Quench-damage-resistant high-temperature superconductor magnets.

Abstract

Techniques are described for improving quench damage tolerance in non-insulated (NI) high-temperature superconductor (HTS) magnets. The techniques may include adjusting the amount of HTS tape within the turns of the windings of an NI-HTS magnet to reduce the variation in critical current across the windings, and / or adjusting the turn-to-turn resistance of the windings by adjusting the turn-to-turn spacing between the windings, thereby reducing the variation in Joule heating between turns during a quench.

Description

[Technical Field]

[0001] This application relates to high temperature superconductor (HTS) magnets, and more particularly to high temperature superconductor magnets that are resistant to damage during a quench event. [Background technology]

[0002]

[0002] A superconductor is a material that has no electrical resistance to electric current (is "superconducting") below a certain critical temperature. For many superconductors, the critical temperature is below 30 K, so operation of these materials in the superconducting state requires significant cooling, for example with liquid or supercritical helium.

[0003]

[0003] High field magnets are often constructed from superconductors due to their ability to carry large currents without resistance. Such superconducting magnets can, for example, carry currents greater than 5 kA. Summary of the Invention [Means for solving the problem]

[0004]

[0004] According to some aspects, a high temperature superconductor (HTS) magnet is provided that includes a coil formed from a plurality of windings, wherein a first winding of the plurality of windings includes a first portion of HTS tape that forms less than one complete turn of the coil.

[0005]

[0005] According to some aspects, a high temperature superconductor (HTS) magnet is provided, comprising a coil formed from a plurality of windings, wherein the plurality of windings comprises a first winding formed from a stack of tapes, the stack of tapes comprising a first number of HTS tapes in a first cross section, the stack of tapes comprising a second number of HTS tapes greater than the first number of HTS tapes in a second cross section outside the first cross section in the first winding, and the stack of tapes comprising a third number of HTS tapes less than the second number of HTS tapes in a third cross section outside the second cross section in the first winding.

[0006]

[0006] According to some aspects, a high temperature superconductor (HTS) magnet is provided that includes a plurality of plates arranged in a stack including a first plate, the first plate including a spiral path portion formed in the first plate including a plurality of turns having a turn spacing, the path portion including a winding of high temperature superconductor (HTS) material, and the turn spacing between the innermost turns of the spiral path portion is less than the turn spacing between the outermost turns of the spiral path portion.

[0007]

[0007] According to some embodiments, a high temperature superconductor (HTS) magnet is provided, comprising a coil formed from a stack of HTS tape, the coil including at least one bend, and at least one additional layer of HTS tape positioned along a portion of the coil to provide a coil including a greater amount of HTS material compared to the amount of HTS material in a second, different portion of the coil.

[0008]

[0008] According to some aspects, a high temperature superconductor (HTS) pancake magnet is provided that includes a base plate formed from a conductive material, the base plate having a groove with a plurality of turns, and a coil formed from an HTS material, the coil being disposed in the groove, the coil having a plurality of turns, and the HTS material being disposed in the groove, wherein the radial distance between adjacent turns of the coil of HTS material varies.

[0009]

[0009] The foregoing apparatus and method embodiments may be realized by any suitable combination of the aspects, features, and operations described above or in further detail below. These and other aspects, embodiments, and features of the present teachings may be more fully understood from the following description taken in conjunction with the accompanying drawings.

[0010] Various aspects and embodiments are described with reference to the following figures. It should be understood that the figures are not necessarily drawn to scale. In the figures, each identical or nearly identical component shown in the various figures is represented by a like numeral. For clarity, not every component may be labeled in every figure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an isometric view of a non-insulated (NI) high temperature superconducting (HTS) magnet, according to some embodiments. [Figure 2A]

[0012] 2B and 2C are cross-sectional views of an exemplary stack of plates in a superconducting magnet taken through line AA' in FIG. 2B and FIG. 2C, according to some embodiments. [Figure 2B]

[0013] FIG. 2 illustrates a top view of the plates of a superconducting magnet, according to some embodiments. [Figure 2C] FIG. 2 illustrates a bottom view of a plate of a superconducting magnet, according to some embodiments. [Figure 3]

[0014] FIG. 1 illustrates four turns of an exemplary HTS magnet with the amount of HTS tape varied in the windings, according to some embodiments. [Figure 4]

[0015] FIG. 1 illustrates an exemplary winding with less HTS tape in the innermost and outermost turns of the winding compared to the intermediate turns of the winding, according to some embodiments. [Figure 5A]

[0016] FIG. 10 is a plan view of a portion of four turns of a winding with HTS tape added or removed in a stepwise manner, according to some embodiments. [Figure 5B]

[0017] FIG. 10 is a side view of a portion of a winding where HTS tape has been added or removed in a stepwise manner, according to some embodiments. [Figure 5C]

[0018] 10A-10C illustrate examples where a fixed number of tapes are combined to form a winding, according to some embodiments. [Figure 5D] 10A-10C illustrate examples where a fixed number of tapes are combined to form a winding, according to some embodiments. [Figure 5E] 10A-10C illustrate examples where a fixed number of tapes are combined to form a winding, according to some embodiments. [Figure 6]

[0019] FIG. 1 illustrates an exemplary winding in which the HTS tape count is reduced across all turns of the winding, according to some embodiments. [Figure 7]

[0020] FIG. 10 is a cross-sectional view through two different windings, one of which has a turn-to-turn resistance gradient, according to some embodiments. [Figure 8A]

[0021] 10A-10C illustrate structural plates without inter-turn resistance gradients according to some embodiments. [Figure 8B] FIG. 1 illustrates a structural plate with turn-to-turn resistance gradient, according to some embodiments. [Figure 9]

[0022] FIG. 10 is a cross-sectional view through a winding arranged with a turn-to-turn resistance gradient and an HTS tape gradient, according to some embodiments. [Figure 10]

[0023] 1 is a three-dimensional graphic of a fusion device with portions cut away and removed showing various components of the tokamak, according to some embodiments. [Figure 11]

[0024] 1 is a cross-sectional view of layers of an exemplary coated conductor HTS tape, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0025] High-field superconducting magnets often contain multiple turns of electrically insulated cable grouped in a multi-layer configuration. When the superconducting material is cold enough that it is below its critical temperature (the temperature below which the material's electrical resistivity decreases to zero), driving the magnet allows electrical current to pass through the superconducting path without loss. Generally, superconducting magnets are capable of carrying relatively high current densities (e.g., large amounts of current per unit volume or cross-sectional area of ​​superconducting material) while still producing strong magnetic fields.

[0013]

[0026] Some superconducting magnets may operate in environments where an external magnetic field is present (i.e., external to the magnet). If the external magnetic field varies over time, eddy currents may be induced within the superconducting magnet, which may in turn generate currents in excess of the carry current for which the magnet is designed. These "overcurrents" may cause some of the superconductors to exceed their critical current limit, which may cause the superconductor to exceed its critical temperature and function as a normal conductor, resulting in a quench of the magnet.

[0014]

[0027] High-temperature superconductors (HTS) can be beneficial in superconducting magnets because they remain in a superconducting state at higher temperatures than low-temperature superconductors and therefore do not need to be cooled to as low a temperature to remain in a superconducting state. Furthermore, there may be a larger window of operating temperatures within which quenching can be avoided. As referred to herein, the phrase "HTS material" or "HTS superconductor" refers to a superconducting material that has a critical temperature above 30° K in the absence of a self-magnetic field. One example of an HTS material is rare-earth barium copper oxide (REBCO). An HTS magnet is a magnet that includes one or more HTS materials configured to carry at least a portion of the magnet's electrical current.

[0015]

[0028] One type of HTS magnet is a non-insulated (NI) HTS magnet, in which an electrically conductive, non-superconducting material is disposed between the turns of the magnet. An NI-HTS magnet design may include a stack of conductive plates with one or more grooves provided therein. The HTS material may be disposed (e.g., wound) within the one or more grooves and stacked plates such that the superconductor forms a continuous current path through the plates and forms a spiral path within and / or between the plates (e.g., alternating inside-out and outside-in windings in successive plates in the stack). The conductive plates function as the conductive material disposed between the turns of the HTS material. Thus, adjacent turns of HTS material are not insulated from one another but are instead separated by conventional (i.e., non-superconducting) conductors; thus, a magnet formed by such stacked plates is referred to as an NI-HTS magnet. Because the superconductor has zero resistance compared to the finite resistance of the conductors present between the turns, current flows through the HTS material without crossing the turns when the magnet is operated below the critical temperature of the HTS material.

