A movable cryogenic collimator

Abstract

The present invention discloses a movable low-temperature collimator, comprising: an outer dewar; a cold shield, installed in the outer dewar; a low-temperature vacuum cavity, installed in the cold shield, the cold shield is used to shield the heat radiation of the outer dewar to the low-temperature vacuum cavity; a heat-insulating bellows cavity, installed in the outer dewar, and one end of the heat-insulating bellows cavity is connected to the normal temperature vacuum pump chamber assembly after passing through the end of the outer dewar, and the other end of the heat-insulating bellows cavity is connected to the low-temperature vacuum cavity, and the heat-insulating bellows cavity is used to reduce the heat conduction of the normal temperature vacuum pump chamber assembly to the low-temperature vacuum cavity; a collimator target head, fixed by the outer dewar and installed in the low-temperature vacuum cavity, the collimator target head can move radially along the low-temperature vacuum cavity and absorb high-energy ions to maintain the high vacuum degree of the low-temperature vacuum cavity. The present invention can be used to suppress the dynamic vacuum effect of a high-current heavy ion beam in a heavy ion superconducting synchronous ring, avoid ion loss caused by the dynamic vacuum effect, and cause magnet quench and vacuum avalanche.

Description

Technical Field

[0001] The present invention belongs to the technical field of heavy ion accelerators, and in particular, relates to a movable low-temperature collimator for heavy ion beams. Background Art

[0002] The High Intensity heavy-ion Accelerator Facility (HIAF) is a next-generation high-intensity heavy-ion accelerator device with international leading level, including high-intensity superconducting ion source, superconducting ion linear accelerator, booster and beam transmission lines connecting various parts; experimental terminals include low-energy nuclear structure spectrometer, high-intensity ion beam irradiation terminal, radioactive beam line, external target experiment terminal, high-precision circular spectrometer, electron-ion complex nucleus resonance spectrometer, high-energy integrated terminal and high-energy density physics terminal. HIAF is the most advanced technology of integrated ion superconducting linear accelerator and circular synchrotron accelerator. It is a heavy ion scientific research device with leading beam indicators and multidisciplinary uses. After completion, HIAF will create international leading conditions for basic research in nuclear physics and nuclear astrophysics, provide an advanced experimental platform for heavy ion beam application research, and provide theoretical, methodological, technical and talent support for nuclear energy development, nuclear safety and nuclear technology application.

[0003] At present, high-current heavy ion accelerators in the world usually install beam collimators coated with low-resolution materials in the machine to block ions lost due to charge state changes, reduce the number of resolved particles to maintain the stability of the vacuum system. The movable cryogenic collimator is a key component used in the heavy ion superconducting synchronization ring of the HIAF Phase II project to suppress the dynamic vacuum effect of the high-current heavy ion beam, avoid ion loss caused by the dynamic vacuum effect, and cause magnet quench and vacuum avalanche. It requires preliminary prototype development. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a movable cryogenic collimator, which aims to use the collimator to achieve high-precision movement of the collimator target head in an extremely low temperature and extremely high vacuum environment.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a movable low-temperature collimator, comprising: an outer dewar; a cold shield installed in the outer dewar; a low-temperature vacuum cavity installed in the cold shield, the cold shield is used to shield the heat radiation of the outer dewar to the low-temperature vacuum cavity; a heat-insulating bellows cavity installed in the outer dewar, and one end of the heat-insulating bellows cavity passes through the end of the outer dewar and is connected to a normal temperature vacuum pump chamber assembly, and the other end of the heat-insulating bellows cavity is connected to the low-temperature vacuum cavity, and the heat-insulating bellows cavity is used to reduce the heat conduction of the normal temperature vacuum pump chamber assembly to the low-temperature vacuum cavity; a collimator target head is fixed by the outer dewar and installed in the low-temperature vacuum cavity, the collimator target head can move radially along the low-temperature vacuum cavity and absorb high-energy ions to maintain the high vacuum degree of the low-temperature vacuum cavity; the temperature of the movable low-temperature collimator and the low-temperature vacuum cavity are both 4.2~10K.

[0006] Preferably, the outer Dewar comprises a front end cover, an outer cylinder and a rear end cover, the thermal insulation bellows cavity comprises an outer Dewar sealing flange, an insulating bellows cylinder and a cold shield fixing flange, one end of the insulating bellows cylinder passes through the front end cover and is connected to the normal temperature vacuum pump chamber assembly, and the insulating bellows cylinder is connected to the front end cover through the outer Dewar sealing flange to complete the vacuum seal of the outer Dewar.

