Ground protection structure of ion source test platform

Abstract

The application relates to the field of nuclear experiment devices, in particular to a grounding protection structure of an ion source test platform, which comprises an insulating plate, an insulating fastening assembly, an ion source grounding wire and a vacuum chamber grounding wire, the insulating plate is clamped between a ground electrode flange of the ion source and a vacuum chamber flange of the vacuum chamber, the ion source grounding wire is connected between the ground electrode flange and a main grounding row, and the vacuum chamber grounding wire is connected between the vacuum chamber and the main grounding row; the application sets the insulating isolation with vacuum sealing between the ground electrode flange of the ion source and the vacuum chamber flange, sets independent grounding loops for the ion source and the vacuum chamber respectively, makes the breakdown current discharge through the special path, and maintains the safe low potential of the vacuum chamber.

Description

Technical Field

[0001] This invention relates to the field of nuclear experimental apparatus, and more specifically to a grounding protection structure for an ion source testing platform. Background Technology

[0002] In the development of the neutral beam injection (NBI) heating system for magnetic confinement nuclear fusion devices, the ion source needs to undergo high-voltage commissioning on the test platform before formal installation, with its accelerating voltage typically reaching hundreds of kilovolts. Existing test platforms generally adopt a single-point common grounding method: the ground electrode flange of the ion source is directly bolted to the flange surface of the vacuum chamber of the test platform, and the two are electrically connected through the metal contact surface of the flange and share the same physical grounding busbar.

[0003] During high-voltage commissioning, breakdown and arcing inside the ion source are difficult to completely avoid. When a breakdown occurs, a huge transient discharge current is generated in the circuit in a very short time. When this current flows through the common grounding circuit, a very high electromotive force is induced in the parasitic inductance of the circuit, causing a momentary rise in the local ground potential.

[0004] Because the vacuum chamber and ion source share a common ground, the potential of the vacuum chamber shell is raised, while the power supply terminals of the residual gas analyzer, vacuum gauge, and pumping system installed in the vacuum chamber remain at true zero potential. The potential difference between the two is sufficient to break down the internal circuitry of these precision instruments, resulting in anything from malfunctioning measurements to burn-out components. Replacing the equipment and restoring vacuum conditions often requires interruption and adjustments.

[0005] Several mitigation methods have been attempted in engineering to address the above problems, but none have addressed the root cause of common impedance coupling. One approach is to thicken the grounding conductor and reduce the power frequency grounding resistance of the grounding grid. However, arcing and discharge are transient processes on the order of microseconds, and the parasitic inductance of the circuit, rather than the DC resistance, plays a decisive role. No matter how low the grounding resistance is reduced, the electromotive force induced by the transient current in the common circuit inductance still exists, and the ground potential rise is not eliminated. Another approach is to install isolation power supplies, isolation transmitters, or surge suppression devices at the power supply and signal terminals of each diagnostic instrument. These measures are end-point protection: with a large number of instruments and diverse interface types, installing them on each instrument is costly and difficult to cover all ports. The response time and residual voltage level of surge devices are also difficult to match the extremely steep rise time of high-voltage breakdown. Another approach relies on the fault interlock of the high-voltage power supply to quickly cut off the output after arcing is detected. However, the interlock action occurs after the breakdown, and the initial impact has already occurred, making damage to the instrument unavoidable. These methods are either superficial or too costly; what the testing platform needs is a structural solution that addresses the discharge current path itself. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides a grounding protection structure for an ion source testing platform, which can block the transmission path of ground potential rise under high voltage breakdown conditions without damaging the vacuum conditions of the testing platform.

[0007] This invention is achieved through the following technical solution:

[0008] A grounding protection structure for an ion source testing platform, the testing platform including an ion source and a vacuum chamber, the grounding protection structure including an insulating plate, an insulating fastening assembly, an ion source grounding wire, and a vacuum chamber grounding wire;

[0009] The insulating plate is sandwiched between the ground electrode flange of the ion source and the vacuum chamber flange of the vacuum chamber, and the insulating plate is sealed between itself and the ground electrode flange, and between itself and the vacuum chamber flange.

