A high-energy ion beam generating device with a magnetic expansion cavity structure

Abstract

The present invention provides a high-energy ion beam generating device with a magnetic expansion cavity structure, belonging to the technical field of deep space electric propulsion, comprising a microwave generating system, a microwave transmission system, a magnetic field system, a resonant cavity system, an expansion cavity system, a water cooling system and a plasma diagnostic system which are sequentially arranged from right to left; the present invention optimizes the design of the entire microwave coupling system, a compact solenoid-type controllable electromagnetic coil system and a low-aspect-ratio composite vacuum chamber structure, on the one hand, avoiding corrosion and interference caused by direct contact between a conventional microwave discharge metal antenna and plasma, and on the other hand, by combining a controllable magnetic expansion magnetic potential type with a low-aspect-ratio cavity structure, a magnetic field gradient controls plasma expansion acceleration, a low-aspect-ratio (short and wide) cavity reduces wall loss, reduces interaction between plasma and cavity wall, reduces material erosion, effectively avoids plasma wall loss in the expansion chamber, and improves energy conversion efficiency and plasma generation efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep space electric propulsion, and in particular relates to a high-energy ion beam generating device with a magnetic expansion cavity structure. Background Art

[0002] As a new type of electrostatic thruster, the electron cyclotron resonance (ECR) ion electric thruster has attracted extensive attention from experts and scholars at home and abroad in the field of deep space electric propulsion due to its technical advantages such as easy miniaturization, easy operation, low cost, no internal electrode and long life. However, in terms of application, it still faces the problem that the total thrust efficiency has not been fully and effectively optimized and the thrust power is relatively low. At present, this technology generally has problems such as low microwave energy coupling efficiency, low mass utilization rate and low energy conversion efficiency. How to improve the thrust-power ratio of the electric thruster from the aspects of microwave transmission system structure design and plasma transport parameter optimization, and solve the low thrust performance of the system is a bottleneck problem that needs to be solved in the promotion and application of ECR ​​ion electric thrusters. On the other hand, there is no unified understanding of the physical mechanism of how the hot electron energy of microwave heating achieved by electron cyclotron resonance is converted into the kinetic energy of the working fluid and finally into the efficient thrust of the thruster. In particular, how the plasma cross-field transport driven by plasma electromagnetic instability realizes the generation of ion acceleration barriers, thereby affecting the thrust efficiency of the electric thruster. These two factors seriously restrict the thrust performance and on-orbit test flight of ECR ​​ion electric thrusters. Therefore, how to achieve high-performance propulsion of high-power-ratio micro ECR ion electric thrusters is a difficult problem that needs to be overcome in this technical field. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of low microwave energy coupling efficiency, low mass utilization rate and low energy conversion efficiency of ECR ​​ion electric thrusters. By optimizing the design of the overall structure of microwave energy coupling, a compact solenoid electromagnetic field system and a low aspect ratio composite vacuum chamber are coupled together to provide a high-energy ion beam generating device with a magnetic expansion cavity structure, and a compact solenoid electromagnetic coil is used to realize a magnetic jet type magnetic expansion magnetic field control position, aiming to optimize the problem that the performance of ECR ​​ion electric thrusters in the prior art cannot fully exert the overall efficiency.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: a high-energy ion beam generating device with a magnetic expansion cavity structure, comprising a microwave generating system, a microwave transmission system, a magnetic field system, a resonant cavity system, an expansion cavity system, a water cooling system and a plasma diagnostic system;

[0005] The microwave generating system comprises a microwave source control system and a microwave head magnetron; the microwave transmission system comprises a circulator, a water load, a three-pin adapter and a rectangular waveguide tube; the magnetic field system comprises an electromagnetic coil and a DC control power supply; the resonant cavity system comprises a microwave ceramic window and a small-sized vacuum cavity; the expansion cavity system comprises a large-sized vacuum cavity and a vacuum pump unit; the plasma diagnostic system comprises a Langmuir probe and an ion energy analyzer; wherein one end of the microwave head magnetron is connected to the microwave source control system, and the other end is connected to the circulator and the water load, the left end of the circulator is connected to the three-pin adapter, the left end of the three-pin adapter is connected to the rectangular waveguide tube, the left end of the rectangular waveguide tube is connected to the resonant cavity system, the periphery of the resonant cavity system is connected to a water cooling system, and an electromagnetic coil is placed for covering, the electromagnetic coil is connected to an adjustable DC control power supply, and is cooled by water to prevent overheating, the left end of the resonant cavity system is connected to the expansion cavity system, and the expansion cavity system is connected to the plasma diagnostic system and the vacuum pump unit.

[0006] The present invention has the following beneficial effects:

[0007] The present invention proposes a high-energy ion beam generating device with a magnetic expansion cavity structure. Compared with other discharge forms of plasma, the device has the advantages of simple structure, high ionization degree, large beam energy and high energy coupling efficiency.

[0008] The present invention adopts the microwave ceramic window feeding method to avoid the corrosion and interference of traditional metal electrodes on plasma. On the one hand, the microwave ceramic window can isolate the pressure difference in the plasma discharge area, and on the other hand, it can improve the coupling efficiency of the entire microwave transmission system, and cooperate with three pins, small-scale vacuum chambers, and magnetic field configurations to jointly achieve the improvement of microwave energy coupling efficiency.

[0009] By designing the magnetic expansion magnetic potential type and cavity structure, the magnetic field gradient controls the plasma expansion acceleration, and the low aspect ratio cavity reduces the wall loss, avoids the wall loss of plasma, improves the energy conversion efficiency, and further improves the efficiency of plasma generation. By adjusting the current size of the inductor coil to adjust the magnetic field strength and divergence in the resonance area, the controllable ECR resonant discharge conditions can be quickly and accurately achieved. By combining the controllable magnetic expansion magnetic potential type and the low aspect ratio cavity structure, the low aspect ratio cavity reduces the wall loss, reduces the interaction between the plasma and the cavity wall, reduces the erosion of the material, effectively avoids the wall loss of the plasma, improves the energy conversion efficiency, and greatly improves the efficiency of plasma generation. At present, there is still a high-energy ion beam with an energy of nearly 20 electron volts at a position 60cm away from the source area.

[0010] The water cooling system of the resonant cavity has been optimized, and an inverted "L"-shaped water cooling jacket is used to reduce the high-temperature heating of the microwave ceramic window by the plasma, thereby reducing the risk of its rupture.

[0011] The three-pin adapter is used to achieve precise impedance matching, and the microwave ceramic window is used to isolate metal pollution, thereby increasing the microwave energy transmission efficiency to more than 95%, and can efficiently generate high-energy ion beams of tens of electron volts. The device of the present invention optimizes the energy transmission structure, improves the microwave energy transmission efficiency, and combines the controllable magnetic expansion magnetic type with the low aspect ratio cavity structure, the magnetic field gradient controls the plasma expansion acceleration, the low aspect ratio cavity reduces the wall loss, reduces the interaction between the plasma and the cavity wall, reduces the material erosion, and effectively avoids the plasma wall loss.

[0012] The present invention optimizes the design of the entire microwave coupling system, a compact solenoid-type controllable electromagnetic coil system, and a low-aspect-ratio composite vacuum chamber structure. On the one hand, it avoids corrosion and interference caused by direct contact between the traditional microwave discharge metal antenna and the plasma. On the other hand, it combines the controllable magnetic expansion magnetic potential type with the low-aspect-ratio cavity structure, controls the plasma expansion acceleration with the magnetic field gradient, and reduces the wall loss of the low-aspect-ratio (short and wide) cavity, reduces the interaction between the plasma and the cavity wall, reduces material erosion, effectively avoids the wall loss of the plasma in the expansion chamber, and improves the energy conversion efficiency and the plasma generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a cross-sectional schematic diagram of the overall structure of a high-energy ion beam generating device with a magnetic expansion cavity structure according to the present invention;

[0014] Figure 2 It is a three-dimensional overall structural schematic diagram of a high-energy ion beam generating device with a magnetic expansion cavity structure according to the present invention;

[0015] Figure 3 This is a schematic diagram of the resonant cavity structure in a high-energy ion beam generating device with a magnetic expansion cavity structure according to the present invention;

[0016] Figure 4 It is a structural schematic diagram of a large-size expansion chamber in a low-aspect-ratio chamber in a high-energy ion beam generating device of a magnetic expansion chamber structure of the present invention;

[0017] Figure 5 This is an ECR resonance magnetic field distribution diagram in a high-energy ion beam generating device with a magnetic expansion cavity structure according to the present invention;

[0018] Figure 6 This is a diagram of the ECR resonance magnetic field intensity in a high-energy ion beam generating device with a magnetic expansion cavity structure according to the present invention;

[0019] Figure 7 The present invention is a characteristic curve diagram of a plasma diagnosed by a probe in a high-energy ion beam generating device with a magnetic expansion cavity structure, wherein (a) is a volt-ampere characteristic curve diagram, and (b) is an electron density distribution diagram;

[0020] Figure 8 The invention discloses a high energy ion energy distribution diagram diagnosed by an ion energy analyzer in a high energy ion beam generating device with a magnetic expansion cavity structure.

[0021] Wherein, the accompanying drawings are marked as follows:

[0022] Microwave source control system 1, microwave head magnetron 2, circulator 3, water load 4, three-pin dispenser 5, rectangular waveguide 6, electromagnetic coil 7, DC control power supply 8, microwave ceramic window 9, small-size vacuum cavity 10, large-size vacuum cavity 11, vacuum pump group 12, Langmuir probe 13, ion energy analyzer 14, ceramic step window 9001, stainless steel support 9002, boron nitride sheet 9003, water cooling jacket 1001, vacuum cavity 1002, aluminum cylinder 1003, CF150 flange port 1101, CF100 flange port 1102, CF63 flange port 1103, CF35 flange port 1104. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned purpose, the present invention adopts the following technical scheme.

[0024] like Figure 1-2As shown, a high-energy ion beam generating device with a magnetic expansion cavity structure of the present invention includes a microwave generating system, a microwave transmission system, a magnetic field system, a resonant cavity system, an expansion cavity system, a water cooling system and a plasma diagnostic system; the microwave generating system includes a microwave source control system 1 and a microwave head magnetron 2; the microwave transmission system includes a circulator 3, a water load 4, a three-pin adapter 5 and a rectangular waveguide 6; the magnetic field system includes an electromagnetic coil 7 and a DC control power supply 8; the resonant cavity system includes a microwave ceramic window 9 and a small-sized vacuum cavity 10; the expansion cavity system includes a large-sized vacuum cavity 11 and a vacuum pump group 12; the plasma diagnostic system includes a Langmuir probe 13 and an ion energy analyzer 14. From right to left, the microwave source control system 1, the microwave head magnetron 2, the circulator 3, the water load 4, the three-pin adapter 5, the rectangular waveguide 6, the electromagnetic coil 7, the DC control power supply 8, the microwave ceramic window 9, the small-sized vacuum cavity 10, the large-sized vacuum cavity 11, the vacuum pump group 12, the Langmuir probe 13, and the ion energy analyzer 14 are arranged in sequence. Among them, one end of the microwave head magnetron 2 is connected to the microwave source control system 1, and the other end is connected to the circulator 3 and the water load 4. The left end of the circulator 3 is connected to the three-pin adapter 5, the left end of the three-pin adapter 5 is connected to the rectangular waveguide 6, and the left end of the rectangular waveguide 6 is connected to the resonant cavity system. An electromagnetic coil 7 is placed at the outer end of the resonant cavity system, and the electromagnetic coil 7 is connected to an adjustable DC control power supply 8. The left end of the resonant cavity system is connected to the expansion cavity system, and the expansion cavity system is connected to the plasma diagnostic system.

[0025] The microwave source control system 1 is connected to the microwave head magnetron 2 through a magnetron power line, the microwave head magnetron 2 is connected to the circulator 3 through a BJ26 interface, the circulator 3, the water load 4, the three-pin dispenser 5, and the rectangular waveguide 6 are all connected through the BJ26 interface, the other end of the rectangular waveguide 6 is connected to the small-sized vacuum cavity 10 through the BJ26 interface, the microwave ceramic window 9 is placed at the front end of the small-sized vacuum cavity 10, the electromagnetic coil 7 is connected to the DC control power supply 8 through a power line and the electromagnetic coil 7 is placed outside the microwave ceramic window 9 and the small-sized vacuum cavity 10, the large-sized vacuum cavity 11 is connected to the small-sized vacuum cavity 10 through a CF100 flange, the vacuum pump group 12 is connected to the large-sized vacuum cavity 11, and the Langmuir probe 13 and the ion energy analyzer 14 are connected to the large-sized vacuum cavity 11 through a CF35 flange.

[0026] The microwave source control system 1 is used to power the microwave head magnetron 2 and control and adjust the microwave head magnetron 2 to generate microwave energy with a frequency of 2.45GHz. The microwave energy is set to 700-1200W. The microwave source control system 1 provides an external excitation source and control commands for the microwave generation system. The microwave head magnetron 2 uses the movement of electrons in a constant magnetic field and electric field to interact with the high-frequency electromagnetic field to convert energy to generate microwaves. The microwave head magnetron 2 excites and generates microwaves with a frequency of 2.45GHz. The reflected power is adjusted to be less than 5W through impedance matching of the microwave transmission system, wherein the microwave head magnetron 2 is connected to water cooling for cooling; the microwave energy generated by the microwave head magnetron 2 is regulated in the propagation direction through the circulator 3 and the water load 4. The circulator 3 ensures that the microwave energy can only propagate in one direction. The water load 4 is used to absorb the reflected power to prevent the microwave energy from reflux and causing damage to the microwave head magnetron 2; the microwave energy is impedance adjusted through the three-pin adapter 5 before entering the resonant cavity system; the microwave energy can be fed into the small-sized vacuum cavity 10 through the rectangular waveguide 6 and the microwave ceramic window 9.

[0027] like Figure 3As shown, the resonant cavity system includes a microwave ceramic window 9 and a small-sized vacuum cavity 10; the microwave ceramic window 9 is placed at the front end of the small-sized vacuum cavity 10, which can isolate the pressure difference between the discharge area and the waveguide area, maintain the discharge pressure, and the microwave energy first passes through the microwave ceramic window 9 through the rectangular waveguide 6 to enter the small-sized vacuum cavity 10, and couples the energy to the neutral gas. The small-sized vacuum cavity 10 is a plasma excitation generation area. The microwave ceramic window 9 includes a ceramic step window 9001, a stainless steel support plate 9002, and a boron nitride sheet 9003. The boron nitride sheet 9003 is placed at the front end of the microwave ceramic window 9 to prevent secondary electron sputtering and to insulate the ceramic step window 9001. During the discharge process, the discharge state of the boron nitride sheet 9003 and whether there is ablation should be observed at any time. Ablation can cause the boron nitride sheet 9003 to break or even fail to achieve stable discharge. The small-sized vacuum chamber 10 includes a water-cooling jacket 1001, a vacuum chamber 1002, and an aluminum tube 1003, wherein the water-cooling jacket 1001 is used to water-cool the small-sized vacuum chamber 10 to remove the heat generated by the discharge. In order to cooperate with the controllable compact solenoid electromagnetic coil 7, the water-cooling structure is designed to be nested in an inverted "L" shape; the vacuum chamber 1002 forms a closed space in the discharge area and is provided with a sandwich process to facilitate water-cooling of the discharge environment; the boron nitride sheet 9003 is closely attached to the aluminum tube 1003, and is used to absorb a large amount of heat in the microwave energy, which is beneficial to protecting the microwave ceramic window 9 and increasing the density of the plasma; the aluminum tube 1003 is arranged in the inner layer of the vacuum chamber 1002, which is conducive to easier generation of plasma. In order to achieve the cyclotron resonance condition of ECR ​​discharge, the DC control power supply 8 applies a stable DC current to the electromagnetic coil 7 to generate a stable magnetic field, and is placed outside the microwave ceramic window 9 and the small-sized vacuum chamber 10. The current output of the DC power supply 8 is controlled so that the electromagnetic coil 7 generates a stable magnetic field environment of about 875G required for discharge, and realizes the magnetic expansion magnetic field configuration. Regulating the generation of high-energy ions driven by non-uniform gradients can promote the conversion of plasma thermal energy into kinetic energy.

[0028] like Figure 4 As shown, the large-size vacuum chamber 11 is a stainless steel tank with a length of 1.5 m and a diameter of 0.5 m, on which a plurality of flanges are provided. The sizes of the flanges are respectively CF150 flange 1101, CF100 flange 1102, CF63 flange 1103, and CF35 flange 1104. The vacuum pump group can pump the air pressure in the large-size vacuum chamber 11 to less than 1×10 -4Pa, CF150 flange port 1101 is used to install the vacuum pump group 12, CF100 flange port 1102 and CF63 flange port 1103 are used to install the observation window or the resonant cavity system, and CF35 flange port 1104 is used to install the gas feeding system and the plasma diagnostic system. The large-sized vacuum cavity 11 and the small-sized vacuum cavity 10 can together constitute a composite low-aspect ratio discharge chamber, which, in conjunction with the controllable divergent magnetic field configuration, can effectively drive the generation of high-energy ions and reduce the wall loss of plasma.

[0029] The plasma diagnostic system includes a Langmuir probe and an ion energy analyzer 14. A Langmuir probe 13 is placed on a large-sized vacuum chamber 11. The Langmuir probe 13 has an electrostatic probe array arranged in an "L-shaped" shape, which is used to diagnose the parameters of the plasma at different positions. The parameters include the electron density and electron temperature of the plasma. The ion energy analyzer 14 is used to diagnose the ion energy and spatial distribution of the plasma. The Langmuir probe 13 includes an array probe, a probe holder, and a stepper motor, wherein the array probe is composed of ten groups of electrostatic probe systems arranged evenly with a spacing of 2 cm. The array probe is driven by a stepper motor to drive the Langmuir probe array 13 to move radially in the large-sized vacuum chamber 11, and then combined with the radial movement, the measurement of the plasma parameter distribution of the entire low aspect ratio discharge chamber can be realized.

[0030] The electromagnetic coil system includes a compact solenoid-type controllable electromagnetic coil and a matching DC control power supply and a water cooling system, and the electromagnetic coil package covers the outside of the resonant cavity. The controllable electromagnetic coil forms a compact spiral tube through multiple sets of copper wire windings, which can generate a magnetic field that is nearly uniform in the center and divergent at the end. The maximum magnetic field in the center is 3000G. In order to achieve electron cyclotron resonance discharge, the input current of the matching control power supply is set to 55A, corresponding to the central magnetic field near the resonant cavity is about 875G, and the magnetic expansion magnetic field distribution of the magnetic spray structure is realized in the large-size cavity area on the end surface, and the controllable magnetic field gradient drives the plasma expansion acceleration.

[0031] One end of the small-sized vacuum chamber 10 is connected to the microwave ceramic window 9, and the other end is connected to the large-sized vacuum chamber 11 through a CF100 flange. The diameter ratio of the small and large vacuum chambers is greater than 50 times, and it is covered by the electromagnetic coil 7, and an aluminum cylinder 1003 is placed inside, close to the inner wall of the small-sized vacuum chamber 10. A water cooling system for the "L"-shaped resonant cavity is used to reduce the high-temperature heating of the ceramic dielectric window by the plasma, thereby reducing the risk of its rupture.

[0032] The left end of the large-sized vacuum chamber 11 is connected to the small-sized vacuum chamber 10 through a CF100 flange to form a composite vacuum chamber structure with a low aspect ratio, and the right end is encapsulated through an end face flange. The large-sized vacuum chamber 11 is connected to the vacuum pump group 12, the plasma diagnostic system, etc. through a flange. The low-aspect ratio chamber with a short length and a small diameter inside the resonant cavity, namely the small-sized vacuum chamber 10, and the magnetic expansion magnetic potential type chamber with a long length and a large diameter, namely the large-sized vacuum chamber 11, constitute a composite vacuum chamber structure with a low aspect ratio.

[0033] Figure 5 , Figure 6 This is a resonant magnetic field distribution diagram and magnetic field intensity diagram generated by the electromagnetic coil in a high-energy ion beam generator with a magnetic expansion cavity structure of the present invention. The blue line is the ECR resonance area. The DC control current corresponding to the electromagnetic coil 7 is 55A. The magnetic field at the center of the magnetic field generated is as high as 1200 Gauss, and the magnetic field near the small-sized vacuum chamber 10 is about 875 Gauss. Figure 5 , 6 It can be seen that the spatial distribution and intensity curve of the magnetic field generated by the electromagnetic coil 7 under the ECR electron cyclotron resonance discharge condition, under which the electron cyclotron resonance condition and the high-efficiency coupling of microwave energy can be achieved.

[0034] like Figure 7 As shown, the present invention uses the Langmuir probe 13 to diagnose and measure the plasma characteristic curves at different microwave powers, where (a) is the voltammetric characteristic curve and (b) is the electron density of the plasma. It can be seen that there is still a high plasma density in the expansion cavity area, indicating that the microwave conversion efficiency is relatively high, which is of great significance to the generation of high-energy ion beams.

[0035] like Figure 8 FIG. 1 is a graph showing the ion energy distribution curve diagnosed by the ion energy analyzer 14 of the present invention. It can be seen that a high energy ion beam up to 17 electron volts can still be generated at a position far from the source region.

[0036] The present invention can obtain stable electron cyclotron resonance plasma by regulating conditions such as magnetic field, gas pressure and microwave power, and can diagnose the electron density and ion energy of the generated plasma.

[0037] The above detailed description of the present invention with reference to the embodiments is illustrative rather than restrictive. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A high-energy ion beam generating device with a magnetic expansion cavity structure, characterized in that: It includes microwave generation system, microwave transmission system, magnetic field system, resonant cavity system, expansion cavity system, water cooling system and plasma diagnostic system; The microwave generating system comprises a microwave source control system and a microwave head magnetron; the microwave transmission system comprises a circulator, a water load, a three-pin adapter and a rectangular waveguide tube; the magnetic field system comprises an electromagnetic coil and a DC control power supply; the resonant cavity system comprises a microwave ceramic window and a small-sized vacuum cavity; the expansion cavity system comprises a large-sized vacuum cavity and a vacuum pump unit; the plasma diagnostic system comprises a Langmuir probe and an ion energy analyzer; wherein one end of the microwave head magnetron is connected to the microwave source control system, and the other end is connected to the circulator and the water load, the left end of the circulator is connected to the three-pin adapter, the left end of the three-pin adapter is connected to the rectangular waveguide tube, the left end of the rectangular waveguide tube is connected to the resonant cavity system, the periphery of the resonant cavity system is connected to a water cooling system, and an electromagnetic coil is placed for covering, the electromagnetic coil is connected to an adjustable DC control power supply, and is cooled by water to prevent overheating, the left end of the resonant cavity system is connected to the expansion cavity system, and the expansion cavity system is connected to the plasma diagnostic system and the vacuum pump unit.

2. A high energy ion beam generating device with a magnetic expansion cavity structure according to claim 1, characterized in that: The microwave source control system provides an external excitation source and control commands for the microwave generation system. The microwave head magnetron utilizes the movement of electrons in a constant magnetic field and electric field to interact with the high-frequency electromagnetic field, converting energy to generate microwaves. The microwave head magnetron excites and generates microwaves with a frequency of 2.45 GHz.

3. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 1, characterized in that: The microwave energy generated by the microwave head magnetron couples the energy to the plasma through the microwave transmission system. The microwave energy passes through the circulator, the water load, the three-pin adapter and the rectangular waveguide in sequence and enters the small-sized vacuum cavity through the microwave ceramic window. The circulator allows the microwave energy to be transmitted along one direction of the circulator; the water load is used to absorb the reflected power; the three-pin adapter is used to adjust the impedance of microwave energy transmission; and the rectangular waveguide is used to transmit microwave energy.

4. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 1, characterized in that: The DC control power supply is used to apply current to the electromagnetic coil to generate a stable uniform magnetic field, maintaining the uniform magnetic field of plasma discharge at a uniform magnetic field of 875G.

5. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 1, characterized in that: The microwave ceramic window is arranged at the front end of a small-sized vacuum cavity. Microwave energy first passes through the microwave ceramic window through a rectangular waveguide and enters the small-sized vacuum cavity, coupling the energy to the neutral gas. The small-sized vacuum cavity is a low-aspect ratio chamber and is a plasma excitation generation area.

6. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 5, characterized in that: The large-size vacuum chamber is a magnetic expansion magnetic position type chamber, which is a 314 stainless steel tank with a length of 1.5m and a diameter of 0.5m, and is used to assemble into a low aspect ratio discharge chamber structure for plasma discharge. It is provided with several flange openings, and the sizes of the flange openings are CF150, CF100, CF63, and CF35 respectively.

7. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 6, characterized in that: The CF150 flange port is used to install the vacuum pump group, the CF100 and CF63 flange ports are used to install the observation window or the resonant cavity system, and the CF35 flange port is used to install the gas feeding system and the plasma diagnostic system; the vacuum pump group pumps the gas pressure in the large-sized vacuum chamber to less than 1×10 -4 Pa.

8. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 1, characterized in that: The plasma diagnostic system includes a Langmuir probe and an ion energy analyzer, wherein the Langmuir probe has an electrostatic probe array arranged in an "L-shaped" shape and is used to diagnose the electron density and electron temperature of the plasma, and the ion energy analyzer is used to diagnose the ion energy and spatial distribution of the plasma.

9. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 1, characterized in that: The microwave source control system is connected to the microwave head magnetron through a power line, the microwave head magnetron is connected to the circulator through a BJ26 interface, the circulator, the water load, the three-pin dispenser, and the rectangular waveguide are all connected through the BJ26 interface, the other end of the rectangular waveguide is connected to the small-sized vacuum cavity through the BJ26 interface, the microwave ceramic window is placed at the front end of the small-sized vacuum cavity, the electromagnetic coil is connected to the DC control power supply through the power line and the electromagnetic coil is placed on the microwave ceramic window and the periphery of the small-sized vacuum cavity, the large-sized vacuum cavity is connected to the small-sized vacuum cavity through a CF100 flange, the vacuum pump group is connected to the large-sized vacuum cavity, and the Langmuir probe and the ion energy analyzer are all connected to the large-sized vacuum cavity through a CF35 flange.

10. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 8, characterized in that: The Langmuir probe includes an array probe, a probe holder, and a stepper motor, wherein the array probe is composed of ten groups of electrostatic probe systems that are evenly arranged with a spacing of 2 cm.

11. The high energy ion beam generating device with a magnetic expansion cavity structure according to claim 5, characterized in that: The microwave ceramic window includes a stainless steel support structure, a ceramic step window and a boron nitride sheet. The small-sized vacuum chamber is composed of a vacuum cavity, an aluminum tube and a water-cooling jacket. The water-cooling jacket is used to provide water cooling to the small-sized vacuum cavity to prevent the ceramic step window from breaking. The vacuum cavity forms an enclosed space in the discharge area. The boron nitride sheet is close to the aluminum tube, and the aluminum tube is arranged in the inner layer of the vacuum cavity to increase the plasma ionization degree.

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