CN105430861A - A temperature-controllable low-temperature plasma generation method - Google Patents

Abstract

The invention provides a temperature-controlled low-temperature plasma generation method, and belongs to the technical field of plasma discharge reactors. According to the method, a gas supply device supplies a gas with a certain pressure under the conditions of an atmospheric pressure and a room temperature; the gas is introduced into a gas control device and is transmitted to a vortex tube according to certain flow and pressure; the gas which is cooled in real time enters a plasma generator and discharges to generate a low-temperature plasma under the control of a high voltage power supply; and a temperature monitoring device can detect and display the temperature of the gas which is cooled by the vortex tube and the temperature of the generated low-temperature plasma. Through matched adjustment of the power supply voltage, the frequency and the gas pressure and flow, the controlled temperature of the low-temperature plasma from 200 DEG C to -4 DEG C is achieved; a working gas is cooled by a passive vortex tube in real time; the temperature-controlled plasma which is lower than a low temperature or even the room temperature can be obtained after the plasma generator discharges; and only the flow and the pressure of the working gas input into the vortex tube need to be adjusted in the control of the plasma temperature.

Description

A temperature-controllable low-temperature plasma generation method

technical field

The invention relates to a method for generating low-temperature plasma, which belongs to the technical field of plasma discharge reactors.

Background technique

Atmospheric pressure low-temperature plasma has a wide range of applications in the fields of material surface modification, sterilization, and biomedicine. When modifying the surface of polymers and biological materials, the temperature of the plasma has a significant impact on the performance of the material. In particular, when modifying biologically active objects such as cells, bacteria, skin, and tissues, the protein coagulation temperature is reached. The above plasma temperature will directly inactivate the organism, which will make the modification process difficult to control; when the plasma is used to etch semiconductor materials, the temperature will directly affect the etched nanostructure and surface integrity. At the same time, the temperature of cold plasma used for material surface modification is usually difficult to control, and its temperature is generally above room temperature, so that when the plasma acts on the surface of the material, it is equivalent to superimposing a heating process. This is the application of plasma in precision processing and biomedicine. issues that need to be resolved urgently. The invention patent with the publication number CN100394542C introduces a plasma etching device with controllable gas temperature. The electric heating wire heats the gas at the inlet end to control the temperature of the gas to change the movement speed of the gas molecules, so that the gas in the reaction chamber The medium is evenly distributed. The invention patent with the publication number CN103165368A proposes a temperature-adjustable plasma confinement device. Pipelines filled with heat exchange fluid are arranged in the area where the gas passes through to regulate the temperature of the plasma confinement device. The temperature of the device can be kept constant at 50 The value between ℃～90℃. The invention patent with the publication number CN103906336A introduces a gas discharge plasma generating device with adjustable pressure and temperature. The pressure in the gas tank is stabilized by a pump in the range of 0-1.1Mpa, and the gas can be heated to a maximum of 100Mpa by using a heating plate. ℃. The above-mentioned inventions all adopt the method of heating or exchanging heat to control the temperature of the plasma and the device, and it is impossible to obtain and control the low-temperature plasma at or below room temperature.

Contents of the invention

The invention provides a temperature-controllable low-temperature plasma generation method, which controls the temperature of the plasma by cooling the gas and then discharging it.

The invention uses a vortex tube to cool the gas under the condition of atmospheric pressure and room temperature, and then generates low-temperature plasma in the form of bare electrode discharge.

A temperature-controllable low-temperature plasma generation method, the device used in the method includes a gas supply device, a gas control device, a vortex tube, a high-voltage power supply, a plasma generator and a temperature monitoring device; the gas supply device provides a working pressure with a certain pressure Gas, the working gas leads to the gas control device, and is transported to the vortex tube according to a certain flow rate and pressure; the working gas enters the plasma generator after being cooled by the vortex tube; the high-voltage power supply controls the discharge process of the plasma generator, and generates low-temperature plasma body; the temperature monitoring device is used to monitor the temperature of the cooled working gas and the temperature of the generated low-temperature plasma; by adjusting the working gas pressure, flow rate and parameters of the vortex tube input to the vortex tube, the temperature of the working gas input into the plasma generator is controlled, In order to control the temperature of the low-temperature plasma generated by the plasma generator; through the coordinated adjustment of power supply voltage, frequency, gas pressure and flow rate, the temperature of the low-temperature plasma can be controlled from 200°C to -4°C.

