Patent Description:
High-field magnets are often constructed from superconductors due to the capability of superconductors to carry a high current without resistance. Such magnets may, for instance, carry currents greater than <NUM> kA. <CIT> discloses an assembly for carrying electrical current in a coil of a magnet. The assembly comprises a pre-formed housing of thermally and electrically conductive material which comprises a channel configured to retain high temperature superconductor, HTS, tape. A plurality of layers of HTS tape are fixed within the channel. The channel has at least one pre-formed curved section. <CIT> discloses a hollow superconductive wire tightly fitted adjacent one another in an axial direction in the coiling recesses of a plate-shaped winding frame so that a superconductive coil is formed. Since the coiling recesses are provided on both the sides of each winding frame, the superconductive wires overlap one another between the adjacent winding frames in the axial direction of the coil. The winding frames except for the central one are provided with the recesses on only their sides facing the outside in the axial direction, so that the wires in the recesses are all directly supported by the winding frames both in the radial direction and in the axial direction. <CIT> and belonging to the state of the art under Article <NUM>(<NUM>) EPC, discloses depositing a superconductor directly onto a magnet structure including depositing a buffer, superconductor and protection onto a plate. Photolithography or laser etching methods can be used to selectively remove superconductor to form windings on the plate. Multiple plates can then be assembled similar to the assembly of a traditional Bitter plate magnet. Cooling channels can be integrated into the base structure, before or after superconductor deposition.

<CIT> reveals a first HTS tape stack being arranged next to a second HTS tape stack in a plate where the tape stacks are disposed in spiral grooved plates and a coolant channel is defined by a C-shaped member.

According to a first aspect, there is provided a magnet according to claim <NUM>.

According to a second aspect, there is provided a magnet according to claim <NUM>.

A high-field superconducting magnet often comprises multiple electrically insulated cable turns grouped in a multi-layer arrangement. When the superconducting material is cold enough to be below its critical temperature (the temperature below which the electrical resistivity of the material drops to zero), driving the magnet allows current to pass through the superconducting path without losses. However, for various reasons some or all of the superconducting material may be heated to above its critical temperature and therefore lose its superconducting characteristics. If uncontrolled, such heating can lead to the superconductor losing its superconducting abilities, often referred to as a "quench. " Moreover, if the quench is not properly addressed by the system (e.g., by shutting down), components can be damaged by the heating.

Some superconducting magnet systems handle quench events via a system of active alarms and detection mechanisms. Other superconducting magnet systems handle quenches passively through design of the superconducting magnet itself. An example of the latter approach is a non-insulated (NI) magnet (also referred to as a no-insulation (NI) magnet), in which adjacent superconducting turns of the magnet are not insulated from one another but are instead separated by a conventional conductor (i.e., not a superconductor). When the magnet is operating below the superconductor's critical temperature, current flows through the superconductor and not across turns because the superconductor has zero resistance compared with the finite resistance of the conductor that lies between the turns.

During a quench, however, at least one or more portions of the superconductor may be in a "normal" (non-superconducting) state (i.e., at least one or more portions of the superconductor have a finite resistance rather than a zero resistance which is characteristic of a superconductor). The at least one or more portions of the superconductor having a normal resistance are sometimes referred to as "normal zones" of the superconductor. When normal zones appear, at least some zero resistance current pathways are no longer present, causing the current to flow through the normal zones and/or between the turns, with the balance of current flow between these pathways depending on their relative resistances. By diverting at least some current from the superconducting material when it is normal in this manner, therefore, NI magnets, and in particular non-insulated high temperature superconductor (NI-HTS) magnets (NI magnets that comprise HTS), can in principle be passively protected against quench damage without the need to continuously monitor quench events and/or to actively engage external quench protection mechanisms.

The inventors have recognized and appreciated a non-insulated superconducting magnet design that comprises a stack of conductive plates that each include a spiral groove. A superconductor can be arranged within the grooves and the plates stacked such that the superconductor forms a continuous current path through the plates, making a spiral path within each plate. The conductive plates act as the conductive material that is arranged between the turns of the superconducting magnet in the NI design discussed above. The spiral-grooved, stacked-plate design has the advantage that it is scalable to large bore magnets, and can be configured to have a high overall current density, be thermally stable, and mechanically stable.

