High-voltage bushing for neutral beam negative ion source

Abstract

The invention discloses a high-voltage bushing for a neutral beam negative ion source, which belongs to the field of direct-current high-voltage power transmission and comprises a first voltage bushing component, a second voltage bushing component, two groups of ceramic insulating ring components, two groups of fiber reinforced plastic ring components, a 0 kV flange component and a shell which are coaxially mounted. The sulfur hexafluoride gas transmission line has good insulation capability, can simultaneously transmit two groups of electric energy with different voltages, is simple and flexible in structure, can freely increase the number of the sleeves to transmit the electric energy with multiple groups of voltages, solves the problem that sulfur hexafluoride gas leaks out of the transmission line, and improves the transmission efficiency. And the method can be used in a high vacuum environment or other scenes with strict requirements on sulfur hexafluoride gas leakage.

Description

Technical Field

[0001] The invention belongs to the field of direct current high voltage power transmission, and in particular relates to a high voltage bushing for a neutral beam negative ion source. Background Art

[0002] In particle accelerator systems, especially neutral beam negative ion source systems, high voltage is often used to accelerate particles, and sulfur hexafluoride transmission lines are used to supply electrical energy and other gaseous and liquid working fluids. The particle accelerator is in a vacuum environment, so it is necessary to transport high-voltage electrical energy and other working fluids from the sulfur hexafluoride insulated transmission line to the vacuum chamber. When transporting electrical energy and working fluids to the vacuum chamber, it is necessary to ensure the high-voltage insulation capacity of the sulfur hexafluoride side and the vacuum side. For a high vacuum environment, the connection between the electrode and the insulating material is required to have excellent vacuum sealing performance. There is a large pressure difference between the sulfur hexafluoride insulated transmission line and the vacuum chamber, and it is necessary to ensure that the mechanical strength of the high-voltage bushing installed between the sulfur hexafluoride insulated transmission line and the vacuum chamber can withstand it. The high-voltage bushings of the prior art are usually used in power transmission scenarios of tens of kilovolts. They have poor insulation capacity and large volume. One bushing can only transmit one set of voltage electrical energy, and the leakage rate of sulfur hexafluoride gas is not considered. It is impossible to ensure the sealing performance required for high vacuum, and it is also impossible to withstand the pressure brought by the higher-pressure sulfur hexafluoride insulating gas required for -400kV insulation. Summary of the invention

[0003] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0004] A high-voltage bushing for a neutral beam negative ion source comprises: a first voltage bushing assembly, a second voltage bushing assembly, two groups of ceramic insulating ring assemblies, two groups of fiber-reinforced plastic ring assemblies, a 0kV flange assembly, and a shell which are coaxially mounted; the main parts of the first voltage bushing assembly and the second voltage bushing assembly, the two groups of ceramic insulating ring assemblies, the two groups of fiber-reinforced plastic ring assemblies, and the 0kV flange assembly are located inside the shell, and a part of the first voltage bushing assembly and the second voltage bushing assembly extends downward to the lower side of the shell and the 0kV flange assembly; the shell is mounted on the upper side of the 0kV flange assembly, and the first group of ceramic insulating ring assemblies and the first group of fiber-reinforced plastic ring assemblies are coaxially mounted on the upper side of the 0kV flange assembly and inside the shell, and the first group of ceramic insulating ring assemblies are arranged inside the first group of fiber-reinforced plastic ring assemblies; the first group of ceramic insulating ring assemblies The second voltage bushing assembly is coaxially installed on the upper side of the ring assembly and the first group of fiber-reinforced plastic ring assemblies; the second group of ceramic insulating ring assemblies and the second group of fiber-reinforced plastic ring assemblies are coaxially installed on the upper side of the second voltage bushing assembly, and the second group of ceramic insulating ring assemblies are arranged on the inner side of the second group of fiber-reinforced plastic ring assemblies; the first voltage bushing assembly is coaxially installed on the upper side of the second group of ceramic insulating ring assemblies and the second group of fiber-reinforced plastic ring assemblies; the top of the outer shell is connected to the outer shell of the sulfur hexafluoride insulated transmission line; the first group of ceramic insulating ring assemblies and the first group of fiber-reinforced plastic ring assemblies are used for insulation between the second voltage bushing assembly and the 0kV flange assembly; the second group of ceramic insulating ring assemblies and the second group of fiber-reinforced plastic ring assemblies are used for insulation between the first voltage bushing assembly and the second voltage bushing assembly; wherein the value of the first voltage is greater than the value of the second voltage.