The working gas provided by the gas supply device is one or a mixture of two or more of high-purity nitrogen, argon, helium, chlorine, oxygen, and filtered and dried air.

The discharge form of the plasma generator is bare electrode discharge, dielectric barrier discharge or hollow cathode discharge.

The high-voltage power supply is a DC high-voltage power supply, a low-frequency high-voltage power supply, a radio frequency high-voltage power supply, a microwave high-voltage power supply or a pulse high-voltage power supply.

When the pressure of the working gas input into the vortex tube is 0.5MPa and the flow rate is 18-25mL/min, the vortex tube cools the working gas to 7°C-1°C, using low-frequency sinusoidal AC plasma power supply, discharge voltage 3.0kV, frequency 60kHz , the temperature of the low-temperature plasma generated by the plasma generator is 15°C to 4°C.

When the pressure of the working gas input into the vortex tube is 0.7MPa, and the gas flow rate is 18-30mL/min, the gas cooler will cool the working gas to -10℃～-20℃, using a low-frequency sinusoidal AC plasma power supply, and the discharge voltage is 3.5kV 1. When the frequency is 70kHz, the temperature of the low-temperature plasma generated by the plasma generator is 5℃～-4℃.

The benefit of the present invention lies in that the working gas is cooled in real time by using a passive vortex tube, and a temperature-controllable plasma at a low temperature or even lower than room temperature can be obtained after being discharged by the plasma generator, and the control of the plasma temperature only needs to be adjusted The flow and pressure of the working gas entering the vortex tube.

Description of drawings

The accompanying drawing is a schematic diagram of the temperature-controllable low-temperature plasma generation method of the present invention.

In the figure: 1 gas supply device; 2 gas pipeline; 3 gas control device; 4 vortex tube; 5 plasma generator; 6 high voltage power supply; 7 temperature monitoring device; 8 low temperature plasma.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The invention provides a temperature-controllable low-temperature plasma generation method, the equipment using this method includes a gas supply device 1, a gas transmission pipeline 2, a gas control device 3, a vortex tube 4, a plasma generator 5, and a high-voltage power supply 6 And temperature monitoring device 7.

The working gas with a certain pressure is provided by the gas supply device 1, and is delivered to the gas control device 3 through the gas transmission pipeline 2, and then delivered to the vortex tube 4 after adjusting the flow and pressure of the working gas. The working gas cooled by the vortex tube 4 is sent to the plasma generator 5 , and the front end of the plasma generator 5 can generate low-temperature plasma 8 under the excitation of the high-voltage power supply 6 . The temperature monitoring device 7 can detect and display the temperature of the working gas input into the plasma generator and the temperature of the low-temperature plasma.

Example 1

At a room temperature of 22°C, high-purity nitrogen gas with a purity of 99.999% is supplied from a cylinder, and the gas pressure is 0.5 MPa. After the gas control device adjusted the flow rate to 18mL/min, it was sent to the vortex tube, and the temperature of the cooled gas was measured at 7°C by using a thermocouple digital thermometer. The cooled working gas is delivered to the plasma generator. The plasma generator is powered by a sinusoidal AC low-frequency high-voltage power supply with a frequency of 60kHz and a voltage of 3.0kV. At this time, the macroscopic temperature of the low-temperature plasma generated by the plasma generator is about 15°C. When the flow rate of the working gas input into the vortex tube is increased to 25mL/min, the vortex tube can cool the gas to 1°C, and the macroscopic temperature of the generated low-temperature plasma is 4°C.

Example 2

At a room temperature of 22°C, an air compressor is used to supply air, and the generated compressed air is dried and filtered and sent to the gas control device. The gas control device controls the gas pressure input into the vortex tube to be 0.7MPa, and when the flow rate is 18mL/min, the vortex tube can cool the air to -10°C. The plasma generator is powered by a sinusoidal AC low-frequency high-voltage power supply with a frequency of 70kHz and a voltage of 3.5kV, which can generate low-temperature plasma with a macroscopic temperature of 5°C. When the flow rate of the working gas input into the vortex tube is increased to 30mL/min, the vortex tube can cool the working gas to -20°C and generate a low-temperature plasma with a macroscopic temperature of -4°C.

