Method for reinforcement, quench protection, and stabilization of large all-metal superconducting magnets

Abstract

Disclosed is a technique that enables structural reinforcement and thermal stabilization of the conductor winding in a superconducting coil configuration, and superconducting coils produced via the technique. The superconducting coils generally include coil windings of superconducting materials defining an electrically conductive channel having an inlet and an outlet, where the coil windings are either (i) helically wound around a curve around a central axis or (b) wound in helical layers around a curve around a central axis. One or more of the coil windings are operably coupled to at least one co-wound reinforcement layer, where the at co-wound reinforcement layer(s) are positioned between at least two adjacent superconducting coil windings or layers of superconducting coil windings. The method can significantly improve the packing factor in a coil winding while simplifying quench protection, permitting the construction of all-metal high field magnets with large bore and high magnetic field.

Description

[0001] METHOD FOR REINFORCEMENT, QUENCH PROTECTION, AND STABILIZATION OF LARGE ALL-METAL SUPERCONDUCTING MAGNETS

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] The present application claims priority to U.S. Provisional Patent Application No. 63 / 532,785, filed August 15. 2023, the contents of which are incorporated by reference herein in its entirety.

[0004] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0005] This invention was made with U.S. government support under Contract No. DE-AC02- 09-CH 11466 awarded by the Department of Energy. The government has certain rights in the invention.

[0006] TECHNICAL FIELD

[0007] The present disclosure is drawn to techniques for improving large superconducting magnets to address one of the most challenging issues on quench protection for large all-metal no-insulation superconducting magnets, and specifically, techniques for manufacturing superconducting magnets that reduce construction cost, increase coil radiation resistance, and improve coil structural integrity.

[0008] BACKGROUND

[0009] Superconducting coils have numerous uses, including use in fusion reactors, as well as in commercial nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) applications, and in high field accelerators used in high energy physics applications, and magnets for certain scientific discoveries (such as magnets for dark matter detectors in the cosmic frontiers)..

[0010] Improvements to superconducting coils, especially HTS magnets, often sound promising following small scale experiments, but fail to reliability and / or repeatably perform, and / or are unaffordable when scaled up to the relatively high fields and / or large bores needed for feasible real-world use applications. BRIEF SUMMARY

[0011] In various aspects, a superconducting coil may be provided. The superconducting coil generally includes a plurality of coil windings that include superconducting material(s) (which may be in the form of, e.g., wires, tapes, or cables) defining an electrically conductive channel having an inlet and an outlet. One or more (and preferably all) of the plurality of coil windings may be operably coupled to at least one co-wound reinforcement layer. There are typically two variations of this arrangement. In a first variation, the plurality of coil windings may be helically wound around a curve around a central axis, and at least one co-wound reinforcement layer may be positioned between at least two adjacent superconducting coil windings. In a second variation, the plurality of coil windings may be wound in helical layers around a curve around a central axis, and at least one co-wound reinforcement layer may be positioned between at least two adjacent superconducting coil windings or layers of superconducting coil windings.

[0012] The at least one co-wound reinforcement layer may be coupled to the at least two adjacent superconducting windings by one of friction, winding tension, and clamping forces. The at least one co-wound reinforcement layer may be coupled to the at least two superconducting windings by one of soldering, brazing, diffusion bonding, welding, and conducting glue, depending on the superconductor used. The at least one co-wound reinforcement layer may be coupled to the at least two adjacent windings by bonding the cowound reinforcement layer to the superconducting materials and the rest of a coil-pack by soldering, brazing, diffusion bonding, or gluing after winding the superconducting coil.

[0013] The at least one co-wound reinforcement layer may include a single layer. The at least one co-wound reinforcement layer may include multiple layers. In some embodiments, multiple layers of varying thicknesses (e.g.. layer 1 may be thicker than layer 2. etc.) may be utilized for improving performance integration or integrated coil performance during operation.

[0014] A thickness of the at least one co-wound reinforcement layer may be constant. A thickness of the at least one co-wound reinforcement layer in a first location may be different from a thickness of the at least one co-wound reinforcement layer in a second location. In certain aspects, thickness of the at least one co-wound reinforcement layer may vary continuously, for example, by uniform or variable tapering of at least one co-wound reinforcement layer. In certain aspects, thickness of the co-wound reinforcement layer may change between a set of discrete thicknesses with a relatively short ramp between discrete levels, such as when the ramp has a length of less than one turn around the coil.

