Sealed high-temperature superconducting tape conductor

Abstract

The present application relates to a superconductor comprising a high temperature superconducting tape conductor (HTS tape conductor) and at least one layer of metal foil wrapped helically around the HTS tape conductor in multiple turns and soldered to form a reinforcement that hermetically seals the HTS tape conductor. Such a superconductor may be manufactured by a method including the steps of helically wrapping at least one layer of solder-coated metal foil around a high temperature superconducting tape conductor, heating the metal foil above the melting point of the solder coating, and then cooling below the melting point of the solder coating and connecting the metal foil to the high temperature superconducting tape conductor to form a reinforcement that hermetically seals the high temperature superconducting tape conductor.

Description

[Technical field]

[0001] The present invention relates to a high temperature superconducting tape conductor (HTS tape conductor) that is hermetically sealed against environmental influences by means of a metal foil wrapped helically around the HTS tape conductor in multiple turns. [Background technology]

[0002] High-temperature superconducting tape conductors are used, for example, in cables and bus bars for the transmission of high currents, in the generation of strong magnetic fields in analytical and medical technology, in beam guidance in accelerators, in plasma confinement in nuclear fusion reactors, etc. They can also be used in rapid switches and current limiters, taking advantage of their fast and dynamic transition from the lossless superconducting state to the normal conducting state in the event of an overload.

[0003] In many of these applications, the high temperature superconducting tape conductors are cooled by immersion in a liquid cryogenic medium such as liquid nitrogen (boiling point 77 K), liquid hydrogen (boiling point 21 K), neon (boiling point 27 K), or liquid helium (boiling point 4.2 K).

[0004] Modern high-temperature superconducting tape conductors (so-called second generation or 2G) consist of a flexible metal substrate that is coated with a high-temperature superconducting material using chemical or physical methods. This is usually of the composition RBa 2 Cu 3 O 7The HTS coatings come from the so-called 123 material class (R stands for an element or mixture of elements selected from the group consisting of rare earths (e.g. Gd, Eu, Dy, Hf) or yttrium (Y)). Since the HTS coatings are usually performed at high temperatures (e.g. T>650 °C), the HTS coatings cannot be applied directly to metal foils. Depending on the manufacturing method used, different intermediate layers, the so-called buffer layers, are used. The buffer layers act on the one hand as a diffusion barrier and on the other hand provide a crystal orientation or adjust the parameters of the crystal lattice for the epitaxial growth of the HTS layer. The deposition of the buffer layers and the HTS layers can be carried out using different methods, for example the so-called metal-organic deposition (MOD), metal-organic chemical vapor deposition (MOCVD) or different physical vacuum coating methods (PVD), in which amorphous precursor materials (precursors) are calcined and crystallized by heat treatment to obtain the desired phase.

[0005] During the conversion and growth of the HTS and / or buffer layers, voids can form in the layers. The formation of voids is particularly evident when the layers grow in a columnar manner, for example in the so-called inclined substrate deposition (ISD). In this method, an oriented buffer layer (usually made of MgO) is formed by depositing the material at an oblique angle to the substrate surface at a high deposition rate (see, for example, EP 0 909 340 A1). This results in the formation of a so-called columnar structure, where the columns spread and merge as the layer thickness increases. Thus, the MgO layer appears closed on the surface, but vertical cavities are present. On the other hand, other methods, such as MOD, are prone to the formation of voids in the layers due to solid-state reactions. Also, high-temperature superconducting tape conductors are often cut from a relatively wide line width into narrow tapes during the manufacturing process. In this case, the cut surface exposes the inside of the layer. Also, cracks can form that penetrate into the layer from the side.

[0006] In further manufacturing steps, the HTS tape conductor is wrapped with a thin metal layer, usually made of silver (Ag) or copper (Cu). For example, a Cu layer, usually 5-20 μm thick, can be deposited using galvanic techniques (see JP 7-335051 or EP 1 639 609 A1). These surrounding metal layers serve the purpose of protection, electrical stabilization and current supply to the underlying HTS layer. However, even such Ag or Cu layers are rarely 100% free of damage, holes or grooves. Especially at the ends, i.e. at cut surfaces, the adhesion of these layers is often reduced and they are easily chipped (for example by rubbing against guide rollers during manufacturing) and may open up.

[0007] When such a HTS tape conductor is immersed in a cryogenic bath for several hours, the coolant slowly seeps into the existing voids. This is further enhanced by the fact that the air present in the voids condenses below 77 K, creating a negative pressure that promotes the infiltration of the coolant by capillary action. The infiltration of the coolant into the layers of the HTS tape conductor does not normally lead to functional impairment of the superconductor.

[0008] However, if the HTS tape conductor is suddenly heated, for example by being lifted out of the coolant rapidly, or if a strong localized temperature rise occurs as a result of a so-called quench, the coolant present in the voids can evaporate rapidly, which can lead to a volume change of 700-1000 times. However, since the surface of the HTS tape conductor is almost closed, in contrast to the narrow flow paths in the layers of the HTS tape conductor, where the coolant can slowly penetrate, the gas cannot be evacuated quickly, which results in a very high localized pressure rise, which can cause the surrounding material to burst or expand, forming bubbles. This effect is known as "ballooning". In such cases, the HTS tape conductor is irreversibly destroyed.

