Thermal radiation shielding for superconducting magnets.

Abstract

Structures and techniques for supporting a thermal radiation shield within a superconducting magnet are described. The thermal radiation shield may be supported by a cold mass using structural supports with low thermal conductivity. Structural supports, specifically, thermal radiation shield supports and buffers, may be installed between the cold mass and the radiation shield to mitigate deflection of the radiation shield. The thermal radiation shield supports are attached to both the cold mass and the radiation shield. The buffers may be used in addition to the thermal radiation shield supports and have a first end attached to either the cold mass or the thermal radiation shield and a second end not physically connected to any structure.

Description

[Technical Field]

[0001] Cross-reference section

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 498,917, filed April 28, 2023, which is incorporated herein by reference.

[0002] Statement of Federally Funded Research

[0002] Not applicable. [Background technology]

[0003] As is known in the art, there are several existing techniques for the fabrication of low-temperature superconducting (LTS) magnets. However, these existing techniques may not be sufficient for use in high-temperature superconducting (HTS) magnets. Summary of the Invention [Problem to be solved by the invention]

[0004] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features or combinations of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0005] High-temperature superconducting (HTS) magnets open new opportunities for building high-field magnets for numerous applications. HTS magnets have a smaller critical current sensitivity at operating temperatures compared to that of low-temperature superconducting (LTS) magnets. This smaller current sensitivity allows HTS magnets to operate over a temperature margin greater than that of LTS magnets. Furthermore, HTS magnets operate at higher temperatures than LTS magnets. At such temperatures, the heat capacity of the materials comprising the cold mass of HTS magnets is significantly higher than the LTS compatibility temperature. As a result, HTS magnets are less susceptible to local heating than LTS magnets. Furthermore, HTS magnets provide sufficient cooling to limit the associated temperature rise. By reviewing how these properties affect the production of HTS magnets, the inventors have discovered improvements in the design and manufacture of HTS magnets. [Means for solving the problem]

[0006]

[0006] The present disclosure relates to thermal radiation shields for HTS magnets, and related mounting structures and techniques. Disclosed herein are concepts, structures, and techniques for supporting a radiation shield from the cold mass of an HTS magnet via structural supports (referred to herein as "thermal radiation shield supports" or "spacers"). The thermal radiation shield supports are disposed between the radiation shield and the cold mass and are coupled to both the radiation shield and the cold mass. The cold mass may be coupled to the cryostat by supports separate from the thermal radiation shield supports that pass through the radiation shield.

[0007] Also disclosed is a radiation shield snubber (or more simply snubber) disposed between the radiation shield and the cold mass and coupled to either the radiation shield or the cold mass (but not both).

[0008]

[0008] The thermal radiation shield may be coupled to the cold mass (via one or more thermal radiation shield supports) and then inserted into the cryostat. Through the use of the thermal radiation shield supports described herein, the thermal radiation shield and cold mass may be assembled into a rigid subassembly prior to insertion into the cryostat. This approach significantly reduces the complexity of the assembly process and therefore improves magnet assembly compared to conventional approaches in which both the cold mass and radiation shield are coupled to the cryostat using the same supports.

[0009]

[0009] Described herein are thermal radiation shields and associated mounting structures and techniques for use with superconducting magnets. The thermal radiation shields and associated mounting structures and techniques may be particularly suitable for use with superconducting HTS magnets. In each embodiment, the thermal radiation shield support is connected only to the cold mass and the thermal radiation shield, such that the cold mass mechanically supports the thermal radiation shield. In other words, the thermal radiation shield is attached to the cold mass via a structural support and is mechanically supported thereby. The cold mass (with the magnet) is separately mechanically supported by its own cold-to-warm support that does not contact the thermal radiation shield. In each embodiment, the thermal radiation shield support is a structural support having a first end coupled to the cold mass and a second end coupled to the thermal radiation shield.

[0010] The manner and process of making and using the disclosed embodiments can be understood by reference to the figures in the accompanying drawings. It should be understood that the components and structures shown in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the concepts described herein. Like reference numerals designate corresponding parts throughout the various views. Moreover, embodiments are illustrated in the following figures by way of example, and not by way of limitation. [Brief explanation of the drawings]

[0011] [Figure 1A]1 is a schematic diagram of a cold mass and a prior art thermal radiation shield support structure. [Figure 1B]

[0012] 1 is a schematic diagram of a cold mass and thermal radiation shield support structure with thermal intercept of the prior art; [Figure 2]

[0013] 1 is a schematic diagram of a prior art cold mass cooled by a cryogenic refrigerator; FIG. [Figure 3]

[0014] 1 is a schematic diagram of a high temperature superconducting magnet with thermal radiation shield supports and a buffer. [Figure 4]

[0015] 1 is a schematic diagram of a high temperature superconducting magnet having thermal radiation shield structural supports and shock absorbers and cooled by a cryogenic refrigerator. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0016] Described herein are techniques for combining components within a superconductor magnet operated at different temperatures. Specifically, the superconductor magnet may include a cold mass within the cryostat, in addition to a thermal radiation shield disposed between the cold mass and the cryostat. "Cold mass" is a term that refers to the portion of the magnet that is superconducting during operation, typically including superconducting wire and / or tape incorporated into the structure and maintained at a temperature of about 4 K during operation of the magnet. The cryostat forms an outer vacuum boundary for the cryogenic space therein and is typically maintained at room temperature, while the thermal radiation shield is disposed between the cold mass and the cryostat and maintained at an intermediate temperature (e.g., about 77 K).