[0016]

[0029] Such stacked plate magnet designs have the advantages of being scalable to magnets with large bores, and can be configured to have high total current densities, to be thermally stable, and to be mechanically stable.

[0017]

[0030] During a quench, at least one or more portions of a superconductor may be in a “normal” (non-superconducting) state (i.e., at least one or more portions of a superconductor have finite resistance rather than the zero resistance characteristic of superconductors). At least one or more portions of a superconductor with normal-state resistance are sometimes referred to as the “normal zone” of the superconductor. When the normal zone appears, at least some zero-resistance current paths may no longer exist, and current will flow through the normal zone and / or between turns, with the balance of current flow between these paths depending on their relative resistances. By diverting at least some current away from the superconducting material when it is in this normal state, as a result, NI magnets, and particularly non-insulated high-temperature superconductor (NI-HTS) magnets (NI magnets including HTS), can, in principle, be passively protected from quench damage without the need to continuously monitor for quench events and / or actively engage external quench protection mechanisms.

[0018]

[0031] NI-HTS magnets exhibit a unique response during a quench, with magnetic energy being dissipated within the winding pack and the mechanical structure of the magnet itself. Thus, in principle, NI-HTS magnets could be designed to be passively protected from quench damage, even with large amounts of stored magnetic energy.

[0019]

[0032] Stacked-plate HTS magnets offer considerable design flexibility for achieving quench resistance through the configuration of the HTS conductors, base plate, co-wound auxiliary conductors, and the choice of materials used. For example, an electrically conductive "co-conductor" appropriately thermally and electrically connected to the base plate can be effective in enhancing quench stability and protecting the magnet in the event of a quench. However, as the stored energy per unit volume increases, there are situations in which these techniques alone are not sufficient to avoid damage. This is because quenches can initiate and propagate in undesirable ways, depending on the configuration of the superconducting tapes and the critical current distribution within the magnet.

[0020]

[0033] Using the concepts described herein, the inventors have recognized and understood that two phenomena in particular can limit the quench-safe operating space for NI magnets, one or both of which can result in grinding or crushing forces that can damage stacked plates when a quench occurs. The first of these phenomena is the formation of one or more azimuthally localized, radially connected normal conduction zones. That is, during a quench, normal conduction zones can form in several adjacent turns, centered around a particular azimuthal region. These regions can result in smaller critical currents within a short azimuthal extent of the winding, with smaller critical currents being similar in adjacent turns. This can result in thermally dense regions that can damage the magnet. The inventors have recognized and understood that spatial variations in the critical currents of current paths, both along and across the windings in the magnet, can be the underlying cause of this phenomenon.

[0021]

[0034] A second such phenomenon is high Lorentz I×B body loading in the magnet structure due to current peaking. When a magnet begins to quench, the turns of the coil heat up and reduce their current. However, when the turns of a magnet exhibit different critical currents, the turns do not simultaneously reduce their current; turns exhibiting smaller critical currents reduce their current first. In addition, turns exhibiting larger critical currents increase their current to conserve magnetic flux flowing through them. This results in a cascade, where turns hold current until they quench and then release it to adjacent turns via inductive coupling. Eventually, current flows into the turn exhibiting the largest critical current, which can generate very large currents (e.g., multiple times the magnitude of the terminal current). These large currents can generate very large Lorentz forces that can damage the magnet's mechanical structure (e.g., conventional conductors forming a stack of pancakes).

[0022]

[0035] In a further aspect of the concepts described herein, the inventors have recognized and appreciated that non-insulated (NI) HTS magnet designs employing "HTS tape gradient" and / or "turn-to-turn resistance gradient" techniques enhance (ideally maximize) quench damage tolerance for high energy density non-insulated superconducting magnet designs.

[0023]

[0036] In particular, HTS tape gradients can have the effect of reducing variations in critical current across the magnet's windings. The inventors have recognized and understood that the critical current in an HTS magnet's winding can vary significantly as a function of turn number and can also vary significantly within a given turn. As discussed above, this poses the risk of azimuthally localized, radially connected normal zones forming in adjacent turns during a quench, which is undesirable because it creates localized hot spots that extend across multiple adjacent turns. In non-insulated magnets, current can often flow around localized defects, such as normal zones, by flowing into adjacent turns. However, when the normal zone extends across multiple adjacent turns, current can be forced to flow through the normal zone despite its high resistance.

[0024]

[0037] By applying the HTS tape gradient techniques described herein, the fluctuations in critical current within the magnet can be reduced, which reduces the magnitude of current peaking (and thus localized heating) that occurs during a quench. That is, during a quench, the current increase can be more uniform when HTS tape gradients are used. HTS tape gradients can, for example, allow HTS magnets to be configured so that multiple turns of the magnet quench simultaneously, rather than quenching with one or more localized regions of high current.

[0025]

[0038] In some embodiments, a superconducting magnet may include HTS tape windings including stacks of HTS tape and co-wound tape located within structural grooves (e.g., grooved plates) (where the co-wound tape does not include HTS material but is provided by a non-superconducting material such as copper or a conductive nickel alloy). In some embodiments, stacks of HTS tape and co-wound tape (e.g., copper co-wound tape) may be soldered together to form a composite conductor. Tape gradients allow the amount of HTS tape (e.g., number of HTS tapes, or more generally, amount of HTS material) and / or the amount of copper co-wound tape in the stack to vary with distance along the winding (e.g., winding distance, radial position, etc.), which may include an increase and / or decrease in the number of HTS tapes and / or co-wound tapes at multiple points within the winding. For example, the number of HTS tapes and / or co-wound tapes at one point along the winding within a structural plate may be greater or less than the number of HTS tapes and / or co-wound tapes at a different point along the winding. In some embodiments, the amount of HTS tape in the winding is varied by varying the size of the HTS tape stack (eg, by introducing or removing HTS tape along the winding).

[0026]

[0039] In some embodiments, the amount of HTS tape in a winding is varied by substituting HTS tape for non-HTS tape (e.g., copper or conductive nickel alloy tape) in areas around the perimeter of the winding. Such non-HTS tape may be connected end-to-end with HTS tape, and in some instances, may produce a tape stack formed from a fixed number of tapes, with either HTS tape or non-HTS tape present at each point in the stack.

[0027]

[0040] Tape grading techniques can be applied to reduce (and ideally minimize) the amount of HTS tape used, generally allowing for customization of the critical current map associated with a particular magnet. This can include using the tape grading techniques described herein to customize the critical current map of a magnet so that it is more uniform (or in some instances substantially uniform) across multiple windings and / or within each winding. As described in further detail below, HTS tape can be added to and / or removed from particular portions of a winding (e.g., a winding placed in a groove in a structural plate) to increase or decrease the amount of HTS tape compared to the amount of HTS tape used in the prior art.

[0028]

[0041] According to some embodiments, a superconducting magnet graded in accordance with the techniques described herein may include a stack of HTS tape disposed in a winding, with the amount of HTS tape in the stack varying with radial distance from the center of the winding. For example, a winding of HTS tape disposed in a spiral groove of a structural plate may include less HTS tape in some radial locations of the winding compared to other radial locations. As one example, an inner turn of a winding may include less HTS tape in the stack compared to a middle or outer turn of the winding. As another example, an outer turn of a winding may include less HTS tape in the stack compared to a middle or inner turn of the winding. As yet another example, an outer turn of a winding may include less HTS tape in the stack compared to a middle turn of the winding, and an inner turn of a winding may include less HTS tape in the stack compared to a middle turn of the winding.

[0029]

[0042] The inventors have recognized that the critical current may be higher in tighter bend regions (e.g., smaller radii of curvature) of a single winding. By reducing the amount of HTS tape in such regions, the critical current across the winding may be made more uniform. Thus, according to some embodiments, regions of a winding with a smaller radius of curvature may include less HTS tape than other regions of the same winding with a larger radius of curvature.

