A helicon wave plasma source steady-state discharge device with cooling function

Abstract

The present invention discloses a helicon wave plasma source steady-state discharge device with a cooling function, comprising a cooling cavity formed by a head panel, a head cavity, a middle cavity, a tail cavity, and a tail panel, which are sealed and connected in sequence, and a helicon wave plasma source. The helicon wave plasma source comprises a discharge chamber that passes through the cooling cavity, an annular permanent magnet nested inside the middle and tail cavities, an antenna that is located inside the cooling cavity and surrounds and is in close contact with the outer wall of the discharge chamber, and an electrode rod that connects the radio frequency power supply and the antenna and passes through the head panel. The inlet and outlet of the cooling liquid are arranged on the outer surface of the head panel of the cooling cavity and are connected to the cooling cavity. The present invention effectively reduces the temperature of the antenna when the helicon wave plasma source is operating at a kilowatt-level power, effectively reduces the influence of the temperature inside the cooling cavity on the magnetic field of the annular permanent magnet, realizes long-term steady-state discharge of a kilowatt-level helicon wave plasma device, and demonstrates the possibility of applying permanent magnets to high-power helicon wave plasma sources.

Description

Technical Field

[0001] The present invention relates to the application field of low-temperature plasma sources, and in particular to a helicon wave plasma source steady-state discharge device with a cooling function. Background Art

[0002] A high-density, high-ionization-rate, compact helicon plasma source that can operate efficiently in a stable state is a powerful device for plasma research and applications. For decades, researchers have conducted in-depth studies on helicon plasmas over a wide range of parameters, including device size, magnetic field configuration and intensity, and neutral gas pressure. 20 m -3 ), low temperature (electron temperature from a few eV to more than ten eV), high ionization rate (ionization degree exceeds 70%), low neutral gas pressure (pressure range from 0.1 to several Pa) and low RF power (input RF power is less than a few kilowatts). The helicon wave plasma source is a potential candidate for plasma research. As a plasma source, it can be used in semiconductor manufacturing (plasma etching), gas lasers, construction of divertor plasma environment in magnetic confinement nuclear fusion, plasma accelerators and plasma electric thrusters for deep space exploration of artificial satellites in aerospace. It can also be used as a physical research platform for turbulence in basic plasma physics.

[0003] This helicon wave plasma source is an electrodeless RF plasma source. It uses an RF power source to excite an antenna within an external magnetic field to ionize a neutral gas and generate plasma. Compared to electrode-based plasma discharge, this electrodeless discharge eliminates the need for plasma erosion of electrodes, enabling long-term operation. This is crucial for plasma electric thrusters used for long-term deep space exploration.

[0004] Currently, helicon plasma sources with power levels approaching kilowatts, including water-cooled electromagnetic coils, are generally quite large. To miniaturize kilowatt-class plasma sources and make them more suitable for engineering applications, high-power helicon plasma sources can eliminate the need for complex water-cooled electromagnetic coils, which require an additional power source, to provide the required external magnetic field. Instead, they can utilize annular permanent magnets made of neodymium iron boron (NdFeB) to provide the external magnetic field. To fully utilize the space within the annular permanent magnet, an antenna is placed within the outer wall of the discharge chamber and within the inner channel of the annular permanent magnet. This maximizes space utilization and makes the plasma source more compact. Due to the high power required and compact structure of the plasma source, without a cooling system, overheating of the antenna due to the thermal effects of the current would not only affect the antenna's own characteristics, but the ambient temperature would also quickly exceed the normal operating temperature range of the permanent magnet, causing the annular permanent magnet to demagnetize due to the high temperature, thus affecting the normal operation of the plasma source. To ensure the long-term operation of a high-power helicon plasma source, cooling and protection of the annular permanent magnet and antenna are necessary. Summary of the Invention

[0005] In practical applications, helicon plasma sources require a simple and compact structure that supports long-term kilowatt-level power operation. To achieve a compact helicon plasma source with cooling capabilities and a steady-state discharge in a kilowatt-level annular permanent magnet helicon plasma source, the present invention provides a steady-state discharge device with cooling capabilities. This device also demonstrates the feasibility of using permanent magnets (including annular permanent magnets) in high-power helicon plasma sources.

