A concave cavity helicon plasma source

Abstract

A concave cavity spiral wave plasma source relates to the field of plasma science and technology. To address the technical problems in the prior art, in which linear devices often destroy the device's established magnetic field configuration during discharge, causing experimental deviations and making it difficult to achieve the desired effect under strong magnetic fields, the present invention provides a technical solution: a concave cavity spiral wave plasma source, comprising: a vacuum sealing and support portion, including a quartz bell jar, which is bell-shaped and used to provide a vacuum environment, with its bottom fixed to a main flange, and the main flange is connected to external equipment; the electromagnetic shielding and heat dissipation portion, including a shielding cover, which is cylindrical and used to provide shielding capabilities and is sleeved on the outside of the main flange; an L-shaped antenna, which is used to connect to an external water cooling system and power supply, and is disposed between the quartz bell jar and the shielding cover. The shielding cover is connected to the main flange via an internal thread, and heat dissipation is achieved through a fan and fan-shaped gaps. A plasma source for use in the field of plasma.

Description

Technical Field

[0001] The present invention relates to the field of plasma science and technology, and specifically to a plasma source used in the field of plasma, which can realize steady-state discharge under strong magnetic field conditions, and is used to provide a reliable, stable, and high-ionization-rate experimental environment for basic physics research on magnetic confinement fusion and applications of plasma-related technologies. Background Art

[0002] Plasma, a state of matter containing a large number of unbound charged particles, exhibits diverse characteristics and responses to external disturbances, shaped by the motion and interactions of its numerous microscopic particles. These characteristics are manifested in its interactions with various substances. Furthermore, within the parameter space of energy and density, plasmas exist over a very wide range of parameters. Consequently, when plasma interacts with other substances, the effects it exerts encompass multiple aspects, including force, heat, light, and electricity, offering promising applications.

[0003] As one of today's cutting-edge disciplines and a representative of high-tech industries, plasma science holds profound strategic significance and immense value in promoting social development and the advancement of natural science. Using plasma to process materials is a core process in advanced materials and chip manufacturing; plasma-based space propulsion technology is essential for the power systems of the next generation of in-orbit spacecraft. In particular, plasma is a crucial research topic in the fields of controlled fusion and space physics.

[0004] In the study of fusion plasmas, ring-shaped devices such as tokamaks and stellarators are expensive to construct, resulting in poor reproducibility and operability of experimental conditions. Furthermore, the limited observation window area hinders precise diagnosis of the plasma within these devices. This further limits our ability to observe and study the physical processes within fusion devices. To simulate specific physical processes within fusion devices and enable comprehensive diagnostics, linear devices have emerged. With their relatively low cost, excellent experimental reproducibility and operability, and reduced diagnostic limitations, these devices have become fundamental experimental platforms in the plasma field. However, creating an experimental environment similar to that within a tokamak on a linear device requires more than simply having the same magnetic field configuration. This requires a stable plasma source capable of producing high plasma density and a high ionization rate.

[0005] A helicon wave source is a plasma source that can achieve high plasma density under low-pressure conditions. It typically emits helicon waves through a loop antenna attached to a quartz discharge tube. Through wave-particle interaction, it accelerates specific charged particles in the electric field, ionizing the gas and generating plasma. This non-contact plasma generation avoids the high temperatures and ablation associated with direct plasma contact, significantly improving its lifespan and stability. Furthermore, because plasma generation involves the interaction between electromagnetic waves and particles, typical nonlinear physical phenomena such as turbulence are present. This provides an important experimental foundation for the study of nonlinear plasma physics.

[0006] Numerous linear devices, including the LEAD device at the Southwest Institute of Nuclear Physics, the CSDX device at the University of California, San Diego, and the PANTA device at Kyushu University in Japan, have also used helicon wave sources to conduct extensive scientific and technological research, covering fields such as fusion, space physics, and engineering applications. These include the LEAD device at the Southwest Institute of Nuclear Physics, the CSDX device at the University of California, San Diego, and the PANTA device at Kyushu University in Japan. Using helicon wave sources to study nonlinear effects within plasmas and particle and energy transport mechanisms is also a key topic in cutting-edge research.

[0007] Currently, most helicon wave sources used in linear devices operate in weak magnetic field environments with parameters lower than those of superconducting tokamaks. Extraction of the helicon wave source often involves external magnetic field coils or extraction electrodes to enhance plasma excitation efficiency, increasing beam size and electron density. This design often disrupts the device's established magnetic field configuration during discharge, leading to experimental deviations. Avoiding this requires a complex control system, making it difficult to achieve the desired results in strong magnetic fields. Furthermore, the uncoupled radio frequency wave energy poses a safety risk of leakage, raising the question of how to protect the health and safety of operators and the proper and stable operation of other equipment. Summary of the Invention

[0008] To address the existing technical issues that most helicon wave sources used in linear devices operate in a weak magnetic field environment with parameters lower than those of superconducting tokamaks, and that the helicon wave sources are often extracted through external magnetic field coils or extraction electrodes to improve the excitation efficiency of the plasma, increase the beam size and electron density, but that the established magnetic field configuration of the device is often destroyed during discharge, causing experimental deviations. To avoid this phenomenon, a complex control system is required, and it is difficult to achieve the desired effect under strong magnetic fields. The technical solution provided by the present invention is as follows:

[0009] A concave cavity helicon plasma source, comprising:

[0010] Vacuum sealing and support parts, including

[0011] The quartz bell jar is bell-shaped and is used to provide a vacuum environment.