[0030]

[0043] It should be noted that varying the amount of HTS tape in a single winding may, at least in some instances, involve using pieces of HTS tape that are not completely wrapped around a single winding of a magnet. That is, when a winding includes a stack of HTS tapes with varying numbers of HTS tapes in the winding, some of the HTS tapes may not reach the outermost ends and / or may not reach the innermost ends of the winding, but may include one or two ends located somewhere within the interior of the winding. In some instances, a piece of HTS tape may have a length less than one full turn of the winding, in which case both ends of the piece of HTS tape are located within a single turn of the winding. In some instances, a first piece of HTS tape may be located within the winding for a first number of turns, and a second piece of HTS tape may be located within the same winding for a second number of turns, where the first and second numbers of turns are different.

[0031]

[0044] According to some embodiments, a superconducting magnet graded in accordance with the techniques described herein may include a stack of structural plates, each including a winding of HTS tape arranged in a spiral groove. The number of HTS tapes at a given location within a winding may vary based on the position of the structural plate within the stack of structural plates. For example, a winding of HTS tape arranged within a first structural plate may include more or fewer HTS tapes in that winding compared to a second, different structural plate in the magnet. In some instances, the number of HTS tapes may be varied in this manner in a consistent manner across a winding (e.g., a winding in one plate may have the number of HTS tapes in another winding reduced by a consistent number of HTS tapes across the entire winding). For example, a winding within the middle of a stack of windings may have a consistent number of HTS tapes within that winding, which is less than the number of HTS tapes in another winding in the stack. Additionally or alternatively, windings in a stack of windings may have the amount of HTS tape selectively varied within the winding (e.g., one winding may have less HTS tape in total than another winding, and one portion of the winding may exhibit a greater difference in HTS tape count than another portion of the winding compared to the other winding). As an example, it is noted that the middle windings in a stack of windings may heat up faster than other turns in the stack. Therefore, it may be beneficial to reduce the amount of HTS tape in the middle windings in the stack (or, equivalently, increase the amount of HTS tape in the outermost windings in the stack) to produce a more uniform response across the windings in the stack during a quench.

[0032]

[0045] The inventors have discovered that, in connection with turn-to-turn resistance gradients, turns within a coil may not quench simultaneously. As discussed above, localized quenching can be undesirable because it creates a hot spot across the turns within only a portion of the magnet. The inventors have recognized and understood that in superconducting magnets with superconductor windings, the innermost turns of the windings may quench before the outermost turns. This may be true even in superconducting magnets where the tape gradients discussed above are used to create a consistent critical current across the windings. Even with a constant critical current, a lack of consistency in Joule heating across the turns can result in this quench behavior.

[0033]

[0046] While not intending to be bound by theory, the inventors have recognized that inconsistency in Joule heating can be caused by inconsistent resistance across the turns of the magnet. In stacked plate magnet designs, the resistance between turns is determined in large part by the groove spacing between turns, as this determines the extent to which normal conductor exists between the turns. As a result, by adjusting the plate groove spacing (which further adjusts the spacing between turns), the resistance between turns can be adjusted (or "graded"). For example, since the innermost turns are assumed to quench before the outermost turns, this suggests that Joule heating is higher in the inner turns; therefore, by reducing the resistance between the inner turns, Joule heating can be made more consistent across the turns.

[0034]

[0047] According to some embodiments, a superconducting magnet may include a stack of structural plates, each including a winding of HTS tape arranged in a spiral groove, with the grooves arranged so that the distance between adjacent turns is not constant along the spiral. This distance may be measured along any suitable axis from the center or central region of the structural plate to the outer boundary of the plate. For example, the distance may be measured radially from the center of the plate. Regardless of which axis the distance is measured along, in some examples, the distance between turns of the spiral groove in the plate may be smallest between the two innermost turns and largest between the two outermost turns. In some examples, the distance between turns of the spiral groove may gradually increase from the innermost turn to the outermost turn (i.e., the distance between adjacent turns in each pair is greater than the distance between adjacent turns in adjacent pairs closer to the center of the spiral groove).

[0035]

[0048] A more detailed description of various concepts related to magnet designs using tape gradient and / or inter-turn resistance gradient techniques, and embodiments thereof, is presented below. It should be understood that the various aspects described herein may be implemented in any of numerous ways. Examples of specific implementations are provided herein for illustrative purposes only. Additionally, the various aspects described in the following embodiments may be used alone or in any combination, and are not limited to the combinations explicitly described herein.

[0036]

[0049] Referring to FIG. 1 , a non-insulated (NI) high-temperature superconductor (HTS) magnet 100 includes a plurality of base plates 112A-112N with grooves provided therein, with HTS material disposed within the grooves (the grooves and HTS material are not visible in FIG. 1 ). HTS magnet 100 may be constructed based on the tape grading and / or turn-to-turn resistance grading techniques described above to produce an HTS magnet with greater quench damage resistance compared to that of conventional HTS magnet designs. As described above, tape grading and / or turn-to-turn resistance grading are both techniques that can be applied to provide HTS magnet 100 with higher (and ideally maximized) quench damage resistance properties.

[0037]

[0050] In some embodiments, magnet 100 may include a D-shaped base plate of a grooved stack of plates in which the HTS tape (or tape stack or bundle) is disposed. In some embodiments, the magnet may include 16 base plates, each including a winding including 16 turns of HTS material. In the example of FIG. 1, several base plates 112A-112N are shown as illustrative examples. In some embodiments, at least some of base plates 112A-112N may include grooves having a so-called racetrack shape, although the grooves may be configured in any other suitable shape (e.g., any regular or irregular geometric shape).

[0038]

[0051] 2A-2C illustrate aspects of an exemplary implementation of the base plate shown in FIG. 1 , according to some embodiments. In particular, FIG. 2A illustrates a cross section of an exemplary stack of plates in a superconducting magnet, according to some embodiments. The stack of plates 200 includes two instances of plate 210 and two instances of plate 220, in addition to end plates 230 and 240. Layers of insulating material 250 are disposed in selected regions between adjacent plates. FIG. 2A represents a cross section of the stack of plates through a portion of the plates, shown as cross section A-A' in FIGS. 2B-2C.

[0039]

[0052] Each of the plates comprises a base plate material 210a, 220a, 230a or 240a in which are formed (e.g., via conventional machining processes, via additive and / or subtractive processes, etc.) a cooling path portion 211 and a conductive path portion comprising HTS material 212, a cap 216, and an intervening conductive material 214 that provides electrical and thermal contact between the HTS material 212 and the cap 216.

[0040]

[0053] According to some embodiments, base plates 210, 220, 230, and 240 may comprise or be composed of base plate material 210a, 220a, 230a, and 240a, respectively, that is a high mechanical strength material such as, but not limited to, steel, Inconel®, Nitronic® 40, Nitronic® 50, Incoloy®, or combinations thereof. In some embodiments, base plate material 210a, 220a, 230a, or 240a may be plated with a metal, such as nickel, that facilitates adhesion of other components to the plate, including solder, as described below.

[0041]

[0054] According to some embodiments, the HTS material 212 may include a rare earth barium copper oxide superconductor (REBCO), such as yttrium-barium-copper-oxide (YBCO). In some embodiments, the HTS material 212 may comprise a co-wound stack of HTS tapes.

[0042]

[0055] As used herein, "HTS tape" refers to a long, flat element comprising a layer of HTS material (e.g., polycrystalline HTS) in addition to other layers. In some embodiments, HTS tape can refer to any structure that includes a layer of HTS, e.g., rare earth copper oxide HTS (e.g., REBCO), and that may further include one or more other layers, e.g., one or more buffer layers, stabilizing layers, substrate layers, overlay layers, and / or cladding layers, such as tape 1100 shown in FIG. 11.

[0043]

[0056] For illustrative purposes, FIG. 11 shows a cross-sectional view of layers of an exemplary coated conductor HTS tape, according to some embodiments. The following description may, in some embodiments, apply to the HTS tape described above disposed within a magnet or magnet assembly. FIG. 11 illustrates an example HTS tape 1100 fabricated as a coated conductor, in which the HTS layer 1110 is a layer of REBCO. As noted above, “REBCO” is an acronym for “rare-earth barium copper oxide.” As used herein, at least in some cases, “REBCO” may be used more generally to refer to any rare-earth copper oxide HTS. Thus, unless explicitly stated otherwise, barium may be present in REBCO, but is not required to be present. That said, in the example of FIG. 11 , the REBCO layer is provided as an example of an HTS layer and is not intended to limit the illustrated structure to any particular HTS use.

