CN115767869A - Self-organizing multilayer discharge plasma generating device and method - Google Patents

Abstract

The invention belongs to the technical field of discharge plasma equipment, and particularly relates to a self-organized multilayer discharge plasma generating device and method. The method comprises the following steps: the vacuum cavity is characterized by comprising a vacuum cavity, two electrode connectors are fixedly arranged on the cavity wall of the vacuum cavity through a high-voltage flange, a guide rail is arranged in the vacuum cavity, two sliding support bodies are arranged on the guide rail, an insulating rod is arranged on each sliding support body, an electrode is arranged on each insulating rod, the tips of the two electrodes are oppositely arranged to form a discharge body, and the electrode connectors are connected with the electrodes and a high-voltage power supply through leads; one of the sliding support bodies is fixedly connected with one end of the electrode transmission rod, one end of the electrode transmission rod penetrates through the cavity wall of the vacuum cavity to be connected with the regulator, and the regulator is fixedly arranged on the cavity wall of the vacuum cavity and used for pushing the electrode transmission rod and further driving one of the insulating rods to slide along the guide rail to adjust the distance between the two copper electrodes. The invention can realize plasma discharge under higher air pressure and can also eliminate the plasma discharge controllably.

Description

Self-organizing multilayer discharge plasma generating device and method

Technical Field

The invention belongs to the technical field of discharge plasma equipment, and particularly relates to a self-organized multilayer discharge plasma generating device and method.

Background

Glow discharge plasma is a typical low-temperature plasma which is rich in active particles, such as energetic electrons, ions, excited atoms, and has wide applications in various leading-edge scientific fields, such as material processing, thermonuclear fusion, semiconductor industry, and aerospace. Generally, under the excitation of an electric field, glow discharge generated between electrodes appears as continuous and uniform plasma; under specific parameters, the continuous and uniform plasma can be self-organized into a multilayer plasma with light and dark phases. Such multi-layer discharge plasmas, like the channel constriction effect of glow discharge, physically involve ionization instabilities of the plasma, which are generally considered undesirable because they interfere with the uniformity of the plasma column. For example, for a glow lamp, this means failure of the lamp (Levko D,2021Physics of plasma 28 013506); for plasma etching in the microelectronics industry, it affects the uniformity of the plasma, and further affects key process parameters such as electron energy distribution function and particle flux (Liu Y X, et al, physical Review Letters,116,1-6); in particular, for military high power gas lasers, this instability can directly affect the pumping process and thus the performance of the laser (Daniel J. Emmons II 2017Ph. D. Dispersion, department of the Air force implementation of technology, ohio, p23-24). At present, the generation of such self-organized multilayer discharge plasma is mostly generated and controlled by radio frequency/direct current discharge under low pressure (Pa magnitude), for example, chinese patent publication No. CN106470522B (Li Weizhi, etc.) discloses a plasma device with adaptive radio frequency discharge stripes, which is a typical device for generating glow discharge by applying radio frequency level electric field to both ends of an electrode to perform gas discharge. Another typical glow discharge plasma is produced in a closed dc discharge tube, for example, v.a. lisovski (eur.j. Phys.,2012, 33. The multilayer discharge plasma generated in the discharge tube is closely related to the diffusion of electrons on the wall of the confinement tube. Further, OUYANG Ji-Ting (Chin. Phys. Lett.,2005,22, 2892-2894) reports that multilayer discharge plasma occurs also in a plasma display panel, and the formation of multilayer discharge plasma is associated with distortion of an electric field.

However, the discharge plasma in the prior art is generated under a low pressure condition, and the elimination thereof is not controllable.

Disclosure of Invention

The invention overcomes the defects of the prior art, and solves the technical problems that: a self-organized multilayer discharge plasma generating device and method are provided to generate discharge plasma at higher gas pressure and to achieve controllable elimination of discharge plasma.

In order to solve the technical problems, the invention adopts the technical scheme that: a self-organizing multi-layer discharge plasma generating device, comprising: the electrode assembly comprises a vacuum cavity, two electrode connectors are fixedly arranged on the cavity wall of the vacuum cavity through a high-voltage flange, a guide rail is arranged in the vacuum cavity, two sliding support bodies are arranged on the guide rail, an insulating rod is arranged on each sliding support body, an electrode is arranged on each insulating rod, the tips of the two electrodes are oppositely arranged to form a discharge body, and the electrode connectors are connected with the electrodes and a high-voltage power supply through wires; one of the sliding support bodies is fixedly connected with one end of the electrode transmission rod, the other end of the electrode transmission rod penetrates through the cavity wall of the vacuum cavity to be connected with a regulator, and the regulator is fixedly arranged on the cavity wall outside the vacuum cavity and used for pushing the electrode transmission rod and further driving one of the insulating rods to slide along the guide rail to adjust the distance between the two electrodes;

and an air exhaust valve and an air charging valve are arranged on the wall of the vacuum cavity, the air exhaust valve is connected with a vacuum pump, and the air charging valve is used for injecting gas into the cavity.