[0010] The insulating fastening assembly passes through the ground electrode flange, the insulating plate, and the vacuum chamber flange, fastening the ground electrode flange, the insulating plate, and the vacuum chamber flange together, while maintaining electrical isolation between the ground electrode flange and the vacuum chamber flange;

[0011] The ion source grounding wire is connected between the ground electrode flange and the main grounding busbar, and the vacuum chamber grounding wire is connected between the vacuum chamber and the main grounding busbar.

[0012] Optionally, the insulating fastening assembly includes a fastening bolt and an insulating sleeve. The fastening bolt passes through the ground electrode flange, the insulating plate, and the vacuum chamber flange. The insulating sleeve is fitted over the fastening bolt to electrically isolate the fastening bolt from the ground electrode flange and the vacuum chamber flange.

[0013] Optionally, an annular sealing groove is provided on both the end face of the insulating plate facing the ground electrode flange and the end face facing the vacuum chamber flange, and a sealing ring is embedded in the annular sealing groove.

[0014] Optionally, the sealing ring is a fluororubber O-ring.

[0015] Furthermore, it also includes an overvoltage protection module, which is connected in parallel between the ground electrode flange and the vacuum chamber flange;

[0016] The overvoltage protection module is normally in an open circuit state, and conducts current discharge when the voltage at both ends exceeds the action threshold.

[0017] Optionally, the overvoltage protection module is a high-voltage discharge gap, a gas discharge tube, or a surge arrester.

[0018] Optionally, the insulating board is made of polyetheretherketone, alumina ceramic, or epoxy resin, and the insulating sleeve is made of polyetheretherketone, polytetrafluoroethylene, alumina ceramic, or epoxy resin.

[0019] Optionally, the rated insulation withstand voltage of both the insulating plate and the insulating fastening assembly is greater than 1.2 times the maximum accelerating voltage of the ion source.

[0020] Optionally, both the ion source grounding wire and the vacuum chamber grounding wire are multi-strand copper core braided tapes.

[0021] Optionally, the test platform is a neutral beam injector ion source test platform, and the vacuum chamber is equipped with a residual gas analyzer, a vacuum gauge, and a pumping system.

[0022] This invention provides a vacuum-sealed insulating barrier between the ground electrode flange of the ion source and the vacuum chamber flange, and provides independent grounding circuits for the ion source and the vacuum chamber respectively, so that the breakdown current is discharged through a dedicated path and the vacuum chamber maintains a safe low potential.

[0023] Compared with existing technologies, the insulating plate is sandwiched between the ground electrode flange and the vacuum chamber flange. The insulating fastening assembly maintains electrical isolation between the two flanges while fastening them, cutting off the common impedance coupling path between the ion source and the vacuum chamber. The ignition current no longer flows through the vacuum chamber shell, and the vacuum chamber potential does not rise with the breakdown event, reducing the risk of residual gas analyzers, vacuum gauges and other instruments being broken down due to potential differences. Attached Figure Description

[0024] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0025] Figure 1 This is a schematic diagram of the overall structure of the grounding protection structure of the ion source testing platform provided in an embodiment of the present invention.

[0026] Figure reference numerals: 1-Ion source; 2-Vacuum chamber; 3-Ground electrode flange; 4-Vacuum chamber flange; 5-Insulating plate; 6-Sealing ring; 7-Insulating fastening assembly; 71-Fastening bolt; 72-Insulating sleeve; 8-Overvoltage protection module; 9-Ion source grounding wire; 10-Vacuum chamber grounding wire; 11-Main grounding busbar; 12-Residual gas analyzer; 13-Vacuum gauge tube; 14-Pumping system. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0029] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment provides a grounding protection structure for an ion source 1 test platform. The test platform includes an ion source 1 and a vacuum chamber 2, with the ground electrode flange 3 of the ion source 1 and the vacuum chamber flange 4 of the vacuum chamber 2 arranged opposite to each other.