[0044]

[0057] 11, the exemplary tape 1100 further includes a buffer layer 1112, a Hastelloy® layer 1114, and a copper layer 1116 and a silver layer 1118 disposed above and below the REBCO layer, respectively. The copper layer is sometimes referred to as a "stabilizer" layer. Exemplary dimensions of the tape are shown in FIG. 11, with the tape having a width (X-direction size) of approximately 2 mm to 12 mm and a thickness (Z-direction size) of approximately 0.1 mm.

[0045]

[0058] In some embodiments, the HTS tape can have an aspect ratio (which is the ratio of the width of the tape to the thickness of the tape) that is greater than or equal to 10, 20, 40, 60, 80, 100, 120, or 150. In some embodiments, the HTS tape can have an aspect ratio that is less than or equal to 150, 120, 100, 80, 60, 40, 20, or 10. Any suitable combination of the above ranges is also possible (e.g., aspect ratios greater than or equal to 60 and less than or equal to 100).

[0046]

[0059] In some embodiments, the HTS tape can have a thickness that is 0.005 mm, 0.01 mm, 0.05 mm, 0.1 mm, 0.15 mm, or 0.2 mm or greater. In some embodiments, the HTS tape can have a thickness that is 0.5 mm, 0.2 mm, 0.15 mm, 0.1 mm, 0.05 mm, or 0.01 mm or less. Any suitable combination of the above ranges is also possible, such as a thickness of 0.01 mm or greater (or about 0.01 mm) and 0.1 mm or less (or about 0.1 mm).

[0047]

[0060] In some embodiments, the superconducting magnet shown in Figures 2A-2C may include HTS tape wound around a winding axis such that the x-axis of the tape, as shown in Figure 11, is aligned parallel to the winding axis. In the case of a non-insulated magnet design, for example, the HTS tape may therefore contact the faces of adjacent tapes (the x-y plane in Figure 11). In some embodiments, the superconducting magnet may include windings of a stack of HTS tape along with a non-superconducting conductive material, such as steel or copper. For example, a stack of 10-20 HTS tapes stacked face-on with one or more copper tapes having the same width as the HTS tape (the size in the x-direction in Figure 11) may be wound together in a spiral groove in a base plate.

[0048]

[0061] An HTS tape stack can have one or more lengths of HTS tape with a cross-sectional dimension extending along the length of the tape (y-axis dimension in FIG. 11 ) of about 0.001 mm to about 0.1 mm in height or thickness (i.e., the z-axis dimension shown in FIG. 11 ) and a width (x-axis dimension shown in FIG. 11 ) of about 1 mm to about 12 mm. In some embodiments, the HTS tape can include polycrystalline HTS and / or have a high level of grain alignment. An HTS tape stack can include multiple HTS tapes arranged on top of each other along the width and length directions. The HTS tape stack can thus have a thickness equal to (or approximately equal to) the thickness of an individual tape multiplied by the number of tapes in the stack.

[0049]

[0062] According to some embodiments, cap 216 may include or be made of copper. It may be noted that as a result of base plates 210, 220, 230, and 240 being shown in cross section in Figure 2A, the shape of HTS 212 on the base plate and cap 216 on the base plate is generally spiral (e.g., racetrack spiral) shaped.

[0050]

[0063] According to some embodiments, the conductive material 214 may include Pb and / or Sn solder. In some embodiments, the conductive material 214 may include a metal with a melting point less than 200° C., where at least 50 wt % of the metal is Pb and / or Sn and at least 0.1 wt % of the metal is Cu.

[0051]

[0064] 2A , the cap 216 is disposed within an upper section of the pathway that is wider than a lower section in which the HTS 212 and conductive material 214 are located. In some embodiments, the conductive material 214 may be introduced into the base plates 210, 220, 230, and 240 as molten solder after disposing the HTS 212 and cap 216 within the conductive pathway. As a result, the conductive material 214 may fill any spaces between the HTS 212 and the cap 216, if such spaces exist prior to filling or otherwise occupying the spaces with solder, and / or may fill any spaces around the sides of the HTS 212 and / or cap 216.

[0052]

[0065] In some embodiments, the HTS 212 may be pre-tinned with a metal (e.g., PbSn solder) to promote a good bond between the HTS 212 and the solder. According to some embodiments, the conductive material 214 may be deposited via a vacuum pressure impregnation (VPI) process. Such processing may include one or more of the following steps: cleaning the empty space within the cable using an acid solution followed by a water rinse; evacuating the space within the cable; purging the space with an inert gas; depositing flux within the space to coat the HTS 212 and the conductive material 214; evacuating any excess flux from the cable; heating the cable to a temperature below, equal to, or above the melting temperature of the alloy to be deposited; and flowing the molten alloy (e.g., PbSn solder) into a plate.

[0053]

[0066] According to some embodiments, insulating material 250 may include polyimide (e.g., Kapton®), epoxy, phenolic, glass-epoxy laminate, plastic, elastomer, or combinations thereof. According to some embodiments, insulating material may have a breakdown voltage or dielectric strength greater than 25 kV / mm, greater than 50 kV / mm, greater than 75 kV / mm, or greater than 100 kV / mm. In some instances, the voltages in superconducting magnets may be relatively low, in which case a low-voltage standoff insulating material, such as anodized aluminum, may be used as insulating material 250.

[0054]

[0067] According to some embodiments, plate 210 may include one or more through-holes for attaching the plate to other plates and / or other structures. In some instances, the through-holes may have internal threads to facilitate the insertion of mechanical fasteners, such as screws or bolts 290, into or through the plate.

[0055]

[0068] In the example of Figure 2A, the open cooling path in one of the plates is located adjacent to the conductive path in the adjacent plate. For example, as shown in Figure 2A, the cooling path 211 in each instance of plate 210 is located adjacent to the cap 216 of the adjacent plate 220. In the example of Figure 2A, plates 210, 220, 230, and 240 are held together, at least in part, by bolts 290 connecting adjacent pairs of plates. It can be assumed that such bolts are present at many locations around the perimeter of plates 210, 220, 230, and 240.

[0056]

[0069] The base plate 210 shown in FIG. 2A is shown in more detail in FIGS. 2B and 2C. FIGS. 2B and 2C show top and bottom views of plate 210, respectively, with the cross section of FIG. 2A being through the plane labeled A-A'. In the example of FIGS. 2B-2C, the location of cooling paths 211 that are part of plate 220 disposed above plate 210 is shown for illustrative purposes, although it is understood that these cooling paths may not actually be part of plate 210. As can be seen, the conductive paths of plate 210 in this example have an inward spiral shape when tracing the paths in a clockwise direction as viewed from above.

[0057]

[0070] FIG. 2C shows the underside of plate 210, including the area where insulating material 250 is attached and the exposed area of ​​base plate 210a.

[0058]

[0071] As mentioned above, two ways in which the quench behavior of a magnet, such as the magnet shown in Figures 2A-2C, may be improved are through tape gradients and / or turn-to-turn resistance gradients. Illustrative examples of each of these are described below in relation to the exemplary magnet of Figures 2A-2C, starting with the tape gradient technique.

[0059]

[0072] As mentioned above, HTS tape gradient techniques can include varying the amount of HTS tape in the windings, which can include varying the number of HTS tapes in the HTS tape stack and / or substituting HTS tape for non-HTS tape in the windings. FIG. 3 shows four turns 301, 302, 303, and 304 of an exemplary HTS magnet with varying amounts of HTS tape, according to some embodiments. In the example of FIG. 3, a base plate 310 includes a spiral conductive path, four turns of which are shown in the drawing. The path includes a tape stack 312 including HTS tape alongside a co-conductor 313, with an electrically conductive cap 316 positioned above the HTS tape and co-conductor. Solder 314 is deposited to fill the space between the co-conductor and the cap. The HTS tape stack in FIG. 3 is represented as multiple tapes placed sideways and facing into the page. 3, the number of tapes in HTS tape stack 312 can vary such that there is more tape in turn 301 than in turns 302, 303, or 304 (at least in the cross section of turn 301 shown in FIG. 3). Similarly, turn 302 includes more tapes in HTS tape stack 312 than in turns 303 or 304, and turn 303 includes more tapes in HTS tape stack 312 than in turn 304. Tape stack 312, co-conductor 313, solder 314, and cap 316 together form a winding within the spiral path.