The self-organized multilayer discharge plasma generating device further comprises a hollow cylinder, the bottom of the hollow cylinder is fixedly connected with the insulating rod, an electrode hole is formed in the center of the hollow cylinder, and the electrode is horizontally arranged in the electrode hole.

The regulator is a micrometer.

The material of insulator spindle is polytetrafluoroethylene, slip supporter and guide rail are made for the stainless steel, the vacuum cavity is made for stainless steel material, and its top is provided with the upper flange, both ends have respectively been put the handle about on the upper flange, and the central part has been put and has been observed the window, the electrode is the copper electrode.

The self-organizing multilayer discharge plasma generating device is characterized in that the high-voltage power supply is used for generating voltage with the frequency of 5-20 kHz.

The vacuum cavity is characterized in that a deflation valve and a vacuum measuring gauge are further arranged on the wall of the vacuum cavity, the deflation valve is used for deflating outwards to control the air pressure of the vacuum cavity, and the vacuum measuring gauge is used for measuring the vacuum degree in the vacuum cavity.

In addition, the invention also provides a self-organizing multilayer discharge plasma generating method which is realized by the self-organizing multilayer discharge plasma generating device, and the method comprises the following steps:

the method comprises the following steps: adjusting the electrode spacing to a proper position through a regulator, starting a vacuum pump, vacuumizing the vacuum cavity to below 7kPa, and keeping the air pressure value stable;

step two: filling inert gas into the vacuum cavity until the air pressure in the vacuum cavity is between 9 and 20kPa, and then starting high-voltage to apply 300 to 500V triangular voltage between the two electrodes;

step three: the electrode distance is adjusted through a regulator, or the air pressure of a vacuum cavity filled with inert gas is controlled, or diatom gas is injected into the vacuum cavity, so that the control of the discharge plasma between the electrodes is realized, and the self-organized multilayer argon plasma with alternate light and shade is generated.

The self-organizing multilayer discharge plasma generating method further comprises the following steps:

step four: the elimination of the laminar discharge is realized by continuously filling inert gas, adjusting the electrode spacing or injecting diatomic gas.

In the second step, the injected inert gas is argon;

in the fourth step, the injected diatomic gas is oxygen or nitrogen with the mole fraction of 0.5% -5%.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention provides a self-organizing multilayer discharge plasma generating device and a self-organizing multilayer discharge plasma generating method, which utilize electrode structure optimization, realize inert gas discharge to form layered plasma through gas discharge technology, and the basic principle of discharge layering phenomenon generated under the condition is that the formation of the layered plasma is related to rich metastable atoms generated in the discharge process, the stepwise ionization process caused by the metastable atoms can cause ionization instability, and the instability is transmitted in the form of ionization waves, so that plasma parameters generate longitudinal amplitude modulation, thereby forming the layered plasma with alternate light and shade. The discharge of the layered structure can be effectively eliminated by adding a small amount of diatomic molecular gas, so that the plasma becomes continuous and stable discharge, and the generated multilayer discharge plasma can be controllably eliminated.

2. The invention can generate self-organizing multilayer discharge plasma which is clearly distinguished by naked eyes, which is different from the characteristics of multilayer discharge plasma in a restraint tube under low pressure (Pa magnitude), has simple structure, simple flow, environment-friendly process and continuous and controllable performance, generates and eliminates the multilayer discharge plasma, and has guiding significance for exploring and researching the discharge process in the gas laser. Has important application value in the fields of laser preparation, plasma control and the like.

3. By adding diatomic molecular gas, metastable argon atoms are effectively quenched, and the source of step-by-step ionization is reduced; on the other hand, the electron energy distribution function is changed to trend towards Maxwell distribution, so that the discharge becomes stable.

