Light blocking device for high repetition frequency hard X-ray free electron laser device

Abstract

The invention provides a light blocking device for a high repetition frequency hard X-ray free electron laser device. Comprising a vacuum chamber assembly, a light blocking assembly located in the vacuum chamber assembly, a vacuum pump connected with the vacuum chamber assembly, a movement mechanism penetrating through the vacuum chamber assembly and driving the light blocking assembly to move up and down, and a support fixedly supported at the bottom of the vacuum chamber assembly. The light blocking assembly comprises CVD diamond, SiC and a burn-through detector which are sequentially arranged in the propagation direction of the free electron laser. According to the light blocking device, the diamond and the SiC which are made of light atomic number materials are adopted as materials for bearing heat loads, specifically, the diamond and the SiC are combined and arranged front and back, the light blocking function is achieved, and the problem that the light blocking material loses efficacy due to the fact that the heat loads of hard X-ray free electron lasers with the repetition frequency being 1 MHz are too high is solved.

Description

Technical Field

[0001] The present invention belongs to the fields of beamline engineering and free electron laser thermal radiation absorption, and particularly relates to a photon shutter for a high-repetition-rate hard X-ray free electron laser device, which is used to block hard X-ray free electron lasers, especially high-repetition-rate hard X-ray free electron lasers with high brightness, ultrashort pulses, full coherence, and high repetition rates. Background Art

[0002] SHINE is a high-repetition-rate hard X-ray free electron laser device, which has characteristics such as high brightness, ultrashort pulses, full coherence, high repetition rate, and a wide energy range (0.2 - 15 keV). The repetition rate of SHINE can reach 1 MHz, and the total power and peak power density are as high as 2.1 kW and 253.1 W / urad respectively. 2 。

[0003] The photon shutter is a key component of the front-end equipment protection system and the beamline personal protection system, and is also one of the core components of the beamline. When the photon shutter is open, the beam is transmitted to the downstream; when it is closed, the beam is cut off. In the event of a sudden vacuum accident, the photon shutter is interlocked with the downstream valve, and the photon shutter drops to block the beam before the valve closes, protecting the downstream components from direct beam irradiation; in the standby state, the photon shutter is linked with radiation protection equipment to ensure the safety of staff entering the diagnostic area.

[0004] The photon shutter is a key component of the front-end equipment protection system and the beamline personal protection system, and is also one of the core components of the beamline. The existing photon shutters of synchrotron radiation devices mainly use materials with heavy atomic numbers such as oxygen-free copper, chromium-zirconium copper, or dispersed copper oxide as the materials to withstand heat load, and cooling water pipes are machined inside them to carry out heat through cooling water. The thermal conductivity of these materials to withstand heat load can reach 400 W / m°C.

[0005] However, considering the characteristics of high power density of hard X-ray free electron lasers, for hard X-ray free electron lasers, if materials with heavy atomic numbers are used as the photon shutter materials, there will be problems of thermal damage. Materials with heavy atomic numbers have larger photoelectric effect and Compton scattering cross-sections for X-rays, resulting in more energy being absorbed and converted into heat energy. If the thermal conductivity of the material is low or the heat dissipation is insufficient, the local temperature rise may exceed the melting point or thermal stress threshold of the material, causing damage. Summary of the Invention

[0006] The purpose of the present invention is to provide a photon shutter for a high-repetition-rate hard X-ray free electron laser device, which is used to block hard X-ray free electron lasers, especially high-repetition-rate hard X-ray free electron lasers with high brightness, ultrashort pulses, full coherence, and high repetition rates.

[0007] To achieve the above object, the present invention provides a beam stopper for a high-repetition-rate hard X-ray free electron laser device, comprising a vacuum chamber assembly, a beam blocking assembly located inside the vacuum chamber assembly, a vacuum pump connected to the vacuum chamber assembly, a motion mechanism passing through the vacuum chamber assembly and driving the beam blocking assembly to move up and down, and a bracket supported and fixed at the bottom of the vacuum chamber assembly; the beam blocking assembly includes CVD diamond, SiC and a burn-through detector arranged in sequence along the propagation direction of the free electron laser.