[0060]

[0073] As explained, the amount of co-conductor 313 may vary when the number of HTS tapes in the stack is varied, as shown in Figure 3. For example, there is a greater amount of co-conductor 313 in turn 304 compared to turns 301, 302, or 303.

[0061]

[0074] According to some embodiments, the co-conductor 313 may comprise or be formed of a plurality of conventional conductive (i.e., non-superconducting) tapes. For example, the co-conductor 313 may comprise a stack of copper tapes (or tapes of some other metal), which are long, flat conductive structures with cross-sectional dimensions similar to (or identical to) the HTS tapes. When implemented in this manner, one way to vary the amount of co-conductor 313 in a winding turn is to vary the number of conventional conductive tapes in the winding. One way to vary the number of conventional conductive tapes and HTS tapes in a winding is to increase the number of one while decreasing the other by the same number, thereby resulting in a winding that includes a constant (or approximately constant) number of tapes in total (i.e., the number of co-conductor tapes plus the number of HTS tapes), but in which the number of tapes in each of the two stacks is varied independently. In some embodiments, the total size of the stack of tapes (which is a combination of HTS tapes and co-conductor tapes) can remain constant, and the balance between the co-conductor tapes and HTS tapes varies.

[0062]

[0075] According to some embodiments, the stack of HTS tapes configured as HTS 212 in the example of Figure 2A may be varied in the same manner as shown in Figure 3. For example, although not shown in Figure 2A, HTS 212 may comprise a stack of HTS tapes arranged sideways and stacked from left to right in the drawing in the same manner as the tapes shown more explicitly in Figure 3, with the amount of HTS tape in this stack being varied in the winding.

[0063]

[0076] According to some embodiments, the manner in which the amount of HTS tape in a stack of tape is varied within a winding may be different for different windings in the stack of windings. For example, in the exemplary magnet formed from four windings shown in FIG. 2A, the number of HTS tapes in the stack used to form the HTS material 212 may be different in some windings (e.g., the top or bottom windings) compared to other windings (e.g., the middle windings). These differences may be in the absolute number of HTS tapes and / or how that number varies with distance along the winding. FIGS. 4 and 6 show illustrative examples of two manners in which the amount of HTS tape in a stack of HTS tape may be varied.

[0064]

[0077] FIG. 4 illustrates an exemplary winding, according to some embodiments, in which the amount of HTS tape is reduced in the innermost and outermost turns of the winding compared to the turns midway through the winding. The inventors recognized that the critical current in the winding along one or more of the innermost turns of the winding and one or more of the outermost turns of the winding may be higher. As discussed above, one goal of HTS tape grading is to produce a consistent critical current across the winding. Therefore, in areas of higher critical current, it may be beneficial to place less HTS tape in those areas to produce a “flat” critical current map across the winding. FIG. 4 is an example of such an approach, showing a consistent amount of HTS tape throughout the winding (including the hatched and dotted areas) before grading, and a reduced amount of HTS tape only in the hatched areas after grading. Enlarged portions of winding 400 are shown in insets 410, 420, and 430, which are not drawn to scale for illustrative purposes.

[0065]

[0078] 4, the amount of HTS tape in the two outermost windings is reduced compared to the pre-grading example, while the amount of HTS tape in the middle windings remains the same (as shown in inset 420). For example, excess portions of tape 411 can be seen near the sides of gradient tape stack 412, while no such excess is shown near gradient tape stack 422, which contains the same amount of HTS tape as found in the pre-grading tape stack.

[0066]

[0079] Thus, the exemplary winding 400 includes more HTS tape in the outermost turns of the winding than in intermediate turns of the same winding. One approach to achieving this configuration is to wrap several HTS tapes starting from a location within the winding (e.g., two to four turns in from the outermost turn). The HTS tapes can be included in this approach in a staged manner, gradually transitioning from a first number (e.g., a minimum number of HTS tapes) in the outermost turns of the winding to a larger number of HTS tapes several turns in from the outermost turn. An illustrative example of this approach is shown in Figures 5A-5B.

[0067]

[0080] FIG. 5A shows an enlarged section of a portion of four turns of the winding, and FIG. 5B shows the side of the tape along its length, illustrating the step-like characteristics of the HTS tape when laid down in the manner shown in FIG. 5A.

[0068]

[0081] In the example of FIG. 5A, at each of the points labeled 501, a new or further piece of HTS tape is added and included in the subsequent winding, thereby gradually increasing the number of HTS tapes in the stack along the winding.

[0069]

[0082] 5B, the winding 510 can be formed from an HTS tape stack that includes more tape at the middle portion than at the ends. As a result, when this tape stack is wound to produce a magnet winding, the number of tapes in a cross section of at least a portion of the winding at a first end 510a (e.g., inner end) of the winding is less than the number of tapes in a cross section of at least a portion of the winding 510b, and the number of tapes in a cross section of at least a portion of the winding at a second end 510c (e.g., outer end) is more than the number in the cross section at the first end but less than the number in the cross section at the middle.

[0070]

[0083] 5A-5B, in some embodiments, the amount of HTS tape can be varied by joining or otherwise bonding pieces of HTS tape end-to-end to pieces of non-HTS tape. Thus, a single tape can be wrapped along the entire winding, but only one or more portions of the tape winding can be formed from HTS tape.

[0071]

[0084] In some examples, a magnet winding can be formed from a stack of a fixed number of tapes, with each tape in the stack of tapes being formed from one of: (i) only HTS tape (which may comprise a single continuous piece of HTS tape or multiple pieces of HTS tape joined end-to-end); (ii) one or more regions of HTS tape joined end-to-end with one or more regions of non-HTS tape; or (iii) only non-HTS tape. Non-HTS tapes can include tapes formed from any conventional conductor, including copper tape, or tapes formed from conductive metal alloys, such as nickel alloys (e.g., Hastelloy®, a nickel alloy containing nickel, iron, chromium, and molybdenum). In some embodiments, non-HTS tapes can include conductive metal alloys plated with one or more other materials, such as other metals and / or metal alloys (e.g., solder). For example, a non-HTS tape may be prepared in the same or similar manner as the HTS tape shown in FIG. 11, except that a layer of a conventional conductor is used in place of the HTS layer 1110, such that the non-HTS tape includes, for example, a buffer layer and copper and silver layers disposed above and below the non-HTS conductor layer.

[0072]

[0085] 5C-5E show examples in which a fixed number of tapes are combined to form a winding, according to some embodiments. In the examples of FIGS. 5C-5E, the winding is formed from a stack of tapes 512 that extends into the page (generally along the y-direction defined by the coordinate system shown in FIG. 5C). As with the example of FIG. 3, the vias (unnumbered in FIG. 5C) in the base plate 502 can include HTS material located therein (which can form part or all of the stack of tapes 512, as described below) in addition to solder 514 and caps 516.

[0073]

[0086] As a result of varying the types of tapes in the tape stack 512 from which the windings are formed, cross sections taken at different locations along the length of the tape stack (the "length" of the tape stack is in the y-direction defined by the coordinate system of FIG. 5C) may contain different numbers of HTS tapes. This is shown, for example, in FIG. 5D.

[0074]

[0087] As shown in Figures 5D and 5E, each of cross sections 521, 522, and 523 through the stack of tapes includes a different number of HTS tapes (as indicated by the number of dashed lines representing the HTS tapes present in that cross section). Figure 5E shows the winding shown in Figure 5C from above, without cap 516 shown, so that cross sections 521, 522, and 523 through the stack of tapes 512 can be identified.

[0075]

[0088] According to some embodiments, the number of HTS tapes in a first cross-section of the stack of tapes 512 can be greater than the number of HTS tapes in a second cross-section of the stack of tapes. For example, as shown in FIG. 5D , the number of HTS tapes present in the stack of tapes at cross-section 521 is greater than the number of HTS tapes present in the stack of tapes at cross-section 523, which includes more filler tapes than cross-section 521 (for co-conductor tapes, but where the stack is primarily made up of HTS tapes).