[0012] On the main flange, the main flange is connected to external equipment;

[0013] The electromagnetic shielding and heat dissipation part includes

[0014] The shielding cover is cylindrical and is used to provide shielding capability and is sleeved on the outside of the main flange;

[0015] The antenna is L-shaped and is used to connect to an external water cooling system and a power supply. It is arranged between the quartz bell jar and the shielding cover.

[0016] Furthermore, a preferred embodiment is provided, wherein the lead-out portion of the antenna is fixed and insulated by three types of insulating spacers.

[0017] Furthermore, a preferred embodiment is provided, wherein the shielding cover is connected to the main flange via an internal thread, and heat dissipation is achieved through a fan and a fan-shaped gap.

[0018] Furthermore, a preferred embodiment is provided, which also includes an antenna moving handle, which is fixedly connected to the antenna through a guide groove and is used to adjust the position of the antenna.

[0019] Furthermore, a preferred embodiment is provided, in which the bottom of the quartz bell jar is fixed in the groove of the main flange via a bell jar pressing flange.

[0020] Based on the same inventive concept, the present invention also provides a method for steady-state discharge under strong magnetic field conditions, which is implemented based on the aforementioned concave cavity helicon plasma source and includes:

[0021] Steps for collecting the best discharge position;

[0022] A step of optimizing the parameters of the plasma source according to the magnetic field distribution at the optimal discharge position;

[0023] Steps for simulating the transmission of radio frequency waves;

[0024] The step of generating a discharge signal according to the simulation results.

[0025] Based on the same inventive concept, the present invention also provides a device for steady-state discharge under strong magnetic field conditions, which is implemented based on the aforementioned concave cavity helicon plasma source and includes:

[0026] Module for collecting the best discharge position;

[0027] A module for optimizing parameters of a plasma source according to the magnetic field distribution at the optimal discharge position;

[0028] A module that simulates the transmission of radio frequency waves;

[0029] A module that generates a discharge signal based on simulation results.

[0030] Based on the same inventive concept, the present invention also provides a computer storage medium for storing a computer program. When the computer reads the computer program, the computer executes the method described.

[0031] Based on the same inventive concept, the present invention further provides a computer, comprising a processor and a storage medium. When the processor reads a computer program stored in the storage medium, the computer executes the method described above.

[0032] Based on the same inventive concept, the present invention also provides a computer program product, which is a computer program. When the computer program is executed, the method described above is implemented.

[0033] Compared with the prior art, the technical solution provided by the present invention is beneficial in that:

[0034] The present invention provides a cavity-type helicon plasma source. By designing a sealing groove between the inner concave flange and the main flange and using an O-ring seal, this effectively improves the reliability of the vacuum seal. This ensures uniform stress distribution within the quartz bell jar under high-pressure conditions and prevents potential cracking during experiments. This design not only simplifies the assembly process but also significantly enhances the vacuum sealing performance of the helicon plasma source. Compared to traditional integrated flange designs, it significantly reduces the difficulty of equipment maintenance.

[0035] The present invention provides a cavity-type helicon plasma source with an L-shaped antenna design. Three different types of spacers are used for insulation and fixation, eliminating interference between the antenna and other components within a confined space. In particular, the use of sliding spacers made of polytetrafluoroethylene (PTFE) allows for flexible movement of the antenna within the shielding enclosure, allowing users to manually adjust the antenna position according to experimental needs. This design significantly enhances adaptability to experimental conditions and flexibility in the discharge process compared to traditional fixed antenna methods.

[0036] The present invention provides a cavity-type helicon plasma source with a double-layer shielding design, resolving the difficulty of traditional single-layer shielding structures in simultaneously meeting both electromagnetic shielding and heat dissipation requirements. The shielding cover and outer shielding lid work together to effectively block external interference from radio frequency waves while simultaneously removing heat through an air-cooled heat dissipation system, ensuring long-term stable operation in high-frequency electromagnetic environments. Compared to designs that utilize only a single layer of shielding, this invention improves safety while also ensuring efficient heat dissipation.