[0005] The present invention has the following beneficial effects:

[0006] The present invention uses a coaxial cylindrical electrode structure, and a coaxial ceramic ring and a fiber-reinforced plastic ring double-layer insulation ring are used between the electrodes. The double-layer insulation rings are filled with air with a pressure greater than that of sulfur hexafluoride gas. The present invention has good insulation ability, can simultaneously transmit two groups of electric energy with different voltages, and has a simple and flexible structure. The number of sleeve components can be freely increased to transmit multiple groups of electric energy with voltages. At the same time, it solves the problem of sulfur hexafluoride gas leaking out of the transmission line, and can be used in high vacuum environments or other scenarios with strict requirements on sulfur hexafluoride gas leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1The cross-sectional view of the high-voltage bushing for the neutral beam negative ion source of the present invention, wherein: 1-0kV flange, 6-200kV flange, 7-200kV cylindrical electrode, 8-voltage equalizing ring, 9-cooling water pipeline, 10-cylindrical electric field shield, 11-400kV flange, 12-400kV cylindrical electrode, 13-upper cover, 16-housing, 52-first ceramic insulating ring, 54-first fiber reinforced plastic ring, 62-second ceramic insulating Ring, 64-second fiber reinforced plastic ring, 114-first cathode electrical stress ring, 215-first anode electrical stress ring, 214-second cathode electrical stress ring, 315-second anode electrical stress ring, 531-first metal ring, 532-second metal ring, 551-first compression metal ring, 552-second compression metal ring, 631-third metal ring, 632-fourth metal ring, 651-third compression metal ring, 652-fourth compression metal ring;

[0008] Figure 2 A perspective view of a -200 kV bushing assembly of a high-voltage bushing for a neutral beam negative ion source of the present invention, wherein 9 is a cooling water pipeline, 171 is a first cooling water flow channel, and 172 is a second cooling water flow channel;

[0009] Figure 3 It is a cross-sectional schematic diagram of the first group of ceramic insulating ring components of the high-voltage bushing for the neutral beam negative ion source of the present invention, wherein 52 is a first ceramic insulating ring, 531 is a first metal ring, and 532 is a second metal ring. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions 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 the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0011] The following takes two groups of different voltage values, namely -400 kV (first voltage) and -200 kV (second voltage) as an example to illustrate the specific implementation of the present invention.

[0012] like Figure 1 As shown, the high voltage bushing for the neutral beam negative ion source includes: a -400kV bushing assembly, a -200kV bushing assembly, two groups of ceramic insulating ring assemblies, two groups of fiber reinforced plastic ring assemblies, a 0 kV flange assembly, and a housing 16.

[0013] All components and the housing 16 are coaxially installed. The housing 16 is installed on the upper side of the 0kV flange assembly. The installation (or connection) of the main bodies of other components are located inside the housing 16. A portion of the -400kV bushing assembly and the -200kV bushing assembly extend downward to the lower side of the housing 16 and the 0kV flange assembly.

[0014] The shell 16 is installed on the upper side of the 0kV flange assembly. The first group of ceramic insulating ring assemblies and the first group of fiber-reinforced plastic ring assemblies are coaxially installed on the upper side of the 0kV flange assembly and inside the shell 16. The first group of ceramic insulating ring assemblies are arranged on the inner side of the first group of fiber-reinforced plastic ring assemblies.