[0008] The burn-through detector is used to monitor the failure conditions of the upstream CVD diamond and SiC in real time, and is interlocked with the vacuum valves upstream and downstream of the beam stopper and the electron gun for outputting the electron beam current, so as to drive the rejection of the electron beam current when the CVD diamond and SiC of the beam stopper are detected to fail, and at the same time close the vacuum valves upstream and downstream of the beam stopper.

[0009] Both the CVD diamond and SiC are connected to a water-cooling assembly passing through the vacuum chamber assembly.

[0010] Both the CVD diamond and SiC of the beam blocking assembly include a working-position beam blocking part and a moving-position beam blocking part that are spaced apart from each other and have a fixed relative position. The working-position beam blocking parts of the CVD diamond and SiC are embedded inside the water-cooling assembly and are used to block the beam from passing through when the beam blocking assembly is in the lower position, and the lower position is the working position; the moving-position beam blocking parts of the CVD diamond and SiC are fixed on the upstream-facing surface of the water-cooling assembly and are used to prevent the beam from irradiating the surface of the water-cooling assembly below the beam blocking assembly when the beam blocking assembly moves from the lower position to the upper position.

[0011] The cross-section of the moving-position beam blocking part of the CVD diamond is at least a part of a rectangle with a round hole, and its external dimensions are 31×20×2 mm, and the round hole size is Φ14; the cross-section of the working-position beam blocking part is circular, and the size is Φ21×4 mm; the cross-section of the moving-position beam blocking part of the SiC is at least a part of a rectangle with a round hole, and its external dimensions are 31×20×10 mm, and the round hole size is Φ14; the cross-section of the working-position beam blocking part is circular, and the size is Φ30×10 mm.

[0012] The water-cooling assembly includes a water-cooling copper seat, a retaining ring and a water-cooling outer sleeve located inside the vacuum chamber assembly. The CVD diamond and SiC are embedded at two limiting steps in the through hole of the water-cooling copper seat, and the retaining ring is arranged at the position between the CVD diamond and SiC in the through hole of the water-cooling copper seat; the water-cooling outer sleeve is sleeved outside the water-cooling copper seat and jointly defines a cooling water cavity for heat exchange with the water-cooling copper seat. A cooling water pipe communicated with the cooling water cavity is fixed on the water-cooling outer sleeve, and cooling water is filled in the cooling water pipe.

[0013] The materials of the water-cooled copper seat and the retaining ring are oxygen-free copper; between the water-cooled copper seat and the retaining ring, between the water-cooled copper seat and the water-cooled outer sleeve, between the water-cooled copper seat and the CVD diamond, between the water-cooled outer sleeve and the cooling water pipe, and between the retaining ring and the CVD diamond, brazing or argon arc welding is used for fixed connection; a gold foil is provided between the water-cooled copper seat and the SiC.

[0014] An expansion joint is sleeved outside the cooling water pipe. The space between the expansion joint and the cooling water pipe communicates with the atmosphere, and at least a part of the outside of the expansion joint is located inside the vacuum chamber assembly.

[0015] A photodiode is provided between the SiC and the burn-through detector.

[0016] The burn-through detector includes a helium container with a through hole and two vacuum flanges provided at both ends of the helium container to block the through hole, so as to jointly define a helium cavity by the helium container and the vacuum flanges.

[0017] The beam stopper for the high-repetition-rate hard X-ray free electron laser device of the present invention uses diamond and SiC materials with a low atomic number instead of existing heavy atomic number materials such as oxygen-free copper, chromium-zirconium copper, or dispersed copper oxide as the materials for bearing heat load. Specifically, diamond and SiC are arranged before and after combination to achieve the beam blocking function, solving the problem that the heat load of the hard X-ray free electron laser with a repetition rate of 1 MHz is too high, resulting in the failure of the beam blocking material, covering the laser energy range of 0.2 - 25 keV, and the highest can handle the central high heat load of 2500 W / mm. 2 BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of the principle of the beam stopper for the high-repetition-rate hard X-ray free electron laser device of the present invention.