[0076]

[0089] Exemplary materials for each of the tapes in the stack of tapes forming the winding are shown in graph 520 ( FIG. 5D ). As can be seen from graph 520, each of the tapes in stack 512 is formed from one of a co-conductor (e.g., copper) tape (e.g., as indicated by tapes identified by reference numerals 530 a and 530 b at the top and bottom of the stack, respectively), an HTS tape (e.g., the top tape containing HTS and identified by reference numeral 532), or a tape with one or more lengths of HTS tape joined end-to-end with a “filler” tape (filler tape may also be referred to herein as a non-HTS tape), which may be formed from the same or a different material as the co-conductor tape. For example, the filler tape may include or consist of a nickel alloy, while the co-conductor tape may include or consist of a copper tape. As can be seen from graph 520, in some examples, a tape stack may include a tape formed from multiple separate sections of HTS tape with filler tape disposed between the sections, and another tape formed primarily of HTS tape with small sections of filler tape joined to the HTS tape (indicated by the tape identified by reference numeral 534). In some examples, one of the tapes in the tape stack may include more non-HTS tape (filler tape) than HTS tape (indicated by the tape identified by reference numeral 535).

[0077]

[0090] A winding formed from a fixed number of tapes may provide a simpler winding process compared to adjusting the number of tapes as shown in the example of FIG. 5A. For example, the winding process may first join the HTS and filler tape sections together and place the resulting tape on a separate spool. In some embodiments, a typical winding may include between about 100 and about 200 tapes, each requiring a separate spool. The tapes are pulled together from all spools, bundled into a stack, and inserted into grooves in a structural plate. In embodiments, a winding may include fewer than 100 or more than 200 tapes.

[0078]

[0091] According to some embodiments, tapes including both HTS and non-HTS (filler) tape may be produced at least in part by joining together portions of HTS and non-HTS tape. Such joining processes may include soldering, spot welding (e.g., resistance welding), and / or ultrasonic welding.

[0079]

[0092] 4, as shown in inset 430, the amount of HTS tape in the innermost windings is further reduced compared to the pre-grading example, while the amount of HTS tape in the intermediate windings remains the same. For example, excess portions of HTS tape 431 can be seen near the sides of graded tape stack 432, while no such excess is shown near graded tape stack 422, which remains the same size as the pre-grading tape stack. In some embodiments, the innermost turns (e.g., shown in inset 430) may include less HTS tape than the outermost turns (e.g., shown in inset 410) due to the higher critical current observed in the innermost turns before grading the tape.

[0080]

[0093] The approach to tape gradient shown in FIG. 4 may be particularly beneficial in the outermost winding in a stack of windings (e.g., in the top or bottom windings shown in FIG. 2A), which may otherwise tend to have higher critical currents in the innermost and outermost turns of that winding.

[0081]

[0094] While FIG. 4 shows thinner and wider regions of winding 400, it is understood that this is intended to convey that the amount of HTS tape in these regions is reduced. The tape stack is not necessarily narrower or wider in these sections, given that one approach to reducing the amount of HTS tape is to bond HTS tape together with filler tape, as shown in FIG. 5C . However, in some instances, if the approach of FIG. 5A is followed, where HTS tape is added at specific locations along the winding, the tape stack may actually be narrower in these sections. Thus, regardless of whether the technique of FIG. 5A or the technique of FIG. 5C (or some other technique) is used to effect such variation, FIG. 4 may be understood to convey varying the amount of HTS tape along the winding.

[0082]

[0095] FIG. 6 illustrates an exemplary winding in which the amount of HTS tape is reduced across all turns of the winding, according to some embodiments. The inventors recognize that the critical current in a winding midway through a stack of windings may be much higher (e.g., three times higher) than the critical current in the top or bottom windings within the same stack of windings. A significant reduction in the critical current in the midway windings may be desired to flatten (or substantially flatten) the critical current across the magnet. FIG. 6 illustrates one example of such an approach, showing a constant amount of HTS tape throughout the entire winding 600 before grading (including the hatched and dotted shaded areas), and a roughly constant and significantly reduced amount of HTS tape only in the hatched shaded area after grading. As illustrated by insets 610, 620, and 630 in FIG. 6, respectively, the amount of HTS tape in the outermost winding, the innermost winding, and the midway winding is reduced compared to the amount of HTS tape before grading. For example, the reduction in HTS tape volume 611, 621, and 631 can be seen in the tape stacks with gradients at 612, 622, and 632. Insets 610, 620, and 630 are not drawn to scale relative to one another.

[0083]

[0096] While FIG. 6 shows regions of the winding 600 that are thinner after grading, it is understood that this is intended to convey that the amount of HTS tape in these regions is reduced. Given that one approach to reducing the amount of HTS tape is to bond HTS tape together with filler (non-HTS) tape, as described herein with at least reference to FIGS. 5C-5E, this does not necessarily mean that the tape stack in the winding will be narrower in these sections. However, in some instances, if the approach of FIG. 5A is followed, in which HTS tape is added at specific locations along the winding, the tape stack may actually be narrower in these sections. Thus, FIG. 6 may be understood to convey a reduced amount of HTS tape in the winding, regardless of whether the technique of FIG. 5A or the technique of FIG. 5C (or some other technique) is used to effect such a variation.

[0084]

[0097] Having described techniques for tape gradients, techniques for turn-to-turn resistance gradients are described below. As noted above, adjusting the spacing between turns of an uninsulated magnet can adjust the resistance between the turns and thereby adjust the Joule heating rate of each turn. This adjustment can allow the magnet to be tuned so that quenching occurs more uniformly across the magnet.

[0085]

[0098] An illustrative example of inter-turn resistance gradients, according to some embodiments, is shown in FIG. 7 . In the example of FIG. 7 , a cross-section through a winding in structural plate 701 is shown, with conventional equally sized gaps between adjacent winding turns. As shown, the amount of structural plate between adjacent turns is constant, resulting in equal spacing between each turn. In contrast, the winding in structural plate 702 has a varying gap between adjacent turns. This is highlighted in FIG. 7 by the vertical dashed lines, which are uniformly spaced apart and indicate that the spacing between inner turns in the winding in structural plate 702 is reduced compared to the winding in structural plate 701, and that the spacing between outer turns in the winding in structural plate 702 is increased compared to the winding in structural plate 701. The overall result is that the same number of turns in both 701 and 702 occupy the same total amount of space, but with smaller spacing in some areas and larger spacing in other areas.

[0086]

[0099] Structural plates without and with this inter-turn resistance gradient, according to some embodiments, are shown in Figures 8A and 8B, respectively. In the example of Figure 8A, structural plate 800 is shown formed from base plate 810 with grooves 811 formed therein. As shown, the spacing between each turn of the groove is constant. In contrast, structural plate 801 shown in Figure 8B includes base plate 820 and grooves 821, where the spacing between turns of the groove varies from smaller spacing on the inner turns to larger spacing on the outer turns. Both structural plates 800 and 801 include grooves with 16 turns, but in plate 801, the grooves are positioned relatively closer to each other in some turns compared to other turns.

[0087]

[0100] It has been recognized by the inventors that the volume of the inner turns in a grooved structural plate is smaller than the volume of the outer turns in the plate, and as a result, placing the inner turns closer to each other compared to the proximity of the outer turns to each other makes the resistance between turns more consistent across the turns. Therefore, there may be certain advantages to configuring the distance between turns between grooves in a structural plate as shown in FIG. 8B.

[0088]

[0101] According to some embodiments, the turn-to-turn resistance gradient technique can be applied in conjunction with the tape gradient technique. An illustrative example of the results of applying such an approach, according to some embodiments, is shown in FIG. 9. In the example of FIG. 9, the winding in structural plate 900 includes ten turns 901-910. The structural plate is formed so that the inner turns (e.g., 901, 902) have a turn spacing less than the turn spacing of the outer turns (e.g., 909, 910). In addition, the amount of HTS tape in each turn varies across the turn, with turn 901 having the least amount of HTS tape, turns 906 and 907 having the most, and turns 909 and 910 having less HTS tape than turns 906 and 907 but more HTS tape than turn 901. In this manner, the winding in structural plate 900 can be an example of an outer structural plate in a stack of plates, such as that shown in FIG. 4, to which the addition of a turn-to-turn resistance gradient has been applied. In general, any suitable combination of tape gradient and turn-to-turn resistance gradient may be applied to a given winding, the example of FIG. 9 being shown as just one illustrative approach.

