KR20090011059A - Apparatus for generating plasma - Google Patents

Abstract

A plasma generator is provided to facilitate operation by controlling a plasma repetition rate and the energy delivered to the plasma. A plasma repetition rate and the plasma energy are inputted to an external input unit(10). An interface(30) stores and converts the input signal inputted from the input unit. A power supply unit(20) receives the energy size and frequency information from the interface and supplies the power. A frequency oscillator(40) receives the power from the power supply unit and oscillates the radio frequency or the microwave frequency. The frequency having the energy of the constant size oscillated from the frequency oscillator is transmitted through the transmission line(50). A plasma reactor(100) generates the plasma by reacting the plasma gas injected from a gas supply unit with the electric field induced by the energy with the frequency transmitted though the transmission line.

Description

Plasma Generator {APPARATUS FOR GENERATING PLASMA}

The present invention relates to a plasma generator, and more particularly, to a plasma generator that can be easily handled by a user by controlling the energy and plasma repetition rate delivered to the plasma.

In general, a plasma is known as a fourth material state composed of electrons and ions having electrical polarity, and is generally in a state in which the negative and positive charges are distributed at almost the same density, and thus are almost neutral. Plasma is high temperature plasma like arc and high energy of electrons but low energy of ions, so the actual temperature is classified as low temperature plasma close to room temperature and is mostly generated by electric discharge such as direct current, alternating current, ultra-high frequency and electron beam. In addition, it is used for cleaning, etching and depositing semiconductor parts because the plasma can be stably generated at low pressure. The plasma at atmospheric pressure is used for surface cleaning, environmental pollutant treatment, new material synthesis, and medical treatment. Used in various fields such as appliances.

An electric field of a suitable frequency may be applied to the gas to generate a plasma. For example, the frequency may be a standard frequency (500 kHz band and 2450 MHz band) applicable to electrosurgical surgery. For plasma generation, the oscillating voltage of this frequency is applied to a reactor of an electrode or resonance structure having a suitable structure in order to generate an electric field of a corresponding frequency. The power delivered to the plasma generated by the electrical discharge is controlled by monitoring the power reflected from the electrode or resonator and adjusting the impedance, which in turn increases the plasma power. Korean Patent No. 10-0394994 relates to a plasma torch using electromagnetic waves, which transmits an ultra-high frequency of 2450 MHz to a waveguide, focuses it on a discharge tube installed at a specific position of the waveguide, and then generates an electrodeless microwave plasma by a spark ignition device. . Controlling the emission of carbon fluoride gas (Korean Patent No. 10-0454085) using the above Korean Patent (10-0394994), the chemical poison gas and bacteria removal device sprayed in the air (Korean Patent No. 10-0554712), carbon nanotubes Synthesis (Korean Patent No. 10-0582249), synthesis of nitrogen-doped titanium dioxide nanopowder (Korean Patent No. 10-0613122), plasma flame generator (Korean Patent No. 10-0638109) and the like.

In addition, Korean Patent No. 10-0531427 relates to an electromagnetic plasma torch and welding system for local heating, cutting and joining, and transmits 2450 MHz ultra-high frequency to a waveguide to install a metal nozzle electrode at a specific position of the waveguide to A plasma apparatus capable of focusing. The above-mentioned Korean patents transmit 2450 MHz ultra high frequency waves to a waveguide to install a plasma reactor or electrode at a specific position of the waveguide to expose an electric field induced by 2450 MHz ultra high frequency to the plasma source gas and with the help of a spark or ignition device. There is a common point that continuously generates a high temperature torch plasma.

In the case of the plasma apparatus as described above, the plasma electrode or the reactor is integrated in the ultra-high frequency oscillator and the waveguide, so that it is impossible to easily handle the bulky and heavy. In addition, the ultra-high frequency energy is continuously transferred to the plasma, thereby causing plasma ohmic heating to maintain the plasma close to 5000 ° C.

Therefore, the plasma generator, which can easily handle and control the energy delivered to the plasma, is expected to be very useful, and the development of the system is urgently required.

