False temperature hole pipe cold shrinkage compensation method for superconducting magnet cryostat

Abstract

The invention relates to the technical field of superconducting magnet cryostat heat transfer, in particular to a false temperature hole pipe cold shrinkage compensation method for a superconducting magnet cryostat. The method comprises the steps that a corrugated pipe with the telescopic length is arranged between an outer Dewar end plate and a cold shield end plate, and the corrugated pipe is movably connected to the outer side face of a false temperature hole pipe in a sleeving mode; the left end of the corrugated pipe is provided with a large hoop, the large hoop is connected with the outer Dewar end plate in a penetrating mode from right to left in the axial direction of the false temperature hole pipe, and the outer Dewar end plate and the large hoop are welded in a sealed mode along the junction line of the outer Dewar end plate and the large hoop to form a first welding seam; a small hoop is arranged at the right end of the corrugated pipe, and the small hoop and the false temperature hole pipe are welded in a sealed mode along the joint line to form a second welding seam; wherein the false temperature hole pipe and the corrugated pipe are both made of stainless steel, the false temperature hole pipe is set to be shrunk when cooled, the false temperature hole pipe moves rightwards relative to the large hoop and drives the small hoop to stretch the length of the corrugated pipe so as to compensate the shrinkage deformation quantity of the false temperature hole pipe, weld seam tearing is avoided, and a stable vacuum state is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of heat transfer of superconducting magnet cryostat, in particular to a cold shrinkage compensation method of a pseudo-temperature orifice tube used in a superconducting magnet cryostat. Background Art

[0002] In the accelerator, quadrupole magnets focus or defocus the beam. They usually exist in a combination of three, that is, three quadrupole magnets form a group. Opposite currents are loaded between each two adjacent magnets to form opposite magnetic fields, integrating the beam in the radial direction in a focusing-defocusing-focusing or defocusing-focusing-defocusing manner.

[0003] For three-combination magnets, if superconducting magnets are used, they need to be placed in a cryostat to work properly. If three cryostat are set for three superconducting magnets, that is, each superconducting magnet uses a separate cryostat, the manufacturing price is high, and each cryostat needs to be equipped with a corresponding cryovalve box, the overall heat leakage is large, and the heat load of the cryogenic system is increased. For this reason, consider using one cryostat for three superconducting magnets. This solution only needs to be equipped with one cryovalve box, and the heat leakage of the thermostat is lower than that of three separate cryostat, which can greatly reduce the overall heat load of the cryogenic system and reduce construction costs. However, the length of the three-combination magnet after connection is long, generally 5~6m, and the manufacturing difficulty is relatively large.

[0004] When the accelerator is operating normally, the beam passes through the vacuum pipe inside the superconducting magnet, and the magnetic field radially constrains the beam. There are generally two ways to set up the beam vacuum pipe: one is to place the vacuum pipe in the warm-bore tube of the superconducting magnet cryostat, that is, the beam vacuum tube and the warm-bore tube of the superconducting magnet cryostat are relatively independent, and the inside of the warm-bore tube of the cryostat is the atmospheric environment; the second method is to directly use the warm-bore tube of the superconducting magnet cryostat as the beam tube.

[0005] For the same beam envelope constraints, that is, after the diameter of the beam vacuum pipe is determined, the first setting method will increase the inner diameter of the superconducting magnet, which will correspondingly increase the difficulty and cost of superconducting magnet manufacturing, and even the magnetic field cannot meet the design requirements.