[0032] The grounding protection structure includes an insulating plate 5, an insulating fastening assembly 7, an ion source grounding wire 9, and a vacuum chamber grounding wire 10.

[0033] The insulating plate 5 is sandwiched between the ground electrode flange 3 and the vacuum chamber flange 4. The insulating plate 5 is sealed between the ground electrode flange 3 and the vacuum chamber flange 4, so that the ion source 1 and the vacuum chamber 2 are kept in vacuum communication without metal contact.

[0034] The insulating fastening assembly 7 passes through the ground electrode flange 3 and the vacuum chamber flange 4, pressing the ground electrode flange 3, the insulating plate 5 and the vacuum chamber flange 4 together as one unit, and does not form a conductive path between the ground electrode flange 3 and the vacuum chamber flange 4, so that the two flanges are electrically isolated.

[0035] One end of the ion source grounding wire 9 is connected to the ground electrode flange 3, and the other end is connected to the main grounding busbar 11; one end of the vacuum chamber grounding wire 10 is connected to the shell of the vacuum chamber 2, and the other end is independently connected to the main grounding busbar 11. The two grounding wires do not share conductors and only converge at the same grounding point at the main grounding busbar 11, forming a star-type single-point grounding.

[0036] The insulating plate 5 performs two functions: firstly, it acts as an electrical isolation barrier, establishing a high-voltage-resistant insulating gap between the ground electrode flange 3 and the vacuum chamber flange 4; secondly, it serves as a component of the vacuum boundary, working with the sealing structures on both sides to maintain the airtightness of the cavity. The insulating fastening assembly 7 resolves the contradiction of "needing to tighten without conducting"—the flange seal requires sufficient axial tightening force, while conventional metal bolts, if simultaneously contacting both flanges, will short-circuit the insulating plate 5. Therefore, both tightening and insulation must be achieved in the same assembly.

[0037] The ion source ground wire 9 is the designed discharge path for breakdown current, and its impedance and parasitic inductance directly determine the potential rise amplitude on the ion source side during the discharge process, so a short, straight, thick low-impedance wiring is adopted; the vacuum chamber ground wire 10 only undertakes static grounding and shielding current discharge of the vacuum chamber 2, and no large current passes through it under both normal and fault working conditions. The main ground busbar 11 is the only common point of the two grounding loops, and the star topology ensures that the current of any loop will not generate a voltage drop on the conductor of the other loop.

[0038] During breakdown arcing, the rise time of the discharge current is on the microsecond scale or even shorter, with an extremely high current change rate; the grounding conductor inevitably has a parasitic inductance on the microhenry scale, and the induced electromotive force is proportional to the current change rate and the loop inductance. Even if the DC resistance of the conductor is nearly zero, the transient voltage drop can still reach the kilovolt scale. In the single-point common grounding structure, this voltage drop is directly superimposed on the vacuum chamber shell; in the present invention, the discharge loop and the vacuum chamber grounding loop are physically separated, the induced voltage drop is limited to the ion source side, and the potential reference of the vacuum chamber 2 is not affected.

[0039] During normal commissioning, the insulating plate 5 withstands the potential difference that may occur between the ground electrode flange 3 and the vacuum chamber flange 4, and the vacuum chamber 2 is maintained at zero potential via the vacuum chamber ground wire 10.

[0040] When high-voltage breakdown arcing occurs in the ion source 1, the transient discharge current is blocked on the ion source 1 side by the insulating plate 5 and the insulating fastening assembly 7, and can only be discharged directly to the main ground busbar 11 via the ion source ground wire 9; the electromotive force induced by the discharge current on the parasitic inductance of the ion source ground wire 9 only raises the potential on the ion source 1 side, the vacuum chamber 2 is not in this discharge loop, and its shell potential is basically not disturbed. No large potential difference occurs between the weak-current equipment installed on the vacuum chamber 2 and the vacuum chamber 2, so as to avoid breakdown damage.