Drawings

FIG. 1 is a schematic structural diagram of a self-organized multi-layer discharge plasma generating device according to an embodiment of the present invention;

FIG. 2 is a schematic vertical cross-sectional view of a self-organized multi-layer discharge plasma generating device according to an embodiment of the present invention;

FIG. 3 is a top view of an upper flange according to one embodiment of the present invention;

FIG. 4 is a schematic view of a self-organizing multi-layer discharge plasma observed from an observation window;

FIG. 5 is a discharge image of the plasma obtained in example two of the present invention, in which (a) is an argon discharge image at a gas pressure of 20.17kPa and (b) is an argon discharge image at a gas pressure of 23.37 kPa;

in the figure, 1 is a vacuum cavity, 2 is an upper flange, 3 is a handle, 4 is an observation window, 5 is a high-voltage flange, 6 is an electrode connector, 8 is a high-voltage power supply, 9 is an air suction valve, 10 is an inflation valve, 14 is a guide rail, 15 is a sliding support body, 16 is an insulating rod, 17 is a hollow cylinder 19 is an electrode transmission rod, 18 is an electrode, and 20 is a regulator.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

As shown in fig. 1 to 3, an embodiment of the present invention provides a self-organized multilayer discharge plasma generating apparatus, including: the electrode structure comprises a vacuum cavity 1, wherein two electrode connectors 6 are fixedly arranged on the cavity wall of the vacuum cavity 1 through a high-voltage flange 5, a guide rail 14 is arranged in the vacuum cavity 1, two sliding support bodies 15 are arranged on the guide rail 14, an insulating rod 16 is arranged on each sliding support body 15, an electrode 18 is arranged on each insulating rod 16, the tips of the two electrodes 18 are oppositely arranged to form a discharge body, and the electrode connectors 6 are connected with the electrodes 18 and a high-voltage power supply 8 through leads; one of the sliding support bodies 15 is fixedly connected with one end of an electrode transmission rod 19, the other end of the electrode transmission rod 19 penetrates through the cavity wall of the vacuum cavity 1 to be connected with a regulator 20, and the regulator 20 is fixedly arranged on the cavity wall outside the vacuum cavity 1 and used for pushing the electrode transmission rod 19 and further driving one of the insulating rods 16 to slide along the guide rail 14 to adjust the distance between the two electrodes 18; an air extraction valve 9 and an inflation valve 10 are arranged on the cavity wall of the vacuum cavity 1, the air extraction valve 9 is connected with a vacuum pump, and the inflation valve 10 is used for injecting gas into the cavity.

Specifically, the self-organizing multilayer discharge plasma generating device of the embodiment further comprises a hollow cylinder 17, the bottom of the hollow cylinder 17 is fixedly connected with the insulating rod 16, an electrode hole is formed in the center of the hollow cylinder, and the electrode 18 is horizontally arranged in the electrode hole. The bottom of the hollow cylinder 17 is provided with a connecting column which is sleeved on the top of the insulating rod 16 through a central connecting hole and is fixed with the insulating rod 16 through a bolt.

Specifically, in this embodiment, the regulator 20 is a micrometer, a frame of the micrometer is fixedly disposed on a cavity wall of the vacuum cavity 1, and the measuring rod penetrates through the cavity wall and is fixedly connected to the motor transmission rod 19, so that the distance between the two electrodes can be adjusted by rotating the measuring rod, and after calibration, the reading on the measuring rod can display the distance between the two electrodes.

Specifically, in this embodiment, the insulating rod 16 is made of teflon, the sliding support 15 and the guide rail 14 are made of stainless steel, the vacuum chamber 1 is made of stainless steel, the upper flange 2 is disposed above the vacuum chamber, and the upper flange 2 can open the vacuum chamber to adjust the distance between electrodes in the vacuum chamber. Handles 3 are respectively arranged at the left end and the right end of the upper flange 2, an observation window 4 with the inner diameter of 35mm is arranged at the central part, and the electrode 18 is a copper electrode. In addition, polytetrafluoroethylene is arranged between the two electrode connectors 6 and the high-voltage flange 5 for isolation and insulation.

Specifically, the high voltage power supply 8 is used for generating a triangular wave voltage of 5 to 20 kHz. The volume of the vacuum chamber 1 (length. Times. Width. Times. Height) was 462 mm. Times.210 mm.

Further, in this embodiment, a release valve 11 and a vacuum measuring gauge 12 are further disposed on the cavity wall of the vacuum cavity 1, the vacuum cavity 1 is released by the release valve 11 to control the air pressure of the vacuum cavity 1, and the vacuum measuring gauge 12 is used for measuring the vacuum degree in the vacuum cavity 1. Further, the vacuum pump may be a rotary vane vacuum pump.

