Control device for atmospheric pressure plasma jet based on dynamic multiple composite magnetic fields

Abstract

The present invention discloses a control device for atmospheric pressure plasma jet based on dynamic multiple composite magnetic fields, which adopts a pulsed and constant composite magnetic field to increase the magnetic potential type, reduce heat generation and loss, effectively control the characteristics of the plasma flow, and further meet the needs of atmospheric pressure plasma jet in practical applications. The device includes an excitation electric field composed of a high-voltage electrode and a grounding electrode, which ionizes the working gas to obtain plasma. The device includes a transient strong magnetic field generated by a pulsed electromagnetic coil and a constant magnetic field generated by a gradient magnetic field coil and a permanent magnet array. The three together form a composite magnetic field to increase the magnetic potential type. The transient strong magnetic field can produce a stronger confinement effect and a wider range of modulation effects on charged particles, and can also reduce heat generation and loss, and effectively adjust and control the characteristics of the plasma. When the constant magnetic field is used for the initial magnetization of the plasma, the magnetization effect is guaranteed, and the utilization rate is high.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature plasma jet generation and application, and particularly to a device for regulating an atmospheric pressure plasma jet based on a dynamic multi-composite magnetic field. Background Art

[0002] An atmospheric pressure plasma jet is a low-temperature plasma source with great application value. It has the advantages of high electron temperature, low gas temperature, and rich active particles. At the same time, it is simple to operate and does not require a vacuum chamber, and is widely used in fields such as material processing, biomedicine, and environmental protection.

[0003] As is well known, plasma is a typical functional fluid in a magnetic field, so it is feasible to use the Lorentz force to control its physical properties and parameters. Therefore, introducing a magnetic field to enhance the function of plasma flow is expected to expand the application range of plasma to a broader technical field. In typical plasma magnetic confinement devices, the externally applied magnetic field is basically a weak static magnetic field (based on a magnetic field coil, <0.1T) and a low-pressure environment (<kPa). The influence of such a weak magnetic field on the behavior of atmospheric pressure plasma is extremely limited. For plasma in an atmospheric pressure environment, a stronger magnetic field needs to be introduced. If a magnetic field coil is used, a large driving current is required, and the coil heats up severely during long-term operation, resulting in performance degradation and danger. For example, to generate a static magnetic field of the T magnitude, a superconducting coil needs to be used, which is extremely costly. Therefore, there is an urgent need for a regulation device at present that can solve the problems of insufficient magnetic field coil strength, single magnetic potential type, and severe heating, and control the characteristics of the plasma flow. Summary of the Invention

[0004] In view of this, the present invention provides a device for regulating an atmospheric pressure plasma jet based on a dynamic multi-composite magnetic field, which adopts a pulsed and constant composite magnetic field method to increase the magnetic potential type, reduce heating and loss, effectively control the characteristics of the plasma, and further meet the requirements of the atmospheric pressure plasma jet in practical applications.

[0005] To achieve the above invention purpose, the technical solution of the present invention is as follows:

[0006] A device for regulating an atmospheric pressure plasma jet based on a dynamic multi-composite magnetic field includes a dielectric tube, a pulsed electromagnetic coil, a permanent magnet array, a gradient magnetic field coil, a high-voltage electrode, and a grounded electrode.

[0007] A working gas is input into the dielectric tube to generate a gas plasma after ionization; the permanent magnet array is closely wound around the side wall of the dielectric tube.

[0008] Both the high-voltage electrode and the grounding electrode are annular structures, wrapped around the side wall of the dielectric tube, and the dielectric tube between the two is the discharge area; the pulse electromagnetic coil surrounds the outside of the permanent magnet array, and the two pulse electromagnetic coils are located on both sides of the discharge area; the gradient magnetic field coil surrounds the outside of the permanent magnet array, and its position is between the two pulse electromagnetic coils.

[0009] The permanent magnet array and the gradient magnetic field coil provide a constant magnetic field of the order of 0.01T, and the pulse electromagnetic coil provides a pulse magnetic field of the order of T; the constant magnetic field and the pulse magnetic field form a composite magnetic field.

[0010] Furthermore, the width of the high voltage electrode and the grounding electrode is between 1-5 mm, and the distance between the two electrodes is set at 5-10 mm; the diameter of the dielectric tube is 1-10 mm.

[0011] Furthermore, the pulse electromagnetic coil is externally connected to a pulse current source, and the number of turns of the coil is greater than 2; and the number of turns of the gradient magnetic field coil is greater than 100.

[0012] Furthermore, the permanent magnet array is a ring-shaped or tile-shaped permanent magnet.

[0013] Furthermore, the distance between the ground electrode and the outlet of the medium pipe is not less than 3 mm.

[0014] Furthermore, when the plasma is initially magnetized, the pulsed magnetic field is not turned on and the constant magnetic field is turned on; when the initial magnetization is completed and the plasma is regulated, the pulsed magnetic field is turned on.