[0019] Figures 2A - 2C is a schematic structural diagram of the beam stopper for the high-repetition-rate hard X-ray free electron laser device of the present invention, where Figure 2A shows the overall structure, Figure 2B and Figure 2C show the structural diagrams of the remaining components from different perspectives after removing the housing and the vacuum chamber assembly.

[0020] Figure 3 is a cross-sectional view of the installation method of the beam blocking component and the water-cooling component of the beam stopper for the high-repetition-rate hard X-ray free electron laser device of the present invention.

[0021] Figure 4 is a cross-sectional perspective view of the installation method of the beam blocking component and the water-cooling component of the beam stopper for the high-repetition-rate hard X-ray free electron laser device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention is further described below in conjunction with specific examples. It should be understood that the following examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0023] The light blocker for a high repetition rate hard X-ray free electron laser device of the present invention is based on the following principles:

[0024] The single pulse energy of free electron laser is as high as several μJ to several mJ, which requires that the light blocker must be made of ultra-high vacuum materials with less radiation damage and low atomic number. CVD diamond, boron carbide B4C and SiC materials are commonly used light atomic number materials.

[0025] At the same time, due to the extremely high peak power density and total power of high repetition rate hard X-ray free electron laser, the light blocker must be made of materials with good thermal conductivity. However, the thermal conductivity of B4C is only 50W / m·K, which cannot meet the use requirements even with grazing incidence.

[0026] The present invention adopts diamond and SiC materials with light atomic number to replace the existing heavy atomic number materials such as oxygen-free copper, chromium-zirconium copper or dispersed copper oxide as materials that bear heat load. Specifically, CVD (Chemical Vapor Deposition) diamond and SiC materials are used in a front-to-back combination for light blocking, so as to be suitable for light blocks of high repetition rate hard X-ray free electron laser devices such as SHINE light blocks.

[0027] Among them, the main element of diamond is C, the problem of thermal damage is relatively small, and the thermal conductivity can usually reach 1500W / m℃. Diamond film is usually made by thermal deposition method, which has low density, but it is difficult to make it very thick. Sintered SiC is a good thermal conductive material and is cheap. Therefore, the present invention uses diamond and SiC to arrange the front and back combination to achieve the light blocking function to avoid the problem of thermal damage to the material as much as possible. Therefore, when the hard X-ray free electron laser device is working normally, the light beam is transmitted to the downstream when the light blocker is opened, and the light beam is cut off when it is closed; in the event of a sudden vacuum accident, the light blocker is interlocked with the downstream valve, and the light blocker is dropped before the downstream vacuum valve is closed to block the light beam, protecting the downstream components from direct exposure to the light beam; in standby mode, the light blocker is linked with the radiation protection equipment to ensure the safety of staff entering the diagnosis area.

[0028] In addition, the burn-through detector of the light blocker for a high repetition rate hard X-ray free electron laser device of the present invention is interlocked with the vacuum valves upstream and downstream of the light blocker and the electron gun for outputting the electron beam stream, so as to drive the removal of the electron beam stream when failure of the CVD diamond 10 and SiC 20 of the light blocker is detected, and simultaneously close the vacuum valves upstream and downstream of the light blocker.

[0029] Figure 1 is a schematic diagram of the principle of the beam stopper for a high-repetition-rate hard X-ray free electron laser device of the present invention. As Figure 1 shown, the beam stopper for the high-repetition-rate hard X-ray free electron laser device includes a CVD diamond 10, a SiC 20 (silicon carbide), and a burn-through monitor 30 (BTM) arranged in sequence along the propagation direction of the free electron laser (FEL). Among them, the CVD diamond 10 is mainly used to absorb low-energy photons; the SiC 20 is used to absorb high-energy photons; the burn-through monitor 30 is used to monitor the failure conditions of the upstream CVD diamond 10 and SiC 20 in real time, and is interlocked with the vacuum valves upstream and downstream of the beam stopper and the electron gun for outputting the electron beam current, so as to drive the rejection of the electron beam current when the CVD diamond 10 and SiC 20 of the beam stopper are detected to fail, and at the same time close the vacuum valves upstream and downstream of the beam stopper.