[0015] The co-wound reinforcement layer may include a resistive or conductive coating, including tightly bound layers of copper, silicon, germanium, silicon-carbide, or boriding or carbonizing surface treatments. The location of the resistive or conductive coating for deployment inside the coil winding pack may be guided by the coil design based on its integrated performance during operations.

[0016] At least one co-wound reinforcement layer may include various materials, including carbon, silicon, germanium, silicon carbide, aluminum, copper, and / or silver. At least one cowound reinforcement layer may contain high-strength steel, a superalloy (such as HASTELLOY® superalloys, INCONEL® superalloys, etc.), a maraging alloy, or a high- strength refractory alloy (such as one including tantalum and / or tungsten). Selection of the particular material may be dependent on the application.

[0017] In various aspects, a method of constructing superconducting electro-magnets for structural reinforcement and quench protection may be provided. The method may include coupling at least one co-wound reinforcement layer to a superconducting coil. The method may include embedding at least one co-wound reinforcement layer between at least two windings of the superconducting coil.

[0018] The at least one co-wound reinforcement layer may be coupled to the at least two adjacent superconducting windings by one of friction, winding tension, and clamping forces. The at least one co-wound reinforcement layer may be coupled to the at least two superconducting windings by one of soldering, brazing, diffusion bonding, welding, and conducting glue. The at least one co-w ound reinforcement layer may be coupled to the at least two adjacent windings by bonding the co-wound reinforcement layer to the superconducting materials and the rest of a coil-pack by soldering, brazing, diffusion bonding, or gluing after winding the superconducting coil.

[0019] The method may include tuning at least one co-wound reinforcement layer to provide a desired tum-to-tum electrical contact resistance in an all-metal coil, based on its application.

[0020] The method may include selecting at least one co-wound reinforcement layer to optimize one or more variables, such as strength, specific heat, electrical conductivity, thermal conductivity, and / or cost. If the at least one co-wound reinforcement layer is formed with multiple layers, the method may include selecting at least one layer of the multiple layers to optimize strength, specific heat, electrical conductivity, thermal conductivity, and / or cost.

[0021] The method may include determining one or more thicknesses of the at least one cowound reinforcement layer to match a desired distribution of strength, thermal mass, electrical conductivity, and thermal conductivity.

[0022] The method may include configuring a material or structure of the at least one cowound reinforcement layer to achieve a desired tum-to-tum electric or thermal resistance of the superconducting coil. For example, tum-to-tum electric or thermal resistance may be adjusted by applying a resistive or conductive coating (such as a boriding surface treatment) to at least one co-wound reinforcement layer.

[0023] BRIEF DESCRIPTION OF FIGURES

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the present invention.

[0025] Figure 1 is an illustration of a magnet assembly.

[0026] Figure 2 is a side-view illustration of a coil section.

[0027] Figure 3 is a cut-away side-view illustration of one embodiment of a coil section, showing a portion of an axial layer as indicated in Figure 2.

[0028] Figure 4 is a cut-away side-view illustration of another embodiment of the coil section shown in Figure 3.

[0029] Figure 5 is an illustration of a co-wind reinforcing layer with a ramp in thickness.

[0030] Figures 6A-6B are cut-away side-view illustrations of other embodiments of a coil section.

[0031] Figure 7 is an illustration of a solenoid and magnetic field lines.

[0032] Figure 8 is a plot showing stress distribution in a cross-section of an embodiment of a winding pack with co-wind structural reinforcement.

[0033] Figure 9 is an image of a 3D model of a magnet assembly.

[0034] Figure 10 is an image of a prototype magnet assembly.

[0035] Figure 11 is a side view illustration of a toroidal field coil of non-circular shape, and a cut-away illustration of a coil section with reinforcement of two thicknesses. Figure 12 is a top view illustration of a toroidal field array, in combination with a central solenoid and poloidal field coils.

[0036] Figure 13 is a flowchart of a method.

[0037] It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the sequence of operations as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes of various illustrated components, will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity or illustration.

[0038] DETAILED DESCRIPTION

[0039] Disclosed herein is a method for reinforcement, quench protection, and stabilization of large all-metal high-field superconducting magnets. More particularly, disclosed is a method for constructing superconducting electromagnetic coils of any size and magnetic field strength without the use of conventional electrical insulators, and providing intrinsic superconductor quench protection. This enables the scaling-up of the benefits of all-metal, no-insulation superconducting coils techniques (see, e.g., US 4,760,365 A, US 9.117,578 B2) to large scale coils, needed for fusion, MRI, and other applications.