[0009] In particular, liquid hydrogen and helium have very low viscosity and high diffusivity, allowing them to penetrate into underlying cavities even through very small openings or accesses.

[0010] The above phenomenon also occurs in first generation (1G) high temperature superconductors produced by the metallurgical powder-in-tube (PIT) method. In this method, a powder of HTS material is filled into a metal tube, which is pressed, sintered and rolled to form HTS ceramic filaments in a metal matrix. Again, voids form in the HTS filling and the coolant can seep in through hairline cracks in the metal matrix. AMSC has developed a configuration in which metal foil is laminated and soldered on both sides of the high temperature superconducting tape conductor. The foil overhangs on both sides form two channels along the conductor, which are filled with solder material to form solder bridges on the sides. This configuration is described in EP 1203415. As the geometry of the 1G and 2G tape conductors is similar, this method is also suitable for 2G high temperature superconducting tape conductors. A similar method of laminating a thermoplastic resin film on both sides of the high temperature superconducting tape conductor is described in WO 2013 / 004392.

[0011] A further method for wrapping HTS tape conductors has been developed by Fujikura and is described in EP 2 940 699 and EP 2 770 513. In this method, a solder-coated metal foil twice the width of the HTS tape conductor is folded around the HTS tape conductor along its axis and soldered so that the front and ends are completely covered. This configuration allows the solder to fill the seam on the back of the conductor as well, preventing the ingress of coolant.

[0012] In order to electrically insulate the non-perforated high-temperature superconducting tape conductors, a method has been developed in which a thin plastic tape is wound around the high-temperature superconducting tape conductor. The plastic tape is made of, for example, polyimide (trade name: Kapton) as described in DE 3823938 A1 or polyester (see DE 102004048439 A1). Polyimide has a low thermal expansion coefficient and is not easily embrittled, making it particularly suitable for use at very low temperatures.

[0013] The above-mentioned method for covering high-temperature superconducting tape conductors is actually used, but problems also arise in this case. The metal tapes used in the prior art are often not ideally straight and usually have a certain warp, i.e. a deviation from a straight structure. This makes it difficult to accurately align the three parallel tapes during lamination, and makes it difficult to manufacture long objects. In fact, it is difficult to control the exact position of the inner high-temperature superconducting tape conductor, the so-called insert, relative to the end of the metal tape. Due to a lateral offset, the superconducting tape conductor may be completely shifted to one side, and no overhang or solder bridge of the two metal foils may be formed. At such points, the so-called "sandwich" often bursts, and the coolant may penetrate into the high-temperature superconducting tape conductor.

[0014] In some applications, e.g. superconducting current limiters, a short overload (quench) can cause the HTS tape conductor to heat up further (above 250 °C) and reach the melting point of the solder material, melting the sandwich composite, where the stack no longer provides mechanical protection.

[0015] When the HTS tape conductors are folded over by the folded metal foil, a clamping structure is formed that is at least mechanically stable, and will not come loose when the solder softens. However, this method is mechanically very demanding and can lead to problems at the joints of the HTS tape conductors. Such joints are significantly thicker as a result of the overlapping of the HTS tape conductors, often twice as thick as a single conductor. Also, the folding creates grooves and cavities that are not filled by a typical solder layer of usually about 10 μm.

[0016] Plastic wrapping is simply a material choice and is not suitable for sealing HTS tape conductors against the ingress of coolant, the adhesive backing becomes brittle at low temperatures, the plastic forms small cracks, and even when intact, it is somewhat permeable to gases and light elements.

[0017] SUMMARY OF THE PRESENT EMBODIMENT The present invention therefore aims to at least partially alleviate the above-mentioned disadvantages of the prior art. Summary of the Invention

[0018] The above mentioned technical problem is at least partly solved by the subject matter of the present invention by the independent claims. Exemplary embodiments are the subject matter of the dependent claims.

[0019] In one embodiment, the present invention provides a superconductor comprising a high temperature superconducting tape conductor and at least one layer of metal foil wrapped helically around the high temperature superconducting tape conductor for multiple turns and soldered to form a reinforcement that hermetically seals the high temperature superconducting tape conductor.

[0020] In the context of this application, the term "superconducting" should be understood technically, specifically in the sense of a piece of electrical conductor having superconducting properties. The inventors also recognize that instead of soldering, which is preferred because of its significantly better electrical, thermal and mechanical properties, especially at cryogenic temperatures, other connection techniques can also be used to make the bond between the high temperature superconducting tape conductor and the metal foil, such as, for example, adhesive bonding with an epoxy adhesive having good thermal conductivity. Thus, such alternative superconductors are likewise part of the present invention.