As the size of NI magnets constructed using the spiral-grooved, stacked-plate design increase, however, there is a concomitant increase of the Lorentz loads on various regions of the conductor. Such increased Lorentz loads may lead to reduced structural integrity of the NI magnet. Moreover, the amount of internal volumetric heating may also increase as the magnets become larger. These conditions thereby require further consideration as to how cooling and conductive paths are arranged within a spiral-grooved, stacked-plate NI magnet design.

The inventors have recognized and appreciated schemes for conductor and coolant placement in stacked-plate superconducting magnets. In particular, the inventors have recognized that there are advantages to arranging coolant channels and conducting channels within the plates on opposing faces. If the two types of channels are aligned with one another across the plate stacks, the plates may be stacked such that the cooling channel in one plate is adjacent to the conducting channel of the neighboring plate. By stacking a number of these plates, therefore, cooling may be supplied to each conducting channel through the cooling channels of each neighboring plate. Moreover, by aligning the two types of channels, the stacks of plates may have improved mechanical strength because mechanical load paths may be created through the entire stack that do not pass through any of the channels. If the plates are also formed from (e.g., via traditional machining processes, via additive and/or subtractive processes, etc.) an appropriately strong material, this arrangement of channels may produce a very strong stack of plates that can withstand high Lorentz loads.

One benefit of this design is that cryogenic coolant may make direct contact with material in the conducting channel (which may be, or may include, the superconducting material) along a substantial length of the conducting channel, because the two types of channel are aligned as such. Very efficient cooling can therefore be delivered to the superconducting material in the magnet. Moreover, no dedicated cooling plates are needed, because all of the cooling necessary may be included within the same plates that house the superconductors.

According to some embodiments, the conducting channels of the plates may comprise an HTS superconductor electrically coupled to a second conductor, such as copper. The second conductor may be aligned with the opening of the conducting channel - for instance, the second conductor may have a surface that is flush with the face of the plate in which the conducting channel is arranged. In this case, the HTS superconductor is embedded within the channel beneath the second conductor. In some embodiments, the conducting channels may comprise a third conductor, such as a Pb or Sn solder, which fills the space in the channel other than the second conductor and the HTS superconductor. In some cases, the third conductor may electrically couple the HTS superconductor to the second conductor.

According to some embodiments, a stacked-plate superconducting magnet may comprise alternating types of plates within the bulk of the stack of plates. For instance, a first type of plate may include conducting channels that spiral inward, while a second type of plate may include conducting channels that spiral outward. By arranging suitable connection points between the plates, a continuous conductive path through all of the conducting channels may be arranged, while providing cooling throughout the stack of plates. Such a design may also lead to being particularly modular, since aside from possibly the uppermost and/or lowermost plate (e.g., terminal plates), the bulk of the stack of plates may be formed or arranged by alternating placement of the two types of plates.

According to some embodiments, the conducting channel in a stacked-plate superconducting magnet may be arranged in a racetrack spiral (or simply "racetrack pattern"). In a racetrack spiral, the path follows a racetrack shape (e.g., a rectangle with rounded corners) without spiraling inward or outward for most of the circumference, but includes a number of "jogs" or "joggles" in which the path jogs inward or outward. These jogs cause the racetrack spiral to wind inward or outward, depending on the direction of the jogs.

According to some embodiments, electrically insulating material may be arranged between plates of the stack of plates. In some cases, the insulation may cover part of, but not all, of the face of the plate. Conducting pads electrically connecting neighboring plates may, for instance, not have intervening insulating material between the pads. Moreover, at least some portion of the surface area of neighboring plates may contact one another directly, with the majority of the surface area of the contact between the plates being via insulating material. Arranging insulating material in this way may provide a conductive path between plates of the stack while maximizing the length of the conductive path, which may provide beneficial properties during magnet charging and during a quench.

Following below are more detailed descriptions of various concepts related to, and embodiments of, schemes for conductor and coolant placement in stacked-plate superconducting magnets. It should be appreciated that various aspects described herein may be implemented in any of numerous ways. Examples of specific implementations are provided herein for illustrative purposes only. In addition, the various aspects described in the embodiments below may be used alone or in any combination, and are not limited to the combinations explicitly described herein.