[0013]

[0017] In conventional superconducting magnets described below, supports are arranged to connect the cold mass and radiation shield to the cryostat. These supports mechanically support the cold mass and radiation shield while also minimizing heat leakage from the cold mass through conduction between these components. Because cryogenic systems are much more efficient at cooling at 77 K versus 4 K, systems are conventionally arranged to provide greater cooling to the cold mass at the expense of creating a greater heat load on the radiation shield. Thus, the radiation shield is conventionally located much closer to the cryostat than the cold mass along a common support structure. However, assembling the cold mass and radiation shield to a common support inside the cryostat can be difficult.

[0014]

[0018] Before describing concepts and techniques for joining components within a superconductor magnet, some introductory concepts in the context of conventional superconducting magnets are described below.

[0015]

[0019] 1A, a conventional superconducting magnet cold mass 10 is disposed inside the chamber of a cryostat 12 (reference numeral 10 denotes the boundary of the cryostat chamber). The cold mass comprises superconducting wire incorporated into a structural entity and maintained at cryogenic temperatures within the cryostat chamber. For magnets comprising low temperature superconductor (LTS) material (so-called "LTS magnets"), the cryogenic temperatures of the cold mass are in the range of about 4 K to about 9 K.

[0016]

[0020] The cryostat contains 1.3×10 s of ions in the cryostat chamber (typically about 1.3×10 s). -3 Pa (approx. 10 -5 A vacuum (in the range of 1000 Torr or less) is applied to the cryostat. The cryostat vacuum acts as a thermal insulator between the cold mass, which may be at or near ambient temperature, and the cryostat boundary. The cryostat walls are maintained at room temperature (RT), (approximately 300 K) during magnet operation.

[0017]

[0021] 1A, a thermal radiation shield 14 is disposed around (e.g., at the periphery of) the cold mass and positioned between the cold mass and the cryostat wall. The thermal radiation shield is typically maintained at an intermediate temperature, often corresponding to approximately the boiling temperature of liquid nitrogen (LN2), at a pressure approximately equal to atmospheric pressure (e.g., in the range of about 77 K to about 80 K). At intermediate temperatures (e.g., 70 K to 80 K for LTS systems), the cryostat's available cooling power is in the range of several hundred watts, whereas at low cryogenic temperatures (typically 4 K for an LTS cold mass), it is in the low few watts range.

[0018]

[0022] The cold-to-warm (CW) supports 16a-16d are connected to the cold mass, the thermal radiation shield, and the cryostat and serve to support the cold mass and the thermal radiation shield within the cryostat. Thus, in conventional designs, the same CW supports 16a-16d support both the cold mass and the radiation shield. The connected combination of the cold mass, the radiation shield, and the CW supports may be referred to as a cold mass-thermal radiation shield-CW support subassembly. The CW supports 16a-16d are directly coupled to both the thermal radiation shield and the cold mass. That is, the CW supports 16a-16d directly support both the thermal radiation shield and the cold mass.

[0019]

[0023] However, this approach complicates the magnet design and, given the often-close spacing (or gap) between the radiation shield and the cold mass, this approach also poses significant difficulties when assembling the cold mass-thermal radiation shield-CW support subassembly into the cryostat.

[0020]

[0024] Specifically, the fact that two bodies (i.e., the cold mass and the radiation shield, which are often heavy bodies) are supported by the same CW support makes handling of this subassembly and its final fixation inside the cryostat chamber difficult. These difficulties are compounded when a cryogenic refrigerator is incorporated into the design.

[0021]

[0025] Additionally, the CW supports act as tension links that fix the position of the cold mass and radiation shield inside the cryostat while simultaneously reducing, and ideally minimizing, heat leakage due to thermal conduction between the three components (i.e., between the cold mass, radiation shield, and cryostat wall), each maintained at a different temperature.

[0022]

[0026] In a typical assembly process, the radiation shield is inserted into the cryostat, and then the cold mass is inserted inside it. This assembly technique poses difficulties because it blocks the view of the cold mass and limits access to critical points inside the radiation shield. To resolve these difficulties in the assembly process, multiple notches are made in the radiation shield. These notches are later patched to restore the integrity of the radiation shield. This type of magnet assembly requires professionals with high technical skills to reduce the heat load from the cryostat wall to the radiation shield, especially when the radiation shield is covered with multi-layer insulation.