[0006] When the second setting is adopted, the inner diameter of the superconducting magnet can be reduced, and the difficulty and cost of manufacturing the superconducting magnet can be reduced. At this time, the outer side of the warm hole tube is the interlayer vacuum of the cryostat, and the inner side is the beam vacuum. The cold energy (temperature is about 50K absolute temperature) of the cold shield center tube in the cryostat is transferred to the warm hole tube in the radial direction through radiation heat transfer and solid heat conduction of the support. The cold energy on the warm hole tube can only be conducted to the outside through its side wall. In addition, the warm hole tube is generally made of stainless steel. Stainless steel is a poor conductor of heat at low temperatures, and the cold energy transferred from the cold shield center tube to the warm hole tube cannot be transferred away in time in the form of heat conduction. Therefore, when the accelerator is running, there will be an axial temperature gradient on the warm hole tube using the second setting method, which has characteristics different from those of the traditional warm hole tube. Therefore, the warm hole tube using the second setting method is called a "pseudo warm hole tube".

[0007] However, the two sides of the false temperature hole tube are generally connected to the thermostat flange by welding. After the local low temperature is generated in the center of the false temperature hole tube, there will be a cold shrinkage phenomenon, which will cause the entire false temperature hole tube to shrink toward the middle, increasing the stress at the welding point between the false temperature hole tube and the flanges on both sides of the thermostat. For ordinary superconducting magnet cryostat with a shorter length (generally not longer than 3.5m), even if the middle of the false temperature hole tube produces a local low temperature, due to the short length, the temperature gradient on the false temperature hole tube is not large. Although there is a certain cold shrinkage stress, the end weld can fully bear it. However, for the above three-combination superconducting magnet cryostat, the maximum length is 6m, the axial temperature gradient of the false temperature hole tube is large, the cold shrinkage stress is large, and the overall stress will exceed the yield strength of the stainless steel of the false temperature hole tube. The end weld may tear, resulting in vacuum loss, causing serious consequences. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention proposes a cold shrinkage compensation method for a pseudo warm hole tube of a superconducting magnet cryostat, so as to solve the problem that the warm hole tube of the triple-combination superconducting magnet cryostat is easily torn due to cold shrinkage deformation when used as a beam tube, resulting in loss of vacuum.

[0009] The present invention provides a cold shrinkage compensation method for a pseudo-temperature orifice tube of a superconducting magnet cryostat, the cold shrinkage compensation method comprising: Step S1, a bellows with a retractable length is arranged between the outer Dewar end plate and the cold shield end plate, and the bellows is movably sleeved on the outer side surface of the false temperature hole tube; Step S2, setting the left end of the bellows as a large hoop, setting the large hoop to penetrate the outer Dewar end plate from right to left along the axial direction of the false temperature hole tube, and sealing and welding the outer Dewar end plate and the large hoop along the intersection line to form a first weld; Step S3, setting the right end of the corrugated pipe as a small hoop, and sealing and welding the small hoop and the false warm hole pipe along the intersection line to form a second weld; Among them, the false warm hole tube and the bellows are both made of stainless steel. The false warm hole tube is set to shrink when cooled. The false warm hole tube moves to the right relative to the large hoop and drives the small hoop to stretch the length of the bellows to compensate for the shrinkage deformation of the false warm hole tube.

[0010] According to a method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat provided by the present invention, the large hoop is arranged to penetrate the outer Dewar end plate from right to left along the axial direction of the pseudo-temperature orifice tube, comprising: After the large hoop passes through the outer Dewar end plate, a positioning platform protruding radially is arranged on the inner side of the large hoop, and a false temperature hole tube is arranged to abut against the positioning platform to limit the false temperature hole tube from moving leftward.

[0011] According to a method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat provided by the present invention, the pseudo-temperature orifice tube is arranged to abut against a positioning platform, comprising: A brass sleeve is arranged at the end of the false warm hole pipe, so that the brass sleeve is clamped between the large hoop and the false warm hole pipe, and the outer side of the brass sleeve is in sliding friction contact with the large hoop.

[0012] According to a method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat provided by the present invention, the outer side surface of the brass sleeve is in sliding friction contact with the large hoop, comprising: setting a spacing between the positioning platform and the left end surface of the large hoop less than or equal to the axial length of the brass sleeve.