[0037] The present invention provides a cavity-type helicon plasma source with an adjustable antenna handle, allowing precise adjustment of the antenna position based on the magnetic field distribution and experimental requirements. This design avoids the experimental limitations associated with a fixed antenna position, allowing the plasma source to more flexibly adapt to diverse experimental conditions and magnetic field environments. Compared to traditional fixed antenna designs, this provides users with greater freedom and control during operation, significantly improving the accuracy and repeatability of experimental results.

[0038] The present invention provides a cavity-type helicon wave plasma source that, through double-layer shielding of radio frequency waves and air-cooling heat dissipation, ensures internal heat dissipation while minimizing external electromagnetic interference. In particular, the shielding cover's internal threaded flange connection and the provision of heat dissipation holes in the shield further optimize the heat dissipation path, improving the device's heat dissipation efficiency and safety. Compared with the simple shielding methods used in other existing research, the present invention's double-layer shielding design significantly enhances operational safety and reduces the risk of device failure in strong magnetic fields and high-frequency electromagnetic environments.

[0039] The present invention provides a cavity-type helicon plasma source with a multi-segmented insulation design for the antenna pins, effectively preventing creepage and discharge, ensuring the safety and reliability of the antenna. Compared to traditional single-insulation methods, this segmented design not only enhances the insulation of each antenna component but also ensures its structural stability, particularly in high-voltage discharge environments, further improving the device's durability and service life.

[0040] The present invention provides a concave cavity helicon wave plasma source, which is applied to a plasma source in the field of plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the plasma source assembly;

[0042] Figure 2 for Figure 1 The right side cross-section of

[0043] Figure 3 Assemble the diagram for the quartz bell jar;

[0044] Figure 4 for Figure 3 The right side cross-section of

[0045] Figure 5 This is the assembly drawing of the shielding cover;

[0046] Figure 6 for Figure 5 Right view;

[0047] Figure 7 for Figure 6 sectional view.

[0048] Among them, 1 is the concave flange; 2 is the main flange; 3 is the quartz bell jar; 4 is the bell jar pressure flange; 5 is the gasket; 6 is the antenna; 7 is the spacer; 13 is the shielding cover; 14 is the shielding cover; 15 is the baffle; 16 is the adapter; 17 is the shielding stud; 18 is the handle; 19 is the carrying handle; 20 is the outer shielding cover. DETAILED DESCRIPTION

[0049] In order to make the advantages and benefits of the technical solution provided by the present invention more clearly reflected, the technical solution provided by the present invention is now further described in detail with reference to the accompanying drawings, specifically:

[0050] Embodiment 1: This embodiment provides a concave cavity helicon plasma source, comprising:

[0051] Vacuum sealing and support parts, including

[0052] The quartz bell jar 3 is bell-shaped and is used to provide a vacuum environment.

[0053] On the main flange 2, the main flange 2 is connected to the external equipment;

[0054] The electromagnetic shielding and heat dissipation part includes

[0055] The shielding cover 13 is cylindrical and is used to provide shielding capability and is sleeved on the outside of the main flange 2;

[0056] The antenna 6 is L-shaped and is used to connect to an external water cooling system and a power supply. It is arranged between the quartz bell jar 3 and the shielding cover 13 .

[0057] Specifically, they include:

[0058] Vacuum sealing and supporting parts:

[0059] The utility model comprises: an inner concave flange 1, a main flange 2, a quartz bell jar 3, and a bell jar pressure flange 4.

[0060] The quartz bell jar 3 is a bell-shaped structure fixed to the main flange 2. Its bottom is located in the groove of the main flange 2 and is sealed by an O-ring. The quartz bell jar 3 mainly provides a vacuum environment and protects the internal components. The concave flange 1 is used to connect the vacuum seal to the entire device. The O-ring is installed in the sealing groove to ensure the stability of the vacuum.

[0061] Connection relationship: The quartz bell jar 3 is connected to the main flange 2 through the bell jar pressure flange 4, and the main flange 2 is fixed on the concave flange 1. Each part is sealed and fixed by a polytetrafluoroethylene gasket 5 and an O-ring.

[0062] Antenna 6 and its fixing:

[0063] It includes: an L-shaped antenna 6 and three types of insulating spacers 7.

[0064] The L-shaped antenna 6 is designed to facilitate connection to an external water cooling system and power supply within a limited space while ensuring internal insulation and protection. Three types of spacers 7 are used for insulation and fixation at different locations: the first type insulates the antenna 6 from the lead-out portion outside the shielding case 13; the second type supports and secures the annular portion of the antenna 6 within the shielding case 13; and the third type allows for sliding adjustment of the antenna 6 within the shielding case 13.

[0065] Connection relationship: The antenna 6 is fixed between the shielding cover 13 and the quartz bell jar 3 through various spacers 7, and is connected to the water cooling passage and the power supply.

[0066] Electromagnetic shielding and heat dissipation:

[0067] The system comprises a shielding cover 13, a shielding cover 14, a baffle 15, an outer shielding cover 20 and a fan.