[0030] Among them, the electron beam current is injected by the electron gun, and driving the rejection of the electron beam current means that the electron gun stops injecting the electron beam current. Specifically, through a PLC (programmable logic controller) system, a digital input signal is given to the operation control system of the accelerator, so as to achieve the effect of driving the electron gun to stop injecting the electron beam current.

[0031] Closing the vacuum valves upstream and downstream of the beam stopper is used to prevent the burn-through monitor 30 from being penetrated, resulting in helium leakage into the vacuum systems upstream and downstream of the beam stopper. Specifically, helium is filled inside the burn-through monitor 30 before installation, because the vacuum system is sensitive to helium detection. If the BTM is penetrated, helium will leak into the vacuum system. Therefore, it is necessary to close the vacuum valves upstream and downstream of the beam stopper in time to prevent helium leakage from damaging the vacuum systems upstream and downstream of the beam stopper.

[0032] As Figures 2A - 2C shown, the beam stopper includes a vacuum chamber assembly 40, a beam blocking assembly located inside the vacuum chamber assembly 40, a vacuum pump connected to the vacuum chamber assembly 40, a motion mechanism 50 passing through the vacuum chamber assembly 40 and driving the beam blocking assembly to move up and down, and a bracket 60 supported and fixed at the bottom of the vacuum chamber assembly 40.

[0033] Among them, the beam blocking assembly is the core of the beam stopper, and it includes a CVD diamond 10, a SiC 20, and a burn-through monitor 30 arranged in sequence along the propagation direction of the free electron laser.

[0034] The bracket 60 is used to support and fix the vacuum chamber assembly 40.

[0035] The light shielding component is fixed to the mobile end of the motion mechanism 50 and moves up and down with the mobile end of the motion mechanism 50. When the light shielding component is in the upper position, the light beam is transmitted to the downstream; when the light shielding component is in the lower position (i.e., the working position), the light beam is blocked.

[0036] The vacuum chamber component 40 is used to ensure the smooth transmission of the high-repetition-rate hard X free electron laser, so that all devices in the beam line part operate inside the vacuum system. The vacuum chamber component 40 is generally made by welding stainless steel cavities, and vacuum flanges are left at the upstream, downstream and sides for the installation of vacuum pumps such as ion pumps, the connection of upstream and downstream vacuum devices, the feeding of temperature control devices inside and outside the vacuum, or the feeding of moving parts.

[0037] Both the CVD diamond 10 and the SiC 20 of the light shielding component inside the vacuum chamber component 40 are connected to the water cooling component penetrating the vacuum chamber component 40 to realize the cooling of the light shielding component. Figure 3 and Figure 4 shows the installation method of the light shielding component and the water cooling component. As Figure 3 and Figure 4 shown, the water cooling component includes a water cooling copper seat 71, a retaining ring 72 and a water cooling jacket 73 located inside the vacuum chamber component 40. The CVD diamond 10 and the SiC 20 are embedded at two limiting steps in the through hole of the water cooling copper seat 71. The retaining ring 72 is arranged at the position between the CVD diamond 10 and the SiC 20 in the through hole of the water cooling copper seat 71. The water cooling jacket 73 is sleeved outside the water cooling copper seat 71 and jointly defines a cooling water cavity for heat exchange with the water cooling copper seat 71. A cooling water pipe 74 communicated with the cooling water cavity is fixed on the water cooling jacket 73, and cooling water is filled in the cooling water pipe 74.

