Long-gap atmospheric pressure glow discharge low-temperature plasma source device

Abstract

The invention provides a long-gap atmospheric pressure glow discharge low-temperature plasma source device which comprises a plasma source, the plasma source is composed of a plasma source frame module, an air pre-ionization microelectrode, a seed electron multiplication module and a plasma source output end packaging module, the air pre-ionization microelectrode is arranged in a ceramic frame, and the seed electron multiplication module is arranged in the ceramic frame. The seed electron multiplication module is composed of an axial annular columnar magnet, a cylindrical gold-plated small-round-hole ceramic plate and a cylindrical gold-plated middle-round hole, and the seed multiplication module and the plasma source frame module are connected and fixed through epoxy resin glue, wherein the cylindrical gold-plated small-round-hole ceramic plate and the cylindrical gold-plated middle-round hole ceramic plate are wrapped by a resin insulating layer. The plasma source output end packaging module is a porous array emitter made of copper-nickel alloy. The problems that a traditional plasma generator is high in power consumption and serious in heating, and a traditional plasma source / electrode is prone to oxidation corrosion, poor in stability, short in discharge gap and the like are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of plasma preparation, and in particular relates to a long-gap atmospheric pressure glow discharge low-temperature plasma source device. Background Art

[0002] Plasma is a gas composed of partially or completely ionized atoms, molecules, free radicals, charged particles, electrons and ultraviolet photons. Since the positive and negative charges of the entire system are the same after ionization, it is called the fourth state besides solid, liquid and gas. Low-temperature plasma is a plasma in a non-thermodynamic equilibrium state. The entire system can maintain a low temperature, but the electron energy can reach 0-20 electron volts, which is enough to induce the dissociation and ionization of compounds. Therefore, in recent years, low-temperature plasma technology has attracted more and more attention and has been widely used in the fields of microbial disinfection, biological breeding, air purification and material modification.

[0003] Low-temperature plasma is mainly achieved through corona discharge and dielectric barrier discharge. Among them, corona discharge is a local discharge with low plasma density and easy transition to high-temperature arc discharge. Since the electrode is directly exposed to the air, the discharge electrode is prone to oxidation and corrosion, which shortens its service life and increases the start-up field strength of the next discharge. Therefore, most technologies that can provide large areas and high electron density use dielectric barrier discharge.

[0004] Chinese patent CN201720745630.0 discloses an atmospheric pressure glow plasma generator and a textile material processing device. The patent adopts a dual-medium DBD discharge electrode design to effectively suppress arc discharge. However, the power consumption of dielectric barrier discharge is usually as high as hundreds of watts, resulting in a large amount of thermal effects and accompanied by a large number of filament discharges.

[0005] In order to solve these problems, Chinese patent CN 201510021685.2 discloses a device for achieving uniform glow discharge in air under atmospheric pressure. This patent increases the concentration of initial electrons in the air and reduces the electric field strength required for gas discharge by adsorbing carbon-14 with a half-life of 5710 years on the surface of the discharge electrode, thereby significantly reducing the heat generated during the discharge process and achieving uniform discharge. However, the discharge gap of this method is short, with the longest being only 7mm.

[0006] In addition, Chinese patent CN 114745839 A discloses a surface-body coupled discharge plasma device based on seed electron generation. The device uses coplanar discharge to generate a pre-ionization effect to provide seed electrons, and generates a coupled discharge plasma device above the capillary coplanar discharge array electrode by applying a pulse or AC voltage of opposite polarity. Although it can achieve a long gap discharge up to 50 mm, it fails to effectively increase the action volume of the low-temperature plasma. In addition, the use of conductive but unevenly distributed metals doped in the capillary as electrodes may significantly reduce the uniformity of the discharge. Furthermore, the device requires two excitation power supplies to act simultaneously, which significantly increases the difficulty of operation and still produces a large amount of thermal effects. Glow discharge has broad application prospects due to its large action range, high and uniform plasma density. Generally, glow discharge low-temperature plasma is generated in a low-pressure or rare gas environment. However, in an atmospheric pressure environment, because the mean free path of electrons is shorter than that in a low-pressure environment, the voltage between electrodes is higher, the number of electron impact ionizations increases, and the density of charged ions increases, which is easy to convert into filamentary or arc discharge.