[0068] Shielding cover 13 and shielding cover 14 provide electromagnetic shielding against radio frequency waves from the plasma source and support and guide internal antenna 6. Baffle 15 and outer shielding cover 20 further enhance shielding effectiveness and provide heat dissipation channels through fan-shaped gaps. A fan cools the internal hot air, ensuring stable operation of the device in high-temperature environments.

[0069] Connection relationship: The shielding cover 13 is connected to the main flange 2, the baffle 15 is fixed to the front of the shielding cover by studs, and the fan is installed on the outside of the shielding cover 14 to form an effective heat dissipation system.

[0070] Antenna 6 moving handle 18:

[0071] It includes a handle 18 and a carrying handle 19.

[0072] The handle 18 extends into the cavity and is fixedly connected to the antenna 6 pad 7, and the manual adjustment of the position of the antenna 6 is achieved through the guide groove reserved in the shielding cover 13. The handle 19 connects the handles 18 on both sides to ensure the symmetrical movement of the antenna 6 and avoid eccentricity.

[0073] Connection relationship: The handle 18 is fixedly connected to the antenna 6 pad 7 and is connected to the shielding cover 13 through a guide groove. The external handle 19 ensures synchronous movement of both sides.

[0074] Embodiment 2: This embodiment further limits the concave cavity helicon wave plasma source provided in Embodiment 1. The lead-out portion of the antenna 6 is fixed and insulated by three types of insulating spacers 7 .

[0075] Embodiment 3: This embodiment further limits the concave cavity helicon plasma source provided in embodiment 1. The shielding cover 13 is connected to the main flange 2 through an internal thread, and heat is dissipated through a fan and a fan-shaped gap.

[0076] Embodiment 4: This embodiment further limits the concave cavity helicon wave plasma source provided in embodiment 1, and further includes an antenna 6 moving handle 18, which is fixedly connected to the antenna 6 through a guide groove and is used to adjust the position of the antenna 6.

[0077] Embodiment 5: This embodiment further limits the concave cavity helicon plasma source provided in embodiment 1. The bottom of the quartz bell jar 3 is fixed in the groove of the main flange 2 through the bell jar pressing flange 4.

[0078] Embodiment 6: This embodiment provides a method for steady-state discharge under strong magnetic field conditions. The method is implemented based on a concave cavity helicon plasma source provided in embodiment 1, and includes:

[0079] Steps for collecting the best discharge position;

[0080] A step of optimizing the parameters of the plasma source according to the magnetic field distribution at the optimal discharge position;

[0081] Steps for simulating the transmission of radio frequency waves;

[0082] The step of generating a discharge signal according to the simulation results.

[0083] Specifically:

[0084] include:

[0085] Magnetic field distribution simulation and analysis:

[0086] First, the magnetic field distribution of the high magnetic field device is simulated and analyzed in detail to determine the magnetic field configuration and intensity distribution during the discharge process.

[0087] Detailed Description: Using specialized magnetic field simulation software, the geometric parameters and material properties of the high-magnetic field device are input to simulate the magnetic field distribution within the device. Based on the simulation results, the magnetic field strength and magnetic mirror effect at different locations within the device are analyzed, and the location most conducive to achieving stable plasma discharge is determined. The output of this step, namely the magnetic field distribution data and the optimal discharge location, will serve as input for cavity design optimization.

[0088] Cavity design optimization:

[0089] According to the magnetic field distribution results, the design of the cavity is optimized to ensure that the plasma source can fully utilize the magnetic mirror effect.

[0090] Detailed Description: CAD software was used to design the cavity geometry and dimensions, focusing on the matching of cavity depth with the magnetic mirror field. By repeatedly adjusting the cavity shape, the discharge position was ensured to be precisely within the magnetic mirror field, thereby improving plasma stability and energy coupling efficiency. The final cavity design served as input for subsequent RF wave transmission simulations and adjustments.

[0091] RF wave transmission simulation and adjustment:

[0092] Simulate RF wave transmission and adjust its parameters to optimize the coupling efficiency between RF wave and plasma.

[0093] Detailed Description: After finalizing the cavity design, RF transmission simulation software is used to simulate the RF wave propagation path and energy distribution within the cavity. Based on the simulation results, the design of Antenna 6 and parameters such as the RF wave frequency and power are adjusted to ensure efficient coupling of the RF wave into the plasma in the discharge region, maximizing ionization efficiency. The output of this step, including the optimized RF wave parameters and Antenna 6 design, is used in shielding and heat dissipation design simulations.

[0094] Shielding and thermal design simulation:

[0095] After optimizing the RF wave transmission, the double-layer shielding and heat dissipation system are simulated and designed to ensure the safety and stability of the equipment.

