Superconductor cable arrangement with detachable connection of compound conductors, magnetic coil and use of a superconductor cable arrangement

Abstract

A superconductor cable arrangement (1) for use in a magnet coil for a nuclear fusion plant, comprising a first superconducting compound conductor (2a) and a second superconducting compound conductor (2b), is characterized in that the compound conductors (2a, 2b) have a beveled end section (3a, 3b) with a cut surface (5a, 5b), wherein the cut surfaces are oriented obliquely to a direction of longitudinal extension of the respective compound conductor (2a, 2b), and wherein the cut surfaces (5a, 5b) have the same bevel angle α relative to the direction of longitudinal extension, that the end sections (3a, 3b) of the two compound conductors (2a, 2b) are detachably connected to one another in a connecting section (4), wherein in the connecting section (4) the two cut surfaces (5a, 5b) are arranged parallel to one another and facing one another, and cooling channels of the two Compound conductors (2a, 2b) are aligned,and wherein a clamping device (7) is mounted in the connecting section (4), which clamps the end sections (3a, 3b) of the compound conductors together with a clamping force transverse to the longitudinal extent of the compound conductors (2a, 2b), preferably perpendicular to the longitudinal extent of the compound conductors (2a, 2b), so that the cut surfaces (5a, 5b) are pressed against each other.

Description

Background of the invention

[0001] The invention relates to a superconductor cable arrangement for use in a coil for a nuclear fusion plant, comprising a first superconducting compound conductor and a second superconducting compound conductor, wherein each of the compound conductors comprises a plurality of superconducting wires or strips, a cooling channel for passing a cooling fluid, and a sheath made of a conductive material surrounding the plurality of superconducting wires or strips and the cooling channel.

[0002] Coils for nuclear fusion plants consist of winding packages made of superconducting compound conductors, with each coil having many conductor turns (typically between 100 and 1000). Since superconducting compound conductors are only available in limited lengths, several superconducting compound conductors must be connected together to achieve the length required for the coil windings.

[0003] For connecting individual high-temperature superconductor (HTS) strip conductors, a method is disclosed in [EP0556837] in which two beveled surfaces of the strip conductor are pressed against each other and heat-treated at a temperature of 800°C to 900°C, creating a permanent connection. The superconducting filaments are to be aligned in such a way that a superconducting connection is created through pressing and heating. This requires precise alignment of the beveled surfaces so that the filaments of the HTS conductor are aligned with each other and a superconducting connection is realized. However, a compound conductor comprises a multitude of such HTS conductors, which in turn contain a multitude of filaments. Precise alignment of the enormous number of filaments in a compound conductor is not possible, even with great effort.A further disadvantage of the method known from [EP0556837] is that the HTS strip conductors are permanently connected and cannot be disassembled non-destructively.

[0004] To connect superconducting cables (compound conductors), it is known to connect two superconducting cables using a lap joint. For this purpose, the two cables are overlapped in a connecting section and connected to each other. The current then flows laterally from the first cable into the second cable, for example, via "interface elements" or via a copper sheath of the cable. [US20210376498] discloses such a lap joint for HTS cables, in which the interface elements are directly connected to the cable surface. [Rolando] discloses a lap joint for low-temperature superconductor (LTS) cables, in which each cable is enclosed by a copper sheath and the copper surfaces are pressed together and soldered.

[0005] The disadvantage of such lap joints is that each cable must be cooled via external cooling lines, necessitating complex welding of the cooling lines. Furthermore, the joint has an enlarged diameter in the connecting section, making handling the cable assembly more difficult.

[0006] Another method for connecting two superconducting compound conductors is a butt joint. In this method, two flat, cut ends of the cables to be connected are compressed and then welded together at high temperature with a copper spacer. Since the ends of the superconducting wires in the cable are very close to each other, a low resistance can be achieved. A connection of Nb3Sn cables via a butt joint is disclosed, for example, in [Takahashi]. There, the cable sheaths and the central cooling channel are first removed, and both ends of the cables are inserted into copper tubes. The copper tubes are compressed to reduce the void content in the cable and prevent damage to the strands at the cable ends. The cable assembly is then heat-treated to form Nb3Sn with the compressed parts.The disadvantage of this method is that the two ends must be pressed together under high pressure while being heated to 800 °C. The tools required for this require a lot of space around the joint, making it impossible to create multiple joints side by side in a confined space. Furthermore, such a joint cannot be disassembled; it must be cut.