[0038] In this embodiment, the materials of the water cooling copper seat and the retaining ring are oxygen-free copper. The water cooling copper seat 71 plays a role in heat exchange and serves as a heat conductor for the diamond and SiC. The retaining ring 72 is used to press and fix the diamond and is brazed to the CVD diamond 10 during the processing, and also helps the heat conduction of the CVD diamond 10 on the back

[0039] Brazing or argon arc welding is used for the fixed connection between the water cooling copper seat 71 and the retaining ring 72, between the water cooling copper seat 71 and the water cooling jacket 73, between the water cooling copper seat 71 and the CVD diamond 10, between the water cooling jacket 73 and the cooling water pipe 74, and between the retaining ring 72 and the CVD diamond 10. Among them, the leak rate between the water cooling copper seat 71 and the water cooling jacket 73 and between the water cooling jacket 73 and the cooling water pipe 74 is < 1×10 -12 Torr.L / s.

[0040] Among them, the welding between the CVD diamond 10, the water-cooled copper seat 71, and the retaining ring 72 is to maintain the heat transfer and fixation of the CVD diamond 10, and brazing connection can be adopted.

[0041] Brazing connection can be adopted between the water-cooled copper seat 71 and the water-cooled outer sleeve 73, and a sealed cooling water cavity is defined between the water-cooled copper seat 71 and the water-cooled outer sleeve 73; argon arc welding connection is adopted between the water-cooled outer sleeve 73 and the cooling water pipe 74 to ensure the sealed connection of the water circuit. These two weldings are both to prevent the water in the cooling water pipe 74 from leaking into the vacuum environment where the light shielding component is located.

[0042] A gold foil is provided between the water-cooled copper seat 71 and the SiC 20. Laying the gold foil is to improve the contact area between the water-cooled copper seat 71 and the SiC 20 and increase heat conduction. In this embodiment, the water cooling system adopts single-cycle water cooling. Therefore, the cooling water pipe 74 includes a water inlet pipe and a water outlet pipe, and the cooling water is introduced from the water inlet pipe and led out from the water outlet pipe.

[0043] In this embodiment, the inner diameter of the cooling water pipe 74 is Φ8mm, and the outer diameter is Φ10mm; the working pressure of the cooling water in the cooling water pipe 74 is 6 - 8 kg / cm 2 , and the cooling water flow rate is 6 - 8 L / min.

[0044] To ensure the sealing performance, a pressure test with a pressure of 10 kg / cm 2 is carried out on the water channel weld 78 between the water-cooled copper seat 71 and the water-cooled outer sleeve 73 for 1 hour.

[0045] Please refer to Figure 2C , Figure 3 , Figure 4 , an expansion joint 75 is sleeved outside the cooling water pipe 74, and the space between the expansion joint 75 and the cooling water pipe 74 communicates with the atmosphere, and at least a part of the outside of the expansion joint 75 is located inside the vacuum chamber assembly 40. Thus, the outside of the expansion joint is vacuum, the cavity between the inside of the expansion joint and the water pipe is atmosphere, and the seal between the water and the vacuum is in the atmosphere. Even if the water pipe leaks, it will be directly in the atmosphere and will not directly enter the vacuum, thereby avoiding direct leakage into the vacuum when the water pipe leaks.

[0046] In this embodiment, the expansion joint 75 is connected to the water-cooled copper seat 71 through a CF16 flange 76.

[0047] Both the CVD diamond 10 and the SiC 20 of the light-blocking component include two light-blocking parts that are spaced apart from each other and have a fixed relative position. One is the light-blocking part in the working position, and the other is the light-blocking part in the moving position. Among them, the light-blocking parts in the working position of the CVD diamond 10 and the SiC 20 are embedded inside the water-cooled copper seat 71 of the water-cooling component, and are used to block the beam from passing through when the light-blocking component is in the lower position (that is, the working position); the light-blocking parts in the moving position of the CVD diamond 10 and the SiC 20 are fixed on the upstream-facing surface of the water-cooling component, and are used to prevent the beam from irradiating the water-cooling component (such as the water-cooled copper seat 71, the retaining ring 72, and the water-cooling jacket 73) below the light-blocking component when the light-blocking component moves from the lower position to the upper position.

