A through-wall electrode for transferring ultra-large current in a high vacuum environment

Abstract

The present invention relates to the field of insulating vacuum technology, and in particular to a through-wall electrode for transferring ultra-large current in a high vacuum environment, comprising an electrode core and an insulating cylinder, wherein a welding flange is provided on the electrode core through vacuum brazing, the inner end of the welding flange is connected to an end insulating flange through a thread, and the outer end of the welding flange and the outer wall of the electrode core enclose an annular cavity; the inner end of the insulating cylinder is inserted into the annular cavity and is connected to the welding flange through a thread, and a first sealing ring is provided between the inner end of the insulating cylinder and the bottom of the annular cavity; a step portion is provided on the insulating cylinder, and a connecting flange is provided at the step portion, and a second sealing ring is provided between the connecting flange and the step portion of the insulating cylinder; based on the insulation performance and vacuum performance of the through-wall electrode provided by the present invention fully meet the design requirements, and on the basis of this insulating structure, a vacuum electrode with higher requirements can be designed by only adjusting the creepage distance L and the electrical gap T.

Description

Technical Field

[0001] The invention relates to the field of insulating vacuum technology, and in particular to a through-wall electrode used for switching ultra-large current in a high vacuum environment. Background Art

[0002] The vacuum electrode is a sealed device that can pass through the vacuum chamber wall and transmit various electrical power, electrical signals, motion, fluids and light beams from the atmosphere to the inside of the vacuum chamber. The pressure resistance of the vacuum electrode insulation structure (including the insulation structure and the metal electrode structure) is the first problem to be solved. The conventional technical requirements are: the overall vacuum leakage rate of the electrode is ≤1×10 -9 Pa·m 3 / s, electrode insulation performance DC 60kV, leakage current ≤20μA. If the withstand voltage performance of the insulation structure cannot be guaranteed, not only the performance parameters of the vacuum device cannot be guaranteed, but also electrical breakdown will usually occur, seriously affecting the service life and reliability.

[0003] Conventional vacuum electrodes for transmitting current include: single-needle vacuum electrodes, multi-needle vacuum electrodes and coaxial vacuum electrodes; among them, multi-needle vacuum electrodes are usually used for the transmission of electrical signals or low-power applications, and single-needle vacuum electrodes and coaxial vacuum electrodes are usually used for the transmission of large currents and high powers. Currently, the most widely used vacuum electrode for transmitting current in experimental equipment is the single-needle vacuum electrode.

[0004] Single-needle vacuum electrodes can be widely used in the transmission of high vacuum and large currents. The conventional insulation structure is a ceramic-metal sealing technology that brazes the conductive components into high-purity alumina ceramic insulation. As the current requirements in the experiment increase, the size of the ceramic components also increases accordingly, which is not conducive to the installation of compact experimental equipment. In addition, if under the action of pulse current, the vibration generated by the cable will damage the ceramic components, thereby affecting the insulation and sealing function of the vacuum electrode, so it is necessary to seek a more compact and more stable electrode structure. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a through-wall electrode for transferring ultra-large current in a high vacuum environment, which is used for transferring cables inside and outside the vacuum, conducting ultra-large current and vacuum sealing.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A through-wall electrode for transferring ultra-large current in a high vacuum environment, comprising an electrode core and an insulating tube sleeved on the electrode core, a welding flange being provided on the electrode core by vacuum brazing, an end insulating flange being connected to the inner end of the welding flange by threading, and an annular cavity being enclosed by the outer end of the welding flange and the outer wall of the electrode core;

[0008] The inner end of the insulating cylinder is inserted into the annular cavity and connected to the welding flange through threads, and a first sealing ring is provided between the inner end of the insulating cylinder and the bottom of the annular cavity;

[0009] The insulating cylinder is provided with a step portion, and a connecting flange is provided at the step portion. The connecting flange is connected to the insulating cylinder through threads, and a second sealing ring is provided between the connecting flange and the step portion of the insulating cylinder.

[0010] In a further technical solution, a wet-wrap insulation layer is provided between the end insulating flange and the connecting flange.

[0011] In a further technical solution, the threaded connection between the end insulating flange and the welding flange, the threaded connection between the welding flange and the insulating tube, and the threaded connection between the insulating tube and the connecting flange are all coated with normal temperature resin.

[0012] In a further technical solution, one end of the electrode core adjacent to the end insulating flange is connected to the cable inside the vacuum chamber, and the other end adjacent to the connecting flange is connected to the cable outside the vacuum chamber.