[0023]

[0027] In the case of LTS magnets, this complex assembly procedure is driven primarily by two factors. First, the length of CW support between the cold mass and the radiation shield is required to provide adequate thermal resistance. For LTS magnets utilizing constant-cross-section CW supports, common practice is to divide the length of the CW support by the intermediate temperature (77-80 K) and thermally insulate it in an approximate ratio of 1 (on the cryostat side) to 3 (on the cold mass side). Second, the need to reduce heat conduction to the cold mass to levels in the low few watts requires that the radiation shield be located much closer to the cryostat than to the cold mass.

[0024]

[0028] To further reduce the radiation load on the cold mass, some LTS magnets (e.g., LTS magnets operating at temperatures below 4 K) may use several radiation shields. In some embodiments, the radiation shields may be surrounded by one another and cooled to gradually decreasing temperatures (e.g., from about 77 K to about 40 K to about 20 K).

[0025]

[0029] Unlike radiative heat loads, the heat transferred through a CW support can be defined by (1) the differential warm-to-cold temperature, (2) the thermal conductivity of the CW support over a range of high and low temperatures, and (3) the physical dimensions of the CW support (e.g., the length and cross-sectional area of ​​the CW support).

[0026]

[0030] 1B, in which like elements of FIG. 1A are given like reference numerals, as described above, CW supports 16a-16d provide a thermal path from cryostat 14 to cold mass 10 through the radiation shield, and heat can flow along this path from the cryostat and radiation shield to the cold mass. To reduce the flow of heat from the cryostat to the cold mass, thermal intercepts 18a-18d can be disposed within the path, as shown in FIG. 1B. Thus, thermal intercepts 18a-18d further manage the heat flow and further insulate the cold mass from the heat flux.

[0027]

[0031] 2, in which like elements of Figures 1A and 1B are given like reference numerals, the system includes a two-stage cryogenic refrigerator having a first stage 20 thermally coupled to the radiation shield 14 and a second stage 22 thermally coupled to the cold mass 10. A cryostat flange 24 provides an airtight seal to the cryostat chamber in which the cold mass resides.

[0028]

[0032] The difficulty of connecting the components is compounded by the need to accommodate independent movement of the cold mass 10 and the radiation shield 14. Such independent movement can arise, for example, from differential thermal contraction of the supported items (e.g., differential thermal contraction between the radiation shield and the cold mass).

[0029]

[0033] In embodiments, the cryocooler structure (e.g., stem or barrel) cannot (in most cases) sustain forces greater than about 10 kg. Therefore, conventional designs often incorporate a flexible connection (e.g., a flexible thermal bridge) 25 between the cryocooler first stage flange 22a and the radiation shield 14, and a flexible connection 27 (e.g., a bellows) between the cryostat flange 24 and the cryocooler 28. The need for flexible connections complicates the design and assembly of the system and also reduces the cooling efficiency of the thermal radiation shield by adding more thermal links and contacts.

[0030]

[0034] In accordance with the concepts, systems, structures, and techniques described herein, the inventors have recognized that for HTS magnets, several factors enable different approaches to installing the cold mass and thermal radiation shield within the cryostat. First, the operating temperature of the cold mass when it comprises an HTS superconductor is higher than that of an LTS superconducting magnet, typically about 20 K (versus about 4 K). Second, at this higher temperature, a greater amount of cooling power is available. For example, at 20 K, advanced cryogenic refrigerators can deliver up to 100 W of cooling power (compared to a few watts at 4 K). Third, at higher temperatures, HTS superconductors have a larger temperature margin than LTS superconductors, despite limited local temperature fluctuations.

[0031]

[0035] As described in detail below, the inventors have recognized structures and techniques for reducing (ideally minimizing) the heat load on the cold mass. In accordance with the concepts described herein, the inventors have recognized that structural supports may be utilized to support the radiation shield directly from the cold mass. The structural supports may be made of any low thermal conductivity material that can be used at the cryogenic temperatures contemplated herein and that has sufficient mechanical strength / integrity to withstand the forces that the cold mass-to-radiation shield connection may be subjected to.

[0032]

[0036] This is in contrast to prior art approaches in which both the cold mass and the radiation shield are connected to and supported by the same CW supports (e.g., CW supports 16a-16c described above in connection with Figures 1A and 1B), which are also connected to the cryostat structure (e.g., the cryostat wall) as described above in connection with Figures 1A and 1B.

[0033]

[0037] The inventors have recognized that supporting the thermal radiation shield from the cold mass via structural supports in accordance with the concepts described herein can help to mitigate deflection of the radiation shield and reduce heat conduction, allowing for assembly of the magnet in a manner that is mechanically simpler than conventional approaches.

[0034]

[0038] It should be noted that the techniques for supporting a thermal radiation shield from a cold mass described herein may not achieve the same results (and may not be available) as for superconductor magnets that include LTS superconductors. As noted above, the cooling power available for the cold mass at 4 K (required for LTS superconductors) poses several requirements for the system design, including the need to thermally isolate the radiation shield from the cold mass. This need arises because the operating temperature margin, the difference between the critical temperature and the operating temperature, is approximately 1–2 K in LTS magnets. In addition, the heat capacity of the cold mass material decreases as the operating temperature decreases. As a result, LTS magnets are extremely sensitive to even very small heat fluxes, which can heat portions of the LTS magnet above its critical temperature and quench it. Due to these temperature effects in LTS magnets, the radiation shield must be thermally isolated from the cold mass by placing it between the cold mass and the room-temperature cryostat and attaching it to a cold-to-warm support. This limits the available mechanical design space.

[0035]

[0039] However, in HTS magnets, the operating temperature margin is much larger (e.g., about 10 K or more), and because the operating temperature of HTS magnets is higher than that of LTS magnets, the heat capacity of the cold mass material is also higher in HTS magnets than in LTS magnets. As a result, the mechanical design space (i.e., possible design options) for thermal radiation shielding in HTS magnets is larger (e.g., wider) than in LTS magnets, and as recognized by the inventors, the techniques described herein enable supporting the thermal radiation shield from the cold mass.

[0036]

[0040] In some embodiments, structural supports for radiation shields in high-temperature superconducting (HTS) magnets are described. The radiation shield can be mechanically supported (hereinafter simply "supported") by the cold mass using low-thermal-conductivity structural supports. Structural supports, specifically, bumpers and spacers, can be installed between the cold mass and the radiation shield to mitigate deflection of the radiation shield. Spacers are attached to the cold mass and the radiation shield, and bumpers may be used in addition to spacers or may be attached to either the cold mass or the thermal radiation shield. During normal operation, the bumpers can contact either the cold mass or the radiation shield, leaving a small gap on the opposite side that blocks heat transfer through the bumpers. These structural supports enable improved assembly. By placing the supports on the cold mass, then installing the radiation shield and inserting the subassembly into the cryostat, areas of the cold mass are more easily accessible during assembly, and fewer notches are required in the radiation shield.

[0037]

[0041] 3, superconducting magnet cold mass 30 is disposed within a cryostat chamber of cryostat 32 (reference numeral 32 represents the boundary of the cryostat chamber, and reference numeral 31 represents the cryostat chamber space within or defined by the boundary). Cryostat 32 is configured to provide cooling for the cold mass (including the magnet), radiation shield, radiation shield support, thermal intercept (if any), and cold-to-warm support. In each embodiment, a cryogenic refrigerator may be used to provide such cooling.

[0038]

[0042] The cold mass 30 comprises superconducting wires embedded in a structural entity and maintained at cryogenic temperatures in a cryostat chamber, where for HTS magnets the cryogenic temperatures are above about 9K, typically about 20K.

[0039]

[0043] The cryostat contains 1.3×10 s of ions in the cryostat chamber (typically about 1.3×10 s). -3Pa (approx. 10 -5 A vacuum (in the range of 0.1 Torr or less) is applied to the cryostat. The cryostat vacuum acts as a thermal insulator between the cold mass and the cryostat boundary, which may be at or near ambient temperature. That is, the region outside the cryostat chamber may be maintained at room temperature (RT), (approximately 300°K), during operation of the magnet.

[0040]

[0044] A thermal radiation shield 33 is disposed around (e.g., around) the cold mass 30. The thermal radiation shield 33 has openings 34a-34d formed therein. Cold-to-warm (CW) supports 36a-36d pass through the openings and extend between the cold mass and the cryostat, serving to support the cold mass within the cryostat chamber.

[0041]

[0045] The CW supports 36a-36d are not directly coupled to the thermal radiation shield. That is, in contrast to prior art approaches, the CW supports 36a-36d do not directly support the thermal radiation shield. Rather, the CW supports 36a-36d provide structural support sufficient to at least hold (or maintain) the weight of the cold mass so that it is in a desired position within the cryostat. The CW supports 36a-36d also provide structural support to secure (or hold or maintain) the cold mass in a desired position (or range of positions) when the cold mass is subjected to forces. The physical (e.g., mechanical), electrical, and thermal properties of the CW supports can be selected (ideally optimized) to reduce the thermal load imparted to the cold mass (e.g., the thermal load imparted by an RT cryostat). Such optimization can take into account several factors, including, but not limited to, the geometric and structural properties of the CW supports, the geometric and structural properties of the CW support materials, the temperature dependence of the thermal conductivity coefficients of the materials comprising the CW supports, and the brittleness of the support materials at cryogenic temperatures. The usual optimization is defined by the ratio of the yield strength of the hot end of the CW support to the heat transfer coefficient for a given hot to cold temperature drop.

[0042]

[0046] The thermal radiation shield 33 is supported from the cold mass via one or more thermal radiation shield supports (sometimes referred to herein as “structural supports” or “spacers”); two such thermal radiation shield supports 38a, 38b are shown in the exemplary embodiment of FIG. 3 . Each thermal radiation shield support has a first end attached or otherwise secured to the cold mass and a second end attached or secured to the thermal radiation shield. This attachment can be by permanent attachment means (e.g., via welding) or by removable attachment means (e.g., bolts, nuts, or fasteners) or other additional attachment mechanisms. With this approach, the thermal radiation shield is rigidly attached, without any flexibility, to the cold mass forming a rigid radiation shield-cold mass subassembly.