[0040] The disclosed approach is a method and a process that simultaneously enables structural reinforcement, thermal stabilization and electrical stabilization of the conductor winding in a superconducting coil configuration. The disclosed approach uses a co-wound high-strength reinforcement that supports Lorentz forces when energizing a high field and / or large-bore superconducting electromagnet without requiring other expensive and exotic structures to form the coil winding. This same co-wound reinforcement layer is designed to also provide sufficient cryogenic thermal mass, thermal conductivity, and electrical conductivity needed for superconducting coil quench protection.

[0041] The disclosed approach will enhance the packing factor of the coil by optimization of the co-wound reinforcement for coil structural integrity and thermal stability. It also ensures coil protection in the event of quench where the co-wound structural reinforcement will act as cold mass for thermal protection of the coil winding pack. This is particularly beneficial for expanding the applicability of all-metal coil designs by eliminating the need for separate complex, error-prone vacuum pressure impregnation (VPI) by epoxy or other insulators, and costly quench protection systems that require invasive and fragile fiber optic or acoustic quench sensors, or quench heaters in the winding pack usually used in large superconducting coils for fusion, MRI, and other applications. Because packaging of these fiber optic sensors or quench heaters in the tightly wound coil winding pack is very7challenging, the disclosed methods greatly simplify coil construction and improve coil system reliability7. This method mitigates high field operation risks such as structural failures due to local stresses exceeding coil winding support structural stress limits (for example, screening current induced high local stress), or peak temperature exceeding limits during quench in the winding pack.

[0042] All-metal construction of high-field and large-bore coils enables efficient cooling of the winding pack by eliminating internal insulation, allowing the use of conduction cooling to eliminate the need for large amounts of helium or other cryogenic fluids or gasses. This also simplifies the coil construction and reduces costs.

[0043] Thus, the disclosed method will enable efficient coil winding pack stress and thermal management of all-metal high temperature superconductor (HTS) magnets capable of stable operation at high magnetic fields while reducing cryogenic fluid consumption and cooling costs.

[0044] An important feature of the disclosed method is its ability7to integrate coil stress and thermal protection / cooling management together for winding of high field magnets by optimizing a co-wound structural reinforcement and establishing control of the added cold mass in engineering the tum-to-tum contact resistive heating for quench protection. The thermal energy7can be more uniformly distributed during quench, and risks of slow cryogenic cooling response (vs. fast local heating) can be mitigated. Previously developed structural reinforcement methods and conventional methods for coil quench protection are decoupled and not integrated, complicating the design of the winding pack.

[0045] In the disclosed approach, the coil winding pack structural support (stress management) and coil quench protection system (thermal management and electrical dissipation) are integrated and jointly optimized to simplify the coil design and performance. It is critically important in high-field large magnets, such as for fusion and MRI, that coil support structures can be optimized for desirable winding pack stress distribution while providing sufficient cold mass for quench protection to minimize cryogenic cooling requirements.

[0046] The disclosed method can achieve stress optimization and thermal management of coil winding pack in a high field all metal superconducting coil, thus enabling the manufacture and reliable operation of low cost, high field magnets of a flexible size with reduced cooling requirements than comparable superconducting magnets constructed by other methods where stress management of coil winding pack and coil quench protection are fully decoupled.

[0047] Furthermore, the disclosed method provides co-wound reinforcement coil design in a manner that is easily scalable to different magnet sizes and shapes (fusion magnet relevant) and amenable to automation.

[0048] More particularly, disclosed is the method of coil winding with co-wound structural reinforcement and a process to integrate the structural reinforcement into the coil winding with varying thickness to optimize winding pack stress distribution in a high field superconducting magnet while also using the reinforcement as cold mass for coil quench protection by careful design and selection of reinforcement materials such that stress and thermal management is balanced. The co-wound reinforcement layer can also be designed to control the thermal conduction along and across the superconducting windings, to spread any thermal dissipation, reduce temperature increases, and protect against quench damage.

[0049] In various aspects, a superconducting coil may be provided. Referring to FIG. 1, a magnet assembly (100) may include various sections, which may be formed around a central axis (101). The sections may include a coil section (110), which include the superconducting coils as disclosed herein. The sections may include terminal rings (120), which may be, e.g., a heat conducting material such as copper, and structural materials, such as stainless steel or INCONEL® superalloys. The sections may include one or more preloading rings (130), which may also be a metal. The sections may include a central mandrel (140), which may have a portion (141), such as a hollow cylindrical portion, that extends axially through the magnet assembly (e.g., through the terminal rings, the coil section, and the pre-loading section).

