CN103260329A - Plasma jet device with suspension electrode - Google Patents

Abstract

The invention belongs to the field of plasma technology, and provides a plasma jet device with suspended electrodes, comprising: a dielectric tube with openings at both ends, an air vent sleeved at the inlet end of the dielectric tube, and a The suspension electrode is used to support the support structure of the suspension electrode, the high-voltage electrode wrapped around the outlet end of the medium pipe and the working power supply connected to the high-voltage electrode; when working, the working gas is passed through the vent and passes through the medium The outlet end of the tube flows out and creates a plasma jet with a high density of active particles. Due to the high taper of the tip of the needle electrode, the present invention can form a strong electric field, making ionization more likely to occur, thereby effectively reducing the breakdown voltage, and ionizing active particles more easily, effectively solving the problem of low active particle density in the prior art problem; also being able to increase the cross-sectional area of the plasma, thus enabling larger processing areas in materials processing and biological applications.

Description

A plasma jet device with suspended electrodes

technical field

The invention belongs to the field of plasma technology, and more specifically relates to a plasma jet device with suspended electrodes.

Background technique

Existing plasma jet devices can be divided into the following types: the first one is a plasma generating device of a kilohertz AC power supply as shown in Figure 1, comprising a high-voltage electrode 14 and a ground electrode 12 separated by a dielectric disc 13 , are placed together in the medium pipe 15, the working gas source 16 is nitrogen, and the flow rate is 3 liters/second. The working power source 11 is a high-voltage AC power source with a frequency of 20 kHz. Plasma is ejected from the tube through small holes in the electrodes and dielectric disc. In the second type of radio frequency plasma needle shown in Figure 2, the working power supply 27 is a radio frequency power supply, and a tungsten wire with a diameter of 0.3 mm is connected to the radio frequency power supply as a high voltage electrode 23, and the high voltage electrode is placed within a diameter of 4 mm. The medium pipe 21 is covered with a medium container 22 outside, and the high-voltage electrode, the inner medium pipe and the outer medium container are placed on the base 26 together. The working gas 25 enters the inner dielectric tube through the opening on the base, thereby generating discharge.

In addition, there is a dual-motor dual-frequency power supply as shown in Figure 3, wherein the power supply 31 is a radio frequency power supply connected to the high-voltage electrode 33, and the high-voltage electrode 33 is located in the dielectric tube 32, and the working gas flows through the dielectric tube 32 and is grounded. The electrodes 34 are wrapped on the outside of the dielectric tube. Another AC power supply 36 is connected to an electrode plate 35 and placed under the dielectric tube, and its function is to control the length and thickness of the plasma jet.

The current existing technologies have some shortcomings, such as low density of plasma active particles, high plasma temperature, and small plasma treatment area. These problems make the application effect of plasma unsatisfactory.

Contents of the invention

Aiming at the defects of the prior art, the object of the present invention is to provide a plasma jet device with suspended electrodes, aiming at solving the problem of low density of active particles in the prior art.

In order to achieve the above object, the present invention provides a plasma jet device with suspended electrodes, comprising: a dielectric tube with openings at both ends, a vent hole sleeved at the inlet end of the dielectric tube, and a suspended electrode suspended in the dielectric tube. The electrode is used to support the support structure of the suspension electrode, the high-voltage electrode wrapped at the outlet end of the medium tube and the working power supply connected to the high-voltage electrode; when working, the working gas is passed through the vent and passes through the medium tube The outlet port flows out and produces a plasma jet with a high density of active particles.

Furthermore, the medium tube is a hollow quartz tube or glass tube, and the inner diameter of the medium tube is 6mm-12mm.

Furthermore, the suspension electrodes are stainless steel needles, copper wires or copper rods.

Furthermore, the suspension electrode includes a copper wire and a glass or ceramic tube with one end sealed, and the copper wire is located in the glass or ceramic tube.

Furthermore, the high-voltage electrode is tin foil, copper sheet or iron sheet.