[0013] According to a method for compensating cold shrinkage of a pseudo-warm hole tube for a superconducting magnet cryostat provided by the present invention, the outer side surface of the brass sleeve and the large hoop are in sliding friction contact, comprising: setting the outer side surface diameter of the brass sleeve to be larger than the outer side surface diameter of the pseudo-warm hole tube.

[0014] According to a method for compensating cold shrinkage of a pseudo-warm hole tube for a superconducting magnet cryostat provided by the present invention, the method of setting the pseudo-warm hole tube to shrink when cold includes: The low-temperature thermostat is cooled to reduce the absolute temperature of the helium tank to 4K and the absolute temperature of the cold shield to about 50K; then, the gas in the pseudo-warm hole tube is extracted to form a beam vacuum, and heat is transferred between the cold shield central tube and the pseudo-warm hole tube to form a temperature gradient along the axial direction of the pseudo-warm hole tube. Local low temperature occurs in the middle of the pseudo-warm hole tube, causing the pseudo-warm hole tube to shrink in length toward the middle along its axial direction, and the pseudo-warm hole tube applies a rightward pulling force to the small ring hoop through the second weld.

[0015] According to a method for compensating for cold shrinkage of a pseudo-warm hole tube for a superconducting magnet cryostat provided by the present invention, an initial compression amount is set for the bellows during installation, and the initial compression amount is greater than the shrinkage deformation amount caused by cooling of the pseudo-warm hole tube, so as to prevent the weld from being subjected to additional stress.

[0016] According to a method for compensating for cold shrinkage of a pseudo-warm hole tube for a superconducting magnet cryostat provided by the present invention, the pseudo-warm hole tube is set to restore its initial length, the end of the pseudo-warm hole tube moves to the left relative to the large hoop and drives the small hoop to compress the bellows, so that the bellows returns to the initial compression amount.

[0017] According to a method for compensating cold shrinkage of a pseudo-warm hole tube for a superconducting magnet cryostat provided by the present invention, the setting of the pseudo-warm hole tube to restore the initial length comprises: Filling gas into the tube hole of the pseudo-warm hole tube to remove the beam vacuum, so that the pseudo-warm hole tube is subjected to good heat transfer and the temperature gradient along the axial direction of the pseudo-warm hole tube is removed; Alternatively, the low temperature thermostat itself is set to return to normal temperature to remove the temperature gradient along the axial direction of the pseudo-thermal orifice tube.

[0018] According to a method for compensating for cold shrinkage of a pseudo-warm hole tube for a superconducting magnet cryostat provided by the present invention, a second weld is arranged along the circumference of the pseudo-warm hole tube so that the second weld is closed at both ends to form a ring, which is used to limit the circumferential rotation of the pseudo-warm hole tube.

[0019] The above one or more technical solutions in the present invention have at least one of the following technical effects: By arranging a bellows with retractable length at the end of the dummy temperature hole tube, the bellows can compensate for the length of the dummy temperature hole tube of the cryostat when it contracts and deforms due to cooling, thereby avoiding the tearing of the weld used to connect the dummy temperature hole tube, thereby ensuring that the vacuum state can be stably maintained in the tube hole of the dummy temperature hole tube and the interlayer of the cryostat. The dummy temperature hole tube can replace the conventional vacuum pipe and be used as a beam tube, thereby reducing the diameter of the superconducting magnet and reducing the production cost of the superconducting magnet.

[0020] In addition to the technical problems solved by the present invention, the technical features of the technical solutions constituted, and the advantages brought about by the technical features of these technical solutions described above, other technical features of the present invention and the advantages brought about by these technical features will be further explained in conjunction with the accompanying drawings or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of a pseudo-warm hole tube shrinkage compensation method provided in an embodiment of the present invention.

[0023] Figure 2A schematic diagram of the assembly structure of a superconducting magnet cryostat and a superconducting magnet provided in an embodiment of the present invention.

[0024] Figure 3 for Figure 2 A is an enlarged schematic diagram of the partial view in FIG.