[0007] A special type of butt joint is the CCJ (coax compacted joint). Here, the cables to be joined are coaxial. The ends of the cables are cut flat and brought into contact with each other. However, no current is transferred at the contact point. To ensure the transfer of current from one cable to the other, two 180-degree shells made of NbTi strands and copper are provided, which overlap the two conductor ends (laced unions). These are pressed onto the cables, with contact to the cable conductor being made either with solder or indium. In the connection section, the current flows laterally out of the cable into the "laced unions", from there to the second cable and from the side back into the second cable [Nguyen]. Such connections are used as connections between coil windings or at coil terminals.

[0008] Both the coaxial connection and the previously described overlap and butt connection are used to permanently connect superconducting cables. Magnetic coils constructed from such cable arrangements cannot be disassembled non-destructively and are therefore cumbersome to handle, especially if the magnetic coil needs to be disassembled. Object of the invention

[0009] The object of the invention is to propose a superconductor cable arrangement comprising several superconductor compound cables from which easily removable magnetic coils for nuclear fusion plants can be manufactured. Description of the invention

[0010] This object is achieved according to the invention by a superconductor cable arrangement according to claim 1, a magnetic coil according to claim 18 and a use of a superconductor cable arrangement according to claim 19.

[0011] In the superconductor cable arrangement according to the invention, each of the superconducting compound conductors has a beveled end section with a cut surface, wherein the cut surfaces are oriented obliquely to a direction of longitudinal extension of the respective superconducting compound conductor. The cut surfaces have the same bevel angle relative to the direction of longitudinal extension. The end sections of the two superconducting compound conductors are detachably connected to one another in a connecting section, wherein the two cut surfaces are arranged parallel to and facing one another in the connecting section, and the two cooling channels are aligned.According to the invention, a clamping device is mounted in the connecting section, which clamps the end sections of the superconducting compound conductors together with a clamping force transverse to the longitudinal extent of the superconducting compound conductors, preferably perpendicular to the longitudinal extent of the superconducting compound conductors, so that the cut surfaces are pressed against each other.

[0012] A compound conductor is a composite conductor composed of a plurality of superconducting wires (e.g., 100 or more bundled wires, typically containing LTS material) or a plurality of superconducting ribbons (e.g., 100 or more bundled and / or stacked ribbon conductors, typically containing HTS material), designed for a total operating current of 10 kA or more. A superconducting compound conductor comprises a sheath (also referred to as a tube) in which the plurality of twisted superconducting wires (CICC (cable-in-conduit-conductor) cables) or the plurality of stacked HTS ribbon conductors run. The sheath is preferably made of copper in the connecting section and preferably of steel, titanium, or Inconel® (nickel-chromium-based superalloy) outside the connecting section.The sheath serves as protection against physical damage and can also provide an ohmic current path in the connection section.

[0013] The superconducting wires are typically multifilament wires with diameters of preferably 0.5–5 mm. Each wire comprises a multitude of superconducting filaments embedded in a matrix, preferably 200–10,000 filaments. The superconducting wires can be in the form of round wires and are bundled within the superconducting compound conductor (typically approximately 100–300 wires per superconducting compound conductor). The superconducting compound conductors can also contain copper wires to improve the heat protection of the superconducting compound conductor in the event of a quench.

[0014] The HTS tape conductors (preferably 3-12 mm wide and 0.05-1 mm thick) are typically stacked within the superconducting compound conductor; multiple stacks can also be arranged side by side. A superconducting compound conductor with HTS tape conductors has a copper core that serves as a carrier for the HTS tape conductor packages. The sheath encloses the HTS tape conductors.

[0015] The cut surfaces of the end sections are preferably created using a shell cut. They encompass the entire cross-section of the superconducting wires of the respective compound conductor and are preferably manufactured using fine blanking. The surfaces of the interfaces can also be polished. The surface roughness of the cut surfaces is preferably < 0.1 mm.

[0016] The chamfer angle relative to the longitudinal direction of the superconducting compound conductor is preferably between 5° and 45°, particularly between 10° and 20°. Maintaining a chamfer angle of less than 45° allows for effective transverse pressure to be applied to the cut surfaces.

[0017] In a given superconducting compound conductor, the cooling channel typically runs centrally. The cooling channel can, for example, be formed as a helix.

[0018] Supercritical helium is preferably used as the cooling fluid. Neon or hydrogen, or a mixture of both, are also possible. The cooling channels of the superconducting compound conductors are connected to each other via hydraulic connectors.

[0019] According to the invention, the end sections of the two superconducting compound conductors are detachably connected to one another, i.e., the connection between the two compound conductors can be released non-destructively. This is achieved in particular by the clamping device, which remains mounted during operation of the superconducting cable arrangement, but can be removed, for example, for assembly and disassembly purposes. The end sections are preferably connected exclusively via the clamping device. This means that the end sections are not connected to one another, in particular, by heat treatment or adhesive bonding. The clamping device preferably exerts a pressure of at least 20 MPa, particularly preferably in the range of 25 to 40 MPa, on the cut surfaces.