[0043]

[0047] Insulating the radiation shield 33 may require using thermal radiation shield supports 38a, 38b with an additional layer of a non-structural material having very low thermal conductivity, such as glass-reinforced plastic or fiberglass-reinforced plastic (e.g., fiberglass), polyimide film (e.g., Kapton®, a registered trademark of EI DuPont De Nemours and Company), synthetic polymer with an amide backbone (e.g., nylon), or low thermal conductivity ceramic.

[0044]

[0048] 3, thermal radiation shield supports are shown on only two opposing sides of the cold mass, it should be understood that in each embodiment, thermal radiation shield supports may be on only one side of the cold mass. Furthermore, in each embodiment, thermal radiation shield supports may be on all sides of the cold mass.

[0045]

[0049] The particular number and positioning (i.e., location) of the thermal radiation shield supports coupled to the cold mass will depend on the needs of a particular application. In some embodiments where the magnet comprises an HTS material, N thermal radiation shield supports may be used, where N is an integer greater than or equal to 1. The particular number and positioning (i.e., location) and geometry (e.g., length, cross-sectional shape, and area) of the thermal radiation shield supports coupled to the cold mass will depend on various factors, including, but not limited to, the weight of the thermal radiation shield and the magnitude of forces experienced by the thermal radiation shield in any mode of operation.

[0046]

[0050] In some embodiments, the thermal radiation shield supports may be equally distributed (e.g., equally spaced) along a particular direction of the cold mass (e.g., along an axial direction or along a radial direction, or along the axis of the cold mass). In some embodiments, the thermal radiation shield supports may not be equally distributed (e.g., equally spaced) along a particular direction of the cold mass.

[0047]

[0051] After reading the description provided herein, one skilled in the art will understand the number and positioning of thermal radiation shield supports in a particular application.

[0048]

[0052] In each embodiment, one or more thermal intercepts may optionally be disposed on or thermally coupled to one or more of the cold mass supports. In the example of FIG. 3, each of the CW supports 36a-36d has a respective one of the thermal intercepts 39a-39d thermally coupled thereto. In each embodiment, some or all of the CW supports 36a-36d may optionally have one or more thermal intercepts thermally coupled thereto. In the embodiment of FIG. 3, T warm -T cold The temperature difference is T in the embodiment of FIG. warm -T shield and T shield -T coldNote that the thermal intercepts 39a-39d are different from those described in connection with FIG. 1B because the temperature difference is different compared to the temperature difference.

[0049]

[0053] In each embodiment, one or more snubbers, generally designated 41, may be disposed between the cold mass and the thermal radiation shield; two snubbers 40a, 40b are shown in the exemplary embodiment of FIG. 3 . The snubbers 40a, 40b may be used to cushion the deflection of the thermal radiation shield (or to further cushion the deflection of the thermal radiation shield in combination with one or more thermal radiation shield supports). In each embodiment, the snubbers may be fabricated from substantially the same material as the thermal radiation shield supports (e.g., a low thermal conductivity material) and are disposed between the cold mass and the radiation shield. In each embodiment, the snubbers may be fabricated from a material different from the thermal radiation shield support material. In each embodiment, the snubbers may be fabricated from a material that is not a low thermal conductivity material because a vacuum gap exists that blocks heat transfer from the radiation shield to the cold mass through the snubbers during normal operation. A thermal short circuit through the snubbers may occur under conditions not expected under normal operating conditions (e.g., during a quench or with unusual mechanical unbalance forces), at which point the magnet needs to be shut down.

[0050]

[0054] During normal magnet operation, the snubbers contact only one of these entities. That is, one end of each snubber is fixed to either the cold mass or the thermal radiation shield (but not both), leaving a gap, such as gaps 41a, 41b (generally referred to as 41) in FIG. 3. Thus, in this example, to provide the gaps, snubbers are selected to have lengths such that the second end of each snubber is spaced a predetermined distance from the surface of the thermal radiation shield. That is, the snubber lengths are selected to leave gap 41, and the size of the gap is selected to limit the amount of deformation of the thermal radiation shield. Gaps 41a, 41b need not be the same size.

[0051]

[0055] In the exemplary embodiment of FIG. 3 , the snubbers are shown as being fixed to the cold mass. That is, each snubber has a first end attached to or secured to the cold mass, and a gap exists between the second end of the snubber and the surface of the thermal radiation shield. The attached snubber ends may be attached using bolts, screws, fasteners, welding, or other additional attachment mechanisms (e.g., any of the attachment techniques or means described above in connection with attaching the thermal radiation shield support). In each embodiment, one or more snubbers may be fixed to the cold mass, and one or more snubbers may be fixed to the thermal radiation shield (i.e., not all snubbers need to be coupled to the same structure; it may be desirable to attach some snubbers to the cold mass while others are attached to the thermal radiation shield). In each embodiment, there may be two, four, or more snubbers as needed to suit the needs of a particular application.