[0006] The present invention adopts the following technical solutions:

[0007] A helicon wave plasma source steady-state discharge device with a cooling function, comprising a cooling cavity (1) and a helicon wave plasma source;

[0008] The cooling cavity (1) is formed by sealingly connecting a head end panel (2), a head section cavity (3), a middle section cavity (4), a tail section cavity (5) and a tail end panel (6) in sequence;

[0009] The helicon wave plasma source comprises a discharge chamber (7) penetrating a cooling cavity (1), an annular permanent magnet (11) nested inside a middle cavity (4) and a tail cavity (5), an antenna (12) located inside the cooling cavity (1) and surrounding the outer wall of the discharge chamber (7), and an electrode rod (8) connecting a radio frequency power supply and the antenna (12) and penetrating a head end panel (2);

[0010] The cooling liquid inlet (2a) and the cooling liquid outlet (2b) are both arranged on the outer surface of the front end panel (2) of the cooling cavity (1), and the cooling liquid inlet (2a) and the cooling liquid outlet (2b) are both communicated with the cooling cavity (1).

[0011] Furthermore, the helicon wave plasma source steady-state discharge device further comprises a cavity fixing support structure; the cavity fixing support structure comprises a fixing fixture (9) and a support member (10) for supporting and fixing the cooling cavity (1).

[0012] Furthermore, the sealing method between each panel and cavity (2, 3, 4, 5, 6) is as follows: the connection between the first end panel (2) and the first section cavity (3) is sealed by the first section cavity sealing groove and the fluororubber ring (3a) and is locked and fixed with bolts. The connection between the first section cavity (3) and the middle section cavity (4) is sealed by the middle section cavity front sealing groove and the fluororubber ring (4a) and is locked and fixed with bolts. The connection between the middle section cavity (4) and the tail section cavity (5) is sealed by the middle section cavity rear sealing groove and the fluororubber ring (4b) and is locked and fixed with bolts. The connection between the tail section cavity (5) and the tail end panel (6) is sealed by the tail section cavity sealing groove and the fluororubber ring (5a) and is locked and fixed with bolts.

[0013] Furthermore, the discharge chamber (7) that passes through the cooling cavity (1) is sealed with the head end panel (2) and the tail end panel (6) of the cooling cavity (1). The connection between the discharge chamber (7) and the head end panel (2) is sealed by a discharge chamber head end sealing groove and a fluororubber ring (7a1), and the discharge chamber head end sealing cover (7a) is tightened and fixed by bolts. The connection between the discharge chamber (7) and the tail end panel (6) is sealed by a discharge chamber tail end sealing groove and a fluororubber ring (7b1), and the discharge chamber tail end sealing cover (7b) is tightened and fixed by bolts.

[0014] Furthermore, an annular permanent magnet (11) is provided to provide an external magnetic field for the helicon wave plasma source and is tightly fitted and nested within the middle and tail section cavities (4, 5). A 0.5 mm thick waterproof and heat-resistant 600 degree Celsius insulating coating is evenly applied to the surface of the annular permanent magnet (11). The annular permanent magnet (11) can be formed by arranging and combining a plurality of small annular permanent magnets of different specifications in a specific polarity sequence according to the specific requirements of different magnetic field configurations. In the embodiment of the present invention, the annular permanent magnet (11) can generate a magnetic field of nearly 800 gauss.

[0015] Furthermore, the antenna (12) located inside the cooling cavity (1) and surrounding and closely attached to the outer wall of the discharge chamber (7) and the electrode rod (8) connecting the radio frequency power supply and the antenna (12) and passing through the head end panel (2) are respectively sealed and connected to the water cooling cavity (1). The antenna feeding end (12a) of the antenna (12) and the electrode rod (8) are fixed by bolts, the antenna grounding end (12b) is fixed by bolts to the inner surface of the middle cavity (4), and the cavity grounding end (4c) arranged on the outer surface of the middle cavity (4) is fastened to the ground wire by bolts. The electrode rod (8) passes through the head end panel (2) and is connected to the radio frequency power supply. To avoid short circuit between the two, the connection is sealed by two layers of polytetrafluoroethylene inner and outer insulation layers (8c, 8d) combined with fluororubber rings and is locked and fixed by bolts to the inner and outer sealing covers (8b, 8a) of the electrode rod. The antenna (12) can be placed at any position on the central axis of the internal space of the water cooling cavity according to requirements.

[0016] Furthermore, the cooling liquid inlet and outlet (2a, 2b) are arranged on the outer surface of the front end panel (2) of the cooling cavity (1) and are in communication with the cooling cavity (1). The cooling liquid enters the cooling cavity (1) through the cooling liquid inlet (2a), filling the internal space of the cooling cavity (1), so that the antenna (12) and the annular permanent magnet (11) are immersed in the cooling liquid. As the cooling liquid level rises above the cooling liquid outlet (2b), the cooling liquid flows out from the cooling liquid outlet (2b), takes away the heat generated by the antenna (12) and returns to the cooling liquid machine, completing a cooling liquid cycle.