[0020] The proposed connection establishes a low-resistance electrical contact between the two interfaces of the superconducting compound conductors by pressing them together. The clamping device creates a clamping force perpendicular to the longitudinal extension of the compound conductors. This creates a low-resistance connection while also allowing for easy removal of the connection.

[0021] The superconducting compound conductors are preferably arranged in alignment with each other.

[0022] In a particularly preferred embodiment, an interface element made of a low-resistance material, preferably indium or a solder material, is arranged between the cut surfaces. The interface element serves as a current bridge and improves current distribution in the connecting section. It enables even current distribution across the diameter of the superconductor cable arrangement without the need for precise alignment of the filaments in the connecting section. This enables easy joining of the ends of the superconducting compound conductors. A "low-resistance material" is understood to mean a material that has a resistance of less than 5 nanoohms at the operating temperature of the coil of a fusion magnet (for LTS coils < 10K, for HTS coils < 50K).

[0023] The interface element is preferably designed as a closed ring and surrounds the aligned cooling channels. This allows the interface element to seal the cooling channels. The interface element is preferably a perforated disc that covers (preferably completely) the area where the superconducting wires or strips are exposed and leaves the cross-section of the cooling channel free. The thickness of the interface element is preferably approximately 0.5–2 mm.

[0024] In a specific embodiment of the superconducting cable assembly according to the invention, the superconducting cable assembly is resistive in the connecting section and, in particular, has a resistance of less than 2 nanoohms. The connection of the superconducting compound conductors is therefore not superconducting. However, the resistance should not exceed a value of 2 nanoohms, preferably 0.5 nanoohms.

[0025] To optimize current transmission in the connecting section, it is advantageous if the spaces between the superconducting wires or strips in the superconducting compound conductors are filled with a solder material, in particular with lead and / or silver and / or bismuth and / or indium, at least in the region of the end sections, in a respective connection area of ​​preferably 3 cm to 25 cm. The connection area is preferably longer than the connecting section. As a result, current is already transmitted (in the current direction) in front of and behind the cut surfaces, on the one hand between the superconducting wires (or their filaments or strip conductors) and, on the other hand, also between superconducting wires and any copper wires or copper extruded profiles that may be arranged between the superconducting wires. In general, this achieves a distribution of the current across the entire cross-section of the superconducting compound conductors.Even if the superconducting wires or strips of the two superconducting compound conductors are not aligned at the opposite intersection points, current can still be effectively transferred between the superconducting compound conductors. This connection between the superconducting wires or strips of the superconducting compound conductors, created by the solder material (and possibly the interface element), prevents unwanted current flow in two ways: firstly, between the sheath material (e.g., copper) and the superconductor material, and secondly, between the sheath materials of the two superconducting compound conductors (usually copper to copper), as occurs, for example, in common lap joints or coaxial connections. This improves current distribution and stability in the connection section.Furthermore, the solder material prevents the wires from breaking during cutting due to the mechanical support required for this process. This is particularly advantageous for superconducting wires made of a brittle material such as Nb3Sn. Solder materials containing a selection of Pb, Sn, Ag, Bi, and / or In are particularly well suited for this purpose, as they have a melting point below 200°C, good wetting properties, and low resistance at cryogenic temperatures. The length of the solder-filled connection area preferably depends on the bevel angle of the cut surfaces of the end sections and is, in particular, greater than the length of the connecting section.

[0026] In a preferred embodiment, the superconducting compound conductors are compressed to the same diameter in the connecting section. This ensures that compound conductors with different diameters have the same diameter in the connecting area where the compound conductors are contacted. Furthermore, gaps between the wires or strips are minimized, and current distribution can be evenly achieved within the cross-section of the compound conductors. Due to the compressed end sections, the compound conductors have a smaller diameter in the end sections than in the rest of the superconducting compound conductors. The compound conductors can also be compressed beyond the connecting section.

[0027] In a special embodiment, the two superconducting compound conductors have the same diameter, preferably over the entire length of the compound conductors, but at least in the connecting section. This allows simple complementary interfaces between both end sections to be realized, i.e., interfaces that have the same size and shape. The end sections then complement each other in the contacted state, so that the connecting section has a uniform diameter that essentially corresponds to the diameter of the superconducting compound conductors (ignoring the clamping device).