[0015] Beneficial effects:

[0016] 1. The present invention proposes a control device for atmospheric pressure plasma jet based on dynamic multiple composite magnetic fields, which adopts a pulsed and constant composite magnetic field to increase the magnetic potential type, reduce heat and loss, effectively control the characteristics of the plasma flow, and further meet the needs of atmospheric pressure plasma jets in practical applications. The device includes an excitation electric field composed of a high-voltage electrode and a grounding electrode to ionize the working gas to obtain plasma gas. The device includes a transient strong magnetic field generated by a pulsed electromagnetic coil and a constant magnetic field generated by a gradient magnetic field coil and a permanent magnet array. The three together form a composite magnetic field to increase the magnetic potential type. The transient strong magnetic field can produce a stronger confinement effect and a wider range of modulation effects on charged particles, and can also reduce heat and loss, and effectively adjust and control the characteristics of the plasma. When the constant magnetic field is used for the initial magnetization of the plasma, the magnetization effect is guaranteed and the utilization rate is high.

[0017] 2. In this device, the magnetic field generated by the permanent magnet array is the most non-uniform, followed by the magnetic field generated by the gradient magnetic field coil, and the most uniform is the magnetic field generated by the pulse electromagnetic coil. It can be seen that there is also a non-uniform magnetic field in the composite magnetic field, and the non-uniform magnetic field can change the spatiotemporal transport characteristics of plasmas with different energy densities and gradually increase the volume of the plasma.

[0018] 3. The width of the high-voltage electrode and the grounding electrode in this device is between 1-5 mm, and the distance between the two electrodes is set at 5-10 mm to prevent the electric energy from being exposed, so as to better stimulate the plasma and improve the discharge efficiency.

[0019] 4. The inner diameter of the medium tube in this device is 1-10 mm, which is conducive to the flow of working gas and increases the size and propulsion speed of plasma.

[0020] 5. The device has a simple structure, low cost and good stability. It can indirectly control the plasma by adjusting the transient strong magnetic field and frequency generated by the pulse electromagnetic coil according to actual needs.

[0021] 6. When the device is initially magnetizing the plasma, the pulse magnetic field is not turned on, and the constant magnetic field is turned on; when the initial magnetization is completed and the plasma is regulated, the pulse magnetic field is turned on again. The pulse magnetic field has the characteristics of high energy and transient. It is not turned on when the plasma is initially magnetized. The constant magnetic field is used to fully magnetize it first, and then turned on during the regulation stage, which can improve energy utilization efficiency and reduce energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 2 Schematic diagram of the magnetic induction intensity of the coil.

[0024] Among them, 1-medium tube, 2-pulse electromagnetic coil, 3-permanent magnet array, 4-gradient magnetic field coil, 5-high voltage electrode, 6-ground electrode, 7-discharge area. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 As shown, the present invention proposes a control device for atmospheric pressure plasma jet based on dynamic multiple composite magnetic fields, which can provide a composite magnetic field to effectively control the volume, density, temperature, active particle distribution and concentration distribution of plasma. The control device includes a dielectric tube 1, a pulse electromagnetic coil 2, a permanent magnet array 3, a gradient magnetic field coil 4, a high voltage electrode 5 and a ground electrode 6. The specific working process is as follows:

[0027] The dielectric tube 1 is made of dielectric insulating material (glass, quartz, ceramic and polytetrafluoroethylene) with an inner diameter of 1-10 mm. Working gas (helium, argon, and a mixture of these with nitrogen and oxygen) is input therein and plasma is generated after ionization. The high-voltage electrode 5 and the ground electrode 6 are wound around the side wall of the dielectric tube 1 and are located upstream of the working gas. Plasma is generated between the high-voltage electrode 5 and the ground electrode 6 in a dielectric barrier discharge mode and propagates out of the dielectric tube 1. The permanent magnet array 3 is also tightly surrounded on the side wall of the dielectric tube 1, and the gradient magnetic field coil 4 is surrounded on the outside of the permanent magnet array 3 and can move axially near the discharge area 7. The high-voltage electrode 5 and the ground electrode 6 are both annular structures, wound around the side wall of the dielectric tube 1, and the dielectric tube 1 between the two is the discharge area 7; the two pulse electromagnetic coils 2 are surrounded on the outside of the permanent magnet array 3 and are located on both sides of the discharge area 7.

[0028] The high-voltage electrode 5 and the grounding electrode 6 are annular electrodes with a width of 1-5 mm, which are completely wrapped around the dielectric tube 1. The distance between the two electrodes is set at 5-10 mm, and conductive materials such as aluminum and copper are used. The high-voltage electrode 5 is externally connected to a sinusoidal AC source or a pulse source, and the power supply voltage range is 3-20 kV and the frequency range is from Hz to 100 kHz. The grounding electrode 6 is grounded. The distance between the grounding electrode 6 and the tube mouth of the dielectric tube 1 is not less than 3 mm, the discharge efficiency is high, the electric energy is less exposed, and the effect of exciting plasma is better.