[0050] Referring to FIG. 2, the coil section (110) may include n axial layers (200(1), 200(2), ... , (200(n)), where n may be, e.g., at least 1, at least 2, at least 3, at least 5, at least 10, at least 20, or at least 50, up to no more than 1000, no more than 500, no more than 250, or no more than 100, including all ranges and subranges thereof.

[0051] Two variations are discussed. Generally, the coils can be wound either as a series of pancake or double-pancake sub-coils, with the windings (typically composed of superconducting wires, tapes, or cables, which may contain embedded wires and / or tapes) and co-wound reinforcement stacked radially, or as a layer wound coils with the reinforcement spanning one or multiple windings in the layers, and the reinforcement being aligned with the superconductor or not. These terms will be familiar to knowledgeable practitioners of this field. Referring to FIG. 2, in a first variation, within each axial layer, the superconducting material and the co- wind material may alternate as you move radially outward from the central axis (101). Referring to FIG. 3, an inner surface (305) of each layer may be a distance d\ (330) from the central axis (101) (z / i>0). The superconducting coil includes a plurality of coil windings (310(1), 310(2), .. . ), each of which may be comprised of superconducting material(s) defining an electrically conductive channel having an inlet and an outlet (e.g., from a beginning of an inner winding (301) and an end of an outer winding (302).

[0052] The all-metal superconducting coils may be constructed from any appropriate material, including, e.g., from low-temperature superconductors such as niobium-titanium (NbTi) and niobium-tin (NbsSn). high temperature superconductors such as ReBCO, YBCO, and BSCCO, and medium temperature superconductors such as magnesium di-boride (MgB2). The superconductor winding can be in the form of wires, tapes, or cables composed of wires and tapes.

[0053] The plurality of coil windings may be operably coupled to at least one co-wound reinforcement layer (320). The plurality of coil windings may be helically wound around a curve around a central axis (101). It will be understood that while a cylindrical arrangement is shown, the shape of the windings may vary as needed to create the desired magnetic fields. For example, the cross-sectional area could be a rectangle with rounded comers, a “D” shape (see FIG. 11), or other arbitrary 2D shape.

[0054] At least one co-wound reinforcement layer (320) may be positioned between at least two adjacent superconducting coil windings (e.g., first winding (310(1) and second winding (310(2)).

[0055] In FIG. 3, the co-winding reinforcing layer is shown as a single layer. In some embodiments, as seen in FIG. 4. the co-winding reinforcing layer (420) may include multiple layers (421, 422, 423). In some embodiments, this may include at least 2, at least 3, or at least 4 layers, up to no more than 10, no more than 8, no more than 6, no more than 5, or no more than 4 layers, including all ranges and subranges thereof.

[0056] The high-strength co-wound reinforcement material can be chosen to optimize strength, specific heat, electrical and thermal resistivity, cost, and other properties. Suitable very high- strength reinforcement materials include high-strength steel, superalloys such as Hastelloy, Inconel and maraging alloys, and high-strength refractory' alloys of halfnium, tantalum and / or tungsten. These may be combined with materials with high thermal and electrical conductivity', such as aluminum, copper, silver, carbon fibers or layers thereof. In some embodiments, a thickness (such as first thickness h (331) and second thickness ti (332) of the at least one co-wound reinforcement layer may be constant. In other aspects, the thickness of the reinforcement may be varied through the coil cross-section to match the needed distribution of strength and thermal mass, while minimizing coil cross-section and cost. For example, a thickness of the at least one co-wound reinforcement layer in a first location (e.g., first thickness ti (331)) may be different from a thickness of the at least one co-wound reinforcement layer in a second location (e.g.. second thickness ti (332)), The variation of the thickness can be continuous, e.g., by uniform or variable tapering the co-wound reinforcement, or by change between a set of discrete thicknesses with relatively short ramps in the thickness between the discrete levels. Referring to FIG. 5, a ramp (501) is shown, in the reinforcement layer, in the direction of winding (502). The ramp may generally be shorter than the length of one turn. As shown, the reinforcing layer may have a width w (510). The length I (520) of the ramp is generally relatively short, but long enough that the change in thickness will not damage a superconducting layer that is disposed directly over the ramp. For example, given a mandrel of any shape and size, where the reinforcing layer is intended to wrap around the mandrel at least 360 degrees (e.g.. at least one full turn), the length of the ramp may be the length of 0.25- 1 tum(s). The length of the ramp may be less than 1 turn. The length of the ramp may be at least 0.25 turns, at least 0.3 turns, at least 0.35 turns, at least 0.4 turns, at least 0.45 turns, or at least 0.5 turns, up to no more than 1 turn, no more than 0.9 turns, no more than 0.8 turns, no more than 0.7 turns, or no more than 6 turns, including all ranges and subranges thereof.