<FIG> is a cross-section of a portion of an illustrative plate suitable for use in a stacked-plate superconducting magnet, according to some embodiments. In the example of <FIG>, plate <NUM> comprises a baseplate material <NUM>, in which are formed (e.g., via traditional machining processes, via additive and/or subtractive processes, etc.) cooling channels <NUM> and conducting channels <NUM>. In the conducting channels are arranged an HTS material <NUM>, a cap <NUM> and an intervening conductive material <NUM> which provides electrical and thermal contact between the HTS material <NUM> and cap <NUM>.

It will be appreciated that another portion of plate <NUM> not shown in <FIG> may comprise a "jog" region in which the path of the conductive channel jog outward or inward to move to the next outer or inner racetrack path, respectively. For instance, in the case where the cross-section shown in <FIG> represents a portion of a plate in which the conductive channels <NUM> spiral inward, another portion of the plate may include an inward jog for at least some of the channels to connect the channel to the next innermost channel (e.g., outermost channel to 2nd outermost channel, etc.).

According to some embodiments, cooling channels <NUM> are open channels within the plate <NUM>. The cooling channels may become closed, thereby allowing cryogens to flow through the channels, by arranging the plate <NUM> adjacent to another plate, such as another instance of plate <NUM>. For example, when two instances of the plate <NUM> are stacked on top of one another, the cooling channels <NUM> may contact the caps <NUM> around the edges of each cooling channel. As a result, the cryogen flowing through the cooling channel may be in direct contact with the cap <NUM>.

According to some embodiments, the baseplate <NUM> may comprise, or may consist of, a high mechanical strength material such as but not limited to steel, Inconel®, Nitronic® <NUM>, Nitronic® <NUM>, Incoloy®, or combinations thereof. In some embodiments, the baseplate <NUM> may be plated with a metal such as nickel to facilitate adhesion of other components to the plate, including solder as described below.

According to some embodiments, the HTS <NUM> may comprise a rare earth barium copper oxide superconductor (REBCO), such as yttrium barium copper oxide (YBCO). In some embodiments, the HTS <NUM> may comprise a co-wound stack of HTS tape. In embodiments, the HTS tape may comprise a long, thin strand of HTS material with cross-sectional dimensions in the range of about <NUM> to about <NUM> in thickness (or height) and a width in the range of about <NUM> to about <NUM> (and with a length that extends along the length of the cable, e.g., into and out of the page in the example of <FIG>). According to some embodiments, each strand of HTS tape may comprise an HTS material such as REBCO in addition to an electrically conductive material. In some embodiments, the electrically conductive material may be disposed on the REBCO. In some embodiments, the electrically conductive material may be a cladding material such as copper. In some embodiments, HTS tape may comprise a polycrystalline HTS and/or may have a high level of grain alignment.

According to some embodiments, cap <NUM> may comprise, or may consist of, copper. It may be noted that, as a result of the plate <NUM> being shown in cross-section in <FIG>, that the shapes of the HTS <NUM> in the plate <NUM>, and of the cap <NUM> in the plate <NUM>, are generally that of a spiral (e.g., a racetrack spiral).

According to some embodiments, conductive material <NUM> may comprise a Pb and/or Sn solder. In some embodiments, conductive material <NUM> may comprise a metal having a melting point of less than <NUM>, wherein at least <NUM> wt% of the metal is Pb and/or Sn, and at least <NUM> wt% of the metal is Cu.

As shown in <FIG>, the cap <NUM> is arranged within an upper section of channels <NUM> that is wider than the lower section in which the HTS <NUM> and conductive material <NUM> are located. In some embodiments, the conductive material <NUM> may be introduced into the plate <NUM> as a molten solder subsequent to arranging the HTS <NUM> and cap <NUM> within the conducting channel <NUM>. As a result, the conductive material <NUM> may fill the space between the HTS <NUM> and cap <NUM> and/or may fill any space around the sides of the HTS <NUM> and/or cap <NUM>, should such space be present prior to filling or otherwise occupying the space with the solder.

In some embodiments, the HTS <NUM> may be pre-tinned with a metal (e.g., a PbSn solder) to promote a good bond between the HTS <NUM> and the solder. According to some embodiments, the conductive material <NUM> may be deposited via a vacuum pressure impregnation (VPI) process. Such a process may comprise one or more of the following steps: cleaning the empty space within the cable using an acidic solution following by a water rinse; evacuating the space within the cable; purging the space with an inert gas; depositing flux into the space to coat the HTS <NUM> and the conductive material <NUM>; draining any excess flux from the cable; heating the cable to a temperature below, at, or above a temperature at which the alloy to be deposited will melt; and flowing a molten alloy (e.g., a PbSn solder) into the plate.