[0096] Detailed Description: Electromagnetic shielding simulation software is used to simulate the shielding effectiveness of different shielding materials and structures against RF waves, allowing the optimal shielding solution to be selected. Thermal simulation software is also used to simulate the temperature distribution of the shielding structure during operation. This allows optimization of the design of heat dissipation holes and the layout of air ducts to ensure rapid heat dissipation and prevent equipment failures caused by overheating. The final shielding and heat dissipation design, as the output of the software, guides the actual hardware manufacturing and assembly.

[0097] Embodiment 7: This embodiment provides a device for steady-state discharge under strong magnetic field conditions. The device is implemented based on the concave cavity helicon plasma source provided in embodiment 1, and includes:

[0098] Module for collecting the best discharge position;

[0099] A module for optimizing parameters of a plasma source according to the magnetic field distribution at the optimal discharge position;

[0100] A module that simulates the transmission of radio frequency waves;

[0101] A module that generates a discharge signal based on simulation results.

[0102] Embodiment 8: This embodiment provides a computer storage medium for storing a computer program. When the computer reads the computer program, the computer executes the method provided in embodiment 6.

[0103] Implementation method 9: This implementation method provides a computer, including a processor and a storage medium. When the processor reads the computer program stored in the storage medium, the computer executes the method provided in implementation method 6.

[0104] Embodiment 10: This embodiment provides a computer program product, which is a computer program. When the computer program is executed, the method provided in Embodiment 6 is implemented.

[0105] Implementation Method 11: Combination Figure 1-7 This embodiment further describes the above technical solution in detail through specific examples, specifically:

[0106] The purpose of this embodiment is to provide a cavity-type helicon wave plasma source that can be used in strong magnetic fields. By understanding the magnetic field distribution of a specific device and designing a corresponding cavity, the discharge position of the plasma source is placed inside the magnetic mirror field, thereby coupling the energy into the plasma as much as possible. This embodiment also implements double-layer shielding of radio frequency waves, minimizing the impact on the outside world while ensuring internal heat dissipation, protecting the operator's safety and the stable operation of other instruments. By manually adjusting the position of antenna 6, manual control of the plasma beam can also be achieved. The design requirements of simple structure and easy maintenance are achieved, making it more suitable for helicon wave plasma excitation and research in strong magnetic fields.

[0107] Based on research on helicon plasma discharge, this embodiment designs a simple discharge structure capable of generating large-scale helicon plasma on a linear device with a strong magnetic field (such as superconducting). The hardware system of this embodiment consists of the following three parts:

[0108] The first part is the vacuum seal and support, which is mainly composed of the concave flange 1, the main flange 2, the quartz bell jar 3 and the bell jar pressure flange 4. The quartz bell jar 3, which is one of the main features of the spiral wave source, is fixed to the main flange 2 through the bell jar pressure flange 4. There is no direct contact between the two. The polytetrafluoroethylene gasket 5 is clamped in to keep the quartz bell jar 3 under uniform force and prevent it from breaking under the high pressure that it may be subjected to during assembly or testing. The bottom of the quartz bell jar 3 is in the groove opened on one side of the main flange 2, pressing down the sealing O-ring. The main flange 2 is fixed to a bottom surface of the concave flange 1 column designed to match the device, and a sealing groove is opened on the side of the concave flange 1 on the contact surface to install the sealing O-ring.

[0109] The second part is the antenna 6 and its fixation. Since the internal space of the cavity plasma source is limited, the lead-out and water-cooling connection of the antenna 6 need to be outside the plasma source for easy loading and unloading, so an L-shaped antenna 6 design is adopted. The part of the antenna 6 in the cavity and between the two pins need to be well insulated to prevent creepage or discharge. There are three types of pads 7 for the antenna 6: the first type is the pad 7 that partially covers the insulation of the antenna 6 between the outside of the shielding cover 13 and the lead-out. It needs to be in direct contact with the metal shielding cover 13, so polytetrafluoroethylene material is used to reduce the friction coefficient and improve wear resistance; the second type is for the support and fixation between the annular part of the antenna 6 and the quartz bell jar 3 in the shielding cover 13, and polyetheretherketone material is used to enhance the rigidity and support strength of the structure; the third type of pad 7 is because the inner ring part of the antenna 6 needs to be able to change its relative position in the source by sliding in the shielding cover 13, so a polytetrafluoroethylene slider design is adopted. The first two types of pads 7 need to be in direct contact with the antenna 6 and completely cover it, and adopt a semi-enclosed and mortise-and-tenon design supplemented by screw fixation, thereby improving the insulation between the various parts of the antenna 6 from the overall structure.