[0025] Reference numerals: 1. Outer Dewar end plate; 2. Bellows; 3. Cold shield end plate; 4. Cold shield center tube; 5. Second weld; 6. False temperature hole tube; 7. Brass sleeve; 8. First weld; 9. Positioning table; 10. Large hoop; 11. Small hoop; 12. Low temperature thermostat; 13. Superconducting magnet; 14. Low temperature thermostat interlayer vacuum; 15. Helium tank. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0028] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" 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. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0029] In the embodiments of 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.

[0030] 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 embodiment 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.

[0031] In the present invention, beam envelope is a concept describing the boundary or outline of a particle beam in a particle accelerator, and refers to the spatial range occupied by the particle beam during the transmission process.

[0032] Beam vacuum refers to a very low pressure environment maintained in a particle accelerator, storage ring or other equipment involving the transmission of charged particle beams to ensure efficient and stable transmission of particle beams. It is generally required to be better than 5×10^-8Pa.

[0033] Interlayer vacuum refers to a closed interlayer space formed between the cryostat helium tank (the part that houses the superconducting magnet) and the cryostat outer Dewar. In order to ensure that less low-temperature cold energy is transferred from the inner side to a very low-pressure environment of the outer Dewar, it generally needs to be better than 5×10^-4Pa.

[0034] Absolute temperature refers to temperature measurement using Kelvin (K) as a unit. In an embodiment of the present invention, a pseudo-temperature orifice tube shrinkage compensation method for a superconducting magnet cryostat is introduced.

[0035] like Figure 2As shown, the cryostat 12 includes: a pseudo-temperature orifice tube 6, a helium tank 15 sleeved on the outer periphery of the pseudo-temperature orifice tube 6, and an outer Dewar end plate 1 sleeved on both ends of the pseudo-temperature orifice tube 6. Among them, the helium tank 15 includes a cold shield end plate 3 and a cold shield center tube 4. The superconducting magnet 13 is arranged in the helium tank 15. Between the cold shield end plate 3 and the outer Dewar end plate 1 is a cryostat interlayer vacuum 14.

[0036] like Figure 1 As shown, in order to use the pseudo-warm hole tube 6 of the low-temperature thermostat 12 as a beam tube, a structure is provided at the end of the pseudo-warm hole tube 6 to compensate for the length when the pseudo-warm hole tube 6 shrinks and deforms due to cooling, thereby avoiding the occurrence of weld tearing and vacuum loss.

[0037] Among them, the cold shrinkage compensation method includes: step S1, setting a bellows 2 with a retractable length between the outer Dewar end plate 1 and the cold shield end plate 3, and movably sleeve the bellows 2 on the outer side of the false temperature hole tube 6. Step S2, setting the left end of the bellows 2 as a large hoop 10, setting the large hoop 10 to penetrate the outer Dewar end plate 1 from right to left along the axial direction of the false temperature hole tube 6, and sealing and welding the outer Dewar end plate 1 and the large hoop 10 along the intersection line to form a first weld 8. That is, the large hoop 10 penetrates the outer Dewar end plate 1 from right to left along the axial direction of the false temperature hole tube 6. And the left side of the outer Dewar end plate 1 and the outer peripheral surface of the large hoop 10 are welded and fixed to form a first weld 8.

[0038] Step S3, the right end of the bellows 2 is set as a small hoop 11, and the small hoop 11 and the false warm hole tube 6 are sealed and welded along the intersection line to form a second weld 5. That is, the small hoop 11 and the false warm hole tube 6 are welded and fixed around the boundary edge of the right end face of the small hoop 11 and the outer peripheral surface of the false warm hole tube 6 to form a second weld 5.

[0039] Therefore, the left end of the false warm hole tube 6 is movably embedded in the large hoop 10 and can move axially relative to the large hoop 10. In addition, the false warm hole tube 6 and the bellows 2 are both made of stainless steel, which is a poor conductor of heat at low temperatures. The cold energy radiated from the cold shield center tube 4 to the false warm hole tube 6 cannot be transferred away in time. When the accelerator is operating normally, a temperature gradient will be generated in the middle of the false warm hole tube 6, which will cause the entire false warm hole tube 6 to shrink and deform toward the middle.