[0089]

[0102] FIG. 10 is a three-dimensional graphic of a fusion device with portions cut away to show various components of the tokamak, according to some embodiments. The magnets in the fusion device may be formed from stacks of windings disposed within structural grooves of structural plates arranged in stacks, as described above. FIG. 10 shows a cross section through the fusion device 1000, including an electromagnetic coil 1014 fabricated from or otherwise including stacks of windings disposed within structural grooves of structural plates arranged in stacks, as described above, a neutron shield 1012, and a core region 1011. According to some embodiments, the electromagnetic coil 1014 may be a toroidal field coil or may form part of a toroidal field coil.

[0090]

[0103] Those skilled in the art will recognize other embodiments of the concepts, results, and techniques disclosed herein. It will be understood that superconducting magnets configured according to the concepts and techniques described herein can be useful for a wide variety of applications. For example, one such application is performing nuclear magnetic resonance (NMR) studies, e.g., in solid state physics, physiology, or proteins. Another application is performing clinical magnetic resonance imaging (MRI) for medical scanning of organisms or portions thereof, where a small high-field magnet is required. Yet another application is high-field MRI, where a large-bore solenoid is required. Yet another application is for performing magnetic research in physics, chemistry, and materials science. Further applications are in particle accelerators for materials processing or research, wind turbines and other generators, medical accelerators for proton therapy, radiation therapy, and radiation production in general, superconducting energy storage, magnetohydrodynamic (MHD) generators, and magnets for material separation, e.g., in mining, semiconductor manufacturing, and recycling. It will be understood that the above list of applications is not exhaustive and that there are additional applications to which the concepts, processes, and techniques disclosed herein can be applied without departing from their scope.

[0091]

[0104] As used herein, the expressions "HTS material," "HTS superconductor material," or "HTS superconductor" refer to a superconducting material that has a critical temperature above 30° K in the absence of a self-magnetic field.

[0092]

[0105] Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art.

[0093]

[0106] Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the spirit and scope of the present invention. Moreover, while advantages of the present invention have been illustrated, it should be understood that not all embodiments of the technology described herein include all of the described advantages. Some embodiments may not embody all of the features described herein as beneficial, and in some instances, one or more of the described features may be implemented to achieve further embodiments. Accordingly, the foregoing description and drawings are merely exemplary.

[0094]

[0107] In the foregoing detailed description, various features of the embodiments are grouped together in one or more individual embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claims require more features than are expressly recited therein. Rather, inventive aspects may lie in less than all features of each of the disclosed embodiments.

[0095]

[0108] Further aspects of the present disclosure may include the following.

[0096]

[0109] Aspect 1. A high temperature superconducting (HTS) magnet, the HTS magnet comprising: a coil formed from a stack of HTS tape, the coil including at least one bend; and at least one additional layer of HTS tape disposed along a portion of the coil to increase the width of the portion of the coil.

[0097]

[0110] Embodiment 2. The magnet of embodiment 1, wherein the at least one additional layer of HTS tape comprises a plurality of HTS tapes, each tape having an end offset from the end of an adjacent tape to form a tapered width of a portion of the coil.

[0098]

[0111] Embodiment 3. The magnet of embodiment 1, wherein the HTS tape is disposed along the bend.

[0099]

[0112] Embodiment 4. The magnet of embodiment 3, wherein at least one additional HTS tape is disposed along the periphery of the stack of HTS tapes.

[0100]

[0113] Embodiment 5. The magnet of embodiment 1, wherein the HTS magnet comprises a stack of pancake magnets, each pancake magnet comprising a respective coil formed from a stack of HTS tapes.

[0101]

[0114] Embodiment 6. The magnet of embodiment 5, wherein the plurality of coils includes an additional layer of HTS tape to increase the width of the stack of HTS tape along a portion of the coil.

[0102]

[0115] Embodiment 7. The magnet of embodiment 1, wherein at least one additional layer of HTS tape has a length that is less than the length of the coil.

[0103]

[0116] Aspect 8. A high temperature superconducting (HTS) pancake magnet comprising: a base plate formed from a conductive material, the base plate having a groove with a plurality of turns; and a coil formed from an HTS material, the coil disposed in the groove, the coil having a plurality of turns, the HTS material disposed in the groove, wherein the radial distance between adjacent turns of the coil of HTS material varies.

[0104]

[0117] Embodiment 9. The magnet of embodiment 8, wherein the pancake base plate forms a shape having an inner diameter and an outer diameter.

[0105]

[0118] Aspect 10. The magnet of aspect 9, wherein the distance between adjacent turns of the coil closer to the inner diameter is less than the distance between adjacent turns of the coil closer to the outer diameter.

[0106]

[0119] Embodiment 11. A high temperature superconducting (HTS) magnet, the HTS magnet comprising a coil formed from a plurality of windings, the plurality of windings comprising HTS tape, the plurality of windings comprising: a first portion comprising a first stack of HTS tape having a first thickness; a second portion disposed outside the first portion and comprising a second stack of HTS tape having a second thickness greater than the first thickness; and a third portion disposed outside the first portion and the second portion and comprising a third stack of HTS tape having a third thickness less than the second thickness.

[0107]

[0120] Embodiment 12. The HTS magnet of embodiment 11, wherein the first portion of the plurality of windings includes a plurality of inner turns of the plurality of windings, the third portion of the plurality of windings includes a plurality of outer turns of the plurality of windings, and the second portion of the plurality of windings includes one or more windings between the plurality of inner turns and the plurality of outer turns.

[0108]

[0121] Embodiment 13. The HTS magnet of embodiment 11, wherein the plurality of windings includes at least one HTS tape disposed within a second portion of the plurality of windings and not disposed within the first portion of the plurality of windings and the third portion of the plurality of windings.

[0109]

[0122] Embodiment 14. The HTS magnet of embodiment 11, wherein the plurality of windings further comprises a co-conductor disposed in contact with the HTS tape.

[0110]

[0123] Embodiment 15. The HTS magnet of embodiment 14, wherein the amount of co-conductor increases and decreases within the multiple windings.

[0111]

[0124] Embodiment 16. The HTS magnet of embodiment 15, wherein the plurality of windings have a constant or substantially constant thickness.

[0112]

[0125] Embodiment 17. The HTS magnet of embodiment 11, wherein the HTS magnet further comprises a base plate formed from a conductive material and a groove having a plurality of turns, the groove including: a first portion having a first width and comprising a first portion of the plurality of windings; a second portion having a second width greater than the first width and comprising a second portion of the plurality of windings; and a third portion having a third width less than the second width and comprising a third portion of the plurality of windings.

[0113]

[0126] Embodiment 18. The HTS magnet of embodiment 11, wherein the first portion of the plurality of windings forms less than one complete turn of the coil.

[0114]

[0127] Embodiment 19. The HTS magnet of embodiment 11, wherein the third portion of the plurality of windings forms less than one complete turn of the coil.

[0115]

[0128] Aspect 20. A high temperature superconducting (HTS) magnet, wherein the HTS magnet comprises a coil formed from a plurality of windings, the plurality of windings comprising a stack of HTS tape, the plurality of windings including HTS tape forming less than one full turn of the coil.

[0116]

[0129] Embodiment 21. The HTS magnet of embodiment 18, wherein the plurality of windings further comprises a co-conductor disposed in contact with the stack of HTS tapes.

[0117]

[0130] The above-described embodiments of the technology described herein may be implemented in any of numerous ways. Various aspects of the invention may be used alone, in combination, or in various configurations not explicitly described in the embodiments described hereinabove, and therefore are not limited in their application to the details and arrangements of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

[0118]

[0131] Furthermore, the present invention may be embodied as a method, for which examples are provided. The steps performed as part of the method may be ordered in any suitable manner. Thus, embodiments may be constructed in which steps are performed in an order different from that shown, which may include performing some steps simultaneously even though shown as sequential steps in the exemplary embodiment.

[0119]

[0132] Additionally, some steps are described as being performed by a "user." It should be understood that a "user" need not be a single individual, and that in some embodiments, steps attributed to a "user" may be performed by a team of individuals and / or an individual in combination with computer-assisted tools or other mechanisms.

[0120]

[0133] The use of ordinal terms, e.g., "first," "second," "third," etc., in the claims to modify claim elements does not in itself imply any priority, precedence, or order of a claim element relative to another element, or the chronological order in which method steps are performed, but is merely used as a label to distinguish a claim element with a particular name from another element with the same name (except for the use of ordinal terms) to distinguish claim elements.

[0121]

[0134] The terms "generally" and "about" may be used in some embodiments to mean 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 "generally" and "about" may include the target value. The term "substantially equal" may be used to describe values ​​that are within ±20% of each other in some embodiments, within ±10% of each other in some embodiments, within ±5% of each other, and even in some embodiments within ±2% of each other.

[0122]

[0135] The term "substantially" may be used to refer to values ​​within ±20%, within ±10%, within ±5%, and even within ±2% of a comparative measurement in some embodiments. For example, a first direction that is "substantially" orthogonal to a second direction may refer to a first direction that, in some embodiments, forms a 90° angle with the second direction within ±20%, in some embodiments, forms a 90° angle with the second direction within ±10%, in some embodiments, forms a 90° angle with the second direction within ±5%, and even in some embodiments, forms a 90° angle with the second direction within ±2%.

[0123]

[0136] Moreover, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "including," "involving," and variations thereof herein is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items.

Claims

1. 1. A high temperature superconductor (HTS) magnet, comprising: a coil formed from a plurality of windings, a first winding of the plurality of windings comprising a first portion of HTS tape forming less than one full turn of the coil; HTS magnet.

2. the first portion of HTS tape bonded end-to-end with one or more portions of non-HTS tape formed from a conductive metal or conductive metal alloy; 10. The HTS magnet of claim 1.

3. the combination of the first portion of HTS tape and the one or more portions of non-HTS tape forms a complete winding of the coil.

3. The HTS magnet of claim 2.

4. the first winding comprising a plurality of tapes, each forming a complete turn of the coil, each formed from one or more sections of HTS tape joined end-to-end with one or more sections of non-HTS tape; 4. The HTS magnet of claim 3.

5. the plurality of tapes further comprising one or more co-conductor tapes; 5. The HTS magnet of claim 4.

6. the first winding further comprises a co-conductor disposed in contact with the first portion of the HTS tape.

10. The HTS magnet of claim 1.

7. the co-conductor is a co-conductor tape disposed in contact with the first portion of the HTS tape; 7. The HTS magnet of claim 6.

8. 1. A high temperature superconductor (HTS) magnet, comprising: a coil formed from a plurality of windings, the plurality of windings including a first winding formed from a stack of tapes; the stack of tapes comprises a first number of HTS tapes at a first cross section; the stack of tapes comprises a second number of HTS tapes in a second cross section outside the first cross section in the first winding, the second number of HTS tapes being greater than the first number of HTS tapes; the stack of tapes comprises a third number of HTS tapes in a third cross section outside the second cross section of the first winding, the third number being less than the second number of HTS tapes; HTS magnet.

9. the stack of tapes at the first cross-section has a first thickness, the stack of tapes at the second cross-section has a second thickness greater than the first thickness, and the stack of tapes at the third cross-section has a third thickness less than the second thickness; 9. The HTS magnet of claim 8.

10. the stack of tapes comprises a stack of HTS tapes and a plurality of non-HTS tape sections formed from a conductive metal or conductive metal alloy; 9. The HTS magnet of claim 8.

11. at least some of the portions of non-HTS tape joined end-to-end with portions of HTS tape; 11. The HTS magnet of claim 10.

12. the first cross section is at an inner turn of the first winding; the third cross section is at an outer turn of the first winding; the first winding includes a plurality of turns between the inner turn and the outer turn; 9. The HTS magnet of claim 8.

13. the first winding includes a first portion of HTS tape that is present in the second cross section and that is absent from the first cross section and the third cross section; 9. The HTS magnet of claim 8.

14. the first portion of the HTS tape joined end-to-end with a non-HTS tape formed from a conductive metal or conductive metal alloy; 14. The HTS magnet of claim 13.

15. said stack of tapes comprising one or more co-conductor tapes; 9. The HTS magnet of claim 8.

16. the number of co-conductor tapes increases and decreases within the first winding; 16. The HTS magnet of claim 15.

17. the first winding has a constant or substantially constant thickness; 17. The HTS magnet of claim 16.

18. the HTS magnet further comprising a base plate formed from a conductive material and a helical path portion including a plurality of turns with a turn spacing; the turn spacing between the innermost turns of the spiral path portion is smaller than the turn spacing between the outermost turns of the spiral path portion; 9. The HTS magnet of claim 8.

19. the first cross-section, the second cross-section, and the third cross-section are within different turns of the first winding.

9. The HTS magnet of claim 8.

20. 1. A high temperature superconductor (HTS) magnet, comprising: a plurality of plates arranged in a stack, including a first plate; the first plate comprises a helical path formed in the first plate including a plurality of turns with a turn spacing, the path comprising a winding of a high temperature superconductor (HTS) material; the turn spacing between the innermost turns of the spiral path portion is smaller than the turn spacing between the outermost turns of the spiral path portion; HTS magnet.

21. the turn spacing of the spiral path portion increases from the innermost turn of the spiral path portion to the outermost turn of the spiral path portion; 21. The HTS magnet of claim 20.

22. the winding of HTS material comprising a first portion of HTS tape forming less than one full turn of the winding; 21. The HTS magnet of claim 20.

23. the first portion of HTS tape bonded end-to-end with one or more portions of non-HTS tape formed from a conductive metal or conductive metal alloy; 23. The HTS magnet of claim 22.

24. a combination of the first portion of HTS tape and the one or more portions of the non-HTS tape forming a complete winding along the helical path; 24. The HTS magnet of claim 23.

25. the first winding comprises a plurality of tapes, each forming a complete turn, each formed from one or more sections of HTS tape joined end-to-end with one or more sections of non-HTS tape; 25. The HTS magnet of claim 24.

26. the plurality of tapes further comprising one or more co-conductor tapes; 26. The HTS magnet of claim 25.

27. 1. A high temperature superconductor (HTS) magnet, comprising: a coil formed from a stack of HTS tapes, the coil including at least one bend; at least one additional layer of HTS tape disposed along a portion of the coil to provide the coil with an increased amount of HTS material relative to the amount of HTS material in a second, different portion of the coil; An HTS magnet comprising:

28. the at least one further layer of HTS tape comprises a plurality of HTS tapes, each tape having an end offset from an end of an adjacent tape to form a tapered thickness of the portion of the coil; 28. The magnet of claim 27.

29. The HTS tape is disposed along the bent portion.

28. The magnet of claim 27.

30. the at least one further layer of HTS tape is disposed along the periphery of the stack of HTS tapes; 30. The magnet of claim 29.

31. the HTS magnet comprises a stack of pancake magnets, each pancake magnet comprising a respective coil formed from a stack of HTS tapes; 28. The magnet of claim 27.

32. at least one of the coils includes an additional layer of HTS tape to increase the thickness of the stack of HTS tape along a portion of the coil; 32. The magnet of claim 31.

33. the at least one further layer of HTS tape has a length that is shorter than a length of the coil; 28. The magnet of claim 27.

34. 1. A high temperature superconductor (HTS) pancake magnet, comprising: a base plate formed from a conductive material, the base plate having a groove with a plurality of turns; a coil formed from an HTS material, the coil being disposed within the groove, the coil having a plurality of turns, the HTS material being disposed within the groove; Equipped with the radial distance between adjacent turns of said coil of HTS material varies; HTS pancake magnet.

35. the base plate of the pancake defines a shape having an inner diameter and an outer diameter; 35. The magnet of claim 34.

36. the distance between adjacent turns of the coil closer to the inner diameter is less than the distance between adjacent turns of the coil closer to the outer diameter; 36. The magnet of claim 35.

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