[0110] The third component, electromagnetic shielding and heat dissipation, primarily comprises a shielding cover 13, a shielding cover lid 14, a baffle 15, and an outer shielding cover 20. The shielding cover 13 serves as the first layer of electromagnetic shielding for radio frequency waves within the plasma source. It is connected to the main flange 2 via internal threads and supports and guides the internal antenna 6 mounting block. The baffle 15 is secured to the front of the shielding cover via four studs and then connected to the shielding cover 13 via an adapter ring 16. The metal cavity itself serves as the second layer of shielding cover 13, fully shielding poloidal radio frequency waves in a columnar configuration. The fan-shaped gaps in the outer shielding cover 20 filter diagonal waves, further enhancing the safety of the device. Because the plasma source generates rapidly changing electromagnetic fields during operation, not only does the shielding component need to be grounded, but also the metal heating effect caused by the induced electric field must be prevented. Therefore, air cooling is employed for heat dissipation, with a special air duct designed for this purpose. The shielding cover 13 has cooling holes on its cylindrical surface near the quartz bell jar 3. The shielding cover 14 has holes for installing a fan and provides an air duct. To prevent the fan motor from being affected by magnetic fields during operation and in the working environment, a front iron shield 15 is installed. Air enters the gap between the shielding cover 13 and the cavity through the outer shielding cover 20, enters the interior through the cooling holes in the shielding cover 13, and is finally exhausted by the fan on the shielding cover 14, completing the air cooling cycle.

[0111] The fourth component is the handle 18 for moving the antenna 6. By securing one end of the handle 18, which extends deep into the cavity, to the antenna 6 pad 7, and inserting the convex portion of the handle 18 into the guide groove reserved in the shielding cover 13 as a slider, the position of the antenna 6 can be manually adjusted from outside the cavity. Finally, a carrying handle 19 connects the two handles 18, ensuring that the antenna 6 does not decenter due to a large position difference.

[0112] The concave design of the cavity-type plasma source is a key technical point of this embodiment. By using the known magnetic field configuration and intensity distribution of the device, the appropriate cavity depth is selected to place the discharge position as close as possible to the interior of the local magnetic mirror field. This avoids discharge from outside the magnetic mirror field and the reflection of charged particles caused by the strong magnetic mirror effect, allowing energy to be more efficiently fed into the plasma, thereby increasing the size of the plasma beam. This solution is simple and feasible, without the need for adding magnetic field coils outside the plasma source or extraction electrodes inside the device. At the same time, the cavity-shaped metal barrel can also absorb some of the residual radio frequency wave energy, providing a certain degree of internal shielding.

[0113] One of the characteristics of this embodiment is the two-stage vacuum sealing design. After the traditional integrated concave cavity flange is fully assembled, the assembly and fixation of the various components in the spiral wave source becomes extremely difficult due to the limitation of its internal space. The two-stage sealing design of this embodiment forms a concave cavity through the combination of the inner concave flange 1 and the main flange 2, wherein a sealing groove is provided on one side of the inner concave flange 1 to ensure vacuum sealing. This design not only simplifies the assembly process, but also completes the complete assembly of the spiral wave source by first assembling all the internal parts with the main flange 2 as the base, and then installing the whole on the inner concave flange 1. This two-stage sealing design significantly reduces the difficulty of assembly, effectively overcomes the problem of inconvenience in assembly and disassembly caused by the small internal space in the traditional design, and makes the installation and maintenance of the spiral wave source more efficient and convenient.

[0114] A second feature of this embodiment is its dual-layer shielding and heat dissipation. The spiral source generates radio frequency radiation during operation, which can not only harm the human body but also interfere with other electronic devices. Furthermore, in a high-frequency electromagnetic environment, metals can generate thermal effects due to the induced electric field. Therefore, shielding and heat dissipation are crucial for the safe and stable operation of the spiral source. However, traditional single-layer shielding structures often reduce shielding effectiveness due to the presence of heat dissipation holes, making it difficult to achieve both shielding and heat dissipation. To address this issue, this embodiment employs a dual-layer shielding design to achieve both shielding and heat dissipation. The first shielding layer is the inner shielding layer, primarily composed of a shielding cover 13 and a shielding cover 14. High-conductivity metal materials such as aluminum and copper can be used. Given that the shielding cover 13 needs to provide support for the antenna 6 and the spacer 7, rigidity must also be considered when selecting the material. Aluminum alloy and copper are suitable materials. The second shielding layer is the outer shielding layer, consisting of an inner concave flange 1 and left and right outer shielding covers 20. The left and right outer shielding covers 20 are axisymmetric and secured to the other side of the inner concave flange 1 with screws. The outer shielding cover 20 adopts a fan-shaped grid design, with each grid corresponding to a central angle of 15°. Multiple grids are connected, which not only provides effective shielding for radio frequency waves, but also provides a main air intake channel for the concave cavity of the source. During operation, hot air is mainly concentrated inside the shielding cover 13. In order to effectively dissipate heat, this embodiment installs a 14-centimeter fan on the outside of the shielding cover 14 to accelerate the extraction of hot air through the center opening. The center opening is facing the direction of the antenna 6, and the iron plate supported by four studs is electromagnetically shielded to ensure the normal operation of the fan motor and is not subject to electromagnetic interference. Through this design, this embodiment not only improves the shielding effect and avoids the impact of radio frequency radiation on the human body and other electronic equipment, but also ensures that the spiral source maintains stable working performance while dissipating heat efficiently.

[0115] A third feature of this embodiment is the multi-segment insulation design of antenna 6. Due to the right-angle bend of the L-shaped antenna 6, it is extremely difficult to insert the antenna 6 and complete assembly through a single insulating block. Furthermore, a simple segmented design cannot achieve complete insulation between antennas 6. To address this issue, this embodiment adopts a double-layer segmented design, first ensuring insulation between the pins of antenna 6, and then performing an annular sheathing of antenna 6. The insulation layer of the pins must be integrated to reduce the occurrence of discharge or creepage, which is crucial to ensuring the safety and reliability of antenna 6. The pad 7 in the insulating sheath structure is designed as a straight section and an annular section, both of which adopt a semi-enclosed design to achieve the best insulation effect. The pad 7 in the straight section contains the insulation layer between the pins of antenna 6. The two pads 7 use a combination of upper and lower structures and are fastened with external screws to ensure structural stability. The pad 7 in the annular section is installed on the annular antenna 6 through the inside of the shielding cover 13, and the pad 7 in the straight section is crimped to achieve an overall insulating sheath. To ensure a tighter connection between the pads 7, the design incorporates intricate mortise and tenon joints, such as the cutouts in the annular pads 7 and the protrusions from the insulation layer of the linear pads 7. These details not only enhance structural stability but also improve insulation. This innovative multi-stage, encapsulated insulation design not only improves the insulation performance of the antenna 6 but also ensures ease and reliability of assembly, providing users with a safer and more efficient antenna 6 solution.

[0116] A fourth feature of this embodiment is the adjustable axial position of antenna 6. In conventional helical wave sources, antenna 6 is typically fixed, limiting its positional adjustment during discharge. This embodiment utilizes a specific oblong hole in the shielding cover 13 and incorporates handles 18 in the hole. These handles 18 are fixedly connected to the internal spacer 7. By leveraging the sliding friction between components in contact with the shielding cover 13, precise movement of the internal antenna 6 is achieved. This design allows the user to adjust the position of antenna 6 as needed to accommodate varying discharge conditions. The handles 18 are located on opposite sides of the shielding cover 13 and connected externally by a single handle 19. This design facilitates both control and operation. The handle 19 allows the user to easily adjust the position of antenna 6 to match the device's magnetic field distribution, enabling discharge at different locations and under varying magnetic field conditions, thereby increasing the flexibility and efficiency of the discharge process. This adjustable antenna 6 position design provides users with greater operational freedom, enabling the helical wave source to adapt to a wider range of applications and enhancing its practicality and adaptability.

[0117] in, Figure 1This is a rendering of the plasma source assembly. Based on the Harbin Institute of Technology's Plasma and Surface Interaction Platform (HIT-PSI), a cavity-type helicon plasma source was designed for use on this device. The concave flange 1 has an outer edge diameter of 446mm and a thickness of 20mm. It can be installed on the device using eight M14 screws. The sealing groove is already on one side of the device, eliminating the need for a new one. The outer shield 13 has been designed with sufficient tolerances to avoid interference with the handle 18, the extended portion of the antenna 6, and the shield 13.

[0118] Figure 2 This is a right-side cross-sectional view of the plasma source.

[0119] This linear device features a low-temperature superconducting magnet with a magnetic field exceeding 2 T, making it a leading high-field device both domestically and internationally. To ensure the plasma source is as deep as possible within the device's internal magnetic mirror field, the recessed flange 1 is 520 mm deep. This ensures that as many charged particles generated by the radio frequency wave as possible are confined within the magnetic mirror field.

[0120] Figure 3 This is the assembly drawing of the quartz bell jar 3 and the main flange 2 in the cavity. Figure 4 The figure is a right-side cross-sectional view. The quartz bell jar 3 shown has an inner diameter of 150 mm and a total length of 400 mm. The quartz bell jar 3 is appropriately sized to accommodate the limited space of the cavity while ensuring the insulation and shielding properties of the antenna 6. The protruding edge of the bell jar is 15 mm thick, with rounded corners to facilitate its attachment to the bell jar's pressure flange 4. A 2 mm thick polytetrafluoroethylene gasket 5 is sandwiched between the pressure flange and the bell jar to ensure uniform force during installation and chamber operation under vacuum. A 30 mm external thread should be machined onto the protruding portion of the main flange 2.