[0057] The dimensions of the co-wound reinforcement layer may vary as appropriate, depending on the coil geometry, the materials used, the winding pack size and shape, the magnetic field strength and stored magnetic energy. Any appropriate width is envisioned, which may be smaller or wider than the width of the superconducting wires, tapes, or cables. For a layer-wound coil, the width of the reinforcement could be the width of the layer or wider. For large-bore high-field coils, where the maximum magnetic field on the inside (low? radius side) of the winding pack is 3 or more times higher than the magnetic field at the center of the coil, the thickness of the co-wound reinforcement may be 2-3 time the superconductor thickness. In the lower magnetic field regions, near the outside of the winding pack (large radius side), the thickness of the co-wound reinforcement is likely to be similar to the superconductor thickness or thinner. This is applicable to both pancake-wound coils or layerwound coils. In some embodiments, at least a portion (520) of the co-wound reinforcement layer may include a resistive or conductive coating to encourage or resist electrical current conduction around the structural reinforcement, and to encourage or impede heat penetrating into the reinforcement. In some embodiments, a portion (521) of the co-wound reinforcement layer may be free of a resistive or conductive coating. Referring to FIG. 4, in some embodiments, the resistive or conductive coating may be a surface (424) adjacent to a superconducting winding (410). In some embodiments, the resistive or conductive coating may be a surface (425) that is not adjacent to a superconducting winding. If a resistive coating is utilized, the resistive coating may be a tightly bound layer of silicon, germanium, silicon carbide, or a bonding or carbonizing surface treatment.

[0058] Referring to FIG. 6A. in a second variation, the plurality of coil windings may be wound in helical layers (610(1), ... , 610(n)) around a curve around a central axis (101), and at least one co-wound reinforcement layer (620(1), ... , 620(n)) is positioned between at least two adjacent superconducting coil windings or layers of superconducting coil windings (here, between first layer 610(l-n) and second layer 611(I-n)). In FIG. 6A, a mandrel defining the curve, where the helical layers of the superconductor may, for example, start at or near a first end (601), winding up the mandrel in a helical pattern, and then stop at a second end (620). That first superconductor layer may then be coupled to a reinforcing layer, which may have helical that, for example, start at the second end (620) and wind in a helical pattern down to the first end (601). The process may then repeat as desired. In FIG. 6B, instead of the reinforcing layer being helically wound, the reinforcing layer may simply extend from one end to the other, forming a layer between the first helical layer of the superconductor (e.g., layer (610(l-n)) and the second helical layer of the superconductor (e.g., layer 61 l(l-n)).

[0059] In some embodiments, a radial width or thickness t3 (631) of each reinforcement layer may be identical. In some embodiments, a radial width or thickness t3 (631) of a first set of layers may vary as disclosed herein.

[0060] The coil windings and the co-winding reinforcement layers should be free of organic insulation.

[0061] Referring to FIG. 7, magnetic field lines for a solenoid are shown, with an expanded portion showing screening current directions (e g., alternating portions within the solenoid, with a first portion (701) rotating in a first direction, and a second portion (702) rotating in a second direction) within the solenoid, and an indication of the Lorentz forces in the radial direction. As seen, the Lorentz forces may be directed radially inward for screening currents in a first direction (e.g., first portion (701)) and radially outward for screening currents in a second direction (e.g., second portion (702)).

[0062] Referring to FIG. 8, a plot showing stress distribution in a cross-section of a solenoid winding pack with co-wind structural reinforcement as disclosed herein.

[0063] FIG. 9 is an image showing a 3D model of a magnet assembly as disclosed herein, and FIG. 10 is an image showing a prototype magnet assembly.

[0064] Aside from the arrangement of the layers, the coil windings, co-woundreinforcement layer, and variations are the same as in the first variation, and may be configured as disclosed herein. For example, each co-winding reinforcement layer may be a single or multiple layers, the thickness of the co-winding reinforcement layer may be constant or may vary, etc.

[0065] The co-wound materials may be selected for, e.g., controlling of the winding pack thermal mass for coil quench protection (uniform energy dump), tuning contact resistance between conductor and co-wind for passive protection in NI coils, and / or structural reinforcement to ensure mechanical strain control in superconductor in the winding pack.

[0066] For example, for the coils disclosed herein, the co-wound reinforcement can be tuned and / or engineered to provide the desired tum-to-tum electrical contact resistance in an all-metal coil. For a large bore coil, the contact area between adjacent turns can be very large, resulting in a very low resistance betw een turns. This resistance should preferably be low' enough so the current can easily move around any normal zone by flowing radially between windings, providing quench protection. Higher resistance can be used to increase the coil operating voltage and decrease the charging time. Quench stability can be evaluated and optimized quantitatively. The tum-to-tum resistance can be adjusted by choice of the reinforcement material or by incorporating a conductive or resistive coating to the reinforcement, including tightly bound layers of silicon, germanium, silicon carbide, copper, or bonding or carbonizing surface treatments.

[0067] The reinforcement of the superconductor can be included in the winding of the coil in several ways, including:

[0068] - As a co-wound layer, connected to the superconductor by friction, winding tension, and clamping forces.

[0069] - By bonding to the superconductor by soldering, brazing, diffusion bonding, or using a conducting glue before winding the coil

[0070] - By bonding to the superconductor and the rest of the coil-pack by soldering, brazing, diffusion bonding, or gluing after winding the coil, in the manner described in the Appendix. A number of prototype HTS coil windings were designed, fabricated and are being tested to validate the stress and thermal characteristics using the continuous winding method for stacking of double pancake coils.

[0071] The disclosed approach is constrained by the available properties of reinforcement materials, especially those that are readily available. The material should have: (1) a high Young's modulus for structural reinforcement to minimize mechanical strains in the coil winding pack; (2) high heat capacity and thermal conductivity to be used as heat sinks as part of the cold mass in the winding pack for coil quench protection; and (3) moderate electrical conductivity, so that the winding current can move across layers to avoid any normal (non- superconducting) regions.

[0072] The electrical conductivity of the co-wound reinforcement material can be increased, if necessary, by applying a layer of copper or other high-conductivity material. This can be done by plating, lamination or other physical deposition process.

[0073] The disclosed approach will be particularly beneficial for high-field large bore fusion energy magnets, where design analysis can be performed to identity’ the required balance between stress and thermal management during quench for HTS coils. Referring to FIG. 11. a side view of a non-circular toroidal field coil (1100) can be seen. The coil may be of any appropriate size, including, e.g., a 0.8 m coil, a 2.4 m coil, or a 4 m coil.

[0074] Looking at a cross-sectional view of the toroidal field coil, the magnet may, as disclosed herein, have multiple superconducting layers (1110) and multiple reinforcing layer (1120, 1 121 , 1 122). As seen in FIG. 1 1, each reinforcing layer is disposed between two adjacent superconducting windings or layers, and there may be, e.g., an inner structural portion (1130) and outer structural portion (1131). As shown, the reinforcing layers towards the inner side of the field coil (e.g.. reinforcing layer (1120), towards the inside of the “D” shaped coil) may have thickness that are greater than the thickness at the outer side of the field coil. In FIG. 11, a change in thickness is shown between one turn (1121) and the next turn (1122) of the reinforcing layer. In a preferred embodiment, the windings wrap around the coil in the z direction as shown in FIG. 11 (for example, clockwise around the shape as shown by arrow (1103)).

[0075] In FIG. 12, a set (1200) of toroidal field coils (in a top-down view ) are shown as being arranged to form a toroidal array as may be used in, e.g., a tokamak. As is well understood in the art, the toroidal field coils have a first portion (1101) intended to face inward toward the toroidal array, and a second portion (1102) intended to face outward away from the toroidal array. As will be readily understood, in addition to the toroidal field coils, other magnets may be present as appropriate, including one or more poloidal field magnets (1210), a central solenoid (1220), etc., may also be present. The exact design arrangement may vary as appropriate.

[0076] For a toroidal field coil, the conductor can be pancake wound or layer wind with the disclosed co- wound strategy for quench protection with a flexibility to adjust / tune thermal, electrical and mechanical effects by controlling co-wind material, thickness and winding tension. Scalability of toroidal field coils may be addressed by adjusting the co-wind by the selection of material properties, thickness, and cold mass distribution inside the winding pack to achieve optimal thermal, structural and electrical effect in terms of quench protection.

[0077] The disclosed approach can also be of benefit for reduced cost superconducting magnetic energy storage.