[0007] Preferably: the cold shield comprises a liquid nitrogen tube, a front sealing plate, a support column, a cold shield tube and a rear sealing plate; the liquid nitrogen tube is coiled outside the cold shield tube and led out to the cold mass injection port of the outer Dewar; the front sealing plate and the rear sealing plate are respectively fixed to the front and rear ends of the cold shield tube, and the front sealing plate is connected to the cold shield fixing flange to fix the axial position of the cold shield; a plurality of groups of the support columns are distributedly installed between the cold shield tube and the outer cylinder body, and the cold shield tube is concentrically supported in the outer cylinder body by adjusting the length of the support columns.

[0008] As a preference: the cryogenic vacuum chamber comprises a liquid helium tube, an inner chamber tube and an inner chamber sealing flange, the liquid helium tube is coiled on the inner chamber tube and led out to the cold mass injection port of the outer Dewar; one end of the inner chamber tube is butted with the other end of the thermal insulation bellows tube body, the inner chamber sealing flange is fixed to the other end of the inner chamber tube to complete the vacuum sealing of the cryogenic vacuum chamber, and the common vacuum degree of the cryogenic vacuum chamber and the thermal insulation bellows cavity is 10 -8 ~10 - 12 mbar.

[0009] Preferably, it also includes a vacuum thermal gauge and a vacuum cold gauge. The vacuum thermal gauge passes through the inner cavity sealing flange and extends to the vicinity of the collimator target head, and is used to measure the vacuum degree of the collimator target head area; the vacuum cold gauge is installed on the inner cavity sealing flange, and is used to measure the vacuum degree of the low-temperature vacuum cavity.

[0010] Preferably, the collimator target head comprises a beam absorber, an inner flange, an outer flange and a transmission mechanism; the beam absorber is installed in the low-temperature vacuum chamber via the inner flange, and is used to absorb high-energy ions in the low-temperature vacuum chamber; the transmission mechanism is installed on the outer cylinder via the outer flange, and the transmission mechanism is connected to the beam absorber, and is used to drive the beam absorber to move axially in the low-temperature vacuum chamber.

[0011] Preferably, it also includes a radial positioning rod assembly, which includes an adjusting nut, a mounting flange, an adjusting bellows, a rod and a fixed ball head; 8 groups of the radial positioning rod assemblies are symmetrically fixed on the upper, lower, left and right sides of the outer cylinder through the mounting flange, and one end of the rod is connected to the adjusting nut, and the other end of the rod passes through the outer cylinder and the cold shield cylinder, and the terminal fixed ball head is connected to the inner cavity cylinder to fix the low-temperature vacuum chamber in the outer Dewar, and the radial position of the low-temperature vacuum chamber relative to the outer Dewar can be adjusted by adjusting the adjusting nut of the radial positioning rod assembly; the adjusting bellows is sleeved on the outside of the rod, and the two ends of the adjusting bellows are respectively sealed and connected to the mounting flange and the rod.

[0012] Preferably, it also includes an axial positioning rod assembly, which includes an adjusting nut, a mounting flange, an adjusting bellows, a rod and a fixed ball head; two groups of the axial positioning rod assemblies are fixed to the rear end cover through the mounting flange, and one end of the rod is connected to the adjusting nut, the other end of the rod passes through the rear sealing plate, and the fixed ball head at the end is connected to the inner cavity sealing flange, and the axial position of the low-temperature vacuum chamber relative to the outer Dewar can be adjusted by adjusting the adjusting nut of the axial positioning rod assembly; the adjusting bellows is sleeved on the outside of the rod, and the two ends of the adjusting bellows are respectively sealed with the mounting flange and the rod.

[0013] As a preferred embodiment, the interlayer between the outer Dewar and the cold shield is connected to the interlayer between the cold shield and the low-temperature vacuum chamber, and the vacuum degree is 10 -4 ~10 -6 mbar.

[0014] Preferably, the device further comprises a collimator bracket, the outer dewar is mounted on the collimator bracket, and the collimator bracket is designed with a three-dimensional adjustment component to achieve three-dimensional adjustment of the movable cryogenic collimator.

