System and method for obtaining large-volume plasma by utilizing micro-cavity discharge

Abstract

The invention relates to a system and a method for obtaining large-volume plasma by utilizing micro-cavity discharge. The system comprises a vacuum discharge chamber, a positive high-voltage direct-current power supply, a negative high-voltage direct-current power supply, a vacuum pump, a gas source, a mass flow meter, a barometer and the like, a positive bias anode and a micro-cavity cathode are arranged in the vacuum discharge chamber; the positive bias anode is formed by distributing air holes and molybdenum needles on a molybdenum sheet; according to the micro-cavity cathode, a ceramic sheet is clamped between two layers of molybdenum sheets, and a micro-cavity is formed in a cathode plate of a three-layer structure. The positive electrode of the positive high-voltage direct-current power supply is connected with the molybdenum sheet and the molybdenum needle of the positive bias anode and provides positive bias voltage for the positive bias anode; the anode of the negative high-voltage direct-current power supply is connected with an anode molybdenum sheet in the micro-cavity cathode through a current-limiting resistor R2, and the cathode of the negative high-voltage direct-current power supply is connected with a cathode molybdenum sheet in the micro-cavity cathode through a current-limiting resistor R1; and the negative high-voltage direct-current power supply is used for providing negative high voltage for the micro-hollow cathode. According to the invention, the generation volume of high-density plasma is increased, and the discharge volume can reach more than 10 cm < 3 >.

Description

Technical Field

[0001] The invention relates to a gas discharge plasma generating device, in particular to a system and method for obtaining large volume plasma by using micro cavity discharge. Background Art

[0002] With the gradual deepening of gas discharge in the field of plasma generation, microdischarge plasma technology has been more and more widely used in environmental governance, material modification and preparation, sterilization and disinfection, etc. Microdischarge plasma can produce high-density high-energy particles and active particles. Microcavity discharge can be carried out stably in high-pressure environments, in rare gases and molecular gases, and in DC discharge and pulse discharge modes, and can produce high-density, large-volume plasma, and can also inhibit the transformation of glow discharge to arc discharge to a certain extent. Therefore, microcavity discharge has attracted more and more attention from researchers.

[0003] The basic way to generate micro-discharge plasma is that the discharge is confined to a small spatial area. The methods for generating micro-discharge plasma mainly include various discharge forms such as micro-cavity discharge method, micro-dielectric barrier discharge method and capillary discharge method. The micro-cavity discharge method can produce a hollow cathode effect, but the high-density plasma generated by the micro-cavity discharge is generally confined to the micro-cavity. Since the size of the micro-cavity is generally below the millimeter level, the volume of the high-density plasma generated by the micro-cavity discharge is very small, generally in the order of cubic millimeters or even below. Although the density of the plasma generated in the micro-cavity is very high, the plasma density outside the micro-cavity will drop sharply, which is very unfavorable for the application of micro-cavity discharge. Therefore, how to obtain a large volume of high-density plasma has always been one of the hot issues in the field of plasma. In addition, high plasma density is also easy to cause heat inside the cathode cavity, which will cause certain ablation of the discharge electrode, thereby reducing the service life of the system and affecting the stability of the discharge. The large cathode drop of the high electric field will also have a greater adverse effect on the stability of the discharge. Summary of the invention

[0004] The purpose of the present invention is to provide a system and method for obtaining large-volume plasma using micro-cavity discharge, so as to solve the problem that it is difficult to obtain large-volume high-density plasma in the prior art.

[0005] The object of the present invention is achieved in that: A system for obtaining large-volume plasma using micro-cavity discharge, comprising: The vacuum discharge chamber is a closed chamber made of quartz glass, which is provided with an air inlet, an air outlet and an electrode line interface, and is equipped with a positive bias anode and a micro-cavity cathode arranged opposite to each other; the positive bias anode is a molybdenum needle with air holes distributed on a molybdenum sheet and pointing to the micro-cavity cathode; the micro-cavity cathode is a cathode plate with a three-layer structure formed by sandwiching a ceramic sheet between two layers of molybdenum sheets, and a micro-cavity penetrating the cathode plate is opened in the middle of the cathode plate; A positive high-voltage DC power supply, whose negative electrode is grounded and whose positive electrode is connected to the molybdenum sheet and the molybdenum needle of the positive bias anode; the positive high-voltage DC power supply is used to provide a positive bias voltage for the positive bias anode; A negative high-voltage DC power supply, one of which is grounded in one path and connected to the molybdenum sheet in the micro-cavity cathode opposite to the positive bias anode in the other path through a current-limiting resistor R2; and a negative electrode thereof is connected to the molybdenum sheet in the micro-cavity cathode opposite to the positive bias anode in the other path through a current-limiting resistor R1; the negative high-voltage DC power supply is used to provide negative high voltage for the micro-hollow cathode; A vacuum pump connected to the gas outlet of the vacuum discharge chamber through a vacuum pipeline, and used to control the gas pressure in the vacuum discharge chamber; and The gas source is connected to the gas inlet of the vacuum discharge chamber through an air inlet pipeline, and is used to provide discharge gas into the vacuum discharge chamber.