[0041] The assembly of the structure of this embodiment is carried out in the following sequence: after the lower seal is installed on the side of the insulating plate 5 facing the vacuum chamber flange 4, the insulating plate 5 is placed on the vacuum chamber flange 4 in alignment; the upper seal is installed, and the ion source 1 is hoisted to make the ground electrode flange 3 and the insulating plate 5 centered and fitted; the insulating fastening assembly 7 is inserted, and pre-tightening force is applied uniformly in multiple times in a diagonal sequence to avoid inclination or stress concentration of the insulating plate 5 caused by unilateral compression. Two acceptance tests are carried out after the assembly is completed: the first is insulation acceptance, in which an insulation resistance tester is used to measure the insulation resistance between the ground electrode flange 3 and the vacuum chamber flange 4, and a withstand voltage test is carried out according to the designed withstand voltage value, which is qualified if there is no flashover or breakdown during the pressure holding period; the second is vacuum acceptance, in which leak detection is performed on the flange joint part, and the test platform can be put into commissioning only after the leak rate meets the background vacuum index of the test platform. After both tests are passed, the connecting terminals at both ends of the ion source ground wire 9 and the vacuum chamber ground wire 10 are respectively fastened, and it is confirmed that the contact resistance of the grounding connection meets the requirements.

[0042] Example 2

[0043] This embodiment, based on Embodiment 1, further illustrates the specific implementation of the insulating plate 5 and the insulating fastening assembly 7.

[0044] The insulating fastening assembly 7 includes a fastening bolt 71 and an insulating sleeve 72. The fastening bolt 71 passes through the bolt holes of the ground electrode flange 3 and the vacuum chamber flange 4. The insulating sleeve 72 is fitted over the fastening bolt 71, separating the shank of the fastening bolt 71 from the hole walls of the two flanges, so that the fastening bolt 71 does not form a conductive channel for bridging the insulating plate 5. The specification of the fastening bolt 71 can be selected from M8 to M20 according to the flange size; the insulating sleeve 72 can be made of polytetrafluoroethylene. In other embodiments, the insulating fastening assembly 7 can also be a fastener made entirely of insulating material, such as a glass fiber reinforced epoxy resin bolt, in which case the insulating sleeve 72 is not required.

[0045] The insulating plate 5 is made of polyetheretherketone (PEEK), alumina ceramic, or epoxy resin; the insulating sleeve 72 is made of PEEK, polytetrafluoroethylene (PTFE), alumina ceramic, or epoxy resin. PEEK combines high dielectric strength, mechanical strength, and vacuum compatibility with low outgassing rate, making it suitable as a load-bearing insulating component at vacuum boundaries. The thickness of the insulating plate 5 can be selected from 5mm to 30mm; if the thickness is too small, the pressure tolerance margin will be insufficient, while if it is too large, it will increase the flange spacing and affect the transmission of sealing clamping force.

[0046] To ensure that the insulation structure itself is not broken down under breakdown conditions, the rated insulation withstand voltage of the insulation plate 5 and the insulation fastening assembly 7 are both greater than 1.2 times the maximum accelerating voltage of the ion source 1.

[0047] In addition to the insulating sleeve 72, insulating washers are also provided between both ends of the fastening bolt 71 and the bearing surface of the flange. The insulating washers cover the bolt head and the bearing surface of the nut, and are connected to the insulating sleeve 72, so that the fastening bolt 71 does not come into contact with any metal surface of the flange from the head, shank to the nut. The insulating washers can be made of the same material as the insulating sleeve 72, and their outer diameter is larger than the diagonal dimension of the bolt head to ensure the creepage distance.