[0015] The present invention adopts the above technical solution, which has the following advantages:

[0016] The movable cryogenic collimator provided by the present invention enables the collimator target head to operate in an extremely high vacuum and low temperature environment, absorbs high-energy ions whose charge state has changed due to collision with residual gas in a vacuum pipe, suppresses the dynamic vacuum effect of a high-current heavy ion beam, avoids ion loss caused by the dynamic vacuum effect and causes magnet quench and vacuum avalanche, thereby improving the operating efficiency and reliability of the accelerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings:

[0018] Figure 1 A schematic diagram of the appearance structure of a movable cryogenic collimator provided in one embodiment of the present invention;

[0019] Figure 2 A schematic diagram of a top cross-sectional structure of a movable cryogenic collimator provided in one embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a side cross-sectional structure of a movable cryogenic collimator provided in one embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the structure of a collimator target head provided by an embodiment of the present invention;

[0022] Figure 5 A schematic cross-sectional structure diagram of a radial positioning rod assembly provided in one embodiment of the present invention.

[0023] The reference numerals in the figures are as follows:

[0024] 1- movable low-temperature collimator; 2- normal temperature vacuum pump chamber assembly; 3- collimator bracket;

[0025] 11-external dewar; 111-front end cover; 112-external cylinder; 113-rear end cover;

[0026] 12-cold shield; 121-liquid nitrogen tube; 122-sealing plate; 123-support column; 124-cold shield tube; 125-rear sealing plate;

[0027] 13-insulated bellows cavity; 131-external Dewar sealing flange; 132-insulated bellows cylinder; 133-cold shield fixing flange;

[0028] 14- low temperature vacuum chamber; 141- liquid helium tube; 142- inner chamber tube; 143- inner chamber sealing flange;

[0029] 15-collimator target head; 151-beam absorber; 152-inner flange; 153-outer flange; 154-transmission mechanism;

[0030] 16- radial positioning tie rod assembly; 161- adjusting nut; 162- mounting flange; 163- adjusting bellows; 164- tie rod; 165- fixing ball head;

[0031] 17- axial positioning tie rod assembly; 18- vacuum heat gauge; 19- vacuum cold gauge. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0033] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0038] The movable low-temperature collimator provided by the present invention comprises: an outer dewar 11; a cold shield 12, which is installed in the outer dewar 11; a low-temperature vacuum cavity 14, which is installed in the cold shield 12, and the cold shield 12 is used to shield the heat radiation of the outer dewar 11 to the low-temperature vacuum cavity 14; a heat-insulating bellows cavity 13, which is installed in the outer dewar 11, and one end of the heat-insulating bellows cavity 13 passes through the end of the outer dewar 11 and is connected to the normal temperature vacuum pump chamber component 2, and the other end of the heat-insulating bellows cavity 13 is connected to the low-temperature vacuum cavity 14, and the heat-insulating bellows cavity 13 is used to reduce the heat conduction of the normal temperature vacuum pump chamber component 2 to the low-temperature vacuum cavity 14; a collimator target head 15, which is fixed by the outer dewar 11 and installed in the low-temperature vacuum cavity 14, and the collimator target head 15 can move radially along the low-temperature vacuum cavity 14 and absorb high-energy ions to maintain the high vacuum degree of the low-temperature vacuum cavity 14. The invention can be used in a heavy ion superconducting synchronous ring to suppress the dynamic vacuum effect of a high-current heavy ion beam, thereby avoiding ion loss caused by the dynamic vacuum effect and causing magnet quench and vacuum avalanche.

[0039] A movable cryogenic collimator provided by an embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0040] See also Figure 1 , Figure 2 The movable low-temperature collimator 1 provided in this embodiment includes an external dewar 11, a cold shield 12, a heat-insulating bellows cavity 13, a low-temperature vacuum cavity 14 and a collimator target head 15. The cold shield 12 is installed in the outer dewar 11, and the low-temperature vacuum cavity 14 is installed in the cold shield 12. The cold shield 12 is used to shield the heat radiation of the outer dewar 11 to the low-temperature vacuum cavity 14; the heat-insulating bellows cavity 13 is installed in the outer dewar 11, and one end of the heat-insulating bellows cavity 13 passes through the end of the outer dewar 11 and is connected to the normal temperature vacuum pump chamber assembly 2, and the other end of the heat-insulating bellows cavity 13 is connected to the low-temperature vacuum cavity 14. The heat-insulating bellows cavity 13 is used to reduce the heat conduction of the normal temperature vacuum pump chamber assembly 2 to the low-temperature vacuum cavity 14, and improve the cooling effect of the low-temperature vacuum cavity 14; the collimator target head 15 is fixed by the outer dewar 11 and installed in the low-temperature vacuum cavity 14, and can move along the radial direction of the low-temperature vacuum cavity 14 and absorb high-energy ions to maintain the high vacuum degree of the low-temperature vacuum cavity 14. Among them, the temperature of the movable low-temperature collimator 1 and the low-temperature vacuum cavity 14 are both 4.2~10K.