[0006] Furthermore, the system of the present invention also includes: A mass flow meter, connected in series in the air inlet pipeline, for controlling the flow rate of gas entering the vacuum discharge chamber; and The barometer is connected to the barometer interface of the vacuum discharge chamber through a pipeline, and is used to display the gas pressure in the vacuum discharge chamber in real time.

[0007] Furthermore, the vacuum discharge chamber is a tube body made of quartz glass, and the ports at both ends of the tube body are covered by end covers to form a closed chamber; an electrode line interface and a pressure gauge interface are provided on the tube body of the vacuum discharge chamber; the air inlet and the air outlet are respectively arranged on the two end covers of the vacuum discharge chamber.

[0008] Furthermore, the positive bias anode is fixed at one end of the vacuum discharge chamber near the gas outlet through a bracket; the microcavity cathode is embedded in a quartz glass ring with a groove and is arranged at one end of the vacuum discharge chamber near the gas inlet, and three tracks parallel to the center line of the tube body are evenly distributed along the circumference of the inner wall of the vacuum discharge chamber, and the bayonet on the outer edge of the quartz glass ring is clamped on the track.

[0009] Furthermore, one of the conditions for generating plasma discharge in the vacuum discharge chamber is that a stable gas is introduced into the vacuum discharge chamber at a mass flow of no more than 30 SLM.

[0010] The system of the present invention uses a DC high-voltage power supply as an input power supply, and utilizes a vacuum discharge chamber with flow gas control to generate a large volume of high-density plasma between a micro-cavity cathode and a positively biased anode. A fully transparent discharge chamber structure is adopted, and measures such as air intake and exhaust, cathode slots, and air pressure measurement pipelines are used to make the measurement and photography of the discharge process more convenient, and it is easy to control and adjust the discharge parameters. By controlling the changes in parameters such as the voltage of the positively biased anode and the gas flow rate, a high-density, large-volume stable discharge plasma can be generated under the environmental conditions of a single gas or a mixed gas. The present invention can achieve the generation of high-density, stable plasma under the relevant conditions such as the control of gas flow rate and current range. By adjusting parameters such as the input DC power supply voltage, electrode spacing, and mixed gas ratio, the density, current value, and plasma parameters of the micro-discharge plasma and the discharge space can be changed.

[0011] The present invention provides an electric field through a positive bias anode, which correspondingly weakens the cathode drop in micro-cavity discharge; through the introduction of flowing gas, the temperature in the cathode cavity is effectively reduced, and the ablation of the electrode is reduced, thereby solving the problem of discharge instability associated with the generation of high-density plasma to a certain extent. At the same time, through the introduction of a positive bias anode, the high-density plasma in the micro-cavity of the micro-cavity cathode is led out, thereby increasing the generation volume of high-density plasma, and its discharge volume can reach 10cm 3 above.

[0012] The present invention adopts a structure of a positively biased anode formed by a metal needle array combined with a flat plate electrode, which can greatly improve the electric field strength around the positively biased anode. On the one hand, this can play a greater role in attracting electrons emitted from the inside of the microcavity cathode, thereby promoting the breakdown of the discharge space between the microcavity cathode and the positively biased anode, greatly reducing the breakdown voltage and breakdown current, and making it easier to obtain a large volume of high-density plasma; on the other hand, the design of this electrode structure can improve the ionization and excitation between the microcavity cathode and the positively biased anode to a certain extent, thereby making the discharge space density higher. The introduction of flowing airflow, on the one hand, can bring the electrons in the microcavity into the discharge space between the microcavity and the positively biased anode under the action of the airflow; on the other hand, the flowing gas can effectively reduce the electrode temperature, and overcome the ablation of the microdischarge electrode to a certain extent. The design of the fully transparent vacuum discharge chamber and the design of the interface and pipeline make the experimental operation simpler and the measurement results more controllable and accurate.