According to some embodiments, plate <NUM> may comprise one or more through holes (not shown in <FIG>) for attaching the plate to other plates and/or other structures. In some cases, the through holes may comprise an interior thread to facilitate insertion of mechanical fasteners such as screws or bolts into or through the plate.

In the example of <FIG>, it will be appreciated that while particular shapes of the channels <NUM> and <NUM> are illustrated, the techniques described herein are not limited to channels with these particular shapes. For instance, the channels could have a half-circle cross-section instead of the rectangular cross-section shown, or another other suitable shape cross-section.

<FIG> show different cross-sections of an illustrative stack of plates in a superconducting magnet, according to some embodiments. Stack of plates <NUM> comprises two instances of plate <NUM> and two instances of plate <NUM>, in addition to terminal plates <NUM> and <NUM>. Layers of insulating material <NUM> are arranged at selected regions between neighboring plates. <FIG> represents a cross-section of the stack of plates through the racetrack portion of the channels of the plates, whereas <FIG> represents a cross-section of the stack of plates in the region in which the conducting channels "jog" in or out to switch lanes of the racetrack spiral.

As noted above in relation to <FIG>, the open cooling channels in one plate may be arranged adjacent to the conducting channel of the neighboring plate. For example, as shown in <FIG>, which represents the racetrack portion of the channels, the cooling channels <NUM> in each instance of plate <NUM> are arranged adjacent to the cap <NUM> of the neighboring plate <NUM>. Similarly, the cooling channels <NUM> in plate <NUM> are arranged adjacent to the cap <NUM>, with cooling channels <NUM> arranged in the terminal cap <NUM> arranged adjacent to the uppermost instance of the plate <NUM>.

It may be noted that cooling channels <NUM> in the lowermost instance of plate <NUM> are not strictly needed since there are no conductors adjacent to these channels. However, due to the modular nature of the plates in the stack <NUM>, it may be more convenient to simply use an instance of plate <NUM> rather than fabricate a new type of plate that does not include the lowermost cooling channels <NUM>.

In the example of <FIG>, the plates <NUM>, <NUM>, <NUM> and <NUM> are held together, at least in part, by bolts <NUM>, which connect neighboring pairs of plates as shown in <FIG>. It may be presumed that such bolts are present at a number of locations around the plates <NUM>, <NUM>, <NUM> and <NUM>, although the cross-section shown in <FIG> does not include any such bolts for clarity.

As shown in <FIG>, the plates may include conductive pads to connect the conductive paths in one plate to those of an adjacent plate. For example, the terminal plate <NUM> includes pad <NUM> which is adjacent to and electrically connected to the conductor <NUM> in the conducting channel of plate <NUM>. Thus, the terminal plate may be adjacent to and electrically connected to one end of the conductive channel of plate <NUM>, the other end of which is electrically connected to the pad <NUM>. Pad <NUM> is, in turn, adjacent to and electrically connected to, the conductor <NUM> in the conducting channel of plate <NUM>. The other end of the conductor <NUM> in the conducting channel of plate <NUM> is adjacent to and electrically connected to pad <NUM>, which is adjacent to and electrically connected to the next plate <NUM>, and so forth. In the example of <FIG>, the conductive pads <NUM>, <NUM>, <NUM> and <NUM> are shaded in the same manner as the caps of the plates, although it will be appreciated that in general the pads and caps need not comprise the same material(s).

According to some embodiments, insulating material <NUM> may comprise polyimide (e.g., Kapton®), epoxy resin, phenolic resin, glass epoxy laminate, a plastic, an elastomer, or combinations thereof. According to some embodiments, insulating material may have a breakdown voltage or dielectric strength of greater than <NUM> kV/mm, of greater than <NUM> kV/mm, of greater than <NUM> kV/mm, of greater than <NUM> kV/mm. In some cases, the voltages in the superconducting magnet may be comparatively low, in which case a low voltage standoff insulating material such as anodized aluminum could be utilized as the insulating material <NUM>.

According to some embodiments, the baseplates 210a, 220a, 230a and 240a may each comprise, or may consist of, a high mechanical strength material such as but not limited to steel, Inconel®, Nitronic® <NUM>, Nitronic® <NUM>, Incoloy®, or combinations thereof. In some embodiments, the baseplates 210a, 220a, 230a and 240a may be plated with a metal such as nickel to facilitate adhesion of other components of the plate, including solder.

In the example of <FIG>, bolts <NUM> are arranged within through holes of the plates <NUM>, <NUM>, <NUM> and <NUM> and affix neighboring pairs of plates to one another.

To further illustrate the structure of a stack of plates such as those shown in <FIG>, <FIG> depict upper and lower views of individual plates <NUM> and <NUM>.

<FIG> and <FIG> depict upper and lower views, respectively, of plate <NUM>, wherein the cross-section of <FIG> is through the section marked A-A' and the cross-section of <FIG> is through the section marked B-B'. In the example of <FIG>, the location of cooling channels <NUM>, which are part of plate <NUM> arranged above the plate <NUM>, are shown for purposes of explanation, although it will be appreciated that these cooling channels are not in fact part of the plate <NUM>. As may be noted, the conducting channel of plate <NUM> in this example has an inward spiral when following the channel in a clockwise direction viewed from above.

As may be seen in <FIG>, for the bulk of the racetrack sections of the conducting channel of the plate <NUM> - of which the cap <NUM> is visible - the cooling channels <NUM> of the neighboring plate <NUM> are aligned with the conducting channel. As such, cryogen passing through the cooling channels may directly contact the cap <NUM> and deliver cooling to the HTS material arranged beneath the cap as discussed above.

The region of the plate <NUM> between the coolant inlet and outlet (the two regions where the coolant channels meet the edge of the plate) includes, in the example of <FIG>, a "meandering" region of the cooling channel <NUM> that meanders back and forth over the conducting channels <NUM>. Various other arrangements may be envisioned, including a cooling channel that is aligned with a single conducting channel, but runs back and forth over successive cooling channels in the region between the inlet and outlet.

In some embodiments, the inlet and outlet regions of the plate may be further apart than is shown in the example of <FIG>, such as at opposite ends of the plate from one another. In such cases, the cooling channels may be arranged so that some cooling channels (e.g., half) pass along one side of the plate with the other cooling channels passing along the other side of the plate. An example of such a cooling channel configuration is depicted in <FIG>, which shows a single layer of cooling channels <NUM> in an aerial view. <FIG> depicts the cooling channels <NUM> of the layer of the plate shown in <FIG> with the same aerial view for comparison. It may be noted that alternative cooling channel arrangements such as that shown in <FIG> may be arranged on a plate without altering the structure of the other elements of the plate except for the portion(s) of the baseplate that connect the cooling channels to the edge of the plate. For instance, as shown in <FIG> the cooling channels may be arranged as shown in <FIG> without altering the conductive channels of the plate.

<FIG> illustrates the underside of plate <NUM>, and includes portions to which insulating material <NUM> is attached, and portions for which the baseplate 210a is exposed.

<FIG> and <FIG> depict upper and lower views, respectively, of plate <NUM>, wherein the cross-section of <FIG> is through the section marked A-A' and the cross-section of <FIG> is through the section marked B-B'. In the example of <FIG>, the location of cooling channels <NUM>, which are part of plate <NUM> arranged above the plate <NUM>, are shown for purposes of explanation, although it will be appreciated that these cooling channels are not in fact part of the plate <NUM>. As may be noted, the conducting channel of plate <NUM> in this example has an outward spiral when following the channel in a clockwise direction viewed from above.

In some embodiments, the inlet and outlet regions of the plate may be further apart than is shown in the example of <FIG>, such as at opposite ends of the plate from one another. In such cases, the cooling channels may be arranged so that some cooling channels (e.g., half) pass along one side of the plate with the other cooling channels passing along the other side of the plate.

<FIG> illustrates the underside of plate <NUM>, and includes portions to which insulating material <NUM> is attached, and portions for which the baseplate 220a is exposed.