Furthermore, the air vent is a flexible and airtight pipe structure.

Furthermore, the plasma jet device also includes a pressure reducing valve connected to the vent and a gas reservoir connected to the pressure reducing valve, the working gas is stored in the gas reservoir and passed through the pressure reducing valve Then pass into the medium pipe from the vent.

Furthermore, the working gas is helium, argon, nitrogen, oxygen, air, mixed gas, gaseous compound or gaseous organic compound.

Furthermore, the working power is pulse power, radio frequency power or AC power.

Due to the high taper of the tip of the needle electrode, the present invention can form a strong electric field, making ionization more likely to occur, thereby effectively reducing the breakdown voltage, and ionizing active particles more easily, effectively solving the problem of low active particle density in the prior art problem; also being able to increase the cross-sectional area of the plasma, thus enabling larger processing areas in materials processing and biological applications.

Description of drawings

Fig. 1 is the structural representation of a kind of kilohertz AC plasma jet device provided by the prior art;

Fig. 2 is a schematic structural view of a radio frequency plasma needle provided by the prior art;

Fig. 3 is a schematic diagram of a dual-electrode dual-frequency plasma jet device provided by the prior art;

FIG. 4 is a schematic structural view of a plasma jet device with suspended electrodes provided in the first embodiment of the present invention;

5 is a schematic structural diagram of a plasma jet device with suspended electrodes provided in a second embodiment of the present invention;

Fig. 6 is a schematic structural diagram of different positions of the suspension electrode provided by the embodiment of the present invention;

Fig. 7 is a schematic diagram of an experiment photo of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The plasma jet device with suspended electrodes provided by the present invention can produce plasma jets with high density of active particles; by changing the relative positions of the suspended electrodes and the power electrodes, the suspended electrodes can not only reduce the breakdown voltage of the plasma jet, but also increase the The activity of the plasma also increases the length of the jet. The device of the invention is simple to manufacture, safe and convenient to use, and has a wide range of working gas, which further improves the application range of the plasma.

Figure 4 and Figure 5 show the structure of the plasma jet device with suspended electrodes provided by the embodiment of the present invention. For the convenience of description, only the parts related to the embodiment of the present invention are shown, and the details are as follows:

The plasma jet device with suspended electrodes includes: a dielectric tube 2 with openings at both ends, a vent 10 sleeved at the inlet end of the dielectric tube 2, a suspended electrode 1 suspended in the dielectric tube 2, and a support for supporting the suspended electrode 1 Structure 7, the high-voltage electrode 3 wrapped at the outlet end of the dielectric tube 2 and the working power supply 6 connected to the high-voltage electrode 3; when working, the working gas is passed through the vent 10, flows out through the outlet end of the medium tube 2 and generates active particles High density plasma jet.

Wherein, the medium pipe 2 communicates with the working gas, and the medium pipe 2 is a hollow pipe, which can be a quartz tube or a glass tube, and the inner diameter of the medium pipe is 6mm-12mm.

The suspension electrode 1 is located in the medium tube, not in contact with the wall of the medium tube; the suspension electrode 1 can be a stainless steel needle, copper wire or copper rod. The suspension electrode 1 may also include a copper wire and a glass tube or a ceramic tube sealed at one end, and the copper wire is located in the glass tube or ceramic tube; and placed in the dielectric tube. Due to its high taper, the stainless steel needle is more prone to corona discharge and reduces the breakdown voltage; the use of copper wire or copper rod can reduce the distance between the suspension electrode and the high voltage electrode and promote uniform plasma jet generation.

The high-voltage electrode 3 is a conductive medium wrapped at the outlet of the medium pipe, which can be tin foil, copper sheet or iron sheet or the like.

The support structure 7 is used to suspend the suspension electrode 1 in the dielectric tube 2 without contacting the tube wall, and the support structure 7 is an insulating material.