[0028] Alternatively, the superconducting compound conductors can also have different diameters. In this case, it is advantageous to press the end sections of the two superconducting compound conductors together to the same diameter, at least in the connecting section. Alternatively, a copper sleeve with the same outer diameter but different inner diameters can be placed over each end section of the superconducting compound conductors. This ensures a uniform outer diameter in the connecting section, even if the diameters of the superconducting compound conductors do not match. Some superconducting strips or wires of the smaller-diameter compound conductor will then contact the copper sleeve of the larger-diameter compound conductor and not its superconducting strips or wires, but the current can quickly flow back into the smaller-diameter compound conductor via the copper sleeve.

[0029] The clamping device of the superconductor cable arrangement according to the invention preferably comprises at least one clamping element which is pressed onto at least one of the superconducting compound conductors, wherein the clamping element is preferably screwed.

[0030] In a magnet coil with windings made from the superconductor-cable arrangement according to the invention, a longitudinal tension exists, caused by magnetic forces. The clamping element absorbs this tension and ensures (particularly in combination with at least one wedge element - see below) that the tensile force acting on the superconducting compound conductor along its longitudinal extent is separated from the contact pressure at the cut surfaces.

[0031] The superconducting cable arrangement according to the invention can comprise more than two compound conductors that are connected to one another, with two compound conductors that share a connecting section forming a compound conductor pair. Preferably, a separate clamping element is provided for each superconducting compound conductor pair, which presses the intersection surfaces of the two superconducting compound conductors against each other in the connecting section.

[0032] Preferably, the clamping device is designed and mounted such that the clamping force acts at least substantially parallel to a clamping plane that is perpendicular to the two cutting planes and contains the direction of the longitudinal extension of the superconducting compound conductors, and that this clamping force acts at least substantially perpendicular to the direction of the longitudinal extension of the superconducting compound conductors. This results in a particularly effective clamping of the two cutting surfaces.

[0033] In one embodiment, the two superconducting compound conductors that are connected to each other are of the same type. This means, in particular, that they have the same number and type of superconducting wires or strips. Alternatively, the two compound conductors can also be of different types (e.g., with a different number of wires or strips).

[0034] In a special embodiment of the superconductor cable arrangement according to the invention, the first superconducting compound conductor contains HTS and the second superconducting compound conductor contains LTS.

[0035] Furthermore, it is also possible to use superconducting wires or tapes with different internal configurations (e.g., different number, type, diameter of the wires or tapes) for the first and second superconducting compound conductors. This allows for variation of the superconducting material within the superconductor cable arrangement. This is particularly advantageous for high-field applications where more superconductor material is required for the inner turns of the coil than for the outer turns. With the superconductor cable arrangement according to the invention, such inner and outer turns can be realized with only one superconductor cable arrangement (graded coils).

[0036] The superconducting cable assembly according to the invention preferably has a current-carrying capacity of at least 5 kA, preferably at least 10 kA, particularly preferably at least 50 kA. A single superconducting wire typically has a current-carrying capacity of approximately 200-500 A, while HTS tape conductors can carry up to 1250 A. The superconducting cable assembly according to the invention comprises a plurality of approximately 100-2000 superconducting wires or tapes. A compound conductor made of Nb3Sn or NbTi wires can contain between 100 and 2000 wires, some of which can be made of pure copper (as thermal protection in the event of a quench). An HTS compound conductor made of REBCO (rare-earth barium copper oxide) can have approximately the same number of tapes, depending on the width of the tape. These tapes are arranged on a copper carrier that acts as thermal protection.

[0037] With the superconductor cable arrangement according to the invention, a current carrying capacity of up to 150kA can be achieved.

[0038] A particularly preferred embodiment of the superconductor cable arrangement according to the invention provides for a first guide plate in which at least one first guide channel is formed, in which an end section of the first superconducting compound conductor is received. Furthermore, a second guide plate is provided, in which at least one second guide channel is formed, in which an end section of the second superconducting compound conductor is received. The first guide plate is releasably fastened to the second guide plate by means of an overlap connection. The guide plates serve to guide the compound conductors and to absorb forces acting on the compound conductors.

[0039] Preferably, each guide plate has a plurality of guide channels so that several superconducting compound conductors or their end sections are guided parallel to one another.

[0040] The guide plates, in which the end sections of the two compound conductors are accommodated, are mechanically connected to one another. For this purpose, it is advantageous if the guide plates each have an exposed end in the region of the overlap connection, in which end the at least one guide channel is open towards the other guide plate, wherein at least one projection and one recess are formed at the free end, and wherein a projection of a respective guide plate is hooked into a recess of the other guide plate. The projections therefore engage behind one another. This ensures that tensile stresses acting on the compound conductors are absorbed by the guide plate. The connection between the two guide plates corresponds to a folded joint with a raised area at each end (tabled half lap scarf joint).