[0029] The pulse electromagnetic coil 2 is externally connected to a pulse current source (current peak value greater than 1000A, pulse width between 1us and 1s, peak magnetic field at the axis greater than 1T), and the number of coil turns is greater than 2. The two pulse electromagnetic coils 2 can be connected in series or in parallel and driven by the same pulse current source, or they can be driven by different pulse current sources. The function of the pulse electromagnetic coil 2 is to reduce the problem of magnetic field heating, generate a high-intensity pulse magnetic field to confine the plasma, and thus effectively regulate the characteristics of the plasma.

[0030] The number of turns of the gradient magnetic field coil 4 is greater than 100 and is driven by a DC power supply. Its main function is to adjust the magnetic field configuration at the plasma outlet and improve the magnetic surface distribution. The gradient magnetic field coil 4 is located between the two pulse electromagnetic coils 2 and can move between the two pulse electromagnetic coils 2. The permanent magnet array 3 is a ring-shaped or tile-shaped permanent magnet, which provides a radial gradient magnetic field along the side wall of the medium tube 1 to enhance the plasma reaction rate and activity near the tube wall. The repetition frequency of the magnetic field matches the electric field, so that the generation of the magnetic field is synchronized with the electric field.

[0031] like Figure 2 As shown, the permanent magnet array 3 and the gradient magnetic field coil 4 provide constant magnetic fields (static weak magnetic field, 0.01T level) of magnetic field strength B2 and B3 respectively, ensuring the initial magnetization effect of the plasma and improving the utilization rate of magnetic energy. Figure 2As shown, the pulse electromagnetic coil 2 provides a pulse magnetic field with a magnetic field strength of B1 (transient strong magnetic field, T level), which can produce a stronger confinement effect and a wider range of modulation effects on the plasma. The pulse magnetic field has the characteristics of high energy and transient. It is not turned on when the plasma is initially magnetized, but a constant magnetic field is used to fully magnetize it first, and then turned on in the regulation stage, which can improve the energy utilization efficiency. The constant magnetic field and the pulse magnetic field do not affect each other and form a composite magnetic field. Among them, the magnetic field of the permanent magnet array 3 is the most uneven, followed by the magnetic field of the gradient magnetic field coil 4, and the most uniform is the magnetic field generated by the pulse electromagnetic coil 2. It can be seen that there is also a non-uniform magnetic field in the composite magnetic field, which can change the spatiotemporal transport characteristics of plasmas with different energy densities and gradually increase the volume of the plasma.

[0032] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for controlling atmospheric pressure plasma jet based on dynamic multiple composite magnetic fields, characterized in that: It comprises a medium tube (1), a pulse electromagnetic coil (2), a permanent magnet array (3), a gradient magnetic field coil (4), a high voltage electrode (5) and a ground electrode (6); Working gas is input into the dielectric tube (1), and plasma gas is generated after ionization; the permanent magnet array (3) is closely surrounding the side wall of the dielectric tube (1); The high-voltage electrode (5) and the grounding electrode (6) are both annular structures and are wound around the side wall of the dielectric tube (1), and the dielectric tube (1) between the two is a discharge area (7); the pulse electromagnetic coil (2) is wound around the outside of the permanent magnet array (3), and the two pulse electromagnetic coils (2) are arranged on both sides of the discharge area (7); the gradient magnetic field coil (4) is wound around the outside of the permanent magnet array (3) and is located between the two pulse electromagnetic coils (2); The permanent magnet array (3) and the gradient magnetic field coil (4) provide a constant magnetic field of the order of 0.01 T, and the pulse electromagnetic coil (2) provides a pulse magnetic field of the order of T; the constant magnetic field and the pulse magnetic field form a composite magnetic field; When the plasma is initially magnetized, the pulse magnetic field is not turned on, and the constant magnetic field is turned on; After the initial magnetization is completed and the plasma is regulated, the pulsed magnetic field is turned on.

2. The control device according to claim 1, characterized in that: The width of the high-voltage electrode (5) and the grounding electrode (6) is between 1 and 5 mm, and the distance between the two electrodes is set at 5 to 10 mm; the diameter of the medium tube (1) is between 1 and 10 mm.

3. The control device according to claim 1, characterized in that: The pulse electromagnetic coil (2) is externally connected to a pulse current source, and the number of turns of the coil is greater than 2; the number of turns of the gradient magnetic field coil (4) is greater than 100.

4. The control device according to claim 1, characterized in that: The permanent magnet array (3) is a ring-shaped or tile-shaped permanent magnet.

5. The control device according to any one of claims 1 to 2, characterized in that: The distance between the grounding electrode (6) and the opening of the medium pipe (1) is not less than 3 mm.

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