<FIG> is a perspective view of an illustrative stack of plates of a superconducting magnet, according to some embodiments. Stack of plates <NUM> represents an exterior perspective view of the stack of plates shown in cross-section in <FIG>. As in <FIG>, the cross-section of <FIG> is through the section marked A-A' and the cross-section of <FIG> is through the section marked B-B'.

As shown in the example of <FIG>, the terminal plates at the top and the bottom of the stack each comprise a conductive portion <NUM> and <NUM>, respectively, that extends outward from the stack and that are electrically connected to one another through the spiral conducting paths within the stack. Each cooling channel of the plates of the stack terminates at a common set of ports <NUM> at one end of the channel and at a common set of ports <NUM> at the other end of the channel. Since the ends of the cooling channels are arranged together, with all the inlets together and all the outlets together, a single large inlet or outlet port may be formed (e.g., via traditional machining processes, via additive and/or subtractive processes, etc.) around the set of channels at each end, as shown in <FIG>. This may allow coolant to pass through all the cooling channels of the stack of plates using just a single inlet pipe and a single outlet pipe.

<FIG> is a perspective view of an illustrative stack of plates of a superconducting magnet with an exterior case, according to some embodiments. Subsequent to assembly of the stack of plates, some or all of the exterior of the stack may have an insulating material disposed thereon (e.g. some or all of the exterior of the stack may be wrapped in an insulating material). In the example of <FIG>, the entire stack of plates except for the cooling inlet and outlet <NUM> and <NUM>, and the ends of the terminal plates that include conductive portions <NUM> and <NUM>, are wrapped in an insulating material <NUM> such as polyimide (e.g., Kapton®), epoxy resin, phenolic resin, glass epoxy laminate, a plastic, an elastomer, or combinations thereof. According to some embodiments, the insulating material <NUM> may have a breakdown voltage or dielectric strength of greater than <NUM> kV/mm, of greater than <NUM> kV/mm, of greater than <NUM> kV/mm, of greater than <NUM> kV/mm. In some cases, the voltages in the superconducting magnet may be comparatively low, in which case a low voltage standoff insulating material such as anodized aluminum could be utilized as the insulating material <NUM>.

Subsequent to application of the insulating material <NUM>, the stack of plates are enclosed within a case <NUM>, which provides further structural stability to the stack of plates and may comprise fiberglass, for instance. In some cases, the case <NUM> may comprise a high mechanical strength material such as but not limited to steel, Inconel®, Nitronic® <NUM>, Nitronic® <NUM>, Incoloy®, or combinations thereof. In some embodiments, any gaps between the stack of plates and the case <NUM> may be filled with an insulating material such as epoxy resin.

As discussed above, alignment of the cooling channels and the conducting channels across the plates provides structural benefits, as illustrated in <FIG>, which depicts a cross-sectional view of a stack of plates similar to that shown in <FIG> to depict the structural load on such a stack.

As shown in <FIG>, in zones where the cooling channels and the conducting channels are aligned along the thickness dimension of the stack (the dimensional along which the plates are stacked on top of one another), the high-strength material in the baseplates 610a, 620a, 630a and 640a makes direct contact through the thin insulating material <NUM>. This effectively forms a strong structural 'cage' that surrounds the conductors, shunting the load path around them. As a result, the primary load path passes between the conducting channels and the cooling channels, as shown by the vertical dashed arrows.

Furthermore, out-of-plane IxB body loads from the individual HTS/cap stacks are transferred to this structure, minimizing accumulation of compressive loads on the HTS/cap composite. Similarly, external out-of-plane compressive loads are shunted around the conductors via the cage structure.

As discussed above in relation to <FIG>, the HTS material <NUM> shown in <FIG> may comprise a co-wound stack of HTS tapes. <FIG> illustrates an example of plate <NUM> of <FIG> in which the HTS material is provided as a stack of HTS tapes <NUM>. In <FIG>, the plate <NUM> comprises a baseplate material <NUM>, cooling channels <NUM>, conductive material <NUM> and caps <NUM>. HTS tape may comprise a long, thin strand of HTS material with cross-sectional dimensions in the range of about <NUM> to about <NUM> in thickness (or height) and a width in the range of about <NUM> to about <NUM> (and with a length that extends along the length of the cable, i.e., into and out of the page in the example of <FIG>). According to some embodiments, HTS tapes <NUM> may comprise an HTS material in addition to cladding materials such as copper. In some embodiments, HTS tape may comprise a polycrystalline HTS and/or may have a high level of grain alignment.