[0007] Chinese patent CN107295740A discloses a device, method and process for generating glow discharge under uniform atmospheric pressure. The patent starts with the design of the excitation power supply, and uses the constant current characteristics of the high-voltage resonant power supply to prevent the transitional development of electron collapse, thereby driving a stable filamentary atmospheric pressure glow discharge with an inner diameter range of 10-30mm. However, the device of the patent still uses exposed needle-shaped electrodes, which cannot maintain long-term discharge, and the discharge gap has not been significantly increased, only expanding the scope of action of the two-dimensional plane.

[0008] Based on this, a long-gap atmospheric pressure glow discharge low-temperature plasma source device was proposed, which solves the problems existing in the current low-temperature plasma generation technology, including short discharge gap, high power consumption, small volume of low-temperature plasma generated, limited range of active species generation, easy oxidation and corrosion of exposed electrodes, and high voltage between electrodes that is easy to convert into arc discharge. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a long-gap atmospheric pressure glow discharge low-temperature plasma source device in view of the above-mentioned deficiencies in the prior art, so as to solve the problems raised in the above-mentioned background technology.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is: a long gap atmospheric pressure glow discharge low temperature plasma source device, comprising a plasma source, wherein the plasma source is composed of a plasma source frame module, an air pre-ionization microelectrode, a seed electron multiplication module and a plasma source output end packaging module;

[0011] The plasma source frame module is composed of a ceramic frame with a convex groove and a ceramic frame with a concave groove, which are embedded in each other;

[0012] The air pre-ionization microelectrode is arranged in a ceramic frame, the ionization end of the air pre-ionization microelectrode is a round toothed nine-array microelectrode with a gold-plated surface, an inner hole is arranged in the microelectrode excitation end of the air pre-ionization microelectrode, and an array of rectangular convex grooves is also arranged outside the air pre-ionization microelectrode;

[0013] The seed electron multiplication module is composed of an axial annular cylindrical magnet, a cylindrical gold-plated small-hole ceramic plate and a cylindrical gold-plated middle-hole wrapped by a resin insulation layer, and the seed multiplication module is fixed to the plasma source frame module by epoxy resin glue;

[0014] The plasma source output end packaging module is a porous array emitter made of copper-nickel alloy. The porous array emitter and the plasma source frame module are fixed by epoxy resin glue. The plasma source output end packaging module is used to control the drift movement direction of space charge after the gas medium is polarized, thereby generating uniform plasma.

[0015] As a further illustration of the present invention, the upper and lower surfaces of the air pre-ionization microelectrode are copper-coated through-hole fish-row-shaped rectangular ceramics, and the outer surface of the round tooth-shaped nine-array microelectrode is attached with a layer of conductive silver glue.

[0016] As a further illustration of the present invention, the scalloped nine-array microelectrode ionization end is treated by leaching with a carbon nanotube-nafion composite material, the leaching times are 1, and the action time is 8s at an AC voltage of 400V and a frequency of 1.5kHz, and finally fixed in a vacuum drying oven at 60°C.

[0017] As a further illustration of the present invention, the air pre-ionization microelectrode is connected with the inner array of rectangular grooves and the inner array of rectangular grooves of the plasma source frame through the array of rectangular convex grooves and the array of rectangular convex grooves.

[0018] As a further illustration of the present invention, the upper surface of the porous array emitter and the lower surface of the seed electron multiplier are bonded by conductive silver paste, and the holes are made to face each other, finally forming a "small hole-medium hole-large hole" structure.

[0019] As a further illustration of the present invention, the porous array emitter of the protruding part is sprayed with conductive silver paint, graphene and polytetrafluoroethylene insulating coating in sequence, wherein the polytetrafluoroethylene insulating coating can limit the free growth of the discharge current when discharge occurs, thereby preventing the formation of spark discharge or arc discharge between the electrodes, and forming a dielectric barrier discharge structure.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The present invention overcomes the problems of high power consumption, severe heat generation, easy oxidation corrosion, poor stability and short discharge gap of traditional plasma generators. The plasma discharge gap generated by the low-temperature plasma source can reach 8cm, the power consumption can be adjusted within 0-35W, and the low-temperature plasma generated by a single low-temperature plasma source can cover 148cm 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic cross-sectional view of the internal structure of the present invention;

[0023] Figure 2 It is a schematic diagram of the arrangement of nafion-carbon nanotubes on the surface of the air preionization microelectrode of the present invention;