[0048] The structural dimensions of the insulating sleeve 72 are determined according to the following principles: the sleeve length is not less than the total depth of the bolt holes after the ground electrode flange 3, the insulating plate 5, and the vacuum chamber flange 4 are stacked, ensuring that the shank of the fastening bolt 71 will not directly contact the metal hole wall at any position within the hole; a clearance fit is made between the outer diameter of the sleeve and the flange bolt hole to facilitate insertion during assembly, and a small gap is left between the inner diameter and the bolt shank to limit the radial movement of the bolt; the wall thickness is made as large as possible while meeting the hole diameter space, so that the radial pressure resistance of the sleeve itself is not lower than the overall pressure resistance level of the insulating plate 5. A flange structure can be machined at one end of the sleeve, which is pressed between the insulating gasket and the flange bearing surface, playing an axial positioning role during assembly and preventing the sleeve from slipping along the hole axially under vibration conditions. Before assembly, each sleeve is inspected for cracks and scratches. The PTFE sleeve is relatively soft, and care should be taken to avoid scratching it by the threads during installation, which would reduce the local insulation strength.

[0049] Determining the preload requires considering both ends: insufficient preload will result in inadequate compression of the sealing ring, leading to vacuum seal failure; excessive preload will cause the surface pressure on the insulation plate 5 to exceed the material's allowable value, and long-term creep will lead to attenuation of the clamping force or even cracking of the plate. In engineering practice, the bolt preload is calculated by back-calculating the linear load required for the selected sealing ring to achieve the target compression rate, and then the stress on the bearing surface of the insulation plate 5 is checked. During construction, a torque wrench is used to tighten the bolts in stages according to the calculated torque.

[0050] Polyetheretherketone (PEEK) offers well-balanced overall performance, with high dielectric strength, good creep resistance, and excellent machinability, making it suitable for most applications. Alumina ceramics offer higher pressure and temperature resistance but are more brittle, making them suitable for applications with smaller flange sizes and no impact loads. Epoxy resin (including glass fiber reinforced varieties) is low-cost and easy to cast into large-size plates, making it suitable for platforms with large flange diameters but limited budgets. Regardless of the material chosen, the flatness and surface roughness of both ends of the insulation plate 5 must be processed according to vacuum sealing surface standards to avoid local sealing failure or localized field concentration caused by surface shape errors.

[0051] In addition, annular sealing grooves are provided circumferentially on both the end face of the insulating plate 5 facing the ground electrode flange 3 and the end face facing the vacuum chamber flange 4, and sealing rings 6 are embedded in the annular sealing grooves.

[0052] After the insulating fastening assembly 7 is tightened, the sealing rings 6 on both sides form annular sealing surfaces between the insulating plate 5 and the ground electrode flange 3, and between the insulating plate 5 and the vacuum chamber flange 4, respectively. The vacuum boundary is continuously transitioned through the ground electrode flange 3, sealing ring 6, insulating plate 5, sealing ring 6, and vacuum chamber flange 4, so that the ultra-high vacuum degree of the test platform is not damaged by inserting the insulating plate 5.

[0053] The sealing ring 6 is a fluororubber O-ring, whose temperature resistance and low outgassing rate meet the requirements of ultra-high vacuum systems. In other embodiments, the sealing ring 6 can also be made of a low-outgassing-rate elastic sealing material such as perfluoroether rubber. The cross-sectional dimensions of the annular sealing groove are designed according to the selected O-ring wire diameter, so that the compression rate of the O-ring after assembly is between 15% and 30%, balancing the sealing specific pressure and the life of the sealing ring 6.

[0054] The annular sealing groove is formed on the insulating plate 5 rather than on the flange surface. The ground electrode flange 3 and the vacuum chamber flange 4 are existing components. Re-grooving their sealing surfaces would require the entire ion source or vacuum chamber to be removed from the production line for processing, which is costly. However, the insulating plate 5 itself is a newly added custom component, and the grooving process can be completed simultaneously with the plate processing, requiring zero modification to the existing equipment. The bottom of the sealing grooves on both sides has sufficient remaining wall thickness to ensure that the insulation strength of the grooved area does not become a weakness in the overall pressure resistance of the plate.