The present invention has been made to solve the above problems, an object of the present invention is to provide a plasma device that can be easily handled by the user to control the energy delivered to the plasma.

Plasma generator of the present invention for achieving the above object is an input unit for inputting the plasma energy and repetition rate; An interface for storing and converting an input signal input from the input unit; A power supply unit configured to receive energy magnitude and frequency information from the interface and supply power; A frequency oscillator receiving power from the power supply and oscillating a radio frequency or microwave frequency; A transmission line transmitting a frequency having a predetermined magnitude of energy oscillated from the frequency oscillator; And a plasma reactor for generating plasma by reacting an electric field induced by energy having a frequency transmitted from the transmission line and a plasma source gas injected from a gas supply unit. It is configured to include.

 Plasma generator according to the present invention has the effect of providing a plasma device that can be easily handled by the user by controlling the energy and plasma repetition rate delivered to the plasma.

In addition, the present invention can provide the surface treatment of the material using the plasma, in particular, the plasma energy is delivered to the skin of humans and animals, thereby providing the effect of regenerating, treating, and activating biological tissues.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a plasma generating apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a plasma generator according to an embodiment of the present invention includes an input unit 10, a power supply unit 20, an interface 30, a frequency oscillator 40, a transmission line 50, and a user switch 60. , The gas container 70, the gas supply unit 80, and the plasma reactor 100 are configured.

The power supply unit 20 receives information such as energy magnitude and frequency from the interface 30 storing and converting information input by the input unit 10 and supplies power to the frequency oscillator 40. The frequency oscillator 40 may be a radio frequency or microwave frequency oscillator. When the frequency oscillator 40 oscillates a radio frequency, the frequency thereof is preferably 13.56 MHz, and when oscillating the microwave frequency, 2400 MHz to 2500 MHz is preferable.

The input unit 10 is configured such that any user can input plasma energy and repetition rate. Plasma energy is input or selected in Joules and repetition rate in Hertz.

In addition, the user switch 60 may be connected to the interface 30 to connect the power supply unit 20 to turn on / off plasma generation, and the interface 30 accumulates the plasma repetition rate input by the user. The calculation is displayed on the input unit 10. For example, when the user selects 1J and 4 Hz (means 4 plasma generations per second) to the input unit 10 and turns on the user switch 60 for 10 seconds, the plasma having an energy of 1J is generated. It is displayed on the input unit 10 while being countered by turning on / off 40 times.

In addition, the user switch 60 is connected to the interface 30 to link the gas supply unit 80 connected to the gas container 70 to supply the plasma source gas to the plasma reactor (100). Of course, the gas supply unit 60 may continue to supply the gas to the plasma reactor 100 without interlocking with the interface 30. However, the gas supply unit 60 may be linked with the power supply unit 20 through the interface 30 for efficient use of gas.

The power transmitted from the power supply unit 20 to the frequency oscillator 40 is preferably in the form of a pulse and may be in the form of direct current or alternating current. The sign of the pulse is determined according to the operating characteristics of the frequency oscillator 40. For example, when a 2450 MHz oscillator is used, the pulse sign is negative. The discharge pulse width may be 0.5 ms to 150 ms and is preferably 1 ms to 100 ms, more preferably 2 ms to 50 ms. The discharge pulse width refers to the time width during which the plasma is maintained due to the discharge in the applied voltage pulse, and the treatment pulse width when applied to the treatment of the material. The pulse repetition rate can also be from 0.5 Hz to 20 Hz, preferably from 1 Hz to 7 Hz.

The radio frequency or microwave frequency oscillated from the frequency oscillator 40 is transmitted to the plasma reactor 100 via the transmission line 50. The transmission line 50 may be a coaxial cable, a waveguide, or a strip line. In the plasma reactor 100 connected to the transmission line 50, an induction electric field is formed by the transmitted radio frequency or the microwave frequency to expose the plasma raw material gas to generate plasma by discharge.

Impedance matching means is provided in the plasma reactor 100 to deliver the maximum energy to the plasma, and the shape of the reactor includes a structure having a resonance frequency and an internal electrode and an external electrode such as the transmission line 50. It may be a coaxial reactor and a strip reactor consisting of.