[0041] In the above embodiments, preferably, please refer to Figure 3The outer Dewar 11 includes a front end cover 111, an outer cylinder 112 and a rear end cover 113. The insulating bellows cavity 13 includes an outer Dewar sealing flange 131, an insulating bellows cylinder 132 and a cold shield fixing flange 133. One end of the insulating bellows cylinder 132 passes through the front end cover 111 and is connected to the normal temperature vacuum pump chamber assembly 2. The insulating bellows cylinder 132 is connected to the front end cover 111 through the outer Dewar sealing flange 131 to complete the vacuum sealing of the outer Dewar 11.

[0042] In the above embodiments, preferably, please continue to refer to Figure 3 The cold shield 12 includes a liquid nitrogen pipe 121, a front sealing plate 122, a support column 123, a cold shield tube 124 and a rear sealing plate 125. The liquid nitrogen pipe 121 is coiled around the outside of the cold shield tube 124 and is led out to the cold mass injection port of the outer Dewar 11; the front sealing plate 122 and the rear sealing plate 125 are respectively fixed at the front and rear ends of the cold shield tube 124, and the front sealing plate 122 is connected to the cold shield fixing flange 133 to fix the axial position of the cold shield 12; multiple groups of support columns 123 are distributed and installed at appropriate positions between the cold shield tube 124 and the outer cylinder body 112, and the cold shield tube 124 is concentrically supported in the outer cylinder body 112 by adjusting the length of the support columns 123.

[0043] In the above embodiments, preferably, please continue to refer to Figure 3 The cryogenic vacuum chamber 14 comprises a liquid helium tube 141, an inner cavity tube 142 and an inner cavity sealing flange 143. The liquid helium tube 141 is coiled on the inner cavity tube 142 and led to the cold mass injection port of the outer Dewar 11. One end of the inner cavity tube 142 is butted with the other end of the heat-insulating bellows tube 132. The inner cavity sealing flange 143 is fixed to the other end of the inner cavity tube 142 to complete the vacuum sealing of the cryogenic vacuum chamber 14. The vacuum degree of the cryogenic vacuum chamber 14 and the heat-insulating bellows chamber 13 is 10 -8 ~10 -12 mbar.

[0044] In the above embodiments, preferably, please refer to Figure 2 , Figure 3 , and also includes a vacuum thermal gauge 18 and a vacuum cold gauge 19. The vacuum thermal gauge 18 penetrates the inner cavity sealing flange 143 and extends to the vicinity of the collimator target head 15, and is used to measure the vacuum degree of the collimator target head 15 area; the vacuum cold gauge 19 is installed on the inner cavity sealing flange 143, and is used to measure the vacuum degree of the low-temperature vacuum cavity 14.

[0045] In the above embodiments, preferably, please refer to Figure 4The collimator target head 15 includes a beam absorber 151, an inner flange 152, an outer flange 153 and a transmission mechanism 154. The beam absorber 151 is installed in the low-temperature vacuum chamber 14 through the inner flange 152, and is used to absorb high-energy ions in the low-temperature vacuum chamber 14, reduce the bombardment of these high-energy ions on the surface of the vacuum material, so as to reduce the desorption rate of the vacuum material, thereby maintaining the high vacuum degree of the low-temperature vacuum chamber 14; the transmission mechanism 154 is installed on the outer cylinder 112 through the outer flange 153, and the transmission mechanism 154 is connected to the beam absorber 151, and is used to drive the beam absorber 151 to move radially in the low-temperature vacuum chamber 14.