[0024] Figure 3 is a schematic diagram of the formation of a large number of seed electrons in an embodiment of the present invention;

[0025] Figure 4 This is an exposure diagram of a glow discharge diagram produced when the ground electrode is nickel foam in an embodiment of the present invention;

[0026] Figure 5 This is an exposure diagram of glow discharge produced by placing an air filter element above the grounding electrode in an embodiment of the present invention;

[0027] Figure 6 This is an exposure diagram of glow discharge produced when the grounding electrode is a stainless steel disc in an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] Plasma source frame module 11, ceramic frame with convex grooves 112, ceramic frame with grooves 111, air pre-ionization microelectrode 12, ionization end 121, microelectrode excitation end 122, inner hole 123, array rectangular convex groove 124, seed electron multiplication module 13, axial annular cylindrical magnet 131, resin insulation layer 134, cylindrical gold-plated middle circular hole 135, cylindrical gold-plated small circular hole ceramic plate 136, plasma source output end packaging module 14, packaging outer surface 141. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] like Figure 1-3 As shown, the present invention provides a technical solution: a long gap atmospheric pressure glow discharge low temperature plasma source device, comprising a plasma source, wherein the plasma source is composed of a plasma source frame module 11, an air pre-ionization microelectrode 12, a seed electron multiplication module 13 and a plasma source output end packaging module 14;

[0032] The plasma source frame module 11 is composed of a ceramic frame 112 with a convex groove and a ceramic frame 111 with a concave groove, which are embedded in each other;

[0033] The air pre-ionization microelectrode 12 is arranged in a ceramic frame 111. The ionization end 121 of the air pre-ionization microelectrode 12 is a scalloped nine-array microelectrode with a gold-plated surface. The scalloped nine-array microelectrode ionization end is treated by an leaching method using a carbon nanotube-nafion composite material. The leaching times are 1. At the same time, the action time is 8s under an AC voltage of 400V and a frequency of 1.5kHz, and finally fixed in a 60°C vacuum drying oven.

[0034] An inner hole 123 is arranged inside the microelectrode excitation end 122 of the air pre-ionization microelectrode 12, and an array of rectangular convex grooves 124 are also arranged outside the air pre-ionization microelectrode 12; the upper and lower surfaces of the air pre-ionization microelectrode 12 are through-hole fish-row-shaped rectangular ceramics treated with copper coating, and a layer of conductive silver glue is attached to the outer surface of the round tooth-shaped nine-array microelectrode.

[0035] The air pre-ionization microelectrode 12 is connected with the inner array rectangular groove and the inner array rectangular groove of the plasma source frame through the array rectangular convex groove and the array rectangular convex groove.

[0036] The seed electron multiplication module 13 is composed of an axial annular cylindrical magnet 131, a cylindrical gold-plated small-hole ceramic plate 136 and a cylindrical gold-plated middle-hole 136 wrapped by a resin insulation layer 134, and the seed multiplication module 13 is fixed to the plasma source frame module 11 by epoxy resin glue;

[0037] The plasma source output end packaging module 14 is a porous array emitter made of copper-nickel alloy, and the porous array emitter is fixed to the plasma source frame module 11 by epoxy resin glue. The plasma source output end packaging module 14 is used to control the drift movement direction of space charge after the gas medium is polarized, thereby generating uniform plasma.

[0038] The upper surface of the porous array emitter and the seed electron multiplication module 13 are bonded by conductive silver paste, and the holes are made to face each other, and finally a "small hole-medium hole-large hole" structure is formed. The porous array emitter of the protruding part is sprayed with conductive silver paint, graphene and polytetrafluoroethylene insulation coating in sequence, wherein the polytetrafluoroethylene insulation coating can limit the free growth of the discharge current when the discharge occurs, prevent the formation of spark discharge or arc discharge between the electrodes, and form a dielectric barrier discharge structure. In order to increase the content of free electrons and metastable ions, the ionization end 121 provides a large number of initial electrons for the discharge through the field emission effect of the micro-sized electrode, and at the same time, a large number of metastable ions are generated by gas collision. The setting method of the micro-sized microelectrode can be selected according to the required plasma density, specifically including setting method one and setting method two.

[0039] The first method is to process the ionization end 121 into a needle-shaped electrode through high-precision machining, the processing material is nickel-copper alloy, and a layer of gold is electroplated and deposited on its surface through an electroplating process.