[0078] Thus, in various aspects, a method of constructing superconducting electro-magnets for structural reinforcement and quench protection may be provided. The method generally includes forming (1310) an all-metal winding by coupling (1312) at least one co- wound reinforcement layer as disclosed herein to a superconducting coil as disclosed herein and embedding (1314) the at least one co-wound reinforcement layer between at least two windings of the superconducting coil. Note, this can be performed in any order - it may be coupled, then embedded, or embedded then coupled.

[0079] The at least one co-wound reinforcement layer may be coupled to the at least two windings of the superconducting coil in various ways. For example, the reinforcement layer may be coupled by one of friction, winding tension, and clamping forces. The reinforcement layer may be coupled by one of soldering, brazing, diffusion bonding, welding, and conducting glue. The at least one co-wound reinforcement layer may be coupled to the at least two windings of the superconducting coil by bonding the co-wound reinforcement layer to a superconductor material and a rest of a coil-pack by soldering, brazing, diffusion bonding, or gluing after winding the superconducting coil.

[0080] The method may include tuning (1316) one or more co-wound reinforcement layers to provide a desired tum-to-tum electrical contact resistance in an all-metal coil. Again, this may be done in any order relative to the coupling and embedding - before, after, or between the coupling and embedding.

[0081] The method may include designing (1320) the coil. This may include selecting (1322) at least one co-wound reinforcement layer (or at least one layer within the co-wound reinforcement layer if the co-wound reinforcement layer is made of multiple layers) to optimize for one or more properties of the reinforcement layer, such as strength, specific heat, electrical conductivity, thermal conductivity, and / or cost. Computer-based models for such design tasks are well understood in the art.

[0082] The method may include determining (1324) one or more thicknesses of the at least one co-wound reinforcement layer to match a desired distribution of strength, thermal mass, electrical conductivity, and thermal conductivity.

[0083] The method may include configuring (1326) a material or structure of the at least one co-wound reinforcement layer to achieve a desired tum-to-tum electric or thermal resistance of the superconducting coil. For example, tum-to-tum resistance is adjusted by applying a resistive or conductive coating to at least one co-wound reinforcement layer. As will be understood, this configuration may be designed at the configuration stage (e.g., configuring (1326)), and implemented in the tuning stage (e.g., tuning (1316)). As disclosed herein, any appropriate resistive or conductive coating may be utilized. For example, a coating of conductive copper may be appropriate, or a resistive boriding or other surface treatment may be desirable.

[0084] Inter alia, the disclosed method can also be used to wind large NMR and MRI coils for commercial applications. (90% of the current commercial superconducting magnet market). The disclosed approach may particularly benefit the commercial use of HTS MRI coils, enabling cryogen free magnets can be built at reduced cost with reliable operation.

[0085] No documented methods in the academic and patent literature are thought to be known that combine stress management with coil quench protection and / or thermal management for high field, large bore magnet applications. For decades, various solutions to this problem have been attempted; the lack of a solution has resulted in failures of some large-scale fusion HTS coils.

Claims

What is claimed:

1. A superconducting coil, comprising: a plurality of coil windings comprised of superconducting materials defining an electrically conductive channel having an inlet and an outlet, the plurality of coil windings either being helically wound around a curve around a central axis or being wound in helical layers around a curve around a central axis; wherein one or more or all of the plurality of coil windings are operably coupled to at least one co-wound reinforcement layer; and wherein at least one co-wound reinforcement layer is positioned between at least two adjacent superconducting coil windings or layers of superconducting coil windings.

2. The superconducting coil of claim 1, wherein the plurality of coil windings are helically wound around a curve around a central axis and at least one co-wound reinforcement layer is positioned between at least two adjacent superconducting coil windings.

3. The superconducting coil of claim 1, wherein the plurality of coil windings are wound in helical layers around a curve around a central axis and at least one co-wound reinforcement layer is positioned between at least two adjacent superconducting coil windings.

4. The superconducting coil of claim 1. wherein the plurality of coil windings are wound in helical layers around a curve around a central axis and at least one co-wound reinforcement layer is positioned between at least two adjacent layers of superconducting coil windings.

5. The superconducting coil of any one of claims 1-4, wherein the at least one co-wound reinforcement layer is coupled to the at least two adjacent superconducting windings by one of friction, winding tension, and clamping forces.

6. The superconducting coil of any one of claims 1-4, wherein the at least one co-wound reinforcement layer is coupled to the at least two superconducting windings by one ofsoldering, brazing, diffusion bonding, welding, and conducting glue.