[0017] Furthermore, the cavity fixing support structure includes a fixing fixture (9) and a support member (10) that support and fix the cooling cavity (1). The arcuate surfaces of the support member (10) and the fixing fixture (9) are fitted with the outer surface of the cavity, and bolts are used to lock and fix each section of the cavity with the screw holes (9a) on the fixing fixture; the support member (10) and the fixing fixture (9) are connected by bolts and the screw holes (9b) on the side of the fixing fixture, so that the surfaces of the support member and the fixing fixture can fit tightly with each section of the cavity to fix the cavity. The support member (10) and the device bracket (not shown) are connected by bolts and the screw holes (10a) of the support member. Three sets of fixing fixtures and support members are respectively located at the center of each section of the cavity.

[0018] Furthermore, the material of the cooling cavity 1 can be non-magnetic, electrically conductive, and thermally conductive. Non-magnetic materials facilitate the installation of the cooling cavity (1) and the annular permanent magnet (11); electrically conductive materials can not only provide good grounding but also shield the electromagnetic waves radiated by the antenna (12) to the surrounding environment, thereby reducing the impact on the surrounding electromagnetic environment; and thermally conductive materials can be used to dissipate heat from the device. Lighter and higher-temperature-resistant materials can also be selected for different needs. In the embodiment of the present invention, aluminum metal is selected as the material of the cooling cavity (1).

[0019] Furthermore, the possibility of applying permanent magnets (including annular permanent magnets) to high-power helicon wave plasma sources is demonstrated.

[0020] In one embodiment of the present invention, a helicon wave plasma source steady-state discharge device with a cooling function includes a cooling cavity and a helicon wave plasma source and cavity fixing support structure.

[0021] The cooling cavity includes a front panel, a front cavity, a middle cavity, a rear cavity, and a rear panel. The front panel and the front cavity, the front cavity and the middle cavity, the middle cavity and the rear cavity, and the rear cavity and the rear panel are sealed in sequence using sealing grooves and fluororubber rings, and are fastened together by bolts to form a cooling cavity.

[0022] To miniaturize kilowatt-class plasma sources and better suit engineering applications, high-power helicon plasma sources can eliminate the need for complex, water-cooled electromagnetic coils to provide an external magnetic field, which requires an additional power source. Instead, they utilize annular permanent magnets made of neodymium iron boron (NdFeB) to provide the external magnetic field, fully utilizing the internal channel space of the annular permanent magnets. The helicon plasma discharge device includes a discharge chamber, an antenna for exciting the electromagnetic field, an annular permanent magnet for providing the external magnetic field, and an electrode rod for connecting the antenna to an external RF power supply (not shown in the drawings) within the cooling chamber.

[0023] The annular permanent magnet is formed by merging multiple small annular permanent magnets, and is nested in the internal space formed by the sealed connection between the middle cavity and the tail cavity. The outer surface of the annular permanent magnet is tightly connected with the inner surface of the space formed by the middle and tail cavities, which can prevent the annular permanent magnet from shaking in the cooling cavity and colliding with it, resulting in demagnetization.

[0024] The discharge chamber passes through the head panel, the head cavity, the middle cavity, the annular permanent magnet, the tail cavity and the tail panel in sequence along the central axis of the cooling cavity. The contact surfaces of the two ends of the discharge chamber with the head panel and the tail panel are sealed by a combination of sealing grooves and fluororubber rings, and the fluororubber rings are compressed by tightening the sealing cover with bolts to achieve good sealing performance.

[0025] The antenna is sleeved on the outer wall of the discharge chamber and fits tightly with the outer wall. The antenna can be placed at any position of the central axis of the inner space of the water-cooling cavity according to requirements.

[0026] In order to make the device structure compact, the present invention is placed in the inner hole of the annular permanent magnet. The outer surface of the aluminum cooling cavity is grounded. In order to simplify the antenna grounding, the antenna grounding port is grounded by screwing a bolt into a screw hole with an internal thread on the inner surface of the middle cavity. The antenna feed port is connected to the electrode rod by a bolt, and the electrode rod is then energized through the head panel and the radio frequency power supply (not shown in the drawings). In order to avoid a short circuit between the electrode rod and the head panel, the electrode rod is first insulated and sealed using an inner and outer insulating layer combined with a sealing groove and a fluororubber ring. Then, the contact surface between the outer sealing cover of the electrode rod and the outer insulating layer, the contact surface between the outer sealing cover of the electrode rod and the outer surface of the head panel, the contact surface between the inner sealing cover of the electrode rod and the inner insulating layer, and the contact surface between the inner sealing cover of the electrode rod and the inner surface of the head panel are respectively sealed using a sealing groove combined with a fluororubber ring.

[0027] After the cooling cavity is sealed as described above, the interior space of the cooling cavity has formed a complete sealed space except for the coolant inlet and outlet. This sealed space can serve as a coolant flow channel. The coolant inlet and outlet are respectively welded to the outer surface of the head end panel and communicate with the cooling cavity (1).