[0013] The purpose of the present invention can also be achieved like this: A method for obtaining large-volume plasma by using micro-cavity discharge comprises the following steps: S1. Set up a system for generating large-volume plasma using microcavity discharge according to the present invention.

[0014] S2. Fill the vacuum discharge chamber with gas through the gas source and mass flow meter, and then use the vacuum pump to evacuate the gas. After several times of filling and evacuating, the gas pressure in the vacuum discharge chamber reaches below 0.1Pa. Let it stand for 2min-3min to allow the reaction environment in the vacuum discharge chamber to stabilize.

[0015] S3. Inject gas into the vacuum discharge chamber at a mass flow of no more than 30 SLM. After the gas state is stable, connect the negative high-voltage DC power supply and fine-tune the output negative DC voltage. A luminous light column is generated in the vacuum discharge chamber from the micro-cavity cathode to the positively biased anode, causing discharge breakdown in the discharge space. Continue to increase the discharge current, and the volume of the generated plasma will increase accordingly.

[0016] Further, in step S3, the conditions for forming a large volume high density plasma discharge are: the flow rate of the introduced gas reaches 15 SLM, the electron density outside the micro cavity of the micro cavity cathode increases to 10 11 cm -3 Magnitude.

[0017] The present invention uses a DC high-voltage power supply as the input power supply. Under the control of the flowing gas, a relatively large volume of high-density plasma is generated between the micro-cavity cathode and the positively biased anode, thereby realizing the generation of a high-density, large-volume, stable discharge plasma in a flowing single gas or mixed gas environment. By controlling the gas flow rate and current range, etc., the generation of a high-density, stable plasma can be achieved; when the input end is a negative high-voltage DC power supply, a high-density, large-volume plasma is generated by utilizing the discharge structure of the positively biased anode. At the same time, by adjusting the DC power supply voltage at the input end, the electrode spacing, the mixed gas ratio and other parameters, the micro-discharge plasma density, current value and plasma parameters of the discharge space can be changed. The present invention can generate a volume of up to 10cm in a single gas or mixed gas environment such as air, argon, helium, etc. 3 The above stable plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the system of the present invention.

[0019] Figure 2 It is a structural schematic diagram of a vacuum discharge chamber.

[0020] Figure 3 yes Figure 2 Side view of the vacuum discharge chamber shown.

[0021] Figure 4 It is an evolution diagram of plasma luminescence image with the change of cathode current; among them, the gas flow rate of the four figures in row a is 0SLM, the gas flow rate of the four figures in row b is 5SLM, and the gas flow rate of the four figures in row c is 15SLM.

[0022] In the figure: 1. negative high-voltage DC power supply, 2. positive high-voltage DC power supply, 3. current limiting resistor R1, 4. current limiting resistor R2, 5. ammeter A1, 6. ammeter A2, 7. ammeter A3, 8. vacuum discharge chamber, 9. micro-cavity cathode, 10. positive bias anode, 11. micro-cavity, 12. air inlet, 13. air outlet, 14. air inlet pipeline, 15. exhaust pipeline, 16. mass flow meter, 17. air source, 18. vacuum pump, 19. camera, 20. spectrometer, 21. molybdenum needle, 22. air hole, 23. bolt, 24. track, 25. barometer interface, 26. electrode line interface, 27. base, 28. electrode line interface, 29. air inlet interface, 30. electrode line interface, 31. sealing ring. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 As shown, the system for obtaining large-volume plasma by micro-cavity discharge of the present invention comprises a vacuum discharge chamber 8, a positive high-voltage DC power supply 2, a negative high-voltage DC power supply 1, a vacuum pump 18, a gas source 17, a mass flow meter 16 and a barometer (not shown). The vacuum discharge chamber 8 is a closed chamber made of quartz glass, on which an air inlet 12, an air outlet 13 and an electrode line interface 26 ( Figure 2 ). A positive bias anode 10 and a micro cavity cathode 9 are arranged in the vacuum discharge chamber 8, and the positive bias anode 10 and the micro cavity cathode 9 are arranged opposite to each other.