The gas supply unit 80 is a means capable of operating by receiving an electrical signal from the interface 30, and preferably may be a solenoid valve, a hydraulic valve or a mass flow controller (MFC).

The plasma source gas supplied to the plasma reactor 100 may vary depending on the plasma application and is generally non-toxic or preferably composed of at least two atoms. For example, it may be argon, helium, nitrogen, or a mixed gas thereof, and carbon dioxide may be used as well as the above-listed gases when applied to the human body. However, even if the same energy frequency is delivered to the plasma reactor 100, the temperature and physical characteristics of the plasma gas are different depending on the gas used.

The operation of the plasma generating apparatus according to the embodiment of the present invention will be described with reference to FIG.

Plasma energy and repetition rate are converted into an input signal by the external input unit 10 and transmitted to the power supply unit 20, and the power supply unit 20 transmits a predetermined amount of energy in the form of a pulse to a radio frequency or a microwave frequency. Transfer to oscillator 40.

A frequency having a predetermined amount of energy oscillated from the frequency oscillator 40 is transmitted to the plasma reactor 100 through a transmission line 50, and the plasma reactor 100 transmits energy having the frequency to the plasma reactor 100. Matching means is provided to deliver the maximum power to the circuit.

Plasma source gas is injected into the plasma reactor 100 and the plasma source gas is exposed to the electric field induced in the plasma reactor 100 to generate plasma by discharge, and the plasma is ejected through the plasma reactor outlet and the outside The input plasma repetition rate is accumulated and the number of discharges is counted.

2 is a cross-sectional view showing a power supply unit and a microwave oscillator of the plasma supply apparatus according to an embodiment of the present invention, Figure 3 is a graph showing the voltage waveform of the power supply unit of the plasma supply apparatus according to an embodiment of the present invention, Figure 4 Sectional view showing a transmission line of the plasma supply apparatus according to an embodiment of the present invention, Figure 5 is a cross-sectional view showing the configuration of a plasma reactor of the plasma supply apparatus according to an embodiment of the present invention, Figure 6 is a plasma according to an embodiment of the present invention A photograph of the plasma discharge of the supply device.

2 to 6, a block denoted by 41 denotes a microwave frequency oscillator and is called a magnetron.

The magnetron 41 is composed of a filament 42, an anode or ground electrode 43, and a microwave antenna 47, which operate largely as a cathode. The filament 42 is supplied with power from the filament heating transformer 26 of the power supply unit denoted by reference numeral 22 and the high voltage power supply unit 24 supplies power to the positive electrode 43 and the negative electrode 42.

The filament 42 supplied with power emits hot electrons into a space provided by the anode 43 and the cathode 42 in which an electric field is formed. The anode 43 has chamber sections (not shown) having a resonance structure connected in series in an annular shape. The space provided by the two electrodes is in a vacuum state and a magnetic field perpendicular to the electric field is formed by the permanent magnets 44 disposed above and below the anode 43, and the hot electrons emitted from the cathode 42 are formed by the electric field. Curved and diffracted by a magnetic field accelerated to anode 43 and perpendicular to the electric field, and then enters one of the resonant sections of anode 43. The energy of electrons entering the resonant sections of the anode 43 is transmitted to the microwave antenna 47 and transmitted to the transmission line 50 through the magnetron cap 46.

The frequency of the electrons is then in the range of 2400 MHz to 2500 MHz, preferably 2460 MHz, and the more power is applied to the filament 42, the hotter the greater the amount of electrons emitted. Instead of the permanent magnet 44, an electromagnet composed of a coil may be installed. In general, the magnetron has an electrical energy efficiency close to 70-80%, and the rest is converted into heat and consumed through the anode 43, so that a cooling device such as the cooling fin 45 is provided and cooled by a cooling fan. Instead, a water jacket can do this. The filament 42 may be supplied with alternating current or direct current power.

The high voltage power supply unit 24 applies a high voltage having a frequency and a pulse width specified from the interface 30 to the magnetron 41. The voltage at that time is preferably in the range of -3.5 to -4.5 kV.