Example two

The embodiment of the invention provides a self-organized multilayer discharge plasma generation method, which is realized by adopting the self-organized multilayer discharge plasma generation device of the embodiment I, and comprises the following steps:

the method comprises the following steps: the electrode distance is adjusted to a proper position through the regulator 20, the vacuum pump is started, the vacuum cavity 1 is vacuumized to be below 7kPa, and the air pressure value is kept stable.

Firstly, a guide rail and an electrode are installed in a vacuum chamber 1, the distance between the electrodes is set to be 1-2 mm, for example, and then an upper flange is installed to keep the vacuum chamber well sealed.

Step two: filling inert gas into the vacuum cavity 1 until the air pressure in the vacuum cavity 1 is between 9 and 20kPa, and then starting a high voltage 8 to apply a triangular voltage of 300 to 500V between the two electrodes so as to generate discharge plasma between the electrodes. Specifically, the inert gas is argon.

Step three: the control of the inter-electrode discharge plasma is realized by adjusting the electrode distance through the regulator 20 or controlling the pressure of the vacuum cavity filled with inert gas, so that self-organized multilayer argon plasma with alternate bright and dark is generated.

In this embodiment, the preferable conditions for the self-organized multilayer discharge plasma generation are: the voltage applied on the electrodes is 400V, the frequency of the triangular voltage is preferably 10kHz, the distance between the electrodes is 5mm, and the discharge plasma between the positive electrode and the negative electrode forms self-organized multilayer discharge plasma with light and dark phases after inert gas is slowly filled.

Step four: and the elimination of the laminar discharge is realized by continuously filling inert gas, adjusting the distance between the electrodes or injecting diatomic gas.

In this embodiment, the adjustment of the electrode spacing and the air pressure of the vacuum chamber can realize the adjustment of the number of discharge layers and the spacing.

It has been found experimentally that increasing the electrode spacing to a suitable distance, for example to 5-20mm, allows the number of discharge layers to be adjusted. The multi-layer discharge plasma morphology self-organizes to increase by one for every 2mm increase in the number of discharge layers, but the discharge layer spacing remains unchanged. As shown in fig. 4, the discharge plasma in the vacuum chamber 1 can be observed through the observation window at the top.

Experiments show that the inert gas is gradually filled, the plasma form is self-organized as the inert gas is gradually increased to the chamber pressure to a standard atmospheric pressure, and the number of discharge layers becomes dense and increases after the self-organized multilayer discharge plasma with alternating light and dark is formed, as shown in a and b in fig. 5.

It is also found that when argon gas is generated for discharge stratification (9-20 kPa), if nitrogen gas is slowly filled to increase the pressure of the chamber to 24kPa, the multi-layer plasma form is self-organized into continuous columnar plasma, and the stratified discharge disappears.

Therefore, in the invention, the elimination of the layered discharge can be realized by injecting the diatomic gas, the molar fraction of the injected diatomic molecular gas is 0.5-5%, the nitrogen with the molar fraction of 2% is gradually injected, the layered structure of the argon multilayer discharge plasma is gradually changed into a continuous structure, and the multilayer discharge is effectively eliminated; and introducing nitrogen with the mole fraction of 5%, and extinguishing the plasma.

Therefore, in this embodiment, diatomic molecules can be injected to control the number of discharge layers and the distance between the discharge layers. In addition, the elimination of the laminar discharge can be realized by adjusting the gas pressure, adjusting the electrode spacing or injecting diatomic gas.

In the embodiment, after the multilayer discharge plasma is generated, the guide rail mechanism is slowly controlled and adjusted to increase the electrode spacing from 5mm to 20mm, the multilayer discharge plasma is self-organized to increase the number of discharge layers by one for every 2mm, but the discharge layer interval is kept unchanged. After the multilayer discharge plasma is generated, besides the adjustment of the air pressure and the electrode spacing, the form of the self-organizing multilayer discharge plasma can be controlled by injecting the gas of the diatomic gas which can effectively quench the metastable argon atoms.