[0055] After the vacuum system 14 evacuates the vacuum chamber 2 to the leak detection baseline, helium gas is slowly sprayed through the two rings of joint between the insulating plate 5 and the ground electrode flange 3, and between the insulating plate 5 and the vacuum chamber flange 4, using a spray gun. The leak detector reading is then observed for any response. The two rings of sealing joint should be sprayed segment by segment to pinpoint the specific location in case of a leak. If the joint is obstructed by the external structure and spraying is inconvenient, a partial covering method can be used, covering the entire flange joint area and filling it with helium for overall leak detection. The leak detection pass criterion is determined by converting the baseline vacuum index of the test platform. For any area where the response exceeds the standard, the corresponding insulating fastening component 7 is loosened to check for twisting, slag inclusions, or indentation defects in the sealing ring 6. After treatment, the ring is tightened again and retested.

[0056] Failure modes of the sealing surface also include aging and permanent deformation of the sealing ring. Fluororubber will undergo certain permanent compression deformation under long-term compression, leading to a gradual decrease in the sealing specific pressure. Therefore, the condition of the sealing ring should be checked during the annual maintenance of the testing platform, and those with obvious indentation hardening should be replaced. For platforms with higher vacuum requirements or those requiring baking and degassing, in other embodiments, the single seal can be replaced with an inner and outer double annular sealing groove, with a pre-reserved evacuation detection channel between the two sealing rings. By monitoring the inter-channel pressure, the leakage status of the inner seal can be determined online, further reducing the risk on the vacuum side.

[0057] Example 3

[0058] This embodiment further illustrates the configuration of the overvoltage protection module 8 based on Embodiment 1.

[0059] The grounding protection structure also includes an overvoltage protection module 8, which is connected in parallel between the ground electrode flange 3 and the vacuum chamber flange 4.

[0060] The overvoltage protection module 8 is normally in an open circuit state and does not affect the electrical isolation established by the insulation board 5; when the voltage at its two ends exceeds the action threshold, it conducts to discharge the abnormal overvoltage on the ground electrode flange 3 to the side of the vacuum chamber flange 4 and into the ground through the vacuum chamber grounding wire 10.

[0061] The overvoltage protection module 8 is a high-voltage discharge gap, gas discharge tube, or surge arrester. Its operating threshold is set according to the principle of being higher than the induced voltage that may occur between the two flanges during normal commissioning, but lower than the potential difference that the weak electrical equipment on vacuum chamber 2 can withstand. The operating threshold voltage can be set within the range of 500V to 1000V.

[0062] The overvoltage protection module 8 is a redundant protection for abnormal operating conditions: if the ion source grounding wire 9 is accidentally disconnected due to vibration, maintenance or other reasons, the ion source 1 loses its grounding discharge path and its shell is at risk of being suspended and charged; if a breakdown occurs at this time, the overvoltage protection module 8 will immediately conduct and use the vacuum chamber grounding wire 10 to complete the discharge, so as to prevent the flange on the ion source 1 side from being suspended at a high potential for a long time.

[0063] The installation location and wiring method of the overvoltage protection module 8 significantly affect its protection effect. The leads at both ends of the module should be as short as possible and avoid coiling. They should be connected to the dedicated terminals of the ground electrode flange 3 and the vacuum chamber flange 4, respectively, as close as possible. Excessively long leads will introduce additional inductance, causing the residual voltage to rise at the moment the module is turned on, thus weakening the protection effect. The module body should be installed on the outside of the flange in a location that is easy to observe and replace, without intersecting the vacuum boundary, so that its maintenance does not affect the cavity seal.