The air vent 10 is used to allow the working gas 12 to enter the medium pipe 2. The air vent 10 is socketed on the port of the medium pipe 2. The air vent 10 can adopt a flexible pipe structure and must ensure tight connection.

The working power supply 6 can be a pulse power supply, a radio frequency power supply or an AC power supply and the like. Pulse power supply produces plasma with low temperature and moderate density of active particles, which is suitable for biomedical applications; radio frequency power supply produces plasma with high density of active particles, which is suitable for material processing; AC power supply can generate long-distance jets, and has higher precision for complex three-dimensional The processing power of the target.

In the embodiment of the present invention, the plasma jet device further includes a decompression valve 11 connected to the vent 10 and a gas reservoir 12 connected to the decompression valve 11, the working gas is stored in the gas reservoir 12 and passes through the decompression valve After 11, pass in the medium pipe 2 from the air vent.

The plasma jet device with suspended electrodes provided by the invention can generate plasma jets with low temperature and high density of active particles, and is suitable for various working gases. Wherein, the working gas may be helium, argon, nitrogen, oxygen, air, mixed gas, gaseous compound or gaseous organic compound.

In the embodiment of the present invention, the floating electrode refers to an ungrounded metal electrode. When placed in the electric field formed by the high-voltage electrode, the potential difference can excite electron ionization, thereby obtaining potential, generating plasma, and improving the performance of the plasma. In the device, the high-voltage electrode is set at the outer port of the medium tube, the suspension electrode is placed in the center of the medium tube, and the medium tube is a hollow tube that communicates with the working gas source. The characteristic is that the suspension electrode can not only reduce the breakdown voltage of the plasma jet, but also increase the activity of the plasma, lengthen the length of the plasma jet, and increase the area of the jet.

The invention is simple to manufacture, safe and convenient to use; the range of working gas is wide, and the working gas can be simple gas such as helium, argon, nitrogen, oxygen or mixed gas mixed with other gases, and can also be air, gaseous compound or gaseous Organic matter, etc.; the working power supply can be pulse power supply, radio frequency power supply, AC power supply, etc., which are suitable for a variety of power supplies; the breakdown voltage is low, and a stable jet can be obtained under atmospheric pressure without a vacuum environment; the temperature of the plasma is low, It has a long length and a large area, and can be widely used in various aspects such as plasma material processing and biomedical sterilization.

In order to further illustrate the plasma jet device with suspended electrodes provided by the embodiments of the present invention, the details are as follows with reference to the accompanying drawings and specific examples:

Embodiment 1: As shown in Figure 4, the plasma jet device includes a dielectric tube 2, a suspension electrode 1, a high voltage electrode 3, a vent 10, a working gas 12, and a pressure reducing valve 11, and the dielectric tube 2 is a quartz tube with openings at both ends Or a glass tube with an inner diameter of 8 mm, the suspension electrode 1 is a stainless steel needle, and the high-voltage electrode 3 is closely attached to the outer wall of the medium tube. The power supply 6 is a pulse power supply, and the power supply 6 is connected to the high-voltage electrode 3. The working gas 12 enters from the vent 10 through the pressure reducing valve 11, flows out through the medium pipe 2, and generates plasma 4 on the other side of the medium pipe. The working gas can be simple gas such as helium, argon, nitrogen, oxygen, or a mixed gas mixed with other gases, or it can be air, gaseous compounds, or gaseous organic compounds.

Existing plasma jet devices currently have a low density of plasma active particles. In Example 1, due to the high taper of the needle electrode head, a strong electric field can be formed, making ionization easier to occur, thereby effectively reducing the breakdown voltage, and more The active particles are easily ionized, effectively solving the problem of low active particle density in the prior art.