3 is a voltage waveform when the plasma is applied to the magnetron 41 and generates plasma in the plasma reactor 100. At this time, the voltage is -4.2 kV, the plasma repetition rate is 2 Hz, and the plasma energy is 2J. The capacity of the magnetron 41 may be between 0.8 kW and 6 kW and preferably between 1 kW and 1.4 kW, with continuous current at power above 1 kW being applied to the magnetron 41 within each discharge pulse width. Is provided.

The plasma energy is controlled by increasing or decreasing the discharge pulse width and the range is preferably 0.5 J to 5 J. The electrical energy efficiency transmitted from the power supply unit 20 to the plasma is less than 80% in consideration of the efficiency of the magnetron.

Microwaves oscillated from the magnetron 41 are introduced into the plasma reactor 100 via the transmission line 50.

Referring to FIG. 4, the microwave 48 oscillated from the magnetron 41 is installed in the 2.45 GHz microwave launcher 52 and flows into the microwave coupler 56 over the isolator 54. In FIG. 4, W _I and W _R mean microwave incident waves and reflected waves, respectively. The magnetron 41 is installed at a distance of 1/8 wavelength of 2.45 GHz from the end 51 of the microwave launcher 52. The microwave launcher 52, the isolator 54, the microwave coupler 56 is connected to the flanges 53, preferably in the form of a rectangular or cylindrical waveguide.

The microwave coupler 56 couples the microwave energy from the waveguide to the coaxial line from the coaxial line to the waveguide, and the shape of the coupling antenna 57 is door knob, cylindrical, or horn type. It is preferably installed at a position separated by a quarter wavelength from the coupler end 59.

To prevent the incident microwave 48 from reflecting damage to the magnetron 41 by reflecting a portion of the incident microwave by mismatch with the plasma or mismatch with the microwave coupler 56. To this end, the dummy rod 55 of the isolator 54 consumes reflected wave energy. The extension of the plasma reactor 100 and the connector 58 installed in the microwave coupler 56 is made of a coaxial cable. The impedance of the coaxial cable is preferably 50 ohms.

Referring to FIG. 5, the plasma reactor 100 is largely composed of an internal electrode 90, an external electrode 97, and a dielectric tube 99. The center electrode 91 of the coaxial cable 105 extends and is connected to the inner electrode 90 made of molybdenum or tungsten, and the outer electrode 93 of the coaxial cable 105 is an outer electrode of the plasma reactor 100. Connected with 97.

The center electrode 91 and the external electrode 93 of the coaxial cable 105 are filled with a dielectric such as Teflon (PTFE) to avoid direct contact, and the coaxial cable 105 and the plasma reactor 100 are N-Type. Coaxial connectors (not shown) may be connected to each other.

The inner electrode 90 extends in the axial direction within the outer electrode 97 and a dielectric 102 is inserted between the two electrodes to avoid direct electrical contact between the two electrodes.

The dielectric tube 99 is composed of a low loss dielectric such as quartz having a high thermal resistance, and is inserted between the dielectric 102 and the external electrode 97 and at least microseconds from an end of the external electrode 97. It is preferably installed to extend by a quarter length of the wave wavelength and to be detachable.

The external electrode 97 is provided with a gas supply part 94, and the gas introduced from the gas supply part 94 passes through the gas passage 95 installed in the external electrode 97 and the internal electrode 90 and the dielectric material. It passes through the gas passage 96 formed between the 102 and enters the dielectric tube 99 and exits the plasma outlet 101. The gas supply unit 94 may be installed on the side of the external electrode 97, of course. Preferably, the impedance from the end of the external electrode 97 connected to the end of the coaxial cable 105 to the end of the dielectric 102 is 50 Ω.

If sufficient energy is supplied from the outside, plasma may be generated at the end of the internal electrode 90 and may be easily ejected through the dielectric tube to the plasma outlet 101. However, more reliable plasma generation can be achieved by the coil 98 installed in the dielectric tube 99. The coil 98 is installed in close contact with the inner wall of the dielectric tube 99 and does not contact the internal electrode 90. Therefore, the coil may have a component of capacitance and inductance.