[0048] In this embodiment, the light-blocking part in the working position is located downstream along the propagation direction of the free electron laser, and the light-blocking part in the moving position is located upstream along the propagation direction of the free electron laser, so as to achieve light blocking of the water-cooling component.

[0049] According to different designed apertures, the light-blockers of the light-blocking parts in the working position can be divided into Φ14 light-blockers, Φ25 light-blockers, Φ38 light-blockers, and Φ76 light-blockers. The working principles, cooling methods, etc. of the four types of light-blockers are exactly the same. Here, the Φ14 light-blocker with the highest heat load, the closest distance to the accelerator, and relatively low cost will be taken as an example for description.

[0050] In this embodiment, the cross-section of the light-blocking part in the moving position of the CVD diamond 10 is a rectangle with at least a part of a round hole, and its external dimensions are 31×20×2 mm, and the round hole size is Φ14; the cross-section of the light-blocking part in the working position is circular, and the size is Φ21×4 mm. The cross-section of the light-blocking part in the moving position of the SiC 20 is a rectangle with at least a part of a round hole, and its external dimensions are 31×20×10 mm, and the round hole size is Φ14; the cross-section of the light-blocking part in the working position is circular, and the size is Φ30×10 mm.

[0051] As Figure 3 and Figure 4 shown, a photodiode 80 can also be provided between the SiC 20 and the burn-through detector 30. The photodiode 80 and the burn-through detector 30 are simultaneously interlocked with the vacuum valves upstream and downstream of the light-blocker and the electron gun for outputting the electron beam current to form a double-monitoring interlock protection system.

[0052] Among them, the photodiode is fixed on one side surface of the SiC 20. The burn-through detector 30 includes a helium gas container 31 with a through hole and two CF63-type vacuum flanges 32 provided at both ends of the helium gas container 31 to block the through hole, so as to jointly define a helium gas cavity by the helium gas container 31 and the vacuum flanges 32. The helium gas cavity of the burn-through detector 30 is filled with helium gas before installation.

[0053] The working principle of the burn-through detector 30 is as follows: Since the vacuum chamber assembly 40 is sensitive to helium detection, if the burn-through detector 30 is punctured, helium will leak into the vacuum chamber assembly 40 and be detected. At this time, the upstream and downstream valves need to be closed in time to prevent the helium leakage from damaging the vacuum systems of the upstream and downstream equipment. The helium detection is completed by a quadrupole leak detector built in the vacuum chamber assembly 40.

[0054] Please refer to Figure 2A , the motion mechanism 50 mainly consists of a cylinder 51, a guide post 52, a linear bearing 53, etc. The moving end of the motion mechanism is connected to the light-blocking assembly to drive two sets of CVD diamond 10 and SiC 20 and the burn-through detector 30 to move up and down simultaneously. Among them, the cylinder is fixed on the base and drives the moving end of the motion mechanism to move linearly along the guide post. The moving end forms a low-friction sliding pair with the guide post through the linear bearing. In this embodiment, the motion mechanism is a general model, where the cylinder model is CQ2YA100-65DCMZ_0 and the model of the linear bearing is 00050337.

[0055] The present invention uses diamond and SiC materials with a low atomic number to replace existing materials with a high atomic number such as oxygen-free copper, chromium zirconium copper, or dispersed copper oxide as the materials for bearing the thermal load. Specifically, the diamond and SiC are arranged before and after combination to achieve the light-blocking function, solving the problem that the light-blocking material fails due to the too high thermal load of the hard X-ray free electron laser with a repetition frequency of 1 MHz, covering the laser energy range of 0.2 - 25 keV, and the highest heat load at the center that can be processed is 2500 W / mm 2 of the center high heat load.

[0056] The above-mentioned is only the preferred embodiment of the present invention and is not used to limit the scope of the present invention. Various changes can be made to the above embodiments of the present invention. All simple, equivalent changes and modifications made according to the claims and the content of the specification of the present invention application fall within the scope of the claims of the present invention patent. The content not described in detail in the present invention is all conventional technical content.