[0040] The false warm hole tube 6 is configured to shrink when cooled, and the false warm hole tube 6 moves rightward relative to the large hoop 10 and drives the small hoop 11 to stretch the length of the corrugated tube 2 to compensate for the shrinkage deformation of the false warm hole tube 6 .

[0041] Specifically, when the accelerator is operating normally, the interlayer vacuum 14 of the cryostat 12 is between the outer Dewar end plate 1 and the cold shield end plate 3. The inside of the pseudo-warm hole tube 6 is a beam vacuum. The cold energy from the cold shield center tube 4 is transferred to the pseudo-warm hole tube 6 in the radial direction through radiation heat transfer and solid support heat conduction, causing local low temperature in the middle of the pseudo-warm hole tube 6. The pseudo-warm hole tube 6 shrinks toward the middle, and the second weld 5 drives the bellows 2 to move toward the middle. The bellows 2 is provided with a certain preload during installation, and can compensate for the length in the axial direction. The existence of the first weld 8, on the one hand, ensures the interlayer vacuum 14 of the cryostat 12, and on the other hand, ensures that when the pseudo-warm hole tube 6 undergoes axial shrinkage displacement, the pseudo-warm hole tube 6 moves to the right as a whole, so that the bellows 2 provides compensation for the shrinkage displacement, rather than the overall axial displacement of the bellows 2 assembly.

[0042] Preferably, the second weld 5 is arranged to extend along the circumference of the false warm hole tube 6 to form a ring, so as to integrate the bellows 2 and the false warm hole tube 6 into one, and limit the circumferential rotation of the false warm hole tube 6 .

[0043] In the present embodiment, by providing a bellows 2 with an extendable length at the end of the dummy warm hole tube 6, the bellows 2 can compensate for the length of the dummy warm hole tube 6 of the low-temperature thermostat 12 when it contracts and deforms due to cooling, thereby avoiding the tearing of the weld used to connect the dummy warm hole tube 6, thereby ensuring that the vacuum state can be stably maintained in the tube hole of the dummy warm hole tube 6, so that the dummy warm hole tube 6 can be used as a beam tube instead of a vacuum pipeline, thereby reducing the diameter of the superconducting magnet 13 and reducing the difficulty and cost of manufacturing the superconducting magnet 13.

[0044] Based on the above embodiment, in another embodiment of the present invention, a method for compensating for shrinkage of a pseudo-temperature orifice tube of a superconducting magnet cryostat is introduced.

[0045] A large hoop 10 is arranged to penetrate the outer Dewar end plate 1 from right to left along the axial direction of the pseudo-warm hole tube 6, comprising: after the large hoop 10 penetrates the outer Dewar end plate 1, a positioning platform 9 protruding along its radial direction is arranged on the inner side surface of the large hoop 10, and the pseudo-warm hole tube 6 is arranged to abut against the positioning platform 9 to limit the pseudo-warm hole tube 6 from moving to the left.

[0046] Furthermore, setting the false warm hole tube 6 to abut against the positioning platform 9 includes: setting a brass sleeve 7 at the end of the false warm hole tube 6, so that the brass sleeve 7 is clamped between the large hoop 10 and the false warm hole tube 6, and the outer side surface of the brass sleeve 7 is in sliding friction contact with the large hoop 10.

[0047] Based on the above embodiment, in another embodiment of the present invention, a method for compensating for shrinkage of a pseudo-temperature orifice tube of a superconducting magnet cryostat is introduced.

[0048] The outer side surface of the brass sleeve 7 is in sliding friction contact with the large hoop 10 , including: arranging the spacing between the positioning platform 9 and the left end surface of the large hoop 10 to be less than or equal to the axial length of the brass sleeve 7 .