[0028] In addition, the cooling cavity can be made of non-magnetic materials with good electrical and thermal conductivity. Non-magnetic materials facilitate the installation of the cavity and the annular permanent magnet; materials with good electrical conductivity not only provide good grounding but also shield the electromagnetic waves radiated by the antenna to the surrounding environment, reducing electromagnetic interference with other nearby devices; materials with good thermal conductivity can effectively dissipate heat from the device. Lighter and more heat-resistant materials can also be selected to meet different needs. The embodiments of the present invention use aluminum metal as the cooling cavity material.

[0029] Furthermore, the length, magnetic field configuration, polarity arrangement, and magnetic field strength of the annular permanent magnet can be varied according to actual needs. In an embodiment of the present invention, the annular permanent magnet is made of neodymium iron boron (NdFeB) with a residual magnetic strength of 1.25T. The polarity of the annular permanent magnet is arranged in the order SNSNSNSNSN from left to right. The annular permanent magnet is more convenient for processing.

[0030] In addition, the antenna is made of copper material with good thermal conductivity. As a further improvement of the present invention, the pins of the antenna are led out from one side along the axis of the antenna, which is more convenient for assembly.

[0031] In addition, in the present invention, the working fluid gas enters the discharge chamber from the discharge chamber inlet end (close to the head end panel), is ionized to obtain plasma under the action of the electromagnetic field excited by the antenna, and the plasma is discharged through the discharge chamber outlet end (close to the tail end panel).

[0032] Coolant then flows from the coolant inlet into the cooling chamber, filling the interior, completely immersing the antenna and annular permanent magnet. As the coolant level rises above the cold zone outlet, it flows out, removing heat from the antenna and returning to the coolant machine (not shown), completing the cooling cycle.

[0033] In addition, the annular permanent magnet will be corroded when immersed in the coolant and may short-circuit with the antenna. We apply 0.5mm thick waterproof and 600 degrees Celsius resistant ceramic insulating paint to the entire surface of the annular permanent magnet, wait for the paint to dry and solidify at room temperature, and then assemble it together with the cooling cavity.

[0034] Beneficial effects of the present invention:

[0035] The use of annular permanent magnets to provide an external magnetic field makes the kilowatt-level helical wave plasma source device simpler and more compact, simple to assemble and easy to operate (single-person operation is sufficient), and each component can be replaced in a modular manner if damaged. Annular permanent magnets are more convenient for fixed installation than permanent magnets of other shapes, and can reduce additional power consumption compared to electromagnetic coils. Furthermore, the electrodeless helical wave plasma source can avoid plasma ablation of the electrodes, extending its service life. This invention has great potential for application in electric thrusters in the aerospace field.

[0036] The antenna is fully immersed in the coolant, and the circulating coolant can not only carry away the heat generated by the antenna and cool the temperature of the outer wall of the discharge chamber, but also prevent excess heat from being transferred to the annular permanent magnet, thereby ensuring the normal operating temperature of the annular permanent magnet without demagnetization. The experiment in Example 1 of the present invention proves that it supports long-term steady-state discharge operation of a kilowatt-level power helicon wave plasma device and demonstrates the possibility of using permanent magnets (including annular permanent magnets) in a high-power helicon wave plasma source. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the external structure of a helicon wave plasma source with cooling function.

[0038] Figure 2 This is a schematic diagram of the internal cross-sectional structure of a helicon wave plasma source with cooling function.

[0039] Figure 3 It is a structural diagram of the head end panel and sealing components.

[0040] Figure 4 This is a schematic diagram of the connection between the middle and tail section cavities and the antenna.

[0041] Figure 5 It is a schematic diagram of the polar arrangement of the annular permanent magnet along the z direction.

[0042] Figure 6 3 is an axial magnetic field distribution diagram of the annular permanent magnet in an embodiment of the present invention.

[0043] Figure 7 1 is a magnetic field configuration diagram of an annular permanent magnet in an embodiment of the present invention.

[0044] Figure 8 Graph showing the change in plasma density with power in an embodiment of the present invention.