Embodiment 2: As shown in Figure 5, the parameters of the dielectric tube 2, the high-voltage electrode 3, and the pulse power supply 6 are the same as those in Example 1. The suspension electrode unit 1 is composed of a suspension electrode and a glass tube with one end sealed. The suspension electrode is a copper wire located at In the glass tube; the suspension electrode unit adopts the above structure, and the insulating medium is inserted into the discharge space to form a dielectric barrier discharge. This suspension electrode device not only has the advantages of embodiment 1, but also can increase the cross-sectional area of the plasma, so that it can be used in material processing and biological In medical applications, the treatment area can be increased. Due to the use of glass or ceramics as the dielectric barrier discharge, the temperature of the plasma is low, generally room temperature or slightly higher than room temperature.

Taking helium as an example, the diameter of the inner wall of the dielectric tube is 8 mm. When the gas flow rate is 3 liters per minute, the frequency of the pulse power supply is 10 kHz, the pulse width is 300 nanoseconds, and the position of the suspended electrode is adjusted to generate plasma. The density of bioactive particles is high, the temperature is low, slightly higher than room temperature, and can be directly touched by hands, and the length of the plasma jet can reach more than 5 cm.

When the device does not have a floating electrode, the pulse voltage amplitude is increased to 10 kV, and the plasma has not yet been generated when the distance between the high-voltage electrode and the ground electrode is reduced to 1 cm. Figure 6 is a schematic diagram of the position change of the suspension electrode. When the suspension needle electrode is in the dielectric tube, as shown in Figure 6(a), when the ground electrode is 3 cm away from the high-voltage electrode, the breakdown voltage is 5.6 kV. 6(b) shows 3.2 kV. The dielectric barrier suspension electrode also has a similar phenomenon: the breakdown voltage is 5.02 kV as shown in Figure 6(c) inside the tube, and drops to 3.7 kV outside the tube as shown in Figure 6(d). The above experimental data fully demonstrate that the suspended electrode can reduce the discharge voltage and generate plasma more easily.

The photo of the plasma jet is shown in Figure 7, Figure 7(a)(b)(c)(d) corresponds to Figure 6(a)(b)(c)(d), from Figure 7(b) and ( In d), it can be seen that when the suspended electrode is located outside the tube, the discharge intensity is increased. And it is shown in Fig. 7(d) that when the dielectric barrier suspension electrode is located outside the tube, the plasma jet can form a double channel, which increases the plasma processing area.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (9)

1. A plasma jet device with a suspended electrode is characterized in that it comprises: a dielectric tube with openings at both ends, an air vent sleeved at the inlet end of the medium tube, and a suspended electrode suspended in the medium tube, with For the support structure supporting the suspension electrode, the high-voltage electrode wrapped around the outlet end of the medium tube and the working power supply connected to the high-voltage electrode; When working, the working gas enters through the air vent and flows out through the outlet of the medium pipe to generate a plasma jet with high density of active particles. 2 . The plasma jet device according to claim 1 , wherein the medium tube is a hollow quartz tube or glass tube, and the inner diameter of the medium tube is 6mm-12mm. 3. The plasma jet device according to claim 1, wherein the suspension electrode is a stainless steel needle, a copper wire or a copper rod. 4 . The plasma jet device according to claim 1 , wherein the suspension electrode comprises a copper wire and a glass or ceramic tube with one end sealed, and the copper wire is located in the glass or ceramic tube. 5. The plasma jet device according to claim 1, wherein the high voltage electrode is tin foil, copper sheet or iron sheet. 6. The plasma jet device according to claim 1, wherein the air vent is a flexible airtight pipe structure. 7. The plasma jet device as claimed in claim 1, characterized in that, the plasma jet device also comprises a pressure reducing valve connected with the air vent and an air reservoir connected with the pressure reducing valve, working The gas is stored in the gas storage and flows into the medium pipe from the vent after passing through the pressure reducing valve. 8. The plasma jet device according to claim 1 or 7, wherein the working gas is helium, argon, nitrogen, oxygen, air, mixed gas, gaseous compound or gaseous organic substance. 9. The plasma jet device according to claim 1, wherein the working power is pulse power, radio frequency power or AC power.

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