fiber crystal, or any combination thereof. 6. The method according to claim 1, characterized in that the material includes at least one nanotube. 7. The method according to claim 1, characterized in that the material is at least partially coated with a second material. 8. The method according to claim 1, characterized in that at least one passive plasma catalyst comprises a plurality of elongated electrically conductive positions distributed at different places in the cavity. 9. The method according to claim 8, characterized in that the radiation has electric field lines, each of the elongated positions having a longitudinal axis, while the longitudinal axes are not substantially centered with the electric field lines. 10. The method according to claim 1, characterized in that the plasma catalyst includes at least one electrically conductive component and at least one additive in the ratio, and also that the method further includes plasma confinement, wherein the confinement includes: the direction of the additional electromagnetic radiation into the cavity and allowing the catalyst to be absorbed by the plasma, so that the plasma contains at least one additive. 11. The method according to claim 10, characterized in that the ratio is different for different portions of the catalyst, wherein the possibility includes enabling various parts of the catalyst to be absorbed by the plasma at different times so that the plasma contains a varying ratio of the electrical conductive component, at least to one supplement. 12. The method according to claim 1, characterized in that the multimode cavity is configured to maintain at least the first mode and the second radiation mode, each mode having a maximum electric field vector in the cavity, and each vector has a value, when this ratio between the magnitude of the first mode and the magnitude of the second mode is less than 1:10. 13. The method according to p. 12, characterized in that the ratio is less than 1: 5. 14. The method according to item 13, wherein the ratio is less than 1: 2. 15. The method according to 14, characterized in that the multimode cavity is configured to maintain at least the first mode and the second radiation mode, each mode having a maximum electric field vector in the cavity at a position, the method further moving each of the positions by mixing mods. 16. The method according to claim 1, characterized in that the ignition includes ignition of a plurality of plasma catalysts in various places in the cavity. 17. The method according to claim 1, characterized in that the cavity is a radiation chamber, and the catalyst is placed completely in the chamber so that the catalyst practically does not conduct electric current to the chamber or to any electrically conductive object located outside the chamber. 18. The method according to claim 1, characterized in that the catalyst is located on top of a practically non-conductive extension cord, which passes through the ignition hole in the radiation chamber. 19. The method according to claim 1, characterized in that the catalyst comprises a plurality of discontinuous segments separated and mechanically connected to a plurality of electrically non-conductive segments, during which the catalyst passes through the ignition hole in the cavity between a place inside the cavity and another place outside the cavity . 20. The method according to claim 1, characterized in that the ignition includes igniting the plasma with a catalyst suspended in a cavity. 21. A method of forming a plasma, comprising igniting a plasma by exposing the gas to electromagnetic radiation having a frequency of less than 333 GHz, in the presence of a plasma catalyst comprising a powder. 22. The method according to item 21, wherein the exposure occurs in the chamber, and the method further includes passing gas into the chamber. 23. The method according to item 21, wherein the exposure occurs in a cavity located in the chamber. 24. The method according to item 23, wherein the camera is a multimode camera. 25. The method according to item 21, further comprising introducing the powder into the radiation using a carrier gas. 26. The method according to item 21, further comprising introducing the powder into the radiation using a sequence of operations, where the powder at least temporarily hangs in the cavity, while these operations consist of at least a feed, gravity feed, transfer, spray spraying and blowing. 27. The method according to item 21, further comprising introducing the powder into the cavity through the many holes of the ignition. 28. The method according to item 21, wherein the ignition includes ignition of the plasma, while the powder is in a suspended state. 29. The method according to item 21, wherein the plasma catalyst includes a non-combustible material. 30. The method according to clause 29, wherein the plasma catalyst is at least one of: metal, carbon, carbon-based alloy, an electrically conductive polymer, a conductive silicone elastomer, a polymer nanocomposite and an organic-inorganic composite. 31. A method of forming a plasma, comprising exposing a gas in a cavity to electromagnetic radiation having a frequency of less than 333 GHz, in the presence of an active plasma catalyst comprising at least one ionizing particle. 32. The method according to p, characterized in that at least one ionizing particle comprises a particle beam. 33. The method according to p, characterized in that the particle is at least one particle of the x-ray beam, alpha particle, beta particle, neutron and proton. 34. The method according to p, characterized in that at least one ionizing particle is a charged particle. 35. The method according to p, characterized in that the ionizing particle comprises a radioactive fission product. 36. The method according to clause 35, wherein the cavity is formed in the vessel, which at least partially passes the fission product, the method further includes positioning the fission source outside the cavity so that the source directs the fission product through the vessel into cavity. 37. The method according to clause 35, wherein the vessel and the fission source are inside the radiation chamber, while the camera includes a material that practically prevents the leakage of the product from the camera. 38. The method according to clause 35, further comprising positioning the source of radioactive fission in the cavity, characterized in that the source generates at least one fission product. 39. The method according to p, characterized in that the ionizing particle is a free electron, the method further comprising generating an electron by supplying energy to an electron source. 40. The method according to § 39, wherein the energy supply includes heating an electron source. 41. The method according to p, characterized in that the particle includes a free proton, the method further comprising generating a free proton by ionizing hydrogen. 42. The method according to p, characterized in that the cavity is at least partially open, allowing gas to flow through it. 43. A method of forming a plasma in a system, characterized in that the system has at least one ignition cavity and a second cavity in fluid communication with the first cavity, the method comprising: exposing the gas in the first ignition cavity to electromagnetic radiation having a frequency of less than 333 GHz, so that the plasma in the first cavity causes the formation of plasma in the second cavity; and retention of the second plasma by exposing it to additional electromagnetic radiation. 44. The method according to item 43, wherein the exposure includes exposing the gas to radiation in the presence of a plasma catalyst. 45. The method according to item 43, wherein the first cavity is smaller than the second cavity. 46. The method according to item 45, wherein the first cavity is practically a single-mode cavity, and the second cavity is a multimode cavity. 47. The method according to item 46, wherein the second cavity is high-mode. 48. The method according to item 44, wherein the plasma catalyst includes carbon fiber.

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