[0025] The positive bias anode 10 is a molybdenum sheet with pores 22 and molybdenum needles 21 distributed on it. The pores 22 and molybdenum needles 21 are distributed in an array, and the molybdenum needles 21 all point to the micro-cavity cathode 9. The micro-cavity cathode 9 is a ceramic sheet with a thickness of 0.5 mm and a dielectric sandwiched between two layers of molybdenum sheets with a thickness of 0.5 mm. The upper molybdenum sheet is the anode, and the lower molybdenum sheet is the cathode. The surrounding is fixed by a mica sheet, thus forming a "sandwich" cathode plate with a three-layer structure of metal-dielectric-metal. A micro-cavity 11 with a diameter of 0.5 mm and penetrating the cathode plate is opened at the center of the cathode plate.

[0026] like Figure 2 , Figure 3 As shown, the vacuum discharge chamber 8 is a tube body made of quartz glass, and the ports at both ends of the tube body are sealed by end caps through sealing rings 31, thereby forming a closed chamber. The quartz glass tube body is fixed on the base 27. Three electrode line interfaces 26, 28, 30 and a pressure gauge interface 25 are opened on the tube body of the vacuum discharge chamber 8. The air inlet 12 and the air outlet 13 are respectively arranged on the two end caps of the vacuum discharge chamber 8 ( Figure 2 ).

[0027] The positive bias anode 10 is fixed to one end of the vacuum discharge chamber near the gas outlet 13 by a bracket. The micro-cavity cathode 9 is embedded in a quartz glass ring with a groove and is arranged at one end of the vacuum discharge chamber near the gas inlet 12. Three tracks 24 parallel to the center line of the tube body are evenly distributed along the circumference of the inner wall of the vacuum discharge chamber 8, and three bayonet holes are evenly distributed on the outer edge of the quartz glass ring, and each of the three bayonet holes is clamped on a track 24 to adjust the distance between the micro-cavity cathode 9 and the positive bias anode 10.

[0028] Figure 1 In the embodiment, the positive electrode of the positive high-voltage DC power supply 2 is connected to the molybdenum sheet and the molybdenum needle 21 of the positive bias anode 10, and the negative electrode of the positive high-voltage DC power supply 2 is grounded; the positive high-voltage DC power supply 2 is used to provide a positive bias voltage for the positive bias anode 10. The positive electrode of the negative high-voltage DC power supply 1 is grounded in one way, and the other way is connected to the molybdenum sheet (i.e., the upper molybdenum sheet) in the micro-cavity cathode 9 opposite to the positive bias anode 10 through the current limiting resistor R2; the negative electrode of the negative high-voltage DC power supply 1 is connected to the molybdenum sheet (i.e., the lower molybdenum sheet) in the micro-cavity cathode 9 opposite to the positive bias anode through the current limiting resistor R1; the negative high-voltage DC power supply 1 is used to provide negative high voltage for the micro-hollow cathode 9.

[0029] The vacuum pump 18 is connected to the gas outlet 13 of the vacuum discharge chamber 8 through the exhaust pipeline 15, and is used to control the gas pressure in the vacuum discharge chamber. The gas source 17 includes an argon gas bottle and a helium gas bottle, and is connected to the gas inlet 12 of the vacuum discharge chamber 8 through the intake pipeline 14, and is used to provide discharge gas to the vacuum discharge chamber. A mass flow meter 16 is connected in series in the intake pipeline 14, and is used to control the gas flow rate entering the vacuum discharge chamber. The barometer is connected to the barometer interface 26 of the vacuum discharge chamber 8 through a pipeline, and is used to display the gas pressure in the vacuum discharge chamber in real time.

[0030] In the circuit of the system, the voltage signals of the micro hollow cathode 9 and the positive bias anode 10 are collected by a high voltage probe connected to an oscilloscope. The high voltage probe measures the voltage signal V1 between the current limiting resistor R1 and the micro hollow cathode 9 and the voltage signal V2 between the current limiting resistor R2 and the positive bias anode 10. The inter-electrode voltage between the cathode and the anode in the micro hollow cathode 9 is indirectly measured by voltage difference. The current of the positive bias anode 10 is measured by ammeter A3, the cathode current in the micro hollow cathode 9 is measured by ammeter A1, and the anode current in the micro hollow cathode 9 is measured by ammeter A2.