[0052]

[0056] During a quench, the thermal radiation shield may be deformed by electromagnetic forces caused by eddy currents generated during the magnet quench, and portions of the deformed thermal radiation shield may come into contact with the buffer, thus reducing its deflection and limiting (ideally preventing) the number and / or size of deformations, damage, and even fractures that may occur within the thermal radiation shield.

[0053]

[0057] The particular number (if any) and positioning of snubbers between the cold mass and the thermal radiation shield will depend on the needs of the particular application. The number and positioning of snubbers will be chosen to prevent unacceptable deformation and stress of the radiation shield and to prevent thermal short circuits between the shield and the cold mass in any mode of operation (cooling, charging the superconducting magnet, operation under nominal current, discharging, warming, and quenching).

[0054]

[0058] In some embodiments, the thermal radiation shield support and the snubber may be used together in a single system. In some embodiments, only the thermal radiation shield support may be used (i.e., some embodiments may not include a snubber). For example, the thermal radiation shield support may be located where the snubber is shown in FIG. 3, or the snubber may be omitted or moved to a different location.

[0055]

[0059] In one embodiment, the thermal radiation shield supports and snubbers can be relatively small in size compared to the size of the cold mass 30. The use of rigid spacers in combination with snubbers allows the radiation shield to be thinner and can be made of a higher thermal conductivity material, often with no or less penetration into the radiation shield.

[0056]

[0060] Note that the location of the radiation shield between the cold mass and the cryostat is not determined by the location of the thermal intercept on the CW support. Similarly, the thermal intercepts on the CW support are not determined by their connection points to the radiation shield, but may be located at any point along the length of the CW support and independent of the location of the radiation shield. The thermal intercept is optional and may not be present. A flexible connection to the cooling source may be used instead of or in addition to the thermal intercept.

[0057]

[0061] In embodiments in which the radiation shield is composed of segments (e.g., segments 33a-33d in FIG. 3), the CW supports may be inserted into or otherwise disposed in gaps between the segments. In embodiments in which the radiation shield is adhesive, i.e., not composed of segments, the CW supports may be inserted into or otherwise disposed in notches in the radiation shield.

[0058]

[0062] Referring now to FIG. 4 , in which like elements of FIG. 3 are given like reference numerals, a thermal radiation shield support 38 and a buffer 40 may be utilized in a design having a cryocooler 42 coupled to or attached to the cryostat wall 32 and configured to cool the superconducting magnet 30. A cryostat flange 37 provides an airtight seal for the cryostat chamber in which the cold mass 30 resides. When cooled by a two-stage cryocooler, the thermal radiation shield support 38 and buffer 40 eliminate the need for a flexible connection between the first stage 44 of the cryocooler and the radiation shield 33. However, a flexible connection (such as that described above in FIG. 2 ) may still be used. Both stages 44, 46 of the two-stage cryocooler may be rigidly connected to their respective cooled entities: the first stage 44 to the radiation shield 33 and the second stage 46 to the cold mass 30. In FIG. 4 , the thermal radiation shield support 38 and optional snubber 40 are shown as being disposed between the radiating cold mass 30 and the thermal radiation shield 33. Note that while the schematic diagram in FIG. 4 shows the thermal radiation shield support 38 and snubber 40 adjacent to one another, in reality the snubber 40 is spaced apart from the thermal radiation shield support 38. For example, the snubber and thermal radiation shield support may be spaced apart along the longitudinal axis of the cold mass, and / or may be spaced apart on multiple sides (e.g., opposite sides) of the cold mass, and / or may be spaced apart axially around the cold mass. After reading the disclosure provided herein, one skilled in the art will understand how to space the snubber and thermal radiation shield support.

[0059]

[0063] Through the use of the thermal radiation shield support 38, assembly of the HTS magnet becomes a much simpler and less risky operation compared to prior art techniques. First, the thermal radiation shield is constructed around the cold mass, which is then installed in the cryostat. The thermal radiation shield is firmly attached to the cold mass without any flexibility, forming a rigid radiation shield-cold mass subassembly. Once the radiation shield-cold mass subassembly is installed in the cryostat, the CW support and thermal intercept are installed. As previously mentioned, the CW support passes through one or more gaps or notches in the thermal radiation shield and does not contact the thermal radiation shield.

[0060]

[0064] By first connecting or otherwise positioning or installing the thermal radiation shield support onto the cold mass before installation in the cryostat, and then connecting or otherwise positioning or installing the thermal radiation shield to the thermal radiation shield support, the cold mass area is easily accessible during assembly. Furthermore, the radiation shield may be installed after the cold mass, meaning that fewer cutouts in the radiation shield may be required to install the cold mass. This approach requires fewer patches and fewer gaps in the thermal radiation shield compared to the amount of patches and number of gaps required when using prior art techniques. Furthermore, by forming a rigid radiation shield-cold mass subassembly as described above, assembly and disassembly, tracking and securing instrumentation to the thermal radiation shield, installing multi-layer insulation, and inspecting components and structures are also much easier compared to prior art techniques.