The helical tungsten coil 98 thus acts as a resonator providing a resonant frequency to the operating frequency of the incident microwaves. The coil 98 is installed in close contact with the inside of the dielectric tube 99. The coil 98 is not in contact with the internal electrode 90, and an end thereof is close to an end of the internal electrode 90. For example, when the frequency of the incident microwave is 2.45 GHz (the wavelength at this time is 12.1 cm), the length of the coil 98 is approximately 1.5 cm to 2 cm, pitch 0.5 cm, outer diameter 0.55 cm, coil It is preferable to configure the thickness of 0.2 mm to 0.3 mm.

In addition, the coil 98 not only causes the operating frequency and resonance, but also sparks due to the incident microwaves to serve as an ignition device.

6 is a plasma photograph generated according to the configuration of the embodiment of the present invention described above. The gas used was nitrogen and 5 liters per minute were injected from the side of the external electrode with a plasma energy of 2 J.

1 is a block diagram illustrating a plasma generating apparatus according to an embodiment of the present invention;

2 is a cross-sectional view showing a power supply unit and a microwave frequency oscillator of the plasma generating apparatus according to an embodiment of the present invention;

3 is a graph showing a voltage waveform of a power supply unit of a plasma generator according to an embodiment of the present invention;

4 is a cross-sectional view showing a transmission line of a plasma generating apparatus according to an embodiment of the present invention;

5 is a cross-sectional view showing the configuration of a plasma reactor of the plasma generating apparatus according to an embodiment of the present invention;

6 is a photograph of the plasma discharge of the plasma generating apparatus according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: external input unit 20: power supply unit

30: interface 40: frequency oscillator

50: transmission line 80: gas supply unit

90: internal electrode 97: external electrode

98: coil 99: dielectric tube

100: plasma reactor 105: coaxial cable

Claims (14)

An input unit to which plasma energy and repetition rate are input; An interface for storing and converting an input signal input from the input unit; A power supply unit configured to receive energy magnitude and frequency information from the interface and supply power; A frequency oscillator receiving power from the power supply and oscillating a radio frequency or microwave frequency; A transmission line transmitting a frequency having a predetermined magnitude of energy oscillated from the frequency oscillator; And A plasma reactor generating plasma by reacting an electric field induced by energy having a frequency transmitted from the transmission line and a plasma source gas injected from a gas supply unit; Plasma generating apparatus comprising a. The method of claim 1, The plasma reactor is characterized in that the plasma generator is characterized in that the impedance matching means for delivering the maximum energy to the plasma. The method of claim 1, And the interface accumulates the plasma repetition rate input by the user and displays the accumulated repetition rate on the input unit. The method of claim 1, And a voltage waveform supplied by the power supply unit is a pulse. The method of claim 4, wherein The discharge pulse width of the power supply device is a plasma generator, characterized in that 2 ms to 50 ms. The method of claim 1, Wherein the frequency of the frequency oscillator is a 13.56 MHz radio frequency or a microwave frequency in the 2400 MHz to 2500 MHz range. The method of claim 6, The power of the frequency oscillator is a plasma generator, characterized in that 0.8 kW to 6 kW. The method of claim 1, And a plasma energy value input by the input unit is 0.5 J to 5 J. The method of claim 1, And a pulse repetition rate input by the input means is 1 Hz to 7 Hz. The method of claim 1, The transmission line is a plasma generator, characterized in that consisting of a microwave launcher, microwave coupler or coaxial cable. The method of claim 1, The plasma reactor is characterized in that the plasma generator is characterized in that the coaxial structure is inserted. The method of claim 11, Plasma generator, characterized in that the helical coil is inserted into the dielectric tube. The method of claim 1, The plasma source gas is any one selected from nitrogen, argon, helium, carbon dioxide, oxygen, air and a mixture thereof. The method of claim 1, And a user switch connected to the interface and interlocked with the power supply unit or the gas supply unit.

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