[0049] Alternatively, the outer diameter of the brass sleeve 7 is set to be larger than the outer diameter of the false warm hole tube 6. In this way, when the false warm hole tube 6 moves to the right, the outer peripheral side of its end contacts and slides with the brass sleeve 7. Brass has good wear resistance and its hardness is lower than that of stainless steel, so it will not damage the false warm hole tube 6.

[0050] Based on the above embodiment, in another embodiment of the present invention, a method for compensating for shrinkage of a pseudo-temperature orifice tube of a superconducting magnet cryostat is introduced.

[0051] Setting the pseudo-warm hole tube 6 to shrink under cooling includes: cooling the cryostat 12, reducing the absolute temperature of the helium tank 15 to 4K (Kelvin), and reducing the absolute temperature of the cold shield end plate 3 and the cold shield center tube 4 to 50K (Kelvin); then, extracting the gas in the pseudo-warm hole tube 6 to form a beam vacuum.

[0052] A temperature gradient along the axial direction of the pseudo warm hole tube 6 is formed on the pseudo warm hole tube 6 through supporting heat conduction and radiation heat transfer between the cold shield central tube 4 and the pseudo warm hole tube 6 .

[0053] A local low temperature appears in the middle of the false warm hole pipe 6, causing the false warm hole pipe 6 to shrink in length along its axial direction toward the middle, and the false warm hole pipe 6 applies a rightward pulling force to the small hoop 11 through the second weld 5. The bellows 2 is provided with a certain amount of compression during installation, and the bellows 2 is stretched and lengthened along the axial direction under the pulling of the false warm hole pipe 6, providing length compensation to avoid weld cracking.

[0054] Furthermore, the bellows 2 is provided with an initial compression amount during installation, which is greater than the shrinkage deformation amount caused by the cold-induced ...

[0055] Based on the above embodiment, in another embodiment of the present invention, a method for compensating for shrinkage of a pseudo-temperature orifice tube of a superconducting magnet cryostat is introduced.

[0056] The false warm hole tube 6 is set to restore its initial length, and the end of the false warm hole tube 6 moves leftward relative to the large hoop 10 and drives the small hoop 11 to compress the bellows 2, so that the bellows 2 returns to the initial compression amount.

[0057] Furthermore, setting the pseudo warm hole tube 6 to restore the initial length includes: filling gas into the tube hole of the pseudo warm hole tube 6 to remove the beam vacuum, so that the pseudo warm hole tube 6 is subjected to good heat transfer and the temperature gradient along the axial direction of the pseudo warm hole tube 6 is removed.

[0058] After the beam vacuum in the tube hole of the pseudo warm hole tube 6 is removed, the cold shrinkage deformation of the pseudo warm hole tube 6 will gradually recover, so that the end of the pseudo warm hole tube 6 moves in the opposite direction along its axial direction to the initial position. Due to the presence of the positioning platform 9, the pseudo warm hole tube 6 returns to the position abutting against the positioning platform 9, and the bellows 2 returns to the state with the initial compression amount.

[0059] Alternatively, the low-temperature thermostat 12 itself is set to return to room temperature, that is, the helium tank 15, the superconducting magnet 13, the cold shield end plate 3 and the cold shield central tube 4 are all restored to room temperature. At this time, there is no temperature difference between the cold shield central tube 4 and the pseudo-warm hole tube 6, and the temperature gradient along the axial direction of the pseudo-warm hole tube 6 is removed.

[0060] Furthermore, since the brass sleeve 7 has good wear resistance, damage to the pseudo-temperature orifice tube 6 can be avoided, so that the pseudo-temperature orifice tube 6 can be repeatedly displaced multiple times in the large hoop 10, thereby improving the reliability of the low-temperature thermostat 12.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat, characterized in that: include: Step S1, a bellows with a retractable length is arranged between the outer Dewar end plate and the cold shield end plate, and the bellows is movably sleeved on the outer side surface of the false temperature hole tube; Step S2, setting the left end of the bellows as a large hoop, setting the large hoop to penetrate the outer Dewar end plate from right to left along the axial direction of the false temperature hole tube, and sealing and welding the outer Dewar end plate and the large hoop along the intersection line to form a first weld; Step S3, setting the right end of the corrugated pipe as a small hoop, and sealing and welding the small hoop and the false warm hole pipe along the intersection line to form a second weld; Among them, the false warm hole tube and the bellows are both made of stainless steel. The false warm hole tube is set to shrink when cooled. The false warm hole tube moves to the right relative to the large hoop and drives the small hoop to stretch the length of the bellows to compensate for the shrinkage deformation of the false warm hole tube.

2. The method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to claim 1, characterized in that: The large hoop is arranged to penetrate the outer Dewar end plate from right to left along the axial direction of the false temperature hole tube, and comprises: After the large hoop passes through the outer Dewar end plate, a positioning platform protruding radially is arranged on the inner side of the large hoop, and a false temperature hole tube is arranged to abut against the positioning platform to limit the false temperature hole tube from moving leftward.

3. The method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to claim 2, characterized in that: The provision of the false temperature hole tube abutting against the positioning platform comprises: A brass sleeve is arranged at the end of the false warm hole pipe, so that the brass sleeve is clamped between the large hoop and the false warm hole pipe, and the outer side of the brass sleeve is in sliding friction contact with the large hoop.

4. The method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to claim 3, characterized in that: The outer side of the brass sleeve and the large hoop are in sliding friction contact, including: The distance between the positioning platform and the left end face of the large hoop is set to be less than or equal to the axial length of the brass sleeve.

5. The method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to claim 3, characterized in that: The outer side of the brass sleeve and the large hoop are in sliding friction contact, including: The outer diameter of the brass sleeve is set to be larger than the outer diameter of the false temperature hole tube.

6. The method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to any one of claims 1 to 5, characterized in that: The method of setting the false warm hole tube to shrink under cold conditions comprises: The low-temperature thermostat is cooled down, the absolute temperature of the helium tank is reduced to 4K, and the absolute temperature of the cold shield is reduced to 50K; then, the gas in the pseudo-warm hole tube is extracted to form a beam vacuum, and heat is transferred between the cold shield central tube and the pseudo-warm hole tube to form a temperature gradient along the axial direction of the pseudo-warm hole tube on the pseudo-warm hole tube. Local low temperature occurs in the middle of the pseudo-warm hole tube, causing the pseudo-warm hole tube to shrink in length toward the middle along its axial direction, and the pseudo-warm hole tube applies a rightward pulling force to the small ring hoop through the second weld.

7. The method for compensating for cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to claim 6, characterized in that: The bellows is set to have an initial compression during installation, which is greater than the shrinkage deformation caused by the cooling of the pseudo warm hole tube, so as to prevent the weld from being subjected to additional stress.

8. The method for compensating cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to claim 6, characterized in that: The false warm hole pipe is set to return to its initial length, and the end of the false warm hole pipe moves to the left relative to the large hoop and drives the small hoop to compress the bellows, so that the bellows returns to the initial compression amount.

9. The method for compensating for cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to claim 8, characterized in that: The setting of the false temperature hole pipe to restore the initial length includes: Filling gas into the tube hole of the pseudo-warm hole tube to remove the beam vacuum, so that the pseudo-warm hole tube is subjected to good heat transfer and the temperature gradient along the axial direction of the pseudo-warm hole tube is removed; Alternatively, the low temperature thermostat itself is set to return to normal temperature to remove the temperature gradient along the axial direction of the pseudo-thermal orifice tube.

10. The method for compensating for cold shrinkage of a pseudo-temperature orifice tube for a superconducting magnet cryostat according to any one of claims 1 to 5, characterized in that: A second weld is arranged along the circumference of the false warm hole tube, so that the second weld is closed from beginning to end to form a ring, which is used to limit the circumferential rotation of the false warm hole tube.

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