[0041] In a particularly preferred embodiment, a wedge element is clamped into the recess of the first guide plate between the projection of the second guide plate and an unexposed section of the first guide plate, such that the projections of the first guide plate and the second guide plate are pressed against one another. Without the wedge element, the interlocked projections have play (in the direction of the longitudinal extent of the compound conductors) and are clamped against one another by the wedge element, so that the play is eliminated. The projections thus bear firmly against one another, regardless of any momentarily acting clamping force on the connecting section. As a result, the tensile forces acting on the coil, which result from the magnetic forces during coil operation, are transmitted directly and do not influence the clamping effected by the clamping device.

[0042] The wedge element is preferably attached to the first guide plate, in particular screwed to it.

[0043] Additionally, a further wedge element can be clamped into the recess of the second guide plate between the projection of the first guide plate and a non-exposed portion of the second guide plate. The further wedge element is preferably attached to the second guide plate, in particular screwed thereto.

[0044] The invention also relates to a magnetic coil for a nuclear fusion plant, wherein the magnetic coil is preferably a stellarator coil or a tokamak coil comprising a plurality of superconducting compound conductor windings, wherein the magnetic coil forms at least one previously described superconductor cable arrangement.

[0045] The invention also relates to a use of the previously described superconducting cable arrangement or the previously described magnetic coil, wherein a current flows superconductingly in the first superconducting compound conductor, the current in the connecting section transfers from the first superconducting compound conductor to the second superconducting compound conductor, in particular in a normally conducting manner, and the current flows superconductingly in the second superconducting compound conductor, wherein a cooling fluid flows through the cooling channels of the two superconducting compound conductors, wherein the cooling fluid in the connecting section transfers from the cooling channel of the first superconducting compound conductor into the cooling channel of the second superconducting compound conductor, in particular wherein the cooling fluid is a supercritical cooling fluid, in particular a supercritical gas or a supercritical liquid, and wherein the two cutting surfaces are pressed against one another by means of the clamping device in the connecting section.According to the invention, the superconducting cable assembly is used with the clamping device installed. The clamping device is removed only for disassembly or maintenance.

[0046] Further advantages of the invention will become apparent from the description and the drawings. Likewise, the above-mentioned and further-described features can be used individually or in combination in any desired manner. The embodiments shown and described are not intended to be exhaustive, but rather are exemplary in nature for describing the invention. Detailed description of the invention and drawing Fig. 1a shows a schematic diagram of a simple embodiment of a superconductor cable arrangement according to the invention. Fig. 1b shows a schematic diagram of a preferred embodiment of a superconductor cable arrangement according to the invention with interface element. Fig. 2a shows a schematic representation of a superconductor cable arrangement according to the invention with a guide plate with compound conductor pairs in the unconnected state. Fig. 2b shows the superconductor cable arrangement from Fig. 2a in the connected state. Fig. 3 shows a detailed view of a cross section of the Fig. 2b through the mounted clamping element. Fig. Figure 4a shows a schematic cross-section of a compound conductor with a multitude of wires. Fig. Figure 4b shows a schematic cross-section of a compound conductor with a plurality of HTS bands. Fig. 5 shows a magnetic coil for a nuclear fusion plant with a superconductor cable arrangement according to the invention.

[0047] Fig. 1a and Fig. 1b shows side views of two superconductor cable assemblies 1, 1' according to the invention, comprising a first compound conductor 2a with an electrically conductive sheath 18a and a second compound conductor 2b with an electrically conductive sheath 18b. The compound conductors 2a, 2b have end sections 3a, 3b that are connected to one another. For this purpose, the end sections 3a, 3b are beveled in a connecting section 4, so that each end section 3a, 3b has a cut surface 5a, 5b with a bevel angle α. The end sections 3a, 3b are connected to one another via the cut surfaces 5a, 5b, so that the cut surfaces 5a, 5b are aligned parallel to one another. In this way, an electrically conductive connection is realized between the end sections 3a, 3b of the compound conductors 2a, 2b in the connecting region 4.

[0048] The compound conductors 2a, 2b comprise connection regions 19a, 19b, which are preferably filled with a solder material in order to achieve a distribution of the current over the entire cross section of the superconducting compound conductors 2a, 2b even before the connection section 4.

[0049] In the Fig. In the superconductor cable arrangements 1 shown in Figure 1a, the compound conductors 2a, 2b are directly connected to each other via their interfaces 5a, 5b, ie the interfaces 5a, 5b touch each other. Fig. In the superconducting cable arrangements 1' shown in Figure 1b, the compound conductors 2a, 2b are contacted with one another via an interface element 6 (for example, made of indium), i.e., the interface surfaces 5a, 5b touch the interface element 6. The interface element 6 forms a resistive but low-ohm electrical connection between the two compound conductors 2a, 2b. Current that is superconductingly conducted within the individual compound conductors 2a, 2b is conducted through the interface element from the first compound conductor 2a to the second compound conductor 2b, even if the superconducting components of the individual compound conductors 2a, 2b are not aligned. The interface element 6 thus serves as a current bridge between the two compound conductors 2a, 2b.