[0046] In the above embodiments, preferably, please refer to Figure 5 , and also includes a radial positioning rod assembly 16 and an axial positioning rod assembly 17, both of which include an adjusting nut 161, a mounting flange 162, an adjusting bellows 163, a rod 164 and a fixed ball head 165; 8 groups of radial positioning rod assemblies 16 are symmetrically fixed on the upper, lower, left and right sides of the outer cylinder 112 through the mounting flange 162, and one end of the rod 164 is connected to the adjusting nut 161, and the other end of the rod 164 passes through the outer cylinder 112 and the cold shield cylinder 124, and the fixed ball head 165 at the end thereof is connected to the inner cavity cylinder 142 to fix the low-temperature vacuum chamber 14 in the outer Dewar 11, and the radial position adjustment of the low-temperature vacuum chamber 14 relative to the outer Dewar 11 can be achieved by adjusting the adjusting nut 161 of the radial positioning rod assembly 16. The adjusting bellows 163 is sleeved on the outside of the pull rod 164, and the two ends of the adjusting bellows 163 are respectively sealed with the mounting flange 162 and the pull rod 164. The adjusting bellows 163 can seal the vacuum when the pull rod 164 is led out of the outer dewar 11. At the same time, when the pull rod 164 is adjusted in length outside the outer dewar 11, the adjusting bellows 163 can play a contraction role without destroying the vacuum inside the outer dewar 11.

[0047] Two sets of axial positioning rod assemblies 17 are fixed on the rear end cover 113 through the mounting flange 162, and one end of the rod 164 is connected to the adjusting nut 161, and the other end of the rod 164 passes through the rear sealing plate 125, and the fixed ball head 165 at the end is connected to the inner cavity sealing flange 143. By adjusting the adjusting nut 161 of the axial positioning rod assembly 17, the axial position adjustment of the low-temperature vacuum chamber 14 relative to the outer Dewar 11 can be achieved.

[0048] In the above embodiment, preferably, the interlayer between the outer dewar 11 and the cold shield 12 is connected to the interlayer between the cold shield 12 and the low-temperature vacuum chamber 14, and the vacuum degree is 10 -4 ~10 -6 mbar.

[0049] In the above embodiments, preferably, please refer to Figure 1, and also includes a collimator bracket 3, the outer Dewar 11 is installed on the collimator bracket 3, and the collimator bracket 3 is designed with a three-dimensional adjustment component, which can realize the three-dimensional adjustment of the movable low-temperature collimator 1.

[0050] The movable cryogenic collimator 1 provided by the present invention is installed in a heavy ion superconducting synchronization ring when working, and operates in a low-temperature and extremely high vacuum environment. The working environment of the movable cryogenic collimator 1 is provided by a room temperature vacuum pump chamber assembly 2 to provide an extremely high vacuum degree of a cryogenic vacuum chamber 14. The beam absorber 151 of the collimator target head 15 moves in the cryogenic vacuum chamber 14, absorbs high-energy ions whose charge state changes due to collision with residual gas in the vacuum pipe, suppresses the dynamic vacuum effect of the high-current heavy ion beam, avoids ion loss caused by the dynamic vacuum effect, and causes magnet quench and vacuum avalanche phenomenon, thereby improving the operating efficiency and reliability of the accelerator.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A movable cryogenic collimator, characterized in that: include: Outer Dewar; A cold shield installed in the outer dewar; A low-temperature vacuum cavity is installed in the cold shield, and the cold shield is used to shield the heat radiation of the external dewar to the low-temperature vacuum cavity; A heat-insulating bellows cavity is installed in the outer Dewar, and one end of the heat-insulating bellows cavity passes through the end of the outer Dewar and is connected to the normal temperature vacuum pump chamber assembly, and the other end of the heat-insulating bellows cavity is connected to the low temperature vacuum chamber, and the heat-insulating bellows cavity is used to reduce the heat conduction from the normal temperature vacuum pump chamber assembly to the low temperature vacuum chamber; A collimator target head is fixed by the outer dewar and installed in the cryogenic vacuum chamber. The collimator target head can move radially along the cryogenic vacuum chamber and absorb high-energy ions to maintain a high vacuum degree of the cryogenic vacuum chamber. The temperatures of the movable cryogenic collimator and the cryogenic vacuum chamber are both 4.2-10K.

2. The movable cryocollimator according to claim 1, characterized in that: The outer Dewar includes a front end cover, an outer cylinder and a rear end cover, the thermal insulation bellows cavity includes an outer Dewar sealing flange, an insulating bellows cylinder and a cold shield fixing flange, one end of the insulating bellows cylinder passes through the front end cover and is connected to the normal temperature vacuum pump chamber assembly, and the insulating bellows cylinder is connected to the front end cover through the outer Dewar sealing flange to complete the vacuum seal of the outer Dewar.