[0031] One of the conditions for generating plasma discharge in the vacuum discharge chamber is that a stable gas is introduced into the vacuum discharge chamber at a mass flow of not more than 30 SLM.

[0032] The method of obtaining large-volume plasma by using micro-cavity discharge of the present invention comprises the following steps: S1. Set up a system for generating large-volume plasma using microcavity discharge according to the present invention.

[0033] S2. Fill the vacuum discharge chamber 8 with gas through the gas source 17 and the mass flow meter 16, and then evacuate the gas using the vacuum pump 18. After several times of filling and evacuating, the gas pressure in the vacuum discharge chamber reaches below 0.1 Pa. Let it stand for 2-3 minutes to allow the reaction environment in the vacuum discharge chamber to stabilize.

[0034] S3, gas is introduced into the vacuum discharge chamber 8 at a mass flow rate of 0-30SLM. After the gas state is stable, the negative high-voltage DC power supply 1 is connected, and the negative DC voltage output is fine-tuned. A phenomenon of light beams being generated in the vacuum discharge chamber 8 from the micro-cavity cathode 9 to the positive bias anode 10 is generated, causing discharge breakdown in the discharge space. The discharge current is continuously increased, and the volume of the generated plasma increases accordingly. The conditions for forming a large-volume high-density plasma discharge are: the flow rate of the introduced gas reaches 15SLM, and the electron density outside the micro-cavity of the micro-cavity cathode increases to 10 11 cm -3 Magnitude.

[0035] In order to further verify the properties of the discharge plasma in the flowing gas environment, the plasma parameters are further analyzed using the data derived from the oscilloscope. First, the voltage signal of the discharge circuit is collected by the oscilloscope probe in the circuit and transmitted back to the oscilloscope. The voltage signal image is presented at the image output end of the oscilloscope. By analyzing the collected voltage data and the current data of each electrode measured by the corresponding ammeter through computer software, the properties of the plasma in the discharge gas discharge unit at different stages can be obtained. After analysis, as the gas flow rate increases, the formation of discharge can be promoted.

[0036] In addition, the discharge luminescence data collected by the spectrometer 20 is compared and analyzed with the luminescence data in the discharge unit. Within a certain gas flow range (0-15SLM), the gas flow can effectively increase the electron density outside the microcavity, thereby promoting the formation of large-volume high-density plasma discharge.

[0037] The effects of the embodiments of the present invention are as follows: Figure 4 As shown in the figure, the experiment captured the MCSD luminescence image at different gas flow rates as the cathode current changes. b The positive bias anode 10 has a loading voltage V of 200 kΩ. A2 The voltage is 200 V, and the distance D between the anode of the micro-cavity cathode 9 and the positive bias anode 10 is A1-A2The discharge experiment was carried out under the condition of 30mm, and the discharge experimental gas was pure helium. In the flowing gas environment, when the cathode current is low, the axial length of the luminescent image is longer than the length of the luminescent image in the static gas environment. When the gas flow rate is 5SLM, when the cathode current is higher than 1600, the change in the MCSD glow volume is no longer obvious. However, with the increase of the cathode current, the grayscale value in the center of the MCSD glow area increases, that is, the brightness increases. When the gas flow rate is 15SLM, its change law with the cathode current is similar to that when the flow rate is 5SLM. When the gas flow rate increases to 5SLM, the grayscale value in the central area of ​​the MCSD glow area increases, that is, the brightness of the luminescent image increases.

[0038] The present invention can intuitively discover the relevant properties of the discharge plasma in the flowing gas environment. As the gas flow rate increases, the luminous brightness of the discharge glow zone between the microcavity 11 and the positive bias anode 10 gradually increases, and the luminous brightness at the positive bias anode increases. When the gas flow rate increases to 5SLM, the length of the brighter MCSD glow zone can be estimated from the luminous image to be 28mm, and the volume reaches 13cm 3 The electron density range calculated from the collected spectra is about 5.0×10 11 cm -3 -9.0×10 11 cm -3 When the gas flow rate increases to 15 SLM, the length of the brighter MCSD glow area is 26 mm and the volume is 11 cm 3 Magnitude.