In some situations in which the HTS material is provided as an HTS tape, it may be desirable to vary the number of HTS conductors in a stack of co-wound HTS tapes according to their location within the magnet, thereby reducing the total amount of HTS tape needed to construct the magnet. <FIG> illustrates an example of plate <NUM> of <FIG> in which the conducting channels <NUM> comprise a stack of co-wound HTS tapes <NUM> in addition to conductive co-wound tape <NUM> (e.g., copper tape). As may be noted from <FIG>, the number of HTS tapes is decreased in each turn going from right to left in <FIG>, while the number of conductive co-wound tapes is increased right-to left. The width of the cap <NUM> is varied in conjunction with number of conductive co-wound tapes such that their combined cross-sectional area is roughly constant in every turn. In this way, the resistance per unit length of the co-conductor is maintained constant throughout the winding pack.

Tuning the amount of HTS tape <NUM>, co-wound conductive tape <NUM>, and the size of the cap <NUM> may provide a way to control the rate of magnetic energy dissipation during a quench, and in some cases may dissipate the magnetic energy uniformly throughout the winding pack during a full magnet quench event. In addition, tuning the amount of HTS tape <NUM>, co-wound conductive tape <NUM>, and the size of the cap <NUM> may alter an amount of magnetic energy deposition in adjacent areas. This may allow, for instance, reduction of the magnetic energy deposition in critical areas such as in regions with joints.

While in each of the examples discussed above, the cooling channels are arranged on the opposite side of a plate from the conducting channels, in some cases it may be preferable to provide the cooling channels within the conducting channels. <FIG> is a cross-section of a portion of an illustrative plate suitable for use in a stacked-plate superconducting magnet in which the cooling channels are arranged within the conducting channels, according to some embodiments.

As shown in <FIG>, the conducting channels <NUM> also comprise the cooling channels <NUM>, which are formed (e.g., via traditional machining processes, via additive and/or subtractive processes, etc.) by appropriate shaping of the caps <NUM> (although any portion of the conducting channel could be shaped as desired in general). The co-linear conducting channels <NUM> and cooling channels <NUM> are arranged within the baseplate <NUM>. While in the example of <FIG> the conductive material <NUM> have the cooling channels provided therein, it will be appreciated that cooling channels could be in general formed (e.g., via traditional machining processes, via additive and/or subtractive processes, etc.) in the conductive material and/or HTS <NUM>, depending on the geometrical arrangement of the conductive material and HTS within the conductive channel, since the cooling channels may be formed or provided from at least portions of concave regions of the upper portion of the material within the conductive channel.

In the example of <FIG>, the plate <NUM> can thereby be stacked on top of multiple instances of itself to produce a stack of plates in which the cooling channels are adjacent to the conducting channels. This stacking may be performed in two different ways, which are depicted in <FIG> and <FIG>.

As shown in <FIG>, a magnet <NUM> may comprise two instances of the plate <NUM> stacked on top of one another, wherein a planar face of one of the plates rests over the cooling channels, thereby bounding the cooling channels. As a result, when coolant is passed through the magnet <NUM>, it may contact the conductive material <NUM> in one plate and the baseplate material in the adjacent plate. An insulating layer <NUM> may be arranged between the baseplates <NUM>.

Alternatively, as shown in <FIG>, a magnet <NUM> may comprise two instances of the plate <NUM> stacked on top of one another wherein the orientation of one plate <NUM> is flipped so that the cooling channels contact one another and are aligned, forming cooling channels <NUM>, which are actually a combination of the cooling channels <NUM> formed in each of the two plates and aligned so that their surfaces bound one another. An insulating layer <NUM> may be arranged between the baseplates <NUM>. It will be appreciated that some or all of insulating layer <NUM> in <FIG> may comprise air as an insulator. For instance, the illustrated layer may not extend all the way to the cooling channels <NUM> as shown, with a small air gap left between the two layers of conductive material <NUM> adjacent to the cooling channels.