[0045] Explanation of the reference numerals: 1 is a cooling cavity; 2 is a front end panel, 2a is a coolant inlet, 2b is a coolant outlet; 3 is a first section cavity, 3a is a sealing groove and a fluororubber ring of the first section cavity; 4 is a middle section cavity, 4a is a front sealing groove and a fluororubber ring of the middle section cavity, 4b is a rear sealing groove and a fluororubber ring of the middle section cavity, 4c is a cavity grounding terminal; 5 is a tail section cavity, 5a is a sealing groove and a fluororubber ring of the tail section cavity; 6 is a tail end panel; 7 is a discharge chamber, 7a is a sealing cover at the first end of the discharge chamber, 7a1 is a sealing groove and a fluororubber ring at the first end of the discharge chamber, 7a2 is a screw hole for the sealing cover of the discharge chamber, 7b is a sealing cover at the tail end of the discharge chamber, 7b1 is a sealing groove and a fluororubber ring at the tail end of the discharge chamber; 8 is an electrode rod, 8a is an outer sealing cover of the electrode rod, 8a1 is an outer sealing cover of the electrode rod, 8a2 is the second sealing groove and fluororubber ring of the outer sealing cover of the electrode rod, 8b is the inner sealing cover of the electrode rod, 8b1 is the first sealing groove and fluororubber ring of the inner sealing cover of the electrode rod, 8b2 is the second sealing groove and fluororubber ring of the inner sealing cover of the electrode rod, 8b3 is the screw hole of the electrode rod sealing cover, 8c is the inner insulating layer, 8d is the outer insulating layer, 8d1 is the sealing groove and fluororubber ring of the outer insulating layer, 8e is the inner screw hole of the electrode rod; 9 is a fixing fixture, 9a is the screw hole on the fixing fixture, 9b is the side screw hole of the fixing fixture, 10 is a support, 10a is the screw hole of the support, 11 is an annular permanent magnet, 12 is an antenna, 12a is the antenna feeding end, 12b is the antenna grounding end, and 13 is the cavity bolt hole. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0047] Figure 1-4 A schematic diagram of a helicon plasma source with cooling functionality is shown. The device comprises a cooling chamber, a helicon plasma source, and a cavity support structure. The cooling chamber 1 consists of five main components: a front panel 2, a front cavity 3, a middle cavity 4, a rear cavity 5, and a rear panel 6. These components are sealed together in sequence.

[0048] The internal space of the cooling cavity 1 serves as a coolant flow channel; the helicon wave plasma source includes a quartz tube discharge chamber 7, an annular permanent magnet 11, an antenna 12 and an electrode rod 8, and the helicon wave plasma source generates helicon wave plasma; the device fixed support structure includes a fixing clamp 9 and a support member 10.

[0049] The specific connection methods of each component are as follows:

[0050] like Figure 1 As shown, the specific size of the cooling cavity 1 can be set according to the specific size of the helicon plasma source.

[0051] like Figure 2 As shown, the connection between the first end panel 2 and the first section cavity 3 is sealed by the first section cavity sealing groove and the fluororubber ring 3a. The connection adopts M8 bolts passing through 8 cavity bolt holes 13 evenly distributed on the first end panel 2 to press and seal;

[0052] The connection between the first section cavity 3 and the middle section cavity 4 is sealed by the front sealing groove of the middle section cavity and the fluororubber ring 4a. The connection method is also to use M8 bolts to pass through 8 cavity bolt holes evenly distributed at the connection between the first section cavity 3 and the middle section cavity 4 to tightly seal.

[0053] The connection between the middle cavity 4 and the tail cavity 5 is sealed by the middle cavity rear sealing groove and the fluororubber ring 4b. The connection method also adopts M8 bolts passing through 8 cavity bolt holes evenly distributed at the connection between the middle cavity 4 and the tail cavity 5 to tightly seal.

[0054] The connection between the tail section cavity 5 and the tail end panel 6 is sealed by the tail section cavity sealing groove and the fluororubber ring 5a. The connection method uses M8 bolts to pass through 8 cavity bolt holes evenly distributed at the connection between the tail section cavity 5 and the tail end panel 6 for tight sealing.

[0055] The cooling cavity 1 can be made of a non-magnetic material with good electrical and thermal conductivity. Non-magnetic materials facilitate the installation of the cooling cavity 1 and the annular permanent magnet 11. Highly conductive materials not only provide good grounding but also shield the electromagnetic waves radiated from the antenna 12 to the surrounding environment, reducing the impact on the surrounding electromagnetic environment. Highly thermally conductive materials can effectively dissipate heat from the device. Lighter, higher-temperature-resistant materials can also be selected to meet different needs. The embodiment of the present invention uses aluminum as the material for the cooling cavity 1.

[0056] like Figure 2 As shown, the connection and sealing between the helicon wave plasma source and the cooling cavity 1 are described as follows:

[0057] The cylindrical discharge chamber 7 is along the central axis of the cooling cavity (eg Figure 2 The discharge chamber 7 is connected to the front panel 2 by a sealing groove at the front end of the discharge chamber and a fluororubber ring 7a1, and the connection method is to use bolts passing through four discharge chamber sealing cover screw holes 7a2 (including internal threads) evenly distributed at the connection between the discharge chamber front end sealing cover 7a and the front end panel 2 to form a tight seal. The discharge chamber 7 is connected to the rear panel 6 by a sealing groove at the rear end of the discharge chamber and a fluororubber ring 7b1, and the connection method is to use bolts passing through four discharge chamber sealing cover screw holes (including internal threads) evenly distributed at the connection between the discharge chamber rear end sealing cover 7b and the rear end panel 6 to form a tight seal.