[0064] The selection of the three types of devices has different focuses: high-voltage discharge gaps have a simple structure, strong current carrying capacity, and adjustable electrode spacing, making them suitable for applications where the action threshold needs to be set on-site, but their action dispersion is relatively large; gas discharge tubes have good action voltage consistency and small size, making them suitable for batch deployment with fixed thresholds; surge arresters (such as metal oxide varistor types) have fast response and smooth residual voltage characteristics, but their aging margin under repeated impacts needs to be calculated. Regardless of which type is selected, its static insulation status should be checked regularly—the module must remain open-circuited under normal conditions. If leakage current occurs due to deterioration from repeated actions, a bypass will form between the two flanges, weakening the isolation established by the insulation board 5, and it should be replaced in time.

[0065] Example 4

[0066] This embodiment provides a specific application example of the above-mentioned grounding protection structure on the test platform of neutral beam injector ion source 1.

[0067] The test platform is a megawatt-level neutral beam injector ion source 1 test platform. The maximum test acceleration voltage of ion source 1 is in the range of 50kV to 120kV. The vacuum chamber 2 is equipped with a residual gas analyzer 12, a vacuum gauge tube 13, and a pumping system 14. The ion source grounding wire 9 and the vacuum chamber grounding wire 10 are both multi-strand copper core braided tapes with a cross-sectional area of ​​not less than 50mm² to reduce the impedance and parasitic inductance of the discharge circuit.

[0068] During the high-voltage commissioning of the ion source 1 in the HL-3 tokamak NBI system, the target parameters were 120kV / 40A. A 10mm thick polyetheretherketone (PEEK) insulating plate 5 was custom-made to fit the dimensions of the ground electrode flange 3. Annular sealing grooves were machined on both sides to match the selected O-ring wire diameter. After inserting the fluororubber O-ring 6, it was placed between the ground electrode flange 3 and the vacuum chamber flange 4, and tightened with M12 bolts 71 through a PTFE insulating sleeve 72.

[0069] A multi-strand copper core braided tape with a cross-sectional area of ​​not less than 50 mm² is connected at one end to the ground electrode flange 3 and at the other end directly to the laboratory main grounding bar 11. The vacuum chamber 2 is connected to the same main grounding bar 11 by another independent braided tape.

[0070] Under this structure, even if a high-voltage spark occurs during a 120kV discharge experiment, the potential fluctuation of the vacuum chamber 2 is still limited to a safe range, and the residual gas analyzer 12 and the molecular pump of the pumping system 14 both maintain stable operation.

[0071] After the structural assembly passed insulation and leak detection acceptance, a aging discharge was first performed at a low voltage level to observe the frequency of sparking and the recovery of vacuum. Then, the acceleration voltage was gradually increased in steps according to the set increments. Each level was operated stably, and the readings of the residual gas analyzer 12 and vacuum gauge 13 were confirmed to be normal before proceeding to the next level, until the target voltage of 120kV was reached. During commissioning, a high-voltage differential probe was used to monitor the potential waveform of the vacuum chamber 2 shell relative to the main grounding busbar 11, serving as a direct criterion for the isolation effect. When a sparking event occurred, the shell potential waveform showed only a very small disturbance, contrasting sharply with the dramatic rise under the single-point common ground structure before the modification.

[0072] Throughout the entire pressurization and commissioning process, the residual gas analyzer 12 continuously acquired spectra without interruption, the vacuum gauge 13 reading did not show any jumps or resets, and the molecular pump speed and drive current of the pumping system 14 remained stable, verifying the protective effect of the grounding protection structure on various weak electrical equipment on the vacuum chamber 2.

[0073] Regularly check the tightness and contact resistance of the terminals at both ends of the ion source grounding wire 9 and the vacuum chamber grounding wire 10 to prevent potential hazards caused by loosening due to vibration; check the cleanliness of the exposed creepage surface of the insulation board 5, and promptly remove dust and metal sputtering deposits to avoid surface flashover; check the static insulation status of the overvoltage protection module 8 as described above. All of the above maintenance items can be completed without disrupting the vacuum, and the maintenance window is consistent with the regular maintenance cycle of the test platform, without adding extra downtime.