[0040] The second method is that the ionization end 121 is processed into a scalloped nine-array microelectrode by high-precision machining, such as Figure 1 As shown, the processing material is a nickel-copper alloy, and a layer of gold is electroplated and deposited on its surface through an electroplating process.

[0041] In this embodiment, the ionization end 121 is processed into a scalloped nine-array microelectrode by high-precision machining to maximize the number of initial electrons and metastable ions.

[0042] In order to further increase the efficiency of micro-discharge pre-ionization at the ionization end and increase the number of seed electrons and metastable ions, the microelectrode ionization end 121 is treated with a carbon nanotube-nafion composite material by leaching. The number of leaching times is 1. At the same time, the AC voltage is 400V, the frequency is 1.5kHz, and the action time is 8s, so that the carbon nanotubes will be polarized under the influence of the electric field. The parallel direction of the carbon nanotube axis has a greater polarization ability than the radial direction. This differentiated polarization ability generates torque, causing the carbon nanotubes to be oriented in the direction of the applied electric field against the viscous resistance of the substrate. Figure 3 As shown, the samples were finally fixed in a vacuum drying oven at 60°C.

[0043] By adjusting the position of the array rectangular convex groove 124 and the plasma source frame module 113, the ionization end 121 is 1-3mm away from the upper surface of the cylindrical gold-plated small circular hole ceramic plate 136 to form a pre-ionization discharge channel. The seed electron multiplication module 13 is composed of an axial annular magnet wrapped with two layers of cylindrical gold-plated micro-circular hole ceramics with a thickness of 2mm, a diameter of 8mm, and different apertures, wherein the annular magnet has a Gauss value of 3000GS, an outer diameter of 15mm, an aperture of 10mm, and a thickness of 3.5mm. The ring is separated from the two layers of cylindrical gold-plated micro-circular hole ceramics by a resin layer with a thickness of 1mm and a height of 4mm. The micropore aperture of the cylindrical gold-plated small circular hole ceramic plate 136 is 0.5mm, and the micropore aperture of the cylindrical gold-plated medium circular hole ceramic plate 135 is 0.7mm. Two layers of gold-plated microporous ceramics are connected by conductive silver glue to keep the micropores connected to each other, forming a "small hole to center hole" structure. The openings of each layer of cylindrical gold-plated microporous ceramics are arranged in an array, and each layer of cylindrical gold-plated microporous ceramics has 124 array microcircular holes.

[0044] First, a layer of conductive silver paste with a thickness of about 0.3 mm was sprayed on the outer surface 141 of the plasma source output end packaging module 14. After the conductive silver paste dried, a layer of graphene with a thickness of 0.1 mm and a polytetrafluoroethylene insulation coating with a thickness of 0.05 mm were sprayed in sequence. After that, the entire plasma source output module 14 was placed in a vacuum drying oven at 80° C. and dried for 50 minutes.

[0045] Then, if Figure 1 As shown, the air pre-ionization microelectrode 12, the seed electron multiplier module 13 and the plasma source output end packaging module 14 are assembled on the plasma source frame module 11, wherein the upper surface 142 of the plasma source output end packaging module is bonded to the lower surface of the cylindrical gold-plated medium-hole ceramic plate 135 through conductive silver glue. The single circular hole of the copper-nickel alloy porous array emitter, with a diameter of 0.8 mm, forms a "small hole-medium hole-large hole" structure with the seed electron multiplier module 13.

[0046] Finally, the gaps of the plasma source frame module 11 are filled with liquid paraffin, thereby preparing a low-temperature plasma source.

[0047] Example 2

[0048] The high voltage output end of the adjustable high voltage pulse excitation source is connected to the microelectrode excitation end 122 of the low temperature plasma source described in Example 1 by soldering. The excitation source described in the present invention can be obtained commercially for experimental purposes. The low temperature plasma source is installed directly above the nickel foam grounding electrode with a length and width of 6 cm by an adjustable height bracket. By adjusting the excitation source power supply parameters, a diffusely distributed atmospheric pressure glow discharge is formed, such as Figure 4The discharge effect diagram is shown, and the plasma action distance and volume produced are shown in the following table.