[0013] In a further technical solution, one end of the insulating tube away from the welding flange is connected to an insulating extension tube via threads.

[0014] Compared with the prior art, the present invention has the following technical effects:

[0015] The insulation performance and vacuum performance of the through-wall electrode provided by the present invention fully meet the design requirements. On the basis of this insulation structure, it is only necessary to adjust the creepage distance L and the electrical clearance T to design a vacuum electrode with higher requirements.

[0016] In addition, the through-wall electrode provided by the present invention can be directly used in the current transmission of vacuum test equipment. It has a wide applicable voltage range and can meet the vacuum electrode requirements of different requirements by adjusting parameters, providing a reliable data basis for subsequent vacuum magnet design and cable transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a through-wall electrode for transferring ultra-large current in a high vacuum environment provided according to a specific embodiment of the present invention;

[0018] Explanation of the numbers in the figure: 01, electrode core; 02, end insulating flange; 03, first sealing ring; 04, welding flange; 05, wet-wrap insulating layer; 06, insulating tube; 07, connecting flange; 08, second sealing ring; 09, insulating extension tube. DETAILED DESCRIPTION

[0019] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific drawings.

[0020] It should be noted that, in the present invention, when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0022] In the present invention, for the convenience of description, the end close to the inside of the vacuum chamber is defined as the inner end, and the end close to the outside of the vacuum chamber is defined as the outer end.

[0023] As mentioned above, combined with Figure 1 As shown, the present invention provides a through-wall electrode for transferring ultra-large current in a high vacuum environment, the through-wall electrode comprising an electrode core 01 and an insulating tube 06 sleeved on the electrode core 01, a welding flange 04 is provided on the electrode core 01 by vacuum brazing, the inner end of the welding flange 04 is connected to an end insulating flange 02 by threads, the outer end of the welding flange 04 and the outer wall of the electrode core 01 enclose an annular cavity, the inner end of the insulating tube 06 is inserted into the annular cavity and connected to the welding flange 04 by threads, and a first sealing ring 03 is provided between the inner end of the insulating tube 06 and the bottom of the annular cavity; a step portion is provided on the insulating tube 06, and a connecting flange 07 is provided at the step portion, the connecting flange 07 is connected to the insulating tube 06 by threads, and a second sealing ring 08 is provided between the connecting flange 07 and the step portion of the insulating tube 06.

[0024] A wet-wrap insulation layer 05 is provided between the end insulation flange 02 and the connection flange 07;

[0025] The threaded connection between the end insulating flange 02 and the welding flange 04 , the threaded connection between the welding flange 04 and the insulating tube 06 , and the threaded connection between the insulating tube 06 and the connecting flange 07 are all coated with normal temperature resin.

[0026] The electrode core 01 has one end adjacent to the end insulating flange 02 connected to the cable outside the vacuum chamber, and one end adjacent to the connecting flange 07 connected to the cable outside the vacuum chamber.

[0027] One end of the insulating tube 06 away from the welding flange 04 is connected to an insulating extension tube 09 via threads.

[0028] In the present invention, the insulation design mainly considers two basic parameters, creepage distance L and electrical clearance T. L is the distance from point a to point b in vacuum, and L is the distance from point c to point d outside vacuum. T is the distance between the electrode core surface and the outer wall of the insulating cylinder, T=T1+T2;

[0029] Uo≤k×L;

[0030] Uo≤s1×T1+s2×T2;

[0031] Among them, Uo-electrode theoretical withstand voltage, kV; L-creepage distance, mm; T-electrical clearance, mm; T1-air clearance, mm; T2-insulation tube thickness, mm; s1-air breakdown coefficient, 10kV / mm in non-vacuum environment; s2-G10 epoxy board breakdown coefficient, 1kV / mm in non-vacuum environment and pollution level I; k-creepage coefficient, 0.5kv / mm in vacuum environment, 0.3kV / mm in non-vacuum environment and pollution level I.

[0032] The distance from c to d outside the vacuum can be much larger than the distance from a to b inside the vacuum, so the creepage distance inside the vacuum should be ensured during design. Since s1 is larger than other coefficients, the electrical clearance is better selected. Taking the vacuum electrode withstand voltage of 60kV as an example, T1 is calculated to be 6mm, T2 is calculated to be 5mm, and L is calculated to be 160mm.