[0074] The structure of this embodiment is also applicable to other occasions that require high-voltage isolation and independent discharge, such as ion source aging table, wire assembly testing device at the front end of neutralization chamber, etc. As long as there is a flange connection interface between the protected cavity and the high-voltage component, the insulation plate 5, insulation fastening assembly 7 and independent grounding circuit can be installed in the same way.

[0075] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0076] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0077] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A grounding protection structure for an ion source testing platform, the testing platform comprising an ion source and a vacuum chamber, characterized in that, The grounding protection structure includes an insulating plate (5), an insulating fastening assembly (7), an ion source grounding wire (9), and a vacuum chamber grounding wire (10). The insulating plate (5) is sandwiched between the ground electrode flange (3) of the ion source (1) and the vacuum chamber flange (4) of the vacuum chamber (2). The insulating plate (5) is sealed between the ground electrode flange (3) and between the insulating plate (5) and the vacuum chamber flange (4). The insulating fastening assembly (7) passes through the ground electrode flange (3), the insulating plate (5) and the vacuum chamber flange (4), fastening the ground electrode flange (3), the insulating plate (5) and the vacuum chamber flange (4) together, and maintaining electrical isolation between the ground electrode flange (3) and the vacuum chamber flange (4); The ion source grounding wire (9) is connected between the ground electrode flange (3) and the main grounding busbar (11), and the vacuum chamber grounding wire (10) is connected between the vacuum chamber (2) and the main grounding busbar (11).

2. The grounding protection structure of the ion source testing platform according to claim 1, characterized in that, The insulating fastening assembly (7) includes a fastening bolt (71) and an insulating sleeve (72). The fastening bolt (71) passes through the ground electrode flange (3), the insulating plate (5), and the vacuum chamber flange (4). The insulating sleeve (72) is fitted over the fastening bolt (71) to electrically isolate the fastening bolt (71) from the ground electrode flange (3) and the vacuum chamber flange (4).

3. The grounding protection structure of the ion source testing platform according to claim 1, characterized in that, The insulating plate (5) has an annular sealing groove on both the end face facing the ground electrode flange (3) and the end face facing the vacuum chamber flange (4), and a sealing ring (6) is embedded in the annular sealing groove.

4. The grounding protection structure of the ion source testing platform according to claim 3, characterized in that, The sealing ring (6) is a fluororubber O-ring (6).

5. The grounding protection structure of the ion source testing platform according to claim 1, characterized in that, It also includes an overvoltage protection module (8), which is connected in parallel between the ground electrode flange (3) and the vacuum chamber flange (4); The overvoltage protection module (8) is normally in an open circuit state, and conducts current discharge when the voltage at both ends exceeds the action threshold.

6. The grounding protection structure of the ion source testing platform according to claim 5, characterized in that, The overvoltage protection module (8) is a high-voltage discharge gap, a gas discharge tube, or a surge arrester.

7. The grounding protection structure of the ion source testing platform according to claim 2, characterized in that, The insulating plate (5) is made of polyether ether ketone, alumina ceramic or epoxy resin, and the insulating sleeve (72) is made of polyether ether ketone, polytetrafluoroethylene, alumina ceramic or epoxy resin.

8. The grounding protection structure of the ion source testing platform according to claim 1, characterized in that, The rated insulation withstand voltage of the insulating plate (5) and the insulating fastening assembly (7) are both greater than 1.2 times the maximum accelerating voltage of the ion source (1).

9. The grounding protection structure of the ion source testing platform according to claim 1, characterized in that, Both the ion source grounding wire (9) and the vacuum chamber grounding wire (10) are multi-strand copper core braided tapes.

10. The grounding protection structure of the ion source testing platform according to any one of claims 1 to 9, characterized in that, The test platform is a neutral beam injector ion source (1) test platform, and the vacuum chamber (2) is equipped with a residual gas analyzer (12), a vacuum gauge (13) and a pumping system (14).

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