[0049] Power(W) Discharge gap height (cm) <![CDATA[Plasma interaction volume (cm 3 )]]> 17 8 148

[0050] Example 3, based on Example 2, an air filter element with a length and width of 7 cm and a thickness of 3 cm is placed above the nickel foam grounding electrode, and a diffuse atmospheric pressure glow discharge is formed above the air filter element by adjusting the excitation source power supply parameters, such as Figure 5 The discharge effect diagram is shown, and the plasma action distance and volume produced are shown in the following table.

[0051] Power(W) Discharge gap height (cm) <![CDATA[Plasma action volume (cm 3 )]]> 17 5 93

[0052] Example 4: The foam nickel grounding electrode is replaced with a columnar metal grounding electrode, and a stainless steel disc with a diameter of 10 mm and a thickness of 0.5 mm is placed above the columnar metal. By adjusting the discharge parameters of the excitation source power supply, a glow discharge with the discharge channel concentrated on the stainless steel disc can be formed, such as Figure 6 The discharge effect diagram is shown, and the plasma action distance and volume produced are shown in the following table.

[0053] Power(W) Discharge gap height (cm) <![CDATA[Plasma interaction volume (cm 3 )]]> 17 6 20

[0054] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A long gap atmospheric pressure glow discharge low temperature plasma source device, characterized in that: It comprises a plasma source, which is composed of a plasma source frame module (11), an air pre-ionization microelectrode (12), a seed electron multiplication module (13) and a plasma source output end packaging module (14); The plasma source frame module (11) is composed of a ceramic frame (112) with a convex groove and a ceramic frame (111) with a concave groove, which are interlocked with each other; The air pre-ionization microelectrode (12) is arranged in a ceramic frame (111); the ionization end (121) of the air pre-ionization microelectrode (12) is a round toothed nine-array microelectrode with a gold-plated surface; an inner hole (123) is arranged in the microelectrode excitation end (122) of the air pre-ionization microelectrode (12); and an array of rectangular convex grooves (124) are also arranged outside the air pre-ionization microelectrode (12); The seed electron multiplication module (13) is composed of an axial annular columnar magnet (131), a cylindrical gold-plated small-hole ceramic plate (136) and a cylindrical gold-plated middle-hole (135) wrapped by a resin insulation layer (134), and the seed multiplication module (13) is fixed to the plasma source frame module (11) by epoxy resin glue; The plasma source output end packaging module (14) is a porous array emitter made of copper-nickel alloy, and the porous array emitter is fixed to the plasma source frame module (11) by epoxy resin glue. The plasma source output end packaging module 14 is used to control the drift movement direction of space charges after the gas medium is polarized, thereby generating uniform plasma.

2. A long gap atmospheric pressure glow discharge low temperature plasma source device according to claim 1, characterized in that: The upper and lower surfaces of the air pre-ionization microelectrode (12) are made of through-hole fish-row-shaped rectangular ceramics that are copper-coated, and the outer surface of the round tooth-shaped nine-array microelectrode is attached with a layer of conductive silver glue.

3. The long gap atmospheric pressure glow discharge low temperature plasma source device according to claim 1, characterized in that: The scalloped nine-array microelectrode ionization end is treated by leaching with a carbon nanotube-nafion composite material, the leaching times are 1, and the action time is 8 seconds at an AC voltage of 400V and a frequency of 1.5kHz, and finally fixed in a 60°C vacuum drying oven.

4. The long gap atmospheric pressure glow discharge low temperature plasma source device according to claim 1, characterized in that: The air pre-ionization microelectrode (12) is connected with the inner array rectangular groove and the inner array rectangular groove of the plasma source frame through the array rectangular convex groove and the array rectangular convex groove.

5. The long gap atmospheric pressure glow discharge low temperature plasma source device according to claim 1, characterized in that: The upper surface of the porous array emitter and the lower surface of the seed electron multiplication module (13) are bonded by conductive silver paste, and the holes are made to face each other, finally forming a "small hole-medium hole-large hole" structure.

6. The long gap atmospheric pressure glow discharge low temperature plasma source device according to claim 5, characterized in that: The porous array emitter on the protruding part is sprayed with conductive silver paint, graphene and polytetrafluoroethylene insulating coating in sequence. The polytetrafluoroethylene insulating coating can limit the free growth of the discharge current when discharge occurs, prevent the formation of spark discharge or arc discharge between the electrodes, and form a dielectric barrier discharge structure.

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