A long gap atmospheric pressure glow discharge low temperature plasma source device

Abstract

The application provides a long-gap atmospheric pressure glow discharge low-temperature plasma source device, which comprises a plasma source 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; the seed electron multiplication module is composed of an axial annular cylindrical magnet, a cylindrical gold-plated small-hole ceramic plate wrapped by a resin insulation layer and a cylindrical gold-plated middle-hole; the seed multiplication module and the plasma source frame module are fixedly connected through epoxy resin glue; and the plasma source output end packaging module is a porous array emitter made of copper-nickel alloy. The application overcomes the problems of high power consumption and serious heat generation of traditional plasma generators, and the problems of easy oxidation and corrosion of traditional plasma sources / electrodes, poor stability and short discharge gap.

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 fully ionized atoms, molecules, free radicals, charged particles, electrons, and ultraviolet photons. Because the positive and negative charges of the entire system are equal after ionization, it is called the fourth state of matter, in addition to solid, liquid, and gas. Low-temperature plasma is a plasma in a non-thermodynamic equilibrium state. While the entire system maintains a relatively low temperature, the electron energy can reach 0-20 electron volts, sufficient to induce dissociation and ionization of compounds. Consequently, low-temperature plasma technology has attracted increasing attention in recent years, with applications in a wide range of fields, including microbial disinfection, biological breeding, air purification, and material modification.

[0003] Low-temperature plasma is primarily achieved through corona discharge and dielectric barrier discharge. Corona discharge is a localized discharge with low plasma density and an easy transition to high-temperature arc discharge. Because the electrodes are directly exposed to air, they are susceptible to oxidation and corrosion, shortening their service life and increasing the field strength required for the next discharge. Therefore, most technologies that can provide large areas and high electron density utilize dielectric barrier discharge.

[0004] Chinese patent CN201720745630.0 discloses an atmospheric pressure glow plasma generator and textile material processing device. This patent utilizes a dual-dielectric DBD discharge electrode design to effectively suppress arc discharge. However, the power consumption of dielectric barrier discharge is typically as high as hundreds of watts, resulting in significant thermal effects and accompanied by numerous filamentary discharges.

[0005] To address these issues, Chinese patent CN 201510021685.2 discloses a device for achieving uniform glow discharge in air at atmospheric pressure. This patent increases the concentration of initial electrons in the air by adsorbing carbon-14, which has a half-life of 5710 years, on the surface of the discharge electrode. This reduces the electric field strength required for gas discharge, significantly reducing the heat generated during the discharge process and achieving uniform discharge. However, this method results in a short discharge gap, with a maximum of only 7mm.

[0006] Furthermore, Chinese patent CN 114745839 A discloses a surface-to-body coupled discharge plasma device based on seed electron generation. This device utilizes a coplanar discharge to generate a preionization effect to provide seed electrons. The coupled discharge plasma device is generated above the electrodes of a capillary coplanar discharge array by applying pulses or alternating voltages of opposite polarity. Although it can achieve long-gap discharges up to 50 mm, it fails to effectively increase the active volume of the low-temperature plasma. Furthermore, the use of electrodes containing conductive but unevenly distributed metals doped within the capillary tubes can significantly reduce discharge uniformity. Furthermore, the device requires two excitation power sources to operate simultaneously, significantly increasing operational difficulty and still generating significant thermal effects. Glow discharge has broad application prospects due to its wide active range and high, uniform plasma density. Typically, glow discharge low-temperature plasma is generated in low-pressure or rare gas environments. However, at atmospheric pressure, the mean free path of electrons is shorter than at low pressure, resulting in higher voltages between the electrodes, increased electron impact ionization, and a higher density of charged ions, making it prone to conversion to filamentary or arc discharges.

[0007] Chinese patent CN107295740A discloses a device, method, and process for generating a uniform atmospheric-pressure glow discharge. This patent utilizes the constant current characteristics of a high-voltage resonant power supply to prevent the excessive development of electron avalanches, thereby driving a stable filamentary atmospheric-pressure glow discharge with an inner diameter ranging from 10-30 mm. However, the device still utilizes exposed needle-shaped electrodes, making it unable to sustain a long-term discharge. Furthermore, the discharge gap does not increase significantly, and the effective range is only expanded to a 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 a short discharge gap, high power consumption, a small volume of low-temperature plasma generated, a limited range of active species generation, easy oxidation and corrosion of exposed electrodes, and a 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] 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 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 scalloped 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 further arranged on the outside of 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 is fixed to the plasma source frame module by epoxy resin glue. The plasma source output end packaging module is used to control the direction of space charge drift 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 made of copper-coated through-hole fish-pattern rectangular ceramic, and the outer surface of the scalloped nine-array microelectrode is covered 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 an extraction method using a carbon nanotube-nafion composite material, with an extraction number of 1, and an AC voltage of 400V and a frequency of 1.5kHz for 8s, 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 to 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, ultimately forming a "small hole-medium hole-large hole" structure.

[0019] As a further illustration of the present invention, 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, 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 and corrosion of traditional plasma sources / electrodes, poor stability and short discharge gap. The plasma discharge gap generated by this low-temperature plasma source can reach 8cm, the power consumption is adjustable 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 This is a schematic diagram of the arrangement of nafion-carbon nanotubes on the surface of the air pre-ionization microelectrode of the present invention;

[0024] Figure 3 Schematic diagram of 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 pattern 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 ground 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 grooves 124, seed electron multiplication module 13, axial annular cylindrical magnet 131, resin insulation layer 134, cylindrical gold-plated middle hole 135, cylindrical gold-plated small hole ceramic plate 136, plasma source output end packaging module 14, and packaging outer surface 141. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0031] like Figure 1-3 The application provides a technical solution: a long-gap atmospheric pressure glow discharge low-temperature plasma source device, which comprises a plasma source 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 fluted ceramic frame 112 and a grooved ceramic frame 111.

[0033] The air pre-ionization microelectrode 12 is arranged in the ceramic frame 111, and the ionization end 121 of the air pre-ionization microelectrode 12 is a surface gold-plated tooth-shaped nine-array microelectrode, the tooth-shaped nine-array microelectrode ionization end is treated by an immersion method using a carbon nanotube-nafion composite material, the immersion frequency is 1, the treatment is performed under alternating voltage 400 V and frequency 1.5 kHz for 8 s, and finally the tooth-shaped nine-array microelectrode is fixed in a 60 DEG C vacuum drying box.

[0034] The air pre-ionization microelectrode 12 is arranged in the ceramic frame 111, and the ionization end 121 of the air pre-ionization microelectrode 12 is a surface gold-plated tooth-shaped nine-array microelectrode, the tooth-shaped nine-array microelectrode ionization end is treated by an immersion method using a carbon nanotube-nafion composite material, the immersion frequency is 1, the treatment is performed under alternating voltage 400 V and frequency 1.5 kHz for 8 s, and finally the tooth-shaped nine-array microelectrode is fixed in a 60 DEG C vacuum drying box.

[0035] The air pre-ionization microelectrode 12 is arranged in the ceramic frame 111, and the ionization end 121 of the air pre-ionization microelectrode 12 is a surface gold-plated tooth-shaped nine-array microelectrode, the tooth-shaped nine-array microelectrode ionization end is treated by an immersion method using a carbon nanotube-nafion composite material, the immersion frequency is 1, the treatment is performed under alternating voltage 400 V and frequency 1.5 kHz for 8 s, and finally the tooth-shaped nine-array microelectrode is fixed in a 60 DEG C vacuum drying box.

[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 medium-hole 135 wrapped by a resin insulation layer 134, and the seed multiplication module 13 and the plasma source frame module 11 are fixedly connected through epoxy resin glue.

[0037] The plasma source output end packaging module 14 is a porous array emitter made of copper-nickel alloy, the porous array emitter and the plasma source frame module 11 are fixedly connected through epoxy resin glue, and the plasma source output end packaging module 14 is used for controlling the space charge drift direction of the polarized gas medium, 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 pores are made to face each other, eventually forming a "small hole-medium hole-large hole" structure. 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] Method 1 is to process the ionization end 121 into a needle-shaped electrode through high-precision machining, using nickel-copper alloy as the processing material, and electroplating a gold layer on the surface thereof through an electroplating process.