Claims

1. A light blocker for a high repetition rate hard X-ray free electron laser device, characterized in that: It includes a vacuum chamber assembly, a light shielding assembly located inside the vacuum chamber assembly, a vacuum pump connected to the vacuum chamber assembly, a motion mechanism that penetrates the vacuum chamber assembly and drives the light shielding assembly to move up and down, and a bracket that supports and fixes to the bottom of the vacuum chamber assembly; The light blocking component comprises CVD diamond, SiC and a burn-through detector which are sequentially arranged along the propagation direction of the free electron laser.

2. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 1, characterized in that: The burn-through detector is used to monitor the failure of upstream CVD diamond and SiC in real time, and is interlocked with the vacuum valves upstream and downstream of the light blocker, and the electron gun for outputting the electron beam stream, so as to drive the removal of the electron beam stream when the failure of CVD diamond and SiC of the light blocker is detected, and simultaneously close the vacuum valves upstream and downstream of the light blocker.

3. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 1, characterized in that: The CVD diamond and SiC are both connected to a water cooling assembly that runs through the vacuum chamber assembly.

4. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 1, characterized in that: The CVD diamond and SiC of the light-blocking assembly include a working position light-blocking part and a movable position light-blocking part which are spaced apart from each other and fixed in relative position. The working position light-blocking part of the CVD diamond and SiC is embedded in the interior of the water-cooling assembly to block the passage of the light beam when the light-blocking assembly is in the lower position, which is the working position; the movable position light-blocking part of the CVD diamond and SiC is fixed on the upstream facing surface of the water-cooling assembly to prevent the light beam from irradiating the surface of the water-cooling assembly below the light-blocking assembly when the light-blocking assembly moves from the lower position to the upper position.

5. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 4, characterized in that: The cross section of the moving position light shielding part of the CVD diamond is a rectangle with at least a portion of a circular hole, and its outer dimensions are 31×20×2mm, and the circular hole size is Φ14; the cross section of the working position light shielding part is circular, and the size is Φ21×4mm; The cross section of the SiC movable position light shielding part is a rectangle with at least a portion of a circular hole, and its outer dimensions are 31×20×10mm, and the circular hole size is Φ14; the cross section of the working position light shielding part is circular, and the size is Φ30×10mm.

6. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 3, characterized in that: The water-cooling assembly includes a water-cooling copper seat, a retaining ring and a water-cooling jacket located inside the vacuum chamber assembly; the CVD diamond and SiC are embedded at two limiting steps in the through hole of the water-cooling copper seat; the retaining ring is arranged between the CVD diamond and the SiC in the through hole of the water-cooling copper seat; the water-cooling jacket is arranged on the outside of the water-cooling copper seat and defines a cooling water cavity for heat exchange together with the water-cooling copper seat; a cooling water pipe connected to the cooling water cavity is fixed on the water-cooling jacket, and the cooling water pipe is filled with cooling water.

7. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 6, characterized in that: The water-cooled copper seat and the retaining ring are made of oxygen-free copper; The water-cooled copper seat and the retaining ring, the water-cooled copper seat and the water-cooled jacket, the water-cooled copper seat and the CVD diamond, the water-cooled jacket and the cooling water pipe, and the retaining ring and the CVD diamond are fixedly connected by brazing or argon arc welding; Gold foil is arranged between the water-cooled copper seat and SiC.

8. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 6, characterized in that: The outer sleeve of the cooling water pipe is provided with a bellows, the bellows and the cooling water pipe are connected to the atmosphere, and at least a part of the outer portion of the bellows is located inside the vacuum chamber assembly.

9. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 1, characterized in that: A photodiode is provided between the SiC and the burn-through detector.

10. The light blocker for a high repetition rate hard X-ray free electron laser device according to claim 1, characterized in that: The burn-through detector comprises a helium container with a through hole and two vacuum flanges arranged at both ends of the helium container to seal the through hole, so that a helium cavity is defined by the helium container and the vacuum flanges.

Images