[0021] In particular, the metal foil comprises pure copper, pure aluminum, low-alloy copper, or low-alloy aluminum, and / or has a thickness of 10 μm to 100 μm, preferably 20 μm to 50 μm. Alternatively or in addition, a solder layer having a melting point of 280° C. or less, preferably 250° C. or less, and a thickness of 2 μm to 30 μm, preferably 5 μm to 15 μm, may be provided on at least one surface of the metal foil.

[0022] This sealing reinforcement provides an electrically conductive and mechanically stable coating on the HTS tape conductor. This coating has good bonding properties with the HTS layer and is particularly resistant to typical coolants (LH 2 , LHe, LN 2The coating forms a hermetic seal against the slow infiltration of bacteria, such as bacteria, fungi, and the like. This coating at least partially overcomes the deficiencies of the prior art discussed above.

[0023] Such a superconductor can be produced, for example, by the methods defined in the independent method claims.

[0024] Such a method and the above-mentioned construction principle address the above-mentioned problems, in particular by wrapping the high-temperature superconducting tape conductor with a metal foil that can be reliably applied over seams and irregularities and can self-adjust during winding. For this purpose, the high-temperature superconducting tape conductor is wrapped with, for example, a ductile metal foil. The metal foil may be coated with a thin layer of a solder material and, after winding, can be firmly soldered to the surface of the high-temperature superconducting tape conductor by the action of heat and pressure.

[0025] The metal foil (or metal strip) wound around the high-temperature superconducting tape conductor preferably has a slight plastic deformation property, but on the other hand has sufficient tensile strength so that it does not break even when it is wound around the end of the tape under moderate tensile stresses, for example 10-150 MPa. Metals that are very ductile in the pure state or with small amounts of added alloying elements, such as copper, aluminum, silver, nickel, tin, lead, indium, or metals that can be softened and annealed by heat treatment after rolling to form a thin foil, are very suitable. Copper, aluminum, silver, or soft bronze, optionally with small amounts of alloying additions, are particularly preferred for technical applications. The choice of material is also determined by the application-specific requirements regarding electrical conductivity, thermal conductivity and heat capacity.

[0026] The spiral wrapping of a metal foil around a high temperature superconducting tape conductor as described above avoids the drawbacks of existing methods and has many advantages, particularly in terms of manufacturing: the metal foil thus forms a mechanically strong reinforcement around the encapsulated high temperature superconducting tape conductor.

[0027] It is also possible to place two or more HTS tape conductors and / or one or more further metal tapes as inserts inside to form a composite conductor. The winding ensures that joints, patches and thickness variations are also enclosed. The method is also tolerant of insert warpage, and can accommodate some bending with a slight offset within the acceptable range. For example, a warpage of 5 mm / m or less (deviation from straightness) is acceptable. The spiral winding method of the present invention can also be used several times in succession to achieve a good seal and the desired thickness of the final product. For this purpose, it is recommended to wind the second layer in the same direction, but with an offset, to ensure that the seam of the first layer is covered.

[0028] In particular, the heating and / or cooling can be carried out under the action of contact pressure, preferably the heating is carried out by introducing the wound high temperature superconducting tape conductor into a hot roller or a hot caterpillar.

[0029] For example, after winding, the HTS tape conductor can be passed over hot rollers or hot caterpillars to melt the solder and press the composite materials together when it cools, thus soldering the materials securely together. Furthermore, excess solder will flow by capillary forces into the joints between the loops of the winding, filling the joints.

[0030] In some embodiments, the number of revolutions and the feed rate of the winding are set so that, during winding, the turns of at least one layer of metal foil are placed in contact with each other without overlapping, which improves the shielding against environmental influences, provides a surface that is as homogeneous as possible, and minimizes the additional thickness of the superconductor as much as possible.

[0031] Alternatively or in addition, the number of revolutions and the feed amount during winding may be set so that the pitch angle of the turns is less than 45°, preferably 20° to 30°.

[0032] This makes it possible to manufacture a superconductor in which the metal foil is wound around the high-temperature superconducting tape conductor at an angle of less than 45°, preferably 20° to 30°, relative to the width of the high-temperature superconducting tape conductor. In this case, the windings of at least one layer of the metal foil may be arranged in contact with each other without overlapping each other.

[0033] For example, if the width of the high-temperature superconducting tape conductor is W and the width of the metal foil to be wound is B, the number of rotations and the tape feed amount can be set so that the turns are shifted by the metal foil width B for each revolution, bringing them into contact with each other and forming a helical coating of the high-temperature superconducting tape conductor. The pitch angle φ is obtained from the relationship sinφ=B / 2W. The pitch angle is preferably φ<45° so as not to be too steep, and is particularly preferably in the range of 20° to 30° so that W and B have similar values.

[0034] This allows in particular a simple and quick production of the hermetic seal, which can be formed while minimizing the thickness of the resulting superconductor.

[0035] For some applications, it has been shown to be advantageous to hold at least one layer of the metal foil under a tensile stress of 10 MPa to 100 MPa during wrapping, which not only ensures that the foil adheres well to the high temperature superconducting tape conductor and provides good soldