Air preionization streamer discharge device with double ground electrodes

Abstract

The utility model belongs to low temperature discharge plasma technology field discloses an air preionization efflux discharge device with double grounding electrodes, which comprises a pointed rod electrode, an insulating plug, an insulating sleeve, an upper end grounding electrode and a lower end grounding electrode. The utility model generates preionization in the preionization zone between the upper end grounding electrode and the pointed rod electrode, provides seed electrons for the main discharge zone between the lower end grounding electrode and the pointed rod electrode, and reduces the initial discharge voltage of the pointed rod electrode. Due to the effect of preionization, the length of the plasma plume is longer than that of the efflux of a common needle-ring single grounding electrode device under the same discharge parameters. Meanwhile, there are two discharge zones, i.e. the preionization zone and the main discharge zone, between the two grounding electrodes and the pointed rod electrode, which increases the discharge area, prevents local over-discharge, and improves the stability of the efflux discharge. The air preionization efflux discharge device has practical value in the fields of water treatment, sterilization, biomedicine, etc.

Description

Technical Field

[0001] This utility model belongs to the field of low-temperature discharge plasma technology and relates to an air pre-ionization jet discharge device with dual grounded electrodes. Background Technology

[0002] Atmospheric pressure jet discharge offers excellent controllability. Under the influence of an electric field and a gas flow field, high-energy and reactive particles generated by the discharge are ejected as jets into the downstream working area, making it important in fields such as biomedicine and wastewater treatment. Jet discharge devices have a simple structure, with the discharge area separated from the downstream working area, making them easy to operate. Commonly used working gases for jet discharge devices are air, helium, argon, or mixtures of these gases. Compared to inert gases like helium and argon, using air as the working gas is inexpensive; however, the high oxygen content in air, coupled with the electronegative nature of oxygen, can adsorb electrons, negatively impacting the maintenance of stable jet discharge. This invention presents a novel air pre-ionization jet discharge device with dual grounded electrodes. The device features a pointed rod electrode housed within an insulating sleeve, connected to a high-voltage power supply. Two grounded electrodes are installed on the outer wall of the insulating sleeve, positioned vertically above and below the tip of the pointed rod electrode. The ionized gas in the pre-ionization region between the upper ground electrode and the pointed rod electrode can provide seed electrons for the main discharge region between the lower ground electrode and the pointed rod electrode, reducing the initial discharge voltage of the pointed rod electrode, while promoting the ejection of air jet plasma and extending the length of the plasma plume.

[0003] Chinese invention patent CN101466194A discloses a pre-ionization jet discharge device. This device has two high-voltage electrodes (needle and ring) and a ground electrode. A variable-diameter quartz tube is used, with a high-voltage ring electrode at the smallest diameter point and a ground electrode at the lower end forming the main discharge region. A hollow high-voltage needle electrode is placed inside the variable-diameter quartz tube, through which argon gas is introduced. Utilizing the characteristic that argon gas is more easily ionized, seed electrons are generated, forming a pre-ionization region that provides seed electrons to the main discharge region. Chinese invention patent CN116193697A discloses a pre-ionization jet discharge device consisting of a capillary array high-voltage electrode, a ring high-voltage electrode, and a ground ring electrode. This device reduces the breakdown voltage required for discharge through pre-ionization discharge of the capillary array, and can maintain discharge even when the working gas contains oxygen. Both of the above-mentioned jet discharge devices with pre-ionization processes have complex pre-ionization structures, requiring two high-voltage electrodes and an additional gas inlet for one of the high-voltage electrodes to introduce argon gas to provide the seed electrons required for pre-ionization. The structures are complex and the costs are high. Utility Model Content

[0004] This invention aims to provide an air pre-ionization jet discharge device with dual grounded electrodes. The device has two grounded electrodes. The pre-ionization region between the upper grounded electrode and the pointed rod electrode can provide seed electrons for the main discharge region between the pointed rod electrode and the lower grounded electrode. Compared with the common needle-ring type single grounded electrode structure jet device, the starting discharge voltage is lower, the generated jet is longer, and the discharge effect is better.

[0005] The technical solution of this utility model is as follows:

[0006] An air pre-ionization jet discharge device with dual grounded electrodes includes: a pointed rod electrode, an insulating plug, an insulating sleeve, an upper grounded electrode, and a lower grounded electrode. The insulating sleeve has openings at its top and bottom; the bottom opening serves as the jet outlet, and the top opening allows the pointed rod electrode to pass through. The upper part of the pointed rod electrode is fixed in the top opening by a hollow T-shaped insulating plug, with the tip of the pointed rod electrode located at the lower part of the insulating sleeve. An air inlet is provided on the side of the upper part of the insulating sleeve. The upper and lower grounded electrodes are mounted on the outer wall of the lower part of the insulating sleeve, positioned above and below the tip of the pointed rod electrode along its vertical axis, respectively; both positions are adjustable.

[0007] The pointed rod electrode is a metal electrode, and its material can be tungsten, stainless steel or other metal materials. It is powered by a high-frequency AC power supply, and the frequency of the AC high-voltage power supply is adjustable in the range of 5-14kHz and the voltage is adjustable in the range of 0-20kV.

[0008] The insulating sleeve is made of quartz.

[0009] The upper and lower grounding electrodes are made of metal sheets, such as copper, aluminum, and stainless steel, and are tightly attached to the outside of the insulating sleeve.

[0010] The beneficial effects of this utility model are:

[0011] Compared to common needle-ring type single-grounded electrode jet discharge devices, the air pre-ionization jet discharge device with dual grounded electrodes proposed in this invention has two discharge zones. Because the discharge gap between the upper grounded electrode and the pointed rod electrode in the pre-ionization zone is smaller than the discharge gap in the lower main discharge zone, the electric field strength in the pre-ionization zone is stronger under the same voltage, making air easier to ionize. The air in the pre-ionization zone can discharge at a lower voltage, providing seed electrons for the main discharge zone between the pointed rod electrode and the lower grounded electrode, forming pre-ionization and reducing the discharge and sustaining voltage of the main discharge zone between the pointed rod electrode and the lower grounded electrode. Under the same discharge parameters, the length of the plasma plume generated by the discharge is longer than that of common needle-ring type single-grounded electrode devices, enhancing the discharge effect. Simultaneously, stable discharge is also possible between the pointed rod electrode and the upper grounded electrode, increasing the discharge area, avoiding local overheating caused by local over-discharge, enhancing discharge stability, and generating more chemically active substances. This device only uses air as the working gas, eliminating the need to introduce gases such as argon to provide seed electrons for pre-ionization in the main discharge zone, thus effectively reducing costs and improving economic efficiency. The air pre-ionization jet discharge device of this invention has practical value in the fields of water treatment, sterilization, and biomedicine. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the air pre-ionization jet discharge device with dual grounded electrodes provided by this utility model.

[0013] Figure 2 Different jet discharge devices are used at a voltage of 12kV, a power frequency of 10kHz, and a gas flow rate of 3L·min. -1 Images of jet discharge under the given conditions, where (a) is a needle-ring type single grounded electrode jet device, and (b) is an air pre-ionization jet discharge device with dual grounded electrodes.

[0014] In the diagram: 1. Pointed rod electrode; 2. Insulating plug; 3. Air inlet; 4. Insulating sleeve; 5. Upper grounding electrode; 6. Lower grounding electrode; 7. Jet outlet; 8. Pre-ionization zone; 9. Main discharge zone. Detailed Implementation

[0015] The specific embodiments of this utility model are further described below with reference to the accompanying drawings and technical solutions.

[0016] High O2 content in the air makes it difficult for N2 to break down and maintain discharge. This invention provides an air pre-ionization jet discharge device with dual grounded electrodes. By introducing pre-ionization, the air discharge voltage is reduced. The device includes: a pointed rod electrode 1, an insulating plug 2, an insulating sleeve 4, an upper grounding electrode 5, and a lower grounding electrode 6. The pointed rod electrode 1 is located at the center of the insulating sleeve 4 and is fixed by the T-shaped insulating plug 2. An air inlet 3 is located on one side of the upper end of the insulating sleeve 4. The upper grounding electrode 5 and the lower grounding electrode 6 are installed on the outer wall of the insulating sleeve 4, respectively located above and below the tip of the pointed rod electrode 1 vertically, and their positions and widths are adjustable. The upper grounding electrode 5 and the lower grounding electrode 6 form a pre-ionization region 8 and a main discharge region 9 with the pointed rod electrode 1, respectively.

[0017] like Figure 1 The diagram shows an air pre-ionization jet discharge device with dual grounded electrodes according to this embodiment. The main body of the device is a 150mm long insulating sleeve 4 made of quartz, with an inner diameter of 2.5mm and an outer diameter of 4mm. The top of the insulating sleeve 4 has an opening for the passage of a pointed rod electrode 1, and the bottom of the insulating sleeve 4 has an opening serving as the jet outlet 7. An air inlet 3 is located on the upper side of the insulating sleeve 4, with an inner and outer diameter of 2.5mm and 4mm respectively, through which air is introduced. The pointed rod electrode 1 is made of metal, with a length of 150mm, a diameter of 1mm, and a tip length of 3mm. The pointed rod electrode 1 extends into the insulating sleeve 4, and its upper part is fixed to the center of the insulating sleeve 4 by a T-shaped insulating plug 2. The distance between the tip of the pointed rod electrode 1 and the jet outlet 7 is 25mm. An upper grounded electrode 5 and a lower grounded electrode 6 are respectively provided on the outer side of the lower part of the insulating sleeve 4. The upper grounding electrode 5 is made of aluminum foil, with a width of 4 mm, and is located 5 mm above the vertical axis of the tip of the pointed rod electrode 1. The radial air gap between the upper grounding electrode 5 and the pointed rod electrode 1 is 0.75 mm. The lower grounding electrode 6 is also made of aluminum foil, with a width of 4 mm, and is located 5 mm below the vertical axis of the tip of the pointed rod electrode 1. In actual operation, the jet is ejected from the jet outlet 7, and the jet length is measured from the jet outlet 7. The area between the upper grounding electrode 5 and the pointed rod electrode 1 is the pre-ionization region 8, and the area between the lower grounding electrode 6 and the pointed rod electrode 1 is the main discharge region 9.

[0018] During operation, the pointed rod electrode 1 is connected to the AC high-voltage power supply, and air enters the interior of the insulating sleeve 4 through the air inlet 3. Due to the small radial air gap of 0.75mm between the pointed rod electrode 1 and the upper ground electrode 5, it can discharge under low voltage conditions and generate seed electrons. Under the action of the electric field and the air flow field, the seed electrons move towards the main discharge region between the pointed rod electrode 1 and the lower ground electrode 6, providing seed electrons to the main discharge region, effectively reducing the discharge voltage of the main discharge region, and generating a longer jet length.

[0019] Comparing the air pre-ionization jet discharge device with dual grounded electrodes of this invention with a common needle-ring type single grounded electrode jet discharge device, current probes were connected to the grounding wires of the lower grounding electrodes of the air pre-ionization jet discharge device with dual grounded electrodes and the grounding wires of the grounding electrodes of the needle-ring type single grounded electrode jet discharge device, respectively, to measure the discharge current. The measurements were performed at the same frequency of 10kHz and a gas flow rate of 3L·min. -1 Under certain conditions, increasing the voltage allows common needle-ring type single-grounded electrode jet discharge devices to generate discharge current at 8kV; while air pre-ionization jet discharge devices with dual grounded electrodes can generate discharge current at 5kV, significantly reducing the discharge voltage.

[0020] like Figure 2 The image shows a comparison between a dual-grounded-electrode air pre-ionization jet discharge device (Figure (b)) and a needle-ring type single-grounded-electrode plasma device (Figure (a)) at a voltage of 12 kV, a frequency of 10 kHz, and a gas flow rate of 3 L·min. -1 The images show the jet discharge under the same conditions. It can be seen from the discharge images that, under the same discharge conditions, the air pre-ionized jet discharge device has a longer discharge jet length, approximately 17 mm; while the needle-ring type single-grounded electrode structure plasma device has a jet length of approximately 6 mm and is weak.

[0021] This invention provides an air pre-ionization jet discharge device with dual grounded electrodes, which can generate discharge at a lower voltage and produce a longer jet with better discharge effect. The device has a simple structure, is easy to operate, and has practical significance.

Claims

1. An air pre-ionization jet discharge device with dual grounded electrodes, characterized in that, The air pre-ionization jet discharge device with dual grounding electrodes includes: a pointed rod electrode, an insulating plug, an insulating sleeve, an upper grounding electrode, and a lower grounding electrode; the insulating sleeve has openings at the top and bottom, with the bottom opening serving as the jet outlet and the top opening for the pointed rod electrode to pass through; the upper part of the pointed rod electrode is fixed in the top opening by a hollow T-shaped insulating plug, and the tip of the pointed rod electrode is located at the lower part of the insulating sleeve; an air inlet is provided on the side of the upper part of the insulating sleeve; the upper and lower grounding electrodes are installed on the outer wall of the lower part of the insulating sleeve, and are located above and below the tip of the pointed rod electrode in the vertical axis, respectively, and both positions are adjustable.

2. The air pre-ionization jet discharge device with dual grounded electrodes according to claim 1, characterized in that, The pointed rod electrode is a metal electrode and is powered by a high-frequency AC power supply.

3. The air pre-ionization jet discharge device with dual grounded electrodes according to claim 2, characterized in that, The pointed rod electrode is made of tungsten or stainless steel, and the frequency of the high-frequency AC power supply is adjustable in the range of 5-14kHz, and the voltage is adjustable in the range of 0-20kV.

4. The air pre-ionization jet discharge device with dual grounded electrodes according to claim 1, characterized in that, The insulating sleeve is made of quartz.

5. The air pre-ionization jet discharge device with dual grounded electrodes according to claim 1, characterized in that, The upper and lower grounding electrodes are made of metal sheets and are tightly attached to the outside of the insulating sleeve.

6. The air pre-ionization jet discharge device with dual grounded electrodes according to claim 1, characterized in that, The materials of the upper and lower grounding electrodes are copper, aluminum, or stainless steel.

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