<FIG> is a three-dimensional graphic of a fusion power plant with a cutaway portion illustrating various components of the power plant, according to some embodiments. A magnet within a fusion power plant may be formed from superconductor arrangement as described above. <FIG> shows a cross-section through a power plant and includes a magnet coil <NUM>, which is fabricated from, or otherwise includes, a superconducting magnet comprising a stack of plates as discussed and described above, a neutron shield <NUM>, and a core region <NUM>. According to some embodiments, the magnet coil <NUM> may be, or may form part of, a toroidal field coil. Magnet coil <NUM> may be fabricated from, or otherwise includes, a superconducting magnet comprising a stack of plates as discussed and described above. According to some embodiments, the magnet coil <NUM> may be, or may form part of a central solenoid and/or other poloidal field solenoidal coils.

Persons having ordinary skill in the art may appreciate other embodiments of the concepts, results, and techniques disclosed herein. It is appreciated that superconducting cables configured according to the concepts and techniques described herein may be useful for a wide variety of applications, including applications in which the superconducting cable is wound into a coil to form a magnet. For instance, one such application is conducting nuclear magnetic resonance (NMR) research into, for example, solid state physics, physiology, or proteins, for which such cables may be wound into a magnet. Another application is performing clinical magnetic resonance imaging (MRI) for medical scanning of an organism or a portion thereof, for which compact, high-field magnets are needed. Yet another application is high-field MRI, for which large bore solenoids are required. Still another application is for performing magnetic research in physics, chemistry, and materials science. Further applications is in magnets for particle accelerators for materials processing or interrogation; electrical power generators; medical accelerators for proton therapy, radiation therapy, and radiation generation generally; superconducting energy storage; magneto hydrodynamic (MHD) electrical generators; and material separation, such as mining, semiconductor fabrication, and recycling. It is appreciated that the above list of applications is not exhaustive, and there are further applications to which the concepts, processes, and techniques disclosed herein may be put without deviating from their scope.

As used herein, a "high temperature superconductor" or "HTS" refers to a material that has a critical temperature above <NUM>, wherein the critical temperature refers to the temperature below which the electrical resistivity of the material drops to zero.

Illustrative examples of conducting channels and cooling channels are described herein and illustrated in the drawings. It will be appreciated that the particular size and shape of these channels are provided merely as examples and that no particular cross-sectional shape or size is implied as being necessary or desirable unless otherwise noted.

Having thus described several aspects of at least one embodiment which illustrate the described concepts, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art.

The terms "approximately" and "about" may be used to mean within ±<NUM>% of a target value in some embodiments, within ±<NUM>% of a target value in some embodiments, within ±<NUM>% of a target value in some embodiments, and yet within ±<NUM>% of a target value in some embodiments. The terms "approximately" and "about" may include the target value. The term "substantially equal" may be used to refer to values that are within ±<NUM>% of one another in some embodiments, within ±<NUM>% of one another in some embodiments, within ±<NUM>% of one another in some embodiments, and yet within ±<NUM>% of one another in some embodiments.

The term "substantially" may be used to refer to values that are within ±<NUM>% of a comparative measure in some embodiments, within ±<NUM>% in some embodiments, within ±<NUM>% in some embodiments, and yet within ±<NUM>% in some embodiments. For example, a first direction that is "substantially" perpendicular to a second direction may refer to a first direction that is within ±<NUM>% of making a <NUM>° angle with the second direction in some embodiments, within ±<NUM>% of making a <NUM>° angle with the second direction in some embodiments, within ±<NUM>% of making a <NUM>° angle with the second direction in some embodiments, and yet within ±<NUM>% of making a <NUM>° angle with the second direction in some embodiments.

Claim 1:
A magnet comprising:
a plurality of plates (<NUM>) arranged in a stack that includes a first plate and a second plate (<NUM>; <NUM>,<NUM>), the first plate comprising:
a conducting channel (<NUM>) on a first side of the first plate, at least part of the conducting channel being arranged in a spiral path, the conducting channel comprising a high temperature superconductor, HTS, material (<NUM>) and a conductive material (<NUM>); and
a first plurality of cooling channels (<NUM>; <NUM>, <NUM>) on a second side of the first plate, the second side opposing the first side;
the second plate comprising a second plurality of cooling channels, and
the first and second plates (<NUM>; <NUM>, <NUM>) being arranged next to one another in the stack such that the second plurality of cooling channels (<NUM>; <NUM>, <NUM>) are adjacent to the conductive material (<NUM>) in the conducting channel (<NUM>) of the first plate.