The invention finds a self-organized argon multi-layer discharge plasma in a chamber without a confinement tube (free space) under higher gas pressure (kPa grade), and finds thisThe multilayer discharge plasma is characterized by the manifestation of discharge instability, wherein the instability is related to the volume loss rate of charged particles, and dissociative recombination is a main channel for the loss of the charged particles; it is mixed with an inert gas, e.g. He of helium ₂ ⁺ The vibrational rotation population is related because the potential energy curves of the molecular state and the anti-bonding state intersect in the third vibrational energy level region, which results in a strong non-linear relationship of the recombination velocity to the electron temperature and the gas temperature (from boltzmann distribution at the gas temperature to boltzmann distribution at the electron temperature, depending on the discharge conditions). The invention discloses a main physical mechanism of helium discharge instability for recognizing and understanding the discharge delamination and contraction properties of helium under various conditions, and fills a part of blank of people on the recognition of the instability. In addition, the invention has important application value in the fields of laser preparation, plasma control and the like.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A self-organized multilayer discharge plasma generating device, comprising: the electrode structure comprises a vacuum cavity (1), wherein two electrode connectors (6) are fixedly arranged on the cavity wall of the vacuum cavity (1) through a high-pressure flange (5), a guide rail (14) is arranged in the vacuum cavity (1), two sliding support bodies (15) are arranged on the guide rail (14), an insulating rod (16) is arranged on each sliding support body (15), an electrode (18) is arranged on each insulating rod (16), the tips of the two electrodes (18) are oppositely arranged to form a discharge body, and the electrode connectors (6) are connected with the electrodes (18) and a high-voltage power supply (8) through wires; one of the sliding support bodies (15) is fixedly connected with one end of an electrode transmission rod (19), the other end of the electrode transmission rod (19) penetrates through the cavity wall of the vacuum cavity (1) to be connected with a regulator (20), and the regulator (20) is fixedly arranged on the cavity wall outside the vacuum cavity (1) and used for pushing the electrode transmission rod (19) so as to drive one of the insulating rods (16) to slide along the guide rail (14) to adjust the distance between the two electrodes (18);

an air extraction valve (9) and an inflation valve (10) are arranged on the wall of the vacuum cavity (1), the air extraction valve (9) is connected with a vacuum pump, and the inflation valve (10) is used for injecting gas into the cavity.

2. A self-organized multilayer discharge plasma generating device according to claim 1, further comprising a hollow cylinder (17), wherein the bottom of the hollow cylinder (17) is fixedly connected with the insulating rod (16), an electrode hole is arranged at the center, and the electrode (18) is horizontally arranged in the electrode hole.

3. A self-organizing multi-layer discharge plasma generating device according to claim 1, characterized in that said regulator is a micrometer (20).

4. The self-organized multilayer discharge plasma generating device according to claim 1, wherein the insulating rod (16) is made of polytetrafluoroethylene, the sliding support (15) and the guide rail (14) are made of stainless steel, the vacuum chamber (1) is made of stainless steel, an upper flange (2) is arranged above the vacuum chamber, the left end and the right end of the upper flange (2) are respectively provided with a handle (3), the central part is provided with an observation window (4), and the electrode (18) is a copper electrode.

5. A self-organizing multi-layer discharge plasma generating device as recited in claim 1, wherein said high voltage power supply (8) is adapted to generate a voltage with a frequency of 5 to 20 kHz.

6. The self-organized multilayer discharge plasma generating device as claimed in claim 1, wherein a gas release valve (11) and a vacuum measuring gauge (12) are further disposed on the wall of the vacuum chamber (1), the gas release valve (11) is used for releasing gas outwards to control the gas pressure of the vacuum chamber (1), and the vacuum measuring gauge (12) is used for measuring the vacuum degree in the vacuum chamber (1).

7. A self-organized multilayer discharge plasma generation method, which is realized by using the self-organized multilayer discharge plasma generation device of claim 1, comprising the steps of:

the method comprises the following steps: adjusting the electrode spacing to a proper position through an adjuster (20), starting a vacuum pump, vacuumizing the vacuum cavity (1) to below 7kPa, and keeping the air pressure value stable;

step two: filling inert gas into the vacuum cavity (1) until the air pressure in the vacuum cavity (1) is between 9 and 20kPa, and then starting a high-voltage (8) to apply 300 to 500V triangular voltage between the two electrodes;

step three: the electrode distance is adjusted through the regulator (20), or the air pressure of the vacuum cavity (1) filled with inert gas is controlled, or diatomic gas is injected into the vacuum cavity (1), so that the discharge plasma between the electrodes is controlled, and self-organized multilayer argon plasma with alternate light and shade is generated.

8. A self-organizing multi-layer discharge plasma generating method as recited in claim 7, further comprising the steps of:

step four: the elimination of the laminar discharge is realized by continuously filling inert gas, adjusting the electrode spacing or injecting diatomic gas.

9. The method as claimed in claim 8, wherein in the second step, the injected inert gas is argon;

in the fourth step, the injected diatomic gas is oxygen or nitrogen with the mole fraction of 0.5% -5%.

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