[0061]

[0065] It will be understood that although reference may be made herein to particular materials, other materials having similar functional and / or structural properties may be substituted, if desired, and that those skilled in the art would understand how to select such materials and incorporate them into embodiments of the concepts, techniques, and structures described herein without departing from the scope of these teachings.

[0062]

[0066] Various embodiments of the concepts, systems, devices, structures, and techniques sought to be protected are described herein with reference to the associated drawings. Alternate embodiments may be devised without departing from the scope of the concepts, systems, devices, structures, and techniques described herein. It should be noted that various connections and relationships (e.g., above, below, adjacent, etc.) are described between elements in the above specification and drawings. These connections and / or relationships may be direct or indirect unless otherwise specified, and the described concepts, systems, devices, structures, and techniques are not intended to be limiting in this respect. Thus, coupling of entities can refer to either a direct coupling or an indirect coupling, and relationships between entities may be direct or indirect. The term "connect" can include an indirect "connection" and a direct "connection." The term "direct contact" means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediate elements.

[0063]

[0067] As an example of an indirect positional relationship, a reference herein to providing a structure, part, or device "A" on a structure, part, or device "B" includes situations where one or more intermediate structures, parts, or devices (e.g., part "C") may be between the structure, part, or device "A" and the structure, part, or device "B," so long as the associated properties and functions of the structure, part, or device "A" and the structure, part, or device "B" are not substantially altered by the intermediate structures (20 parts or devices).

[0064]

[0068] The following definitions and abbreviations are to be used for interpreting the claims and the specification. As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing," or any other variation thereof, are intended to encompass what is included non-exclusively. For example, a composition, mixture, process, method, article, or device that includes a list of elements is not necessarily limited to only those elements and can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or device.

[0065]

[0069] Moreover, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs.

[0066]

[0070] The term "one or more" is understood to include any integer greater than or equal to one, i.e., 1, 2, 3, 4, etc. The terms "plurality" and more than one are understood to include any integer greater than or equal to two, i.e., 2, 3, 4, 5, etc.

[0067]

[0071] References herein to "one embodiment," "an embodiment," "exemplary embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic; however, it should be understood that all embodiments may include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with one embodiment, it is understood that it is within the knowledge of one skilled in the art to make changes to such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0068]

[0072] For purposes of the following description, the terms "upper," "lower," "right," "left," "vertical," "horizontal," "top," "bottom," and their derivatives refer to the structures and methods described as oriented in the drawings. The terms "overlying," "atop," "on top," "positioned on," or "positioned atop" mean that a first element, such as a first structure, is on a second element, such as a second structure, and that intervening elements, such as interfacial structures, may be present between the first and second elements.

[0069]

[0073] The use of ordinal numbers such as "first," "second," "third," etc. in the claims to modify claim elements does not in itself imply any priority, precedence, or order of one claim element over another, or the chronological order in which acts of a method are performed, but is merely used as a label to distinguish one claim element having a certain name from another element having the same name (absent the use of ordinal numbers) to distinguish between claim elements.

[0070]

[0074] The terms "approximately" and "about" can be used to mean, in some embodiments, within ±20% of a target value, in some embodiments, within ±10% of a target value, in some embodiments, within ±5% of a target value, and even in some embodiments, within ±2% of a target value. The terms "approximately" and "about" can include the target value.

[0071]

[0075] The term "substantially" may be used to refer to values ​​that are within ±20% of the comparative scale in some embodiments, within ±10%, within ±5%, and even within ±2% in some embodiments. For example, a first direction that is "substantially" orthogonal to a second direction may refer to a first direction that is within ±20% of forming a 90° angle with the second direction in some embodiments, within ±10% of forming a 90° angle with the second direction in some embodiments, within ±5% of forming a 90° angle with the second direction, and even within ±2% of forming a 90° angle with the second direction in some embodiments.

[0072]

[0076] The term "substantially equal" may be used to refer to values ​​that, in some embodiments, are within ±20% of each other, in some embodiments, are within ±10% of each other, in some embodiments, are within ±5% of each other, and even in some embodiments, are within ±2% of each other.

[0073]

[0077] It is to be understood that the disclosed subject matter is not limited in its application to the details of construction and the arrangement of components set forth in the following specification or illustrated in the drawings. The disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. It is also to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Thus, those skilled in the art will appreciate that the conception upon which the disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the disclosed subject matter. The claims, therefore, are to be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.

[0074]

[0078] While the disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments, it will be understood that the disclosure is made by way of example only and that numerous changes in the details of the implementation of the disclosed subject matter can be made without departing from the spirit and scope of the disclosed subject matter.

Claims

1. a thermal radiation shield; Cold mass and one or more thermal radiation shield supports connected to the cold mass and the thermal radiation shield such that the cold mass supports the thermal radiation shield; An assembly comprising:

2. The assembly of claim 1 , wherein the one or more thermal radiation shield supports have a first end connected to the cold mass and a second, opposite end coupled to the thermal radiation shield.

3. The assembly of claim 1 , wherein the cold mass comprises a superconducting magnet.

4. The assembly of claim 1 , wherein the cold mass comprises a high temperature superconducting (HTS) magnet.

5. The assembly of claim 1 , further comprising one or more snubbers, each of the one or more snubbers connected to one of the cold mass or the thermal radiation shield.

6. The assembly of claim 1 , wherein the one or more thermal radiation shield supports comprise a low thermal conductivity material.

7. The assembly of claim 5 , wherein the one or more bumpers comprise a low thermal conductivity material.

8. 10. The assembly of claim 1, further comprising one or more cold-to-warm (CW) supports having a first end coupled to the cold mass and having a second end configured to be coupled to a cryostat.

9. The assembly of claim 8 , further comprising one or more thermal intercepts coupled to at least one of the one or more CW supports.

10. The assembly of claim 1 , wherein the one or more thermal radiation shield supports comprise a low thermal conductivity material.

11. The assembly of claim 1 , wherein the one or more thermal radiation shield supports are connected to the cold mass using at least one of one or more bolts, one or more screws, or one or more fasteners.

12. 1. A method of assembling a superconducting magnet, comprising: connecting a first end of one or more thermal radiation shield supports to the cold mass; connecting second ends of one or more thermal radiation shield supports to a thermal radiation shield disposed around the cold mass; placing the thermal radiation shield and the cold mass in a cryostat; connecting a first end of one or more cold-to-warm (CW) supports to the cryostat; and connecting second ends of one or more CW supports to the cold mass, wherein the one or more CW supports pass through the thermal radiation shield.

13. The method of claim 12 , further comprising connecting a snubber to one of the cold mass or the thermal radiation shield.

14. The method of claim 12 further comprising connecting one or more CW supports to the cold mass.

15. The method of claim 14 , further comprising coupling one or more thermal intercepts to at least one of the one or more CW supports.

16. 16. The method of any of claims 13 to 15, further comprising the step of placing the cold mass and thermal radiation shield in a cryostat chamber of a cryostat.

17. 15. The method of claim 14, wherein the superconducting magnet is a high temperature superconducting (HTS) magnet.

18. The method of claim 14 , wherein the one or more thermal radiation shield supports comprise a low thermal conductivity material.

19. The method of claim 12 , wherein the one or more thermal radiation shield supports comprise a low thermal conductivity material.

20. a cold mass equipped with a superconducting magnet; a thermal radiation shield; one or more thermal radiation shield supports connected to the cold mass and the thermal radiation shield; one or more cold-to-warm supports having a first portion connected to the cold mass and a second portion configured to be coupled to a cryostat, each of the one or more cold-to-warm supports passing through the thermal radiation shield without contacting the thermal radiation shield; A system comprising:

21. The system of claim 20 , wherein the one or more cold-to-warm supports further comprise one or more thermal intercepts.

22. The system of claim 20 , further comprising a snubber connected to one of the cold mass or the thermal radiation shield.

23. The system of claim 20 , further comprising a cryostat thermally coupled to the cold mass and the thermal radiation shield and configured to cool the cold mass and the thermal radiation shield.

24. the cryostat comprises a cryostat chamber; the cold mass and the thermal radiation shield are disposed within the cryostat chamber; the second portion of the one or more cold-to-warm supports is connected to a wall of the cryostat.

24. The system of claim 23.

25. 21. The system of claim 20, wherein the superconducting magnet is a high temperature superconducting (HTS) magnet.

26. The system of claim 20 , wherein the one or more thermal radiation shield supports comprise a low thermal conductivity material.

27. A cryostat and a superconductor magnet including a high temperature superconductor (HTS) material and disposed within the cryostat; a thermal radiation shield disposed within the cryostat and coupled to the superconductor magnet via a plurality of spacers; a plurality of supports coupling the superconductor magnet to the cryostat, the plurality of supports passing through one or more gaps in the thermal radiation shield; A system comprising:

28. 30. The system of claim 27, wherein the plurality of supports pass through the one or more gaps in the thermal radiation shield without contacting the thermal radiation shield.

29. 28. The system of claim 27, wherein each of the plurality of supports passes through a respective gap in the thermal radiation shield.

30. 28. The system of claim 27, further comprising a plurality of snubbers disposed between the superconductor magnet and the thermal radiation shield, each of the plurality of snubbers coupled to either the superconductor magnet or the thermal radiation shield.

31. 30. The system of claim 27, wherein the thermal radiation shield comprises an electrical conductor.

32. 32. The system of claim 31, wherein the thermal radiation shield comprises a plurality of conductive shield segments connected via one or more non-conductive structures.

33. 30. The system of claim 27, further comprising one or more thermal intercepts coupled to at least one of the plurality of supports.

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