7. The superconducting coil of any one of claims 1-4, wherein the at least one co-wound reinforcement layer is coupled to the at least two windings by bonding the co-wound reinforcement layer to the superconductor and the rest of a coil-pack by soldering, brazing, diffusion bonding, or gluing after winding the coil.

8. The superconducting coil of any one of claims 1-7, wherein the at least one co-wound reinforcement layer comprises a single layer.

9. The superconducting coil of any one of claims 1-7, wherein the at least one co-wound reinforcement layer comprises multiple layers.

10. The superconducting coil of any one of claims 1-9, wherein a thickness of the at least one co-wound reinforcement layer is constant.1 1. The superconducting coil of any one of claim 1-10, wherein a thickness of the at least one co-wound reinforcement layer in a first location is different from a thickness of the at least one co-wound reinforcement layer in a second location.

12. The superconducting coil of claim 1 1 , wherein thickness of the at least one co-wound reinforcement layer varies continuously, by uniform or variable tapering of at least one cowound reinforcement layer.

13. The superconducting coil of claim 11, wherein thickness of the co-wound reinforcement layer changes between a set of discrete thicknesses with a ramp between discrete levels, the ramp having a length of less than one turn of the superconductor around the coil..

14. The superconducting coil of any one of claim 1-13, wherein at least a portion of the co-wound reinforcement layer includes a resistive or conductive coating.

15. The superconducting coil of claim 14, wherein the resistive coating a surfacetreatment.

16. The superconducting coil of claim 14, wherein the resistive coating is a tightly bound coating.

17. The superconducting coil of claim 14, wherein the resistive coating is a boriding or carbonizing treatment.

18. The superconducting coil of any one of claim 1-17, wherein the at least one co- wound reinforcement layer contains aluminum, copper, silver, carbon, silicon, germanium, and / or silicon carbide.

19. The superconducting coil of any one of claim 1-18, wherein the at least one co-wound reinforcement layer contains high-strength steel, a superalloy, a maraging alloy, or a high- strength refractory alloy containing molybdenum, hafnium, tantalum and / or tungsten.

20. The superconducting coil of any one of claim 1-19, wherein the superconducting materials are in the form of a w ire, a tape, and / or a cable containing an embedded wire and / or tape.21 . A method of constructing superconducting electro-magnets for structural reinforcement and quench protection, comprising: coupling at least one co-wound reinforcement layer to a superconducting coil; and embedding the at least one co-wound reinforcement layer between at least two windings of the superconducting coil.

22. The method of claim 21, wherein the at least one co-wound reinforcement layer is coupled to the at least two windings of the superconducting coil by one of friction, winding tension, and clamping forces.

23. The method of claim 21, wherein the at least one co-wound reinforcement layer is coupled to the at least two windings of the superconducting coil by one of soldering, brazing, diffusion bonding, welding, and conducting glue.

24. The method of claim 21, wherein the at least one co-wound reinforcement layer is coupled to the at least two windings of the superconducting coil by bonding the co-wound reinforcement layer to a superconductor and a rest of a coil-pack by soldering, brazing, diffusion bonding, or gluing after winding the superconducting coil.

25. The method of any one of claims 21-24. further comprising tuning the at least one cowound reinforcement layer to provide a desired tum-to-tum electrical contact resistance in an all-metal coil.

26. The method of any one of claims 21-25, further comprising selecting the at least one co-wound reinforcement layer to optimize strength, specific heat, electrical conductivity, thermal conductivity, and / or cost.

27. The method of any one of claims 21-26, wherein the at least one co-wound reinforcement layer is made of multiple layers.

28. The method of claim 27, further comprising selecting at least one layer of the multiple layers to optimize strength, specific heat, electrical conductivity, thermal conductivity, and / or cost.

29. The method of any one of claims 21-28, further comprising determining one or more thicknesses of the at least one co-wound reinforcement layer to match a desired distribution of strength, thermal mass, electrical conductivity, and thermal conductivity.

30. The method of any one of claims 21-29, further comprising configuring a material or structure of the at least one co-wound reinforcement layer to achieve a desired tum-to-tum electric or thermal resistance of the superconducting coil.

31. The method of claim 30, wherein tum-to-tum resistance is adjusted by applying a resistive or conductive coating to at least one co-wound reinforcement layer.

32. The method of claim 31, wherein the resistive coating is a surface treatment.

33. The method of claim 31, wherein the resistive coating is a tightly bound coating.

34. The method of claim 31, wherein the resistive coating is a bonding or carbonizing treatment.

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