[0058] The working fluid gas (argon, helium, nitrogen, etc.) enters the discharge chamber 7 from the inlet end (close to the head end panel 2) and is ionized to obtain plasma under the action of the electromagnetic field excited by the antenna 12. The plasma is discharged through the outlet end of the discharge chamber 7 (close to the tail end panel 6).

[0059] like Figure 2 As shown, the antenna 12 is tightly fitted on the outer wall of the discharge chamber 7. Its specific position can be placed at any position along the central axis inside the cooling cavity 1 according to actual needs. The antenna feed end 12a and the electrode rod 8 are connected by bolts passing through the through hole of the antenna feed end and as shown in FIG. Figure 3 Tighten the inner screw hole 8e (with internal thread) of the electrode rod as shown. Figure 4 As shown, the antenna grounding terminal 12b and the cooling cavity 1 are connected by bolts passing through the through hole of the antenna grounding terminal and the screw hole (with internal thread) in the middle cavity and tightened, and the cavity grounding terminal 4c is connected to the ground wire through bolts.

[0060] like Figure 2 、 3 As shown, electrode rod 8 passes through head end panel 2. One end of electrode rod 8, with external threads, is connected to an RF matcher and RF power supply (not shown). Polytetrafluoroethylene is used to insulate the connection between electrode rod 8 and head end panel 2 to prevent short circuits between the two. The connection between electrode rod 8 and head end panel 2 is provided with an insulating layer 8c and an outer insulating layer 8d, sequentially from the inside to the outside. The contact surfaces between electrode rod 8, inner insulating layer 8c, and outer insulating layer 8d are sealed with an outer insulating layer sealing groove and a fluororubber ring 8d1. The contact surface between the electrode rod outer sealing cover 8a and the outer insulating layer 8d is sealed using the electrode rod outer sealing cover's first sealing groove and a fluororubber ring 8a1. The contact surface between the electrode rod outer sealing cover 8a and the head end panel 2 is sealed using the electrode rod outer sealing cover's second sealing groove and a fluororubber ring 8a2. The contact surface between the electrode rod inner sealing cover 8b and the inner insulating layer 8c is sealed using the electrode rod inner sealing cover's first sealing groove and a fluororubber ring 8b1. The contact surface between the electrode rod inner sealing cover 8b and the head end panel 2 is sealed using the electrode rod inner sealing cover's second sealing groove and a fluororubber ring 8b2. To achieve the aforementioned tight compression and securement of the seals, the electrode rod inner sealing cover 8b is connected to the inner surface of the head end panel 2 by bolts tightened through four evenly distributed electrode rod sealing cover screw holes 8b3 (with internal threads). The electrode rod outer sealing cover 8a is connected to the outer surface of the head end panel 2 by bolts tightened through four evenly distributed electrode rod sealing cover screw holes (with internal threads).

[0061] The antenna 12 is made of copper material with good thermal conductivity. As a further improvement of the present invention, the pins of the antenna 12 are led out from one side along the axis of the antenna 12 to protect the integrity of the annular permanent magnet 11 and obtain a regular magnetic field configuration.

[0062] The magnetic pole arrangement order and appearance of the annular permanent magnet 11 are as follows: Figure 5 As shown. Figure 2 As shown, an annular permanent magnet 11 is nested inside the middle cavity 4 and the tail cavity 5, and the outer surface of the annular permanent magnet 11 is tightly fitted with the inner surface of the middle and tail cavities. The annular permanent magnet provides an external magnetic field for the helicon wave plasma.

[0063] The length, magnetic field configuration, polarity arrangement order and magnetic field strength of the annular permanent magnet 11 can be changed according to actual needs. In the embodiment of the present invention, the material of the annular permanent magnet 11 is neodymium iron boron material with a residual magnetic strength of 1.25T. The measured axis magnetic field strength is as follows: Figure 6 As shown, the magnetic field strength in the hole of the annular permanent magnet 11 reaches nearly 800G. The polarity of the annular permanent magnet 11 is arranged in the order of SNSNSNSNSN from left to right. The annular permanent magnet is more convenient to process.

[0064] like Figure 1 As shown, coolant inlet 2a and coolant outlet 2b are welded to the outer surface of head end panel 2. Coolant flows from coolant inlet 2a into the interior of cooling cavity 1, filling the interior of cooling cavity 1 and completely immersing antenna 12 and annular permanent magnet 11 in the coolant. As the coolant level rises above cold zone liquid outlet 2b, the coolant flows out of coolant outlet 2b, dissipating the heat generated by antenna 12 and returning to the coolant machine (not shown), completing a coolant cycle.

[0065] The annular permanent magnet 11 will be corroded and short-circuited with the antenna 12 when immersed in the coolant. We evenly apply 0.5mm thick waterproof and 600 degrees Celsius resistant ceramic insulating paint to the entire surface of the annular permanent magnet and wait for the paint to air-dry at room temperature for 24 hours before assembly.

[0066] like Figure 1 As shown, the cavity fixing support structure includes three sets of fixing clamps 9 and support members 10. The arc-shaped surfaces of the support members 10 and the fixing clamps 9 fit with the outer surface of the cavity, and bolts are used to tighten and fix the various sections of the cavity with the screw holes 9a (with internal threads) on the fixing clamps; the support members 10 and the fixing clamps 9 are connected by bolts and the screw holes 9b (with internal threads) on the side of the fixing clamps, so that the surfaces of the support members and the fixing clamps can fit tightly with the various sections of the cavity to fix the cavity. The support members 10 are connected to the device bracket (not shown in the figure) by bolts and the screw holes 10a of the support members. The three sets of fixing clamps and support members are respectively located at the center of each section of the cavity.

[0067] Example 1

[0068] The embodiment of the present invention uses aluminum metal as the material for the cooling cavity 1, the fixing fixture 9 and the support 10. In this embodiment, the working gas is argon, and the discharge chamber 7 is made of a high-temperature resistant insulating material quartz tube.

[0069] The antenna 12 is made of copper metal and is mounted on the outer wall of the discharge chamber 7, which is made of a quartz tube. The antenna pin extends along the axis, with one end connected to the electrode rod 8 and the other end connected to the cooling chamber 1. The threaded end of the electrode rod 8 is connected to a radio frequency matcher (not shown in the figure), which is in turn connected to a radio frequency power supply with a frequency of 13.56 MHz and a maximum power of 3.5 kW. The cooling chamber 1 is grounded as a whole. The purpose of the radio frequency matcher is to maximize the power transmitted by the radio frequency power supply and apply it to the antenna 12 to generate plasma.

[0070] The material of the annular permanent magnet 11 is neodymium iron boron material with a residual magnetic strength of 1.25T. The measured axis magnetic field strength and permanent magnet position are as follows: Figure 6 As shown, the annular permanent magnet 11 is located at Figure 6 Between the two dotted lines, that is, between the axis position 0mm and 328mm, the magnetic field strength in the hole reaches nearly 800G. The polarity of the annular permanent magnet 11 is arranged from left to right as SNSNSNSNSN. Figure 5 As shown. Arranged in polarity direction, the specifications of the small ring permanent magnets combined into a ring permanent magnet are: outer diameter 110mm, inner diameter 84mm, thickness 40mm; outer diameter 130mm, inner diameter 90mm, thickness 80mm; outer diameter 138mm, inner diameter 92mm, thickness 88mm; outer diameter 130mm, inner diameter 90mm, thickness 80mm; outer diameter 110mm, inner diameter 84mm, thickness 40mm. The magnetic field configuration generated by this arrangement and combination is as follows Figure 7 shown.

[0071] In the embodiment of the present invention, the outer diameter of the quartz tube is 50 mm and the length is 700 mm; the antenna is closely attached to the outer wall of the quartz tube, and the specific position is as follows: Figure 6 As shown, it is located within the axis coordinate range of -30mm to 100mm.

[0072] The overall outer diameter of the cooling cavity is 148 mm and the length is 443 mm. The internal dimensions of the middle and tail sections of the cavity are the same as the outer surface dimensions of the annular permanent magnet.

[0073] During the experimental preparation period, the quartz tube discharge chamber was evacuated to a vacuum degree of 10 -4 Pa starts to discharge.

[0074] To begin the experiment, the chiller (not shown) was turned on and a coolant (water, in this example) was supplied. The coolant entered the cooling chamber through the coolant inlet 2a. When the water level exceeded the coolant outlet 2b, the coolant flowed out of the outlet 2b into the chiller, completing a refrigeration cycle.

[0075] Argon gas enters from the inlet end of the quartz tube ionization chamber 7 (close to the head end panel 2), and the radio frequency power supply is turned on to increase the power. Under the action of the electromagnetic field excited by the energized antenna 12, argon gas is ionized to obtain plasma, and the plasma is discharged from the outlet end of the quartz tube ionization chamber 7 (close to the tail end panel 6).