3. The movable cryocollimator according to claim 2, characterized in that: The cold shield includes a liquid nitrogen pipe, a front sealing plate, a support column, a cold shield tube and a rear sealing plate. The liquid nitrogen pipe is coiled outside the cold shield tube and led out to the cold mass injection port of the outer Dewar; the front sealing plate and the rear sealing plate are respectively fixed to the front and rear ends of the cold shield tube, and the front sealing plate is connected to the cold shield fixing flange to fix the axial position of the cold shield; a plurality of groups of the support columns are distributed and installed between the cold shield tube and the outer cylinder body, and the cold shield tube is concentrically supported in the outer cylinder body by adjusting the length of the support columns.

4. The movable cryocollimator according to claim 3, characterized in that: The cryogenic vacuum chamber comprises a liquid helium tube, an inner chamber tube and an inner chamber sealing flange, wherein the liquid helium tube is coiled on the inner chamber tube and led out to the cold mass injection port of the outer Dewar; one end of the inner chamber tube is butted with the other end of the thermal insulation bellows tube body, and the inner chamber sealing flange is fixed to the other end of the inner chamber tube to complete the vacuum sealing of the cryogenic vacuum chamber, and the common vacuum degree of the cryogenic vacuum chamber and the thermal insulation bellows cavity is 10 -8 ~10 -12 mbar.

5. The movable cryocollimator according to claim 4, characterized in that: It also includes a vacuum heat gauge and a vacuum cold gauge. The vacuum heat gauge passes through the inner cavity sealing flange and extends to the vicinity of the collimator target head, and is used to measure the vacuum degree of the collimator target head area; the vacuum cold gauge is installed on the inner cavity sealing flange, and is used to measure the vacuum degree of the low-temperature vacuum cavity.

6. The movable cryocollimator according to claim 2, characterized in that: The collimator target head includes a beam absorber, an inner flange, an outer flange and a transmission mechanism. The beam absorber is installed in the low-temperature vacuum chamber through the inner flange and is used to absorb high-energy ions in the low-temperature vacuum chamber. The transmission mechanism is installed on the outer cylinder through the outer flange, and the transmission mechanism is connected to the beam absorber and is used to drive the beam absorber to move axially in the low-temperature vacuum chamber.

7. The movable cryocollimator according to claim 4, characterized in that: It also includes a radial positioning rod assembly, which includes an adjusting nut, a mounting flange, an adjusting bellows, a rod and a fixed ball head; 8 groups of the radial positioning rod assemblies are symmetrically fixed on the upper, lower, left and right sides of the outer cylinder through the mounting flange, and one end of the rod is connected to the adjusting nut, and the other end of the rod passes through the outer cylinder and the cold shield cylinder, and the terminal fixed ball head is connected to the inner cavity cylinder to fix the low-temperature vacuum cavity in the outer Dewar, and the radial position adjustment of the low-temperature vacuum cavity relative to the outer Dewar can be achieved by adjusting the adjusting nut of the radial positioning rod assembly; the adjusting bellows is sleeved on the outside of the rod, and the two ends of the adjusting bellows are respectively sealed and connected to the mounting flange and the rod.

8. The movable cryocollimator according to claim 4, characterized in that: It also includes an axial positioning rod assembly, which includes an adjusting nut, a mounting flange, an adjusting bellows, a rod and a fixed ball head; two groups of the axial positioning rod assemblies are fixed to the rear end cover through the mounting flange, and one end of the rod is connected to the adjusting nut, and the other end of the rod passes through the rear sealing plate, and the fixed ball head at the end is connected to the inner cavity sealing flange, and the axial position of the low-temperature vacuum chamber relative to the outer Dewar can be adjusted by adjusting the adjusting nut of the axial positioning rod assembly; the adjusting bellows is sleeved on the outside of the rod, and the two ends of the adjusting bellows are respectively connected to the mounting flange and the rod seal.

9. The movable cryocollimator according to any one of claims 1 to 8, characterized in that: The interlayer between the outer Dewar and the cold shield is connected to the interlayer between the cold shield and the low-temperature vacuum chamber, and the vacuum degree is 10 -4 ~10 -6 mbar.

10. The movable cryocollimator according to any one of claims 1 to 8, characterized in that: It also includes a collimator bracket, the outer dewar is installed on the collimator bracket, and the collimator bracket is designed with a three-dimensional adjustment component to achieve three-dimensional adjustment of the movable low-temperature collimator.

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