[0121] like Figures 5 to 7The figure shows the inner ring structure formed by the shielding cover 13, antenna 6, and its spacer 7. An 8mm outer diameter Green connector is welded to the rear end of antenna 6 to facilitate connection to the water cooling pipe. A square water channel is located within antenna 6, dissipating heat during operation to ensure proper operation. Each pin of antenna 6 has eight M4 through-holes to facilitate secure connection to the copper busbar. The insulating block at the end of the pin extends outward approximately 30mm, completely separating the left and right water and electricity connections of antenna 6. The pins of antenna 6 extend upward, allowing condensed water from cooling during operation to drip under gravity without accumulating and affecting discharge. The annular portion of antenna 6 extends into shielding cover 13 through a pre-reserved slot above shielding cover 13 and is then rotated to achieve the correct orientation to complete assembly. Spacers 7 then enclose antenna 6. Contact between spacer 7 and the shield is achieved solely through two 2mm thick polytetrafluoroethylene rings, ensuring smooth sliding of antenna 6 outside the smooth quartz bell jar 3 and inside shielding cover 13. In addition, the front section of the shielding cover 13 features four 5mm diameter through-holes for easy connection to the shielding lid, and the rear section features 30mm internal threads for connection to the main flange 2. The heat dissipation holes in the shielding cover 13 are all oblong holes, with their length gradually decreasing from the rear end to the front end, while the spacing gradually increases from the rear end to the front end. This is because the bottom of the cavity does not dissipate heat easily, so increasing the size of the heat dissipation holes is necessary to improve cooling efficiency.

[0122] The quartz bell jar 3 can be modified into various hollow cylindrical shapes. Antenna 6 can also be modified into spiral or saddle-shaped coils, in addition to ring shapes. Since the helicon plasma source relies on a non-contact discharge method, the same discharge effect can be achieved by exciting whistler waves with different poloidal modes, as long as sufficient space is left within the cavity. An air inlet can be opened in the main flange 2 or the inner concave flange 1 to allow discharge gas to enter the vacuum chamber from the source side.

[0123] Antenna 6 is made of oxygen-free copper and features square water channels. Water cooling utilizes Green connectors, and copper busbars are crimped together with screws to connect to the impedance matcher and RF power supply. The flanges are all made of stainless steel, with sealing grooves at the joints. These flanges are custom-made using non-standard processing. Shield studs 17 are M3 studs, and standard pre-made parts can be used.

[0124] The above further describes the technical solution provided by the present invention in detail through several specific embodiments in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific embodiments described above are not intended to limit the present invention. Any reasonable modification and improvement of the present invention, combination of embodiments and equivalent replacement based on the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A concave cavity helicon plasma source, characterized in that: include: Vacuum sealing and support parts, including The quartz bell jar is bell-shaped and is used to provide a vacuum environment. On the main flange, the main flange is connected to external equipment; It also includes a concave flange in the column, which forms a concave cavity together with the main flange; Electromagnetic shielding and heat dissipation parts, including The shielding cover is cylindrical and serves as a metal cavity for providing shielding capability. It is sleeved on the outside of the main flange and is specifically connected to the main flange through internal threads. The antenna is L-shaped and is used to connect to an external water cooling system and a power supply. It is arranged between the quartz bell jar and the shielding cover.

2. A concave cavity helicon plasma source according to claim 1, characterized in that: The lead-out portion of the antenna is fixed and insulated by three types of insulating spacers.

3. The concave cavity helicon plasma source according to claim 1, characterized in that: The shielding cover is connected to the main flange via an internal thread, and heat is dissipated through a fan and a fan-shaped gap.

4. The concave cavity helicon plasma source according to claim 1, characterized in that: It also includes an antenna moving handle, which is fixedly connected to the antenna through a guide groove and is used to adjust the position of the antenna.

5. The concave cavity helicon plasma source according to claim 1, characterized in that: The bottom of the quartz bell jar is fixed in the groove of the main flange through the bell jar pressing flange.

6. A method for steady-state discharge under strong magnetic field conditions, characterized in that: The method is implemented based on the concave cavity helicon plasma source according to claim 1, comprising: Steps for collecting the best discharge position; A step of optimizing the parameters of the plasma source according to the magnetic field distribution at the optimal discharge position; Steps for simulating the transmission of radio frequency waves; The step of generating a discharge signal according to the simulation results.

7. A device for steady-state discharge under strong magnetic field conditions, characterized in that: The device is implemented based on the concave cavity helicon plasma source according to claim 1, comprising: Module for collecting the best discharge position; A module for optimizing parameters of a plasma source according to the magnetic field distribution at the optimal discharge position; A module that simulates the transmission of radio frequency waves; A module that generates a discharge signal based on simulation results.

8. A computer storage medium for storing a computer program, characterized in that When the computer reads the computer program, the computer executes the method according to claim 6.

9. A computer comprising a processor and a storage medium, characterized in that When the processor reads the computer program stored in the storage medium, the computer executes the method according to claim 6 .

10. A computer program product, being a computer program, characterized in that When the computer program is executed, the method according to claim 6 is implemented.

Images