[0076] The device is adjusted to a stable discharge state by a radio frequency matching device, and then a movable radio frequency compensated Langmuir single probe is used to measure the plasma density at the same position under different powers and obtain Figure 8 data.

[0077] from Figure 8 It can be concluded that the device can produce a density greater than 10 18 m -3 , and can discharge stably for a long time at a power level of nearly 1000 watts.

[0078] Those skilled in the art can make various other corresponding changes and deformations based on the technical solutions and concepts described above, and all of these changes and deformations should fall within the scope of protection of the claims of the present invention.

Claims

1. A helicon wave plasma source steady-state discharge device with cooling function, characterized in that: It comprises a cooling cavity (1) and a helicon wave plasma source; The cooling cavity (1) is formed by sealingly connecting a head end panel (2), a head section cavity (3), a middle section cavity (4), a tail section cavity (5) and a tail end panel (6) in sequence; The helicon wave plasma source comprises a discharge chamber (7) penetrating a cooling cavity (1), an annular permanent magnet (11) nested inside a middle cavity (4) and a tail cavity (5), an antenna (12) located inside the cooling cavity (1) and surrounding the outer wall of the discharge chamber (7), and an electrode rod (8) connecting a radio frequency power supply and the antenna (12) and penetrating a head end panel (2); The cooling liquid inlet (2a) and the cooling liquid outlet (2b) are both arranged on the outer surface of the front end panel (2) of the cooling cavity (1), and the cooling liquid inlet (2a) and the cooling liquid outlet (2b) are both connected to the cooling cavity (1); the surface of the annular permanent magnet (11) is evenly coated with a waterproof and heat-resistant insulating paint.

2. The device according to claim 1, characterized in that The helicon wave plasma source steady-state discharge device further comprises a cavity fixing support structure; the cavity fixing support structure comprises a fixing fixture (9) and a support member (10) for supporting and fixing the cooling cavity (1).

3. The device according to claim 1, characterized in that The connection between the front end panel (2) and the front section cavity (3) is sealed by the front section cavity sealing groove and the fluororubber ring (3a) and fixed by bolts; the connection between the front section cavity (3) and the middle section cavity (4) is sealed by the middle section cavity front sealing groove and the fluororubber ring (4a) and fixed by bolts; the connection between the middle section cavity (4) and the tail section cavity (5) is sealed by the middle section cavity rear sealing groove and the fluororubber ring (4b) and fixed by bolts; the connection between the tail section cavity (5) and the rear end panel (6) is sealed by the tail section cavity sealing groove and the fluororubber ring (5a) and fixed by bolts.

4. The device according to claim 1, characterized in that The connection between the discharge chamber (7) and the front end panel (2) is sealed by a discharge chamber front end sealing groove and a fluororubber ring (7a1), and the discharge chamber front end sealing cover (7a) is fixed by pressing with bolts; the connection between the discharge chamber (7) and the rear end panel (6) is sealed by a discharge chamber rear end sealing groove and a fluororubber ring (7b1), and the discharge chamber rear end sealing cover (7b) is fixed by pressing with bolts.

5. The device according to claim 1, characterized in that The connection between the electrode rod (8) and the head end panel (2) is sealed by two layers of polytetrafluoroethylene insulation layers combined with a fluororubber ring and is fixed by pressing the electrode rod sealing cover with bolts.

6. The device according to claim 1, characterized in that The antenna feeding end (12a) of the antenna (12) and the electrode rod (8) are fixed by bolts, the antenna grounding end (12b) and the inner surface of the middle cavity (4) are fixed by bolts, and the cavity grounding end (4c) arranged on the outer surface of the middle cavity (4) is fixedly connected to the ground wire by bolts.

7. The device according to claim 1, characterized in that The coolant enters the cooling cavity (1) through the coolant inlet (2a), filling the internal space of the cooling cavity (1), so that the antenna (12) and the annular permanent magnet (11) are immersed in the coolant. As the coolant level is higher than the coolant outlet (2b), the coolant flows out from the coolant outlet (2b), takes away the heat generated by the antenna (12) and returns to the coolant machine, completing a coolant cycle.

8. The device according to claim 2, wherein The arc surface of the support member (10) and the arc surface of the fixing fixture (9) are fitted with the outer surface of the cavity, and the sections of the cavity are fixed by bolts and screw holes (9a) on the fixing fixture; the support member (10) and the fixing fixture (9) are connected by bolts and screw holes (9b) on the side of the fixing fixture.

9. The device according to claim 1, characterized in that The cooling cavity (1) is made of a non-magnetic, electrically conductive and thermally conductive material.

10. The helicon wave plasma steady-state discharge device with cooling function according to claim 1, characterized in that: The annular permanent magnet (11) is formed by arranging and merging a plurality of annular permanent magnets of different specifications in order of polarity.

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