[0050] The end sections 3a, 3b of the two compound conductors 2a, 2b are connected by means of a clamping device 7, wherein the clamping device 7 clamps cutting surfaces 5a, 5b with a clamping force F ktransverse to the longitudinal extent of the superconducting compound conductors 2a, 2b.

[0051] Fig. 2a and Fig. 2b show a preferred embodiment of the superconductor cable arrangements 1" according to the invention, in which the compound conductors 2a, 2b are arranged in guide channels 8a, 8b of guide plates 9a, 9b. The compound conductors 2a, 2b can be completely accommodated in one or more guide plates. At least the end sections 3a, 3b are accommodated in the guide plate 9a, 9b. The compound conductors 2a, 2b each have a central cooling channel 17a, 17b through which a cooling fluid can be passed. The cooling channels 17a, 17b penetrate the cut surfaces 5a, 5b, wherein in Fig. 1a the cutting surface 5b is covered by the interface element 6 and is therefore not visible.

[0052] In the Fig. 2a and Fig. In the embodiment shown in FIG. 2b, several compound conductor pairs (compound conductors 2a, 2b to be connected) are provided. The respective first compound conductors 2a are accommodated in first guide channels 8a of the first guide plate 9a, while the respective second compound conductors 2b are accommodated in second guide channels 8b of the second guide plate 9b.

[0053] The guide plates 9a, 9b have exposed ends 10a, 10b, in which the guide channels 8a, 8b are open toward the respective other guide plates 9a, 9b. At least one projection 11a, 11b and one recess 12a, 12b are formed at each of the exposed ends 10a, 10b.

[0054] Fig. Figure 2b shows the superconductor cable arrangements 1" in the assembled state, in which the two guide plates 9a, 9b are hooked into each other, wherein the projection 11a of the first guide plate 9a engages the recess 12b of the second guide plate 9b and vice versa. The projections 11a, 11b and recesses 12a, 12b are dimensioned such that they have a play. This play is eliminated by clamping a first wedge element 13a. For this purpose, the first wedge element 13a is clamped between the projection 11b of the second guide plate 9b and a non-exposed section of the first guide plate 9a, so that the projection 11a of the first guide plate 9a and the projection 11b of the second guide plate 9b are pressed against each other. In addition, a second wedge element 13b can be provided, which is arranged between the projection 11a of the first guide plate 9a and a non-exposed section of the second guide plate 9b is clamped.

[0055] The cut surfaces 5a, 5b of the end sections 3a, 3b of the compound conductors 2a, 2b are pressed against each other in the connecting section 4 by means of clamping elements 14, so that the interface element 6 is clamped between the cut surfaces 5a, 5b, forming a current bridge between the cut surfaces 5a, 5b and sealing the cooling channels 17a, 17b. The clamping element 14 is mechanically connected to the first guide plate 9a by means of fastening means 15 (e.g., screws) and presses the end sections 3a, 3b in the connecting section 4 against the guide channel 8b of the second guide plate 9b. The clamping elements 14, together with the fastening means 15 and the first guide plate 9a, form the clamping device 7.

[0056] In the Fig. In the embodiment shown in Figure 2b, a separate clamping element 14 is provided for each compound conductor pair. However, it is also conceivable that a common clamping element is provided for several compound conductor pairs (not shown).

[0057] A detailed section of a cross-section of the Fig. The superconductor cable arrangement 1" shown in Figure 2b is Fig. 3. The clamping element 14 is mounted in a recess of the first guide plate 9a on the first guide plate 9a. On the side facing the end section 3a of the first compound conductor 2a, the clamping element 14 preferably has a groove 16, with which the clamping element 14 presses onto the end section 3a of the first compound conductor 2a. The shape of the groove follows the conductor shape and in particular comprises a circular section. The groove 16 forms the contact area to the end section 3a. Overall, the clamping element 14 preferably has a T-shape, wherein the fastening of the clamping element 14 to the first guide plate 9a takes place in an area in which the T-shaped clamping element 14 overlaps the contact area. The clamping element 14 is preferably flush with the guide plate 9a, as in Fig. 3 shown.