[0033] In the present invention, the vacuum leakage rate is mainly ensured by the first sealing ring 03 and the second sealing ring 08. Preferably, the first sealing ring 03 and the second sealing ring 08 are selected from unite seals sealing rings, and the measured vacuum leakage rate can reach 1.9×10 - 11 Pa·m 3 / s.

[0034] The manufacturing process of the through-wall electrode for transferring ultra-large current in a high vacuum environment provided by the present invention is as follows:

[0035] Electrode core 01 is brazed and sealed with welding flange 04, and helium mass spectrometer is used for leak detection, with a leak rate of ≤1×10 -9 Pa·m 3 / s;

[0036] Apply room temperature resin to the threaded joints of the end insulating flange 02, insulating tube 06, and connecting flange 07; select SWR400-100 glass fiber to form a wet-wrap insulating layer 05, and then perform helium mass spectrometry leak detection after curing. The leak rate is required to be ≤1×10 -9 Pa·m 3 / s; After connecting the insulating extension tube 09, the vacuum electrode is tested at a voltage of DC60kV, and the leakage current is required to be ≤20μA.

[0037] Voltage measurement data: Under DC-60kV high voltage, the maximum leakage current of vacuum electrode to ground insulation is 8μA, and the overall sealing leakage rate can reach as low as 2.2×10 -11 Pa·m 3 / s.

[0038] Conclusion: The insulation performance and vacuum performance of the vacuum electrode with this structure fully meet the design requirements. Based on this insulation structure, it is only necessary to adjust the creepage distance L and the electrical clearance T to design a vacuum electrode with higher requirements.

[0039] The above shows and describes the basic principles, main features and characteristics of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the attached claims and their equivalents.

Claims

1. A through-wall electrode for transferring ultra-large current in a high vacuum environment, characterized in that: It comprises an electrode core (01) and an insulating tube (06) sleeved on the electrode core (01), wherein a welding flange (04) is provided on the electrode core (01) by vacuum brazing, the inner end of the welding flange (04) is connected to an end insulating flange (02) by threading, and the outer end of the welding flange (04) and the outer wall of the electrode core (01) enclose an annular cavity; The inner end of the insulating cylinder (06) is inserted into the annular cavity and is connected to the welding flange (04) by means of threads, and a first sealing ring (03) is provided between the inner end of the insulating cylinder (06) and the bottom of the annular cavity; The insulating cylinder (06) is provided with a step portion, and a connecting flange (07) is provided at the step portion, the connecting flange (07) and the insulating cylinder (06) are connected to each other via threads, and a second sealing ring (08) is provided between the connecting flange (07) and the step portion of the insulating cylinder (06); One end of the electrode core (01) adjacent to the end insulating flange (02) is connected to the cable inside the vacuum chamber, and the other end adjacent to the connecting flange (07) is connected to the cable outside the vacuum chamber; One end of the insulating tube (06) away from the welding flange (04) is connected to an insulating extension tube (09) via a thread; The theoretical withstand voltage of the electrode must meet the following conditions: Uo≤k×L; Uo≤s1×T1+s2×T2; Where L is the creepage distance, T is the electrical clearance, In vacuum, L is the distance from point a to point b, and outside vacuum, L is the distance from point c to point d. T is the distance between the electrode core surface and the outer wall of the insulating cylinder, T=T1+T2; Uo-theoretical withstand voltage of electrode, kV; L-creepage distance, mm; T-electrical clearance, mm; T1-air clearance, mm; T2-insulation tube thickness, mm; s1-air breakdown coefficient, 10kV / mm in non-vacuum environment; s2-G10 epoxy board breakdown coefficient, 1kV / mm in non-vacuum environment and pollution level I; k-creepage coefficient, 0.5kv / mm in vacuum environment, 0.3kV / mm in non-vacuum environment and pollution level I; When L outside vacuum takes the distance from c to d, it is greater than L inside vacuum takes the distance from point a to point b. When the vacuum electrode withstand voltage is 60kV, T1 takes 6mm, T2 takes 5mm, and L takes 160mm. The first sealing ring 03 and the second sealing ring 08 are made of unite seals, and the measured vacuum leakage rate is 1.9×10 -11 Pa·m 3 / s; A wet-wrap insulation layer (05) is provided between the end insulation flange (02) and the connection flange (07); The threaded connection between the end insulating flange (02) and the welding flange (04), the threaded connection between the welding flange (04) and the insulating tube (06), and the threaded connection between the insulating tube (06) and the connecting flange (07) are all coated with room temperature resin.

Images