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

[0041] In this embodiment, the ionization end 121 is processed into a nine-array microelectrode in a scalloped shape by high-precision machining, so as 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 leaching number is 1. At the same time, the AC voltage is 400V, the frequency is 1.5kHz, and the action time is 8s. The carbon nanotubes are 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 align 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] The pre-ionization discharge channel is formed by adjusting the position of the array rectangular convex slot 124 and the plasma source frame module 113, so that the ionization end 121 is 1-3 mm away from the upper surface of the cylindrical gold-plated small-hole ceramic plate 136. The seed electron multiplication module 13 is wrapped by an axial annular magnet, two layers of cylindrical gold-plated micro-hole ceramic with a thickness of 2 mm, a diameter of 8 mm and different hole diameters. The annular magnet has a gauss value of 3000GS, an outer diameter of 15 mm, a hole diameter of 10 mm and a thickness of 3.5 mm. Inside the ring, a layer of resin with a thickness of 1 mm and a height of 4 mm separates the two layers of cylindrical gold-plated micro-hole ceramic. The micro-hole diameter of the cylindrical gold-plated small-hole ceramic plate 136 is 0.5 mm, and the micro-hole diameter of the cylindrical gold-plated medium-hole ceramic plate 135 is 0.7 mm. The two layers of gold-plated micro-hole ceramic are connected by conductive silver paste, keeping the micro-hole holes connected, forming a "small hole to large hole" structure. Each layer of cylindrical gold-plated micro-hole ceramic has 124 array micro-holes.

[0044] The packaging outer surface 141 of the plasma source output end packaging module 14 is first sprayed with a layer of conductive silver paste with a thickness of about 0.3 mm. After the conductive silver paste is dried, a layer of graphene with a thickness of 0.1 mm and a layer of polytetrafluoroethylene insulating coating with a thickness of 0.05 mm are sprayed in turn. Then, the entire plasma source output module 14 is placed in a 80℃ vacuum drying box for drying for 50 minutes.

[0045] Next, as shown in Figure 1 The air pre-ionization microelectrode 12, the seed electron multiplication module 13 and the plasma source output end packaging module 14 are assembled in the plasma source frame module 11, wherein the upper surface 142 of the plasma source output end packaging module is connected to the lower surface of the cylindrical gold-plated medium-hole ceramic plate 135 by conductive silver paste. The single-hole diameter of the copper-nickel alloy porous array emitter is 0.8 mm, and the "small hole-medium hole-large hole" structure is formed with the seed electron multiplication module 13.

[0046] Finally, the gaps of the plasma source frame module 11 are filled with liquid paraffin, and the low-temperature plasma source is obtained.

[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 application can be obtained commercially for experimental purposes. The low-temperature plasma source is installed above the 6cm×6cm nickel foam ground electrode by an adjustable height support. By adjusting the excitation source power parameters, a diffuse distribution of atmospheric pressure glow discharge is formed, as shown in Figure 4The discharge effect diagram is shown, and the plasma action distance and volume generated are shown in the following table.

[0049] Power (W) Discharge gap height (cm) <![CDATA[等离子体作用体积(cm 3 )]]> 17 8 148

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

[0051] Power (W) Discharge gap height (cm) <![CDATA[等离子体作用体积(cm 3 )]]> 17 5 93

[0052] Example 4: The nickel foam grounding electrode is replaced with a cylindrical 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 cylindrical 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 generated are shown in the following table.

[0053] Power (W) Discharge gap height (cm) <![CDATA[等离子体作用体积(cm 3 )]]> 17 6 20

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

[0055] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the 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: The plasma source comprises 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 groove, which are interlocked; The air pre-ionization microelectrode (12) is arranged in a ceramic frame (111) with a groove, the ionization end (121) of the air pre-ionization microelectrode (12) is a scalloped nine-array microelectrode with a gold-plated surface, the microelectrode excitation end (122) of the air pre-ionization microelectrode (12) is provided with an inner hole (123), and the air pre-ionization microelectrode (12) is further provided with an array of rectangular convex grooves (124); 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 (135) wrapped by a resin insulation layer (134), and the seed electron 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 direction of space charge drift after the gas medium is polarized, thereby generating uniform plasma.

2. 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 to the inner array of rectangular grooves of the grooved ceramic frame (111) through the array of rectangular convex grooves, and a layer of conductive silver glue is attached to the outer surface of the round toothed nine-array microelectrode.

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 s at an AC voltage of 400 V and a frequency of 1.5 kHz, and finally fixed in a vacuum drying oven at 60°C.

4. 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 together by conductive silver paste, and the holes are made to face each other, ultimately forming a "small hole-medium hole-large hole" structure.

5. The long gap atmospheric pressure glow discharge low temperature plasma source device according to claim 4, 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, preventing the formation of spark discharge or arc discharge between the electrodes, and forming a dielectric barrier discharge structure.

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