[0058] The structure of compound conductors 2a, 2b, which are preferably used for the superconductor cable arrangement 1, 1', 1" according to the invention, is shown schematically in the Fig. 4a, Fig. 4b shown. Fig. Figure 4a shows a cross-section of a compound conductor 2a, 2b with a plurality of superconducting wires 20, the cooling channel 17a, 17b for conducting the cooling fluid, and the sheath 18a, 18b surrounding the plurality of superconducting wires 20. A solder material 21 can be introduced between the wires 20. Fig. Figure 4b shows a cross-section of a compound conductor 2a, 2b with HTS strip conductor stacks 22, the cooling channel 17a, 17b for conducting the cooling fluid, and the sheath 18a, 18b surrounding the HTS strip conductor stacks 22. The HTS strip conductor stacks 22 each contain a plurality of stacked strip conductors 23 and are applied to a copper core 24 surrounding the cooling channel 17a, 17b.

[0059] Fig.5 shows a magnetic coil 25 for a nuclear fusion plant (here, for example, a tokamak coil) forming a superconductor cable arrangement 1, 1', 1". The magnetic coil 25 comprises a plurality of superconducting compound conductor windings 26. List of reference symbols 1 Superconductor cable arrangement without interface element 1' superconductor cable arrangement with interface element 1" superconductor cable assembly with guide plate 2a, 2b Compound conductors 3a, 3b End sections of the compound conductors 4 connecting section 5a, 5b Cutting surface of the end sections 6 Interface element 7 clamping device 8a, 8b Guide channels of the guide plates 9a, 9b guide plates 10a, 10b exposed ends of the guide plates 11a, 11b Projections of the exposed ends 12a, 12b Recesses of the exposed ends 13a, 13b wedge elements 14 Clamping element of the clamping device 15 fasteners 16 U-shaped groove of the clamping element 17a, 17b Cooling channels of the compound conductors 18a, 18b Sheaths of the compound conductors 19a, 19b Connection areas (filled with solder if necessary) 20 superconducting wires 21 Solder material 22 HTRS ribbon conductor stacks 23 HTS band conductors 24 copper core 25 solenoid coil 26 compound conductor windings. α bevel angle Reference list [Takahashi] TAKAHASHI, Y. [et al.]: Development of 46-kA Nb / sub 3 / Sn conductor joint for ITER Model Coils. In: IEEE transactions on applied superconductivity, 2000, vol. 10, no. 1, pp. 580-583. [Rolando] ROLANDO, G. [et al.]: Performance assessment and optimization of the ITER toroidal field coil joints. In: Superconductor Science and Technology, 2013, Volume 26, No. 8, p. 085004. [US20210376498] US 2021 / 0 376 498 A1 [Nguyen] DAO, Clement Nguyen Thanh [et al.]: Development of coax compacted joint assembly process for the ITER central solenoid. In: IEEE Transactions on Applied Superconductivity, 2021, 31. Jg., Nr. 5, S. 1-5. [EP0556837] EP 0 556 837 A1