[0015] A -200kV bushing assembly is coaxially mounted on the upper side of the first ceramic insulating ring assembly and the first fiber reinforced plastic ring assembly, and a portion of the -200kV bushing assembly extends downward to the inner side of the first ceramic insulating ring assembly and the 0kV flange assembly, and axially extends out of the 0kV flange assembly.

[0016] A second group of ceramic insulating ring assemblies and a second group of fiber-reinforced plastic ring assemblies are coaxially mounted on the upper side of the -200kV bushing assembly, and the second group of ceramic insulating ring assemblies are arranged inside the second group of fiber-reinforced plastic ring assemblies.

[0017] A -400kV bushing assembly is coaxially installed on the upper side of the second group of ceramic insulating ring assemblies and the second group of fiber reinforced plastic ring assemblies, and a portion of the -400kV bushing assembly extends downward to the inner side of the second group of ceramic insulating ring assemblies, the -200kV bushing assembly, the first group of ceramic insulating ring assemblies, and the 0kV flange assembly, and axially extends out of the -200kV bushing assembly.

[0018] The -400kV bushing assembly includes an upper cover 13 , a -400kV flange 11 , a -400kV cylindrical electrode 12 , and a first cathode electrical stress ring 114 .

[0019] The -200kV bushing assembly includes a -200kV flange 6 , a -200kV cylindrical electrode 7 , a cooling water pipeline 9 , a cylindrical electric field shield 10 , a grading ring 8 , a second cathode electric stress ring 214 and a first anode electric stress ring 215 .

[0020] The ceramic insulating ring assembly includes a ceramic insulating ring and a metal ring. The first group of ceramic insulating ring assemblies includes a first ceramic insulating ring 52, a first metal ring 531 and a second metal ring 532, and the second group of ceramic insulating ring assemblies includes a second ceramic insulating ring 62, a third metal ring 631 and a fourth metal ring 632. The two groups of ceramic insulating ring assemblies have the same structure.

[0021] The fiber-reinforced plastic ring assembly includes a fiber-reinforced plastic ring and a compression metal ring. The first fiber-reinforced plastic ring assembly includes a first fiber-reinforced plastic ring 54, a first compression metal ring 551 and a second compression metal ring 552, and the second fiber-reinforced plastic ring assembly includes a second fiber-reinforced plastic ring 64, a third compression metal ring 651 and a fourth compression metal ring 652. The two groups of fiber-reinforced plastic ring assemblies have the same structure.

[0022] The 0kV flange assembly includes a 0kV flange 1 and a second anode electrical stress ring 315 .

[0023] The first group of ceramic insulating ring assemblies and the first group of fiber-reinforced plastic ring assemblies are used for insulation between -200kV bushing assemblies and 0kV flange assemblies; the second group of ceramic insulating ring assemblies and the second group of fiber-reinforced plastic ring assemblies are used for insulation between -400kV bushing assemblies and -200kV bushing assemblies.

[0024] The housing 16 is installed on the upper side of the 0kV flange assembly, and the main part of the -400kV bushing assembly, the -200kV bushing assembly, the ceramic insulating ring assembly and the fiber-reinforced plastic ring assembly are contained in the housing 16. The top of the housing 16 is connected to the housing of the sulfur hexafluoride insulated transmission line ( Figure 1 not shown).

[0025] Furthermore, in the -400kV bushing assembly, a -400kV flange 11 is installed on the lower side of the upper cover 13 , a -400kV cylindrical electrode 12 is installed inside the -400kV flange 11 , the lower end of the -400kV cylindrical electrode 12 extends out of the housing 16 , and a first cathode electrical stress ring 114 is installed on the lower side of the -400kV flange 11 .

[0026] Further, in the -200kV bushing assembly, a second cathode electric stress ring 214 is installed on the lower side of the -200kV flange 6, a first anode electric stress ring 215 is installed on the upper side of the -200kV flange 6, and a -200kV cylindrical electrode 7 is installed on the inner side of the -200kV flange 6. The -200kV cylindrical electrode 7 is sleeved on the outer side of the middle section of the -400kV cylindrical electrode 12, and its lower end extends out of the shell 16, and its lower end is a conical opening structure, and a voltage equalizing ring 8 with a diameter equal to that of the lower end of the opening is installed on the lower side of the conical opening structure, and multiple groups of cooling water pipes 9 are radially installed on the outer surface of the -200kV cylindrical electrode 7, and a cylindrical electric field shielding cover 10 is installed on the outer side of the cooling water pipe 9.

[0027] Furthermore, in the 0kV flange assembly, a second anode electrical stress ring 315 is installed on the upper side of the 0kV flange 1 .

[0028] Furthermore, in the high-voltage bushing for a neutral beam negative ion source of the present invention, the outer sides of the upper cover 13, the -400kV flange 11, the second group of fiber-reinforced plastic ring assemblies, the -200kV flange 6 and the first group of fiber-reinforced plastic ring assemblies, the inner side of the outer shell 16 and the space on the upper side of the 0kV flange 1 contain sulfur hexafluoride gas with a pressure of 0.6MPa, and the space containing sulfur hexafluoride gas is connected to the sulfur hexafluoride insulated transmission line.

[0029] Furthermore, in the high-voltage bushing for a neutral beam negative ion source of the present invention, the inner sides of the -400kV flange 11, the second set of ceramic insulating ring assemblies, the -200kV flange 6 and the first set of ceramic insulating ring assemblies, the outer sides of the -400kV cylindrical electrode 12 and the space under the 0kV flange 1 are in a vacuum environment.

[0030] Furthermore, dry air with a pressure of 1 MPa is provided between each set of ceramic insulating ring assemblies and fiber reinforced plastic ring assemblies to prevent sulfur hexafluoride gas from leaking into the vacuum environment and affecting the working performance of the vacuum unit.

[0031] Furthermore, if Figure 3 As shown, the first metal ring 531 and the second metal ring 532 are located on the upper side and the lower side of the first ceramic insulating ring 52. The upper side and the lower side of the first ceramic insulating ring 52 are brazed and fixed to the first metal ring 531 and the second metal ring 532 respectively; the third metal ring 631 and the fourth metal ring 632 are located on the upper side and the lower side of the second ceramic insulating ring 62; the upper side and the lower side of the second ceramic insulating ring 62 are brazed and fixed to the third metal ring 631 and the fourth metal ring 632 respectively. The two groups of ceramic insulating ring assemblies have the same structure. In each group of ceramic insulating ring assemblies, the upper and lower sides of the ceramic insulating ring are respectively brazed and fixed to two metal rings. The four metal rings of the two groups of ceramic insulating ring assemblies are respectively pressed and fixed to the upper side of the 0 kV flange 1, the upper side and the lower side of the -200 kV flange 6, and the lower side of the -400 kV flange 11 by screws. Rubber sealing rings are installed between the metal rings and the 0 kV flange 1, the -200 kV flange 6 and the -400 kV flange 11 for sealing between the vacuum chamber and the dry air.

[0032] Furthermore, in each group of fiber-reinforced plastic ring assemblies, the upper and lower ends of the outer side of the fiber-reinforced plastic ring are each provided with a circle of raised structure. The two groups of fiber-reinforced plastic ring assemblies use a total of four clamping metal rings to clamp the raised structure, and the two groups of fiber-reinforced plastic ring assemblies are respectively fixed between the upper side of the 0kV flange 1 and the lower side of the -200kV flange 6, and between the upper side of the -200kV flange 6 and the lower side of the -400kV flange 11 by means of screw compression. Rubber sealing rings are installed between the two fiber-reinforced plastic rings and the upper side of the 0kV flange 1, the upper side and lower side of the -200kV flange 6, and the lower side of the -400kV flange 11, for sealing between the dry air between the ceramic insulating ring assembly and the fiber-reinforced plastic ring assembly and the sulfur hexafluoride gas on the outside of the fiber-reinforced plastic ring assembly.

[0033] Furthermore, the -400kV cylindrical electrode 12 has various low-voltage cables and fluid delivery pipelines inside, and is connected to the accelerator ion source in the vacuum chamber at the bottom, and transmits electrical energy, provides cooling water and gaseous working fluids, etc. to the ion source.

[0034] Furthermore, the upper side of the upper cover 13 is connected to the -400 kV electrode ( Figure 1 Various low-voltage cables and fluid working medium conveying pipelines are arranged inside the -400 kV electrode of the sulfur hexafluoride insulated transmission line, and various low-voltage cables and fluid working medium enter the -400 kV cylindrical electrode 12 through the upper cover 13.

[0035] Furthermore, if Figure 2 As shown, a first cooling water channel 171 is provided inside the -200kV flange 6, the radial inner side of the first cooling water channel 171 inside the -200kV flange 6 is connected to the upper end of the cooling water pipeline 9, and the radial outer side of the first cooling water channel 171 inside the -200kV flange 6 is connected to the -200kV electrode ( Figure 2 ) connection.

[0036] Furthermore, the voltage-equalizing ring 8 is used to improve and reduce the electric field distribution at the lower end of the -200 kV cylindrical electrode 7, and reduce the electric field strength on the electrode surface. A second cooling water flow channel 172 is provided inside the voltage-equalizing ring 8, the upper side of the second cooling water flow channel 172 is connected to the lower end of the cooling water pipeline 9, and the lower side of the second cooling water flow channel 172 inside the voltage-equalizing ring 8 is connected to the accelerator electrode ( Figure 2 ) and provide cooling water to the accelerator electrodes.

[0037] Furthermore, the first cathode electrical stress ring 114, the second cathode electrical stress ring 214, the first anode electrical stress ring 215, and the second anode electrical stress ring 315 are used to improve and reduce the electric field strength on the surface of the ceramic insulating ring and reduce the electric field strength at the interface between vacuum, metal and ceramic insulating material.

[0038] Furthermore, annular protrusion structures are respectively provided on the lower surface of the -400kV flange 11, the upper surface and lower surface of the -200kV flange 6, and the upper surface of the 0kV flange 1, and are located between the ceramic insulating ring assembly and the fiber reinforced plastic ring assembly, for improving the electric field distribution near the first ceramic insulating ring 52, the second ceramic insulating ring 62, the first fiber reinforced plastic ring 54, and the second fiber reinforced plastic ring 64.

[0039] Furthermore, the number of groups of high-voltage bushing transmission voltages can be expanded by adding an appropriate number of bushing assemblies of other voltages with similar structures to the -200kV bushing assemblies, and adding a corresponding number of ceramic insulating ring assemblies and fiber-reinforced plastic ring assemblies. Similar structures to the -200kV bushing assemblies refer to: the flange structure of the added bushing assemblies of other voltages is the same as the structure and size of the -200kV flange 6, and the cylindrical electrode thereof is the same as the structure of the -200kV cylindrical electrode 7, but the diameter and length of the cylindrical electrode of the added bushing assemblies of other voltages are different from the diameter and length of the -200kV cylindrical electrode 7.

[0040] Preferably, the overall diameter of the high-voltage bushing can be increased, thereby increasing the insulation distance between the electrodes for use with higher voltages. The structures and connection methods of flanges, ceramic insulating ring assemblies, and fiber-reinforced plastic ring assemblies of different voltages in the bushing are the same. By adding flanges, ceramic insulating ring assemblies, fiber-reinforced plastic ring assemblies of other voltages, and cylindrical electrodes of different diameters and lengths, the number of bushing assemblies of other voltages can be conveniently expanded to increase the power transmission adapting to more groups of other voltages.

[0041] The present invention utilizes two groups of coaxial electrodes with different radii to transmit -400kV and -200kV high voltage electric energy from a transmission line to a vacuum chamber, transmits low voltage electric energy, cooling water and gaseous working medium through the internal space of the -400kV electrode, and transmits cooling water through the cooling water flow channel on the -200kV electrode.

[0042] The present invention has better insulation capability, can transmit electric energy of two sets of voltages, and has a simple and flexible structure. It can transmit electric energy of more than two sets of voltages by freely increasing the number of sleeve components. At the same time, it solves the problem of sulfur hexafluoride gas leaking out of the transmission line, and can be used in the high vacuum environment of a neutral beam negative ion source, or other scenarios with strict requirements on gas leakage.

Claims

1. A high voltage bushing for a neutral beam negative ion source, characterized in that: include: A first voltage bushing assembly, a second voltage bushing assembly, two groups of ceramic insulation ring assemblies, two groups of fiber-reinforced plastic ring assemblies, a 0kV flange assembly, and a housing (16) are coaxially mounted; the main parts of the first voltage bushing assembly and the second voltage bushing assembly, the two groups of ceramic insulation ring assemblies, the two groups of fiber-reinforced plastic ring assemblies, and the 0kV flange assembly are located inside the housing (16), and a portion of the first voltage bushing assembly and the second voltage bushing assembly extends downward to the lower side of the housing (16) and the 0kV flange assembly; the housing (16) is mounted on the upper side of the 0kV flange assembly, and the first group of ceramic insulation ring assemblies and the first group of fiber-reinforced plastic ring assemblies are coaxially mounted on the upper side of the 0kV flange assembly and inside the housing (16), and the first group of ceramic insulation ring assemblies are arranged inside the first group of fiber-reinforced plastic ring assemblies; the first group of ceramic insulation ring assemblies The second voltage bushing assembly is coaxially mounted on the upper side of the first group of fiber-reinforced plastic ring assemblies; the second group of ceramic insulation ring assemblies and the second group of fiber-reinforced plastic ring assemblies are coaxially mounted on the upper side of the second voltage bushing assembly, and the second group of ceramic insulation ring assemblies are arranged on the inner side of the second group of fiber-reinforced plastic ring assemblies; the first voltage bushing assembly is coaxially mounted on the upper side of the second group of ceramic insulation ring assemblies and the second group of fiber-reinforced plastic ring assemblies; the top of the housing (16) is connected to the housing of the sulfur hexafluoride insulated transmission line; the first group of ceramic insulation ring assemblies and the first group of fiber-reinforced plastic ring assemblies are used for insulation between the second voltage bushing assembly and the 0kV flange assembly; the second group of ceramic insulation ring assemblies and the second group of fiber-reinforced plastic ring assemblies are used for insulation between the first voltage bushing assembly and the second voltage bushing assembly; wherein the value of the first voltage is greater than the value of the second voltage.

2. A high voltage bushing for a neutral beam negative ion source according to claim 1, characterized in that: The first voltage bushing assembly comprises an upper cover (13), a first voltage flange (11), a first voltage cylindrical electrode (12), and a first cathode electrical stress ring (114); the first voltage flange (11) is installed on the lower side of the upper cover (13), the first voltage cylindrical electrode (12) is installed on the inner side of the first voltage flange (11), the lower end of the first voltage cylindrical electrode (12) extends out of the outer shell (16), and the first cathode electrical stress ring (114) is installed on the lower side of the first voltage flange (11).

3. A high voltage bushing for a neutral beam negative ion source according to claim 2, characterized in that: The second voltage bushing assembly comprises a second voltage flange (6), a second voltage cylindrical electrode (7), a cooling water pipeline (9), a cylindrical electric field shield (10), a voltage equalizing ring (8), a second cathode electric stress ring (214), and a first anode electric stress ring (215); the second cathode electric stress ring (214) is installed on the lower side of the second voltage flange (6), the first anode electric stress ring (215) is installed on the upper side of the second voltage flange (6), and the second voltage cylindrical electrode (7) is installed on the inner side of the second voltage flange (6); the second voltage cylindrical electrode (7) is sleeved on the outer side of the middle section of the first voltage cylindrical electrode (12), and its lower end extends out of the outer shell (16).

4. A high voltage bushing for a neutral beam negative ion source according to claim 3, characterized in that: The lower end of the second voltage cylindrical electrode (7) is arranged as a conical opening structure, a voltage equalizing ring (8) having a diameter equal to that of the lower end of the opening is installed on the lower side of the conical opening structure, a plurality of groups of cooling water pipes (9) are radially installed on the outer surface of the second voltage cylindrical electrode (7), and a cylindrical electric field shielding cover (10) is installed on the outer side of the cooling water pipe (9).

5. A high voltage bushing for a neutral beam negative ion source according to claim 4, characterized in that: The ceramic insulating ring assembly comprises a ceramic insulating ring and a metal ring; the first group of ceramic insulating ring assemblies comprises a first ceramic insulating ring (52), a first metal ring (531) and a second metal ring (532); the second group of ceramic insulating ring assemblies comprises a second ceramic insulating ring (62), a third metal ring (631) and a fourth metal ring (632); the first metal ring (531) and the second metal ring (532) are located on the upper side and the lower side of the first ceramic insulating ring (52); the upper side and the lower side of the first ceramic insulating ring (52) are respectively fixed to the first metal ring (531) and the second metal ring (532) by brazing; the third metal ring (631) and the fourth metal ring (632) are located on the upper side and the lower side of the second ceramic insulating ring (62); the upper side and the lower side of the second ceramic insulating ring (62) are respectively fixed to the third metal ring (631) and the fourth metal ring (632) by brazing.

6. A high voltage bushing for a neutral beam negative ion source according to claim 5, characterized in that: The first metal ring (531), the second metal ring (532), the third metal ring (631) and the fourth metal ring (632) are respectively fixed to the upper side of the 0kV flange (1), the upper side and the lower side of the second voltage flange (6), and the lower side of the first voltage flange (11) by means of screws, and rubber sealing rings are installed between the 0kV flange (1), the second voltage flange (6) and the first voltage flange (11).

7. A high voltage bushing for a neutral beam negative ion source according to claim 6, characterized in that: The fiber-reinforced plastic ring assembly comprises a fiber-reinforced plastic ring and a clamping metal ring; the first fiber-reinforced plastic ring assembly comprises a first fiber-reinforced plastic ring (54), a first clamping metal ring (551) and a second clamping metal ring (552); the second fiber-reinforced plastic ring assembly comprises a second fiber-reinforced plastic ring (64), a third clamping metal ring (651) and a fourth clamping metal ring (652); the upper and lower ends of the outer sides of the first fiber-reinforced plastic ring (54) and the second fiber-reinforced plastic ring (64) are each provided with a circle of protruding structures; the first clamping metal ring (551), the second clamping metal ring (552), the third clamping metal ring (651) and the fourth clamping metal ring (652) are used to clamp the protruding structures, and the two groups of fiber-reinforced plastic ring assemblies are respectively fixed at 0 by screw clamping. Between the upper side of the 0 kV flange (1) and the lower side of the second voltage flange (6), and between the upper side of the second voltage flange (6) and the lower side of the first voltage flange (11), two fiber reinforced plastic rings are installed with rubber sealing rings between the upper side of the 0 kV flange (1), the upper side and the lower side of the second voltage flange (6), and the lower side of the first voltage flange (11).

8. A high voltage bushing for a neutral beam negative ion source according to claim 7, characterized in that: The 0 kV flange assembly comprises a 0 kV flange (1) and a second anode electrical stress ring (315), and the second anode electrical stress ring (315) is installed on the upper side of the 0 kV flange (1).