Claims (10)

1. A temperature-controllable low-temperature plasma generation method is characterized in that the device used in the method comprises a gas supply device, a gas control device, a vortex tube, a high-voltage power supply, a plasma generator and a temperature monitoring device; a gas supply device Provide working gas with a certain pressure, the working gas leads to the gas control device, and is transported to the vortex tube according to a certain flow rate and pressure; the working gas enters the plasma generator after being cooled by the vortex tube; the high-voltage power supply controls the discharge of the plasma generator process, and generate low-temperature plasma; the temperature monitoring device is used to monitor the temperature of the cooled working gas and the temperature of the generated low-temperature plasma; by adjusting the working gas pressure, flow rate and vortex tube parameters input to the vortex tube, the input plasma is controlled The working gas temperature of the plasma generator is used to control the temperature of the low-temperature plasma generated by the plasma generator; through the adjustment of the power supply voltage, frequency, gas pressure and flow rate, the temperature of the low-temperature plasma can be controlled from 200°C to -4°C . 2. The low-temperature plasma generation method according to claim 1, wherein the working gas provided by the gas supply device is one or both of nitrogen, argon, helium, chlorine, oxygen, and filtered and dried air. A mixture of the above. 3. The low-temperature plasma generation method according to claim 1 or 2, characterized in that, the discharge form of the plasma generator is bare electrode discharge, dielectric barrier discharge or hollow cathode discharge. 4. The low-temperature plasma generation method according to claim 1 or 2, characterized in that the high-voltage power supply is a DC high-voltage power supply, a low-frequency high-voltage power supply, a radio frequency high-voltage power supply, a microwave high-voltage power supply or a pulsed high-voltage power supply. 5. The low-temperature plasma generation method according to claim 3, wherein the high-voltage power supply is a DC high-voltage power supply, a low-frequency high-voltage power supply, a radio frequency high-voltage power supply, a microwave high-voltage power supply or a pulsed high-voltage power supply. 6. The low-temperature plasma generation method according to claim 1, 2 or 5, characterized in that, when the pressure of the working gas input into the vortex tube is 0.5 MPa and the flow rate is 18-25 mL/min, the vortex tube cools the working gas To 7 ℃ ~ 1 ℃, using low-frequency sinusoidal AC plasma power supply, discharge voltage 3.0kV, frequency 60kHz, the temperature of the low-temperature plasma generated by the plasma generator is 15 ℃ ~ 4 ℃. 7. The low-temperature plasma generation method according to claim 3, characterized in that, when the pressure of the working gas input into the vortex tube is 0.5 MPa, and the flow rate is 18-25 mL/min, the vortex tube cools the working gas to 7° C. 1°C, using a low-frequency sinusoidal AC plasma power supply, when the discharge voltage is 3.0kV and the frequency is 60kHz, the temperature of the low-temperature plasma generated by the plasma generator is 15°C to 4°C. 8. The low-temperature plasma generation method according to claim 4, characterized in that, when the pressure of the working gas input into the vortex tube is 0.5 MPa, and the flow rate is 18-25 mL/min, the vortex tube cools the working gas to 7° C. 1°C, using a low-frequency sinusoidal AC plasma power supply, when the discharge voltage is 3.0kV and the frequency is 60kHz, the temperature of the low-temperature plasma generated by the plasma generator is 15°C to 4°C. 9. The low-temperature plasma generation method according to claim 1, 2, 5, 7 or 8, characterized in that, when the working gas pressure input into the vortex tube is 0.7MPa, and the gas flow rate is 18-30mL/min, the gas The cooler cools the working gas to -10℃～-20℃, adopts low-frequency sinusoidal AC plasma power supply, when the discharge voltage is 3.5kV and the frequency is 70kHz, the temperature of the low-temperature plasma generated by the plasma generator is 5℃～- 4°C. 10. The low-temperature plasma generation method according to claim 6, characterized in that, when the pressure of the working gas input into the vortex tube is 0.7 MPa and the gas flow rate is 18-30 mL/min, the gas cooler cools the working gas to - 10 ℃ ~ -20 ℃, low frequency sinusoidal AC plasma power supply, discharge voltage 3.5kV, frequency 70kHz, the temperature of the low temperature plasma generated by the plasma generator is 5 ℃ ~ -4 ℃.