Claims

1. A system for obtaining large-volume plasma using microcavity discharge, characterized in that: include: The vacuum discharge chamber is a closed chamber made of quartz glass, which is provided with an air inlet, an air outlet and an electrode line interface, and is equipped with a positive bias anode and a micro-cavity cathode arranged opposite to each other; the positive bias anode is a molybdenum needle with air holes distributed on a molybdenum sheet and pointing to the micro-cavity cathode; the micro-cavity cathode is a cathode plate with a three-layer structure formed by sandwiching a ceramic sheet between two layers of molybdenum sheets, and a micro-cavity penetrating the cathode plate is opened in the middle of the cathode plate; A positive high-voltage DC power supply, whose negative electrode is grounded and whose positive electrode is connected to the molybdenum sheet and the molybdenum needle of the positive bias anode; the positive high-voltage DC power supply is used to provide a positive bias voltage for the positive bias anode; A negative high-voltage DC power supply, one of which is grounded in one path and connected to the molybdenum sheet in the micro-cavity cathode opposite to the positive bias anode in the other path through a current-limiting resistor R2; and a negative electrode thereof is connected to the molybdenum sheet in the micro-cavity cathode opposite to the positive bias anode in the other path through a current-limiting resistor R1; the negative high-voltage DC power supply is used to provide negative high voltage for the micro-hollow cathode; A vacuum pump connected to the gas outlet of the vacuum discharge chamber through a vacuum pipeline, and used to control the gas pressure in the vacuum discharge chamber; and The gas source is connected to the gas inlet of the vacuum discharge chamber through an air inlet pipeline, and is used to provide discharge gas into the vacuum discharge chamber.

2. The system for obtaining large volume plasma by using microcavity discharge according to claim 1, characterized in that: include: A mass flow meter, connected in series in the air inlet pipeline, is used to control the flow rate of gas entering the vacuum discharge chamber; as well as The barometer is connected to the barometer interface of the vacuum discharge chamber through a pipeline and is used to display the gas pressure in the vacuum discharge chamber in real time.

3. The system for obtaining large-volume plasma by using microcavity discharge according to claim 1 or 2, characterized in that: The vacuum discharge chamber is a tube body made of quartz glass, and the ports at both ends of the tube body are covered by end covers to form a closed chamber; an electrode line interface and a pressure gauge interface are opened on the tube body of the vacuum discharge chamber; the air inlet and the air outlet are respectively arranged on the two end covers of the vacuum discharge chamber.

4. The system for obtaining large-volume plasma by using micro-cavity discharge according to claim 3 is characterized in that: The positive bias anode is fixed to one end of the vacuum discharge chamber near the gas outlet through a bracket; the micro-cavity cathode is embedded in a quartz glass ring with a groove and is arranged at one end of the vacuum discharge chamber near the gas inlet, and three tracks parallel to the center line of the tube body are evenly distributed along the circumference of the inner wall of the vacuum discharge chamber, and the bayonet on the outer edge of the quartz glass ring is clamped on the track.

5. The system for obtaining large-volume plasma by using micro-cavity discharge according to claim 1 or 2, characterized in that One of the conditions for generating plasma discharge in the vacuum discharge chamber is that a stable gas is introduced into the vacuum discharge chamber at a mass flow of no more than 30 SLM.

6. A method for obtaining a large volume plasma by using microcavity discharge, characterized in that: The following steps are involved: S1. A system for generating large-volume plasma by using microcavity discharge as described in any one of claims 1 to 5 is provided; S2. Fill the vacuum discharge chamber with gas through the gas source and mass flow meter, and then use the vacuum pump to evacuate the gas; after several times of filling and evacuating the gas, the gas pressure in the vacuum discharge chamber reaches below 0.1 Pa; let it stand for 2-3 minutes to make the reaction environment in the vacuum discharge chamber tend to a stable state; S3, introducing gas into the vacuum discharge chamber at a mass flow of no more than 30 SLM, and after the gas state is stable, connecting the negative high-voltage DC power supply, and fine-tuning the output negative DC voltage, a phenomenon of generating a luminous light column from the micro-cavity cathode to the positive bias anode in the vacuum discharge chamber occurs, causing discharge breakdown in the discharge space; As the discharge current continues to increase, the volume of the generated plasma increases accordingly.

7. The method for obtaining large-volume plasma by using micro-cavity discharge according to claim 6, characterized in that In step S3, the conditions for forming a large volume high density plasma discharge are: the flow rate of the introduced gas reaches 15 SLM, the electron density outside the micro cavity of the micro cavity cathode increases to 10 11 cm -3 Magnitude.

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