9. A high voltage bushing for a neutral beam negative ion source according to claim 8, characterized in that: The outer sides of the upper cover (13), the first voltage flange (11), the second group of fiber-reinforced plastic ring components, the second voltage flange (6), and the first group of fiber-reinforced plastic ring components, the inner side of the housing (16), and the space on the upper side of the 0 kV flange (1) contain sulfur hexafluoride gas at a pressure of 0.6 MPa, and the space containing the sulfur hexafluoride gas is connected to the sulfur hexafluoride insulated transmission line.

10. A high voltage bushing for a neutral beam negative ion source according to claim 9, characterized in that: The first voltage flange (11), the second group of ceramic insulating ring assemblies, the second voltage flange (6) and the inner side of the first group of ceramic insulating ring assemblies, the outer side of the first voltage cylindrical electrode (12) and the space under the 0kV flange (1) are in a vacuum environment; and dry air with a pressure of (1) MPa is provided between each group of ceramic insulating ring assemblies and the fiber-reinforced plastic ring assemblies.

11. A high voltage bushing for a neutral beam negative ion source according to claim 10, characterized in that: The voltage-equalizing ring (8) is used to improve and reduce the electric field distribution at the lower end of the second voltage cylindrical electrode (7), thereby reducing the electric field intensity on the electrode surface; a second cooling water flow channel (172) is provided inside the voltage-equalizing ring (8); the upper side of the second cooling water flow channel (172) inside the voltage-equalizing ring (8) is connected to the lower end of the cooling water pipeline (9); the lower side of the second cooling water flow channel (172) inside the voltage-equalizing ring (8) is connected to the accelerator electrode in the vacuum chamber, and provides cooling water to the accelerator electrode.

12. A high voltage bushing for a neutral beam negative ion source according to claim 11, characterized in that: A first cooling water flow channel (171) is provided inside the second voltage flange (6); the radial inner side of the first cooling water flow channel (171) inside the second voltage flange (6) is connected to the upper end of the cooling water pipeline (9); and the radial outer side of the first cooling water flow channel (171) inside the second voltage flange (6) is connected to the second voltage electrode of the sulfur hexafluoride insulated transmission line.

13. A high voltage bushing for a neutral beam negative ion source according to claim 12, characterized in that: A second cooling water flow channel (172) is provided inside the pressure equalizing ring (8); the upper side of the second cooling water flow channel (172) is connected to the lower end of the cooling water pipeline (9); and the lower side of the second cooling water flow channel (172) inside the pressure equalizing ring (8) is connected to the accelerator electrode in the vacuum chamber.

14. A high voltage bushing for a neutral beam negative ion source according to claim 13, characterized in that: An annular protrusion structure is respectively provided on the lower surface of the first voltage flange (11), the upper surface and the lower surface of the second voltage flange (6), and the upper surface of the 0kV flange (1); the annular protrusion structure is located between the first group of ceramic insulating ring components and the first group of fiber reinforced plastic ring components or between the second group of ceramic insulating ring components and the second group of fiber reinforced plastic ring components, and is used to improve the electric field distribution near the first ceramic insulating ring (52), the second ceramic insulating ring (62), the first fiber reinforced plastic ring (54), and the second fiber reinforced plastic ring (64).

15. A high voltage bushing for a neutral beam negative ion source according to claim 14, characterized in that: By adding a predetermined number of bushing assemblies of other voltages having a structure similar to that of the second voltage bushing assembly, and adding a corresponding number of ceramic insulating ring assemblies and fiber-reinforced plastic ring assemblies, the number of groups of voltages transmitted by the high-voltage bushing is expanded; the bushing assemblies having a structure similar to that of the second voltage bushing assembly are as follows: the flange structure of the added bushing assemblies of other voltages is identical to that of the second voltage flange (6) and has the same size, the cylindrical electrode is identical to that of the second voltage cylindrical electrode (7), and the diameter and length of the cylindrical electrode are different from those of the second voltage cylindrical electrode (7).

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