Claims

[1] Superconductor cable arrangement (1; 1'; 1") for use in a magnetic coil (25) for a nuclear fusion plant with a first superconducting compound conductor (2a) and a second superconducting compound conductor (2b), wherein each of the compound conductors (2a, 2b) comprises a plurality of superconducting wires (20) or strips (23), a cooling channel (17a, 17b) for passing a cooling fluid, and a sheath (18a, 18b) made of a conductive material surrounding the plurality of superconducting wires or strips and the cooling channel (17a, 17b), characterized by , that each of the superconducting compound conductors (2a, 2b) has a bevelled end section (3a, 3b) with a cut surface (5a, 5b), wherein the cut surfaces are aligned obliquely to a direction of a longitudinal extension of the respective superconducting compound conductor (2a, 2b), and wherein the cut surfaces (5a, 5b) have the same bevel angle α with respect to the direction of the longitudinal extension, that the end sections (3a, 3b) of the two superconducting compound conductors (2a, 2b) are detachably connected to one another in a connecting section (4), wherein in the connecting section (4) the two cutting surfaces (5a, 5b) are arranged parallel to each other and facing each other and the cooling channels (17a, 17b) of the two compound conductors (2a, 2b) are aligned, and wherein a clamping device (7) is mounted in the connecting section (4), which clamps the end sections (3a, 3b) of the superconducting compound conductors together with a clamping force transverse to the longitudinal extent of the superconducting compound conductors (2a, 2b), preferably perpendicular to the longitudinal extent of the superconducting compound conductors (2a, 2b), so that the cut surfaces (5a, 5b) are pressed against one another. [2] Superconductor cable arrangement (1', 1") according to claim 1, characterized by that an interface element (6) made of a low-resistance material, preferably of indium or a solder material, is arranged between the cutting surfaces (5a, 5b). [3] Superconductor cable arrangement (1', 1") according to claim 2, characterized by that the interface element (6) is of closed ring-shaped design and surrounds the aligned cooling channels (17a, 17b). [4] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized bythat the superconductor cable arrangement (1; 1'; 1") is resistive in the connecting section, in particular has a resistance of less than 2 nOhm. [5] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that spaces between the superconducting wires or strips in the superconducting compound conductors are filled with a solder material, in particular with lead and / or silver and / or bismuth and / or indium, at least in the region of the end sections (3a, 3b), in a respective connection region (19a, 19b) of preferably 3 cm to 25 cm. [6] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that the superconducting compound conductors (2a, 2b) are each compressed to the same diameter in the connecting section (4). [7] Superconductor cable arrangement according to one of the preceding claims, characterized bythat the two superconducting compound conductors (2a, 2b) have the same diameter. [8] Superconductor cable arrangement according to one of the preceding claims, characterized by that the clamping device (7) comprises at least one clamping element (14) which is pressed onto at least one of the superconducting compound conductors (2a, 2b), in particular wherein the clamping element (14) is screwed. [9] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that the clamping device (7) is designed and mounted so that the clamping force F k acts at least substantially parallel to a clamping plane which is perpendicular to the two cutting surfaces (5a, 5b) and contains the direction of the longitudinal extension of the superconducting compound conductors (2a, 2b), and that this clamping force F k acts at least substantially perpendicular to the direction of longitudinal extension of the superconducting compound conductors. [10] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that the first superconducting compound conductor (2a) contains HTS and the second superconducting compound conductor (2b) contains LTS. [11] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that the clamping device (7) exerts a pressure of at least 20 MPa, preferably in the range of 25 to 40 MPa, on the cutting surfaces. [12] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that the cutting surfaces (5a, 5b) are manufactured by fine cutting. [13] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that the bevel angle α with respect to the direction of the longitudinal extension of the superconducting compound conductor (2a, 2b) is between 5° and 45°, preferably between 10° and 20°. [14] Superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims, characterized by that the superconductor cable arrangement (1; 1'; 1") has a current carrying capacity of at least 5 kA, preferably at least 10 kA, particularly preferably at least 50 kA. [15] Superconductor cable arrangement (1") according to one of the preceding claims, characterized by that a first guide plate (9a) is provided in which at least one first guide channel (8a) is formed, in which an end section (3a) of the first superconducting compound conductor (2a) is received, and a second guide plate (9b) is provided in which at least one second guide channel (8b) is formed, in which an end section (3b) of the second superconducting compound conductor (2b) is received, and that the first guide plate (9a) is detachably fastened to the second guide plate (9b) by means of an overlap connection. [16] Superconductor cable arrangement (1") according to claim 15, characterized by in that in the region of the overlap connection the guide plates (9a, 9b) each have an exposed end (10a, 10b) in which the at least one guide channel (8a, 8b) is open towards the respective other guide plate (9a, 9b), wherein at least one projection (11a, 11b) and one recess (12a, 12b) are formed on the exposed end (10a, 10b), and wherein a projection (11a, 11b) of a respective guide plate (9a, 9b) is hooked into a recess (12a, 12b) of the respective other guide plate (9a, 9b). [17] Superconductor cable arrangement (1") according to claim 16, characterized bythat a wedge element (13a) is clamped into the recess (12a) of the first guide plate (9a) between the projection (11b) of the second guide plate (9b) and a non-exposed section of the first guide plate (9a), so that the projections (11a) of the first guide plate (9a) and the second guide plate (9b) are pressed against one another. [18] Magnetic coil (25) for a nuclear fusion plant, in particular wherein the magnetic coil (25) is a stellarator coil or a tokamak coil, comprising a plurality of superconducting compound conductor windings (26), wherein the magnetic coil (25) forms at least one superconductor cable arrangement (1; 1'; 1") according to one of the preceding claims. [19] Use of a superconductor cable arrangement (1; 1'; 1") according to one of claims 1 to 17 or a magnetic coil (25) according to claim 18, wherein a current flows superconductingly in the first superconducting compound conductor (2a), the current in the connecting section (4) passes from the first superconducting compound conductor (2a) to the second superconducting compound conductor (2b), in particular passes into a normally conducting state, and the current flows superconductingly in the second superconducting compound conductor (2b), wherein the cooling channels (17a, 17b) of the two superconducting compound conductors (2a, 2b) are flowed through by a cooling fluid, wherein the cooling fluid passes in the connecting section from the cooling channel (17a) of the first superconducting compound conductor (2a) into the cooling channel (17b) of the second superconducting compound conductor (2b), in particular wherein the cooling fluid is a supercritical cooling fluid, in particular a supercritical gas or a supercritical liquid, and wherein the two cutting surfaces are pressed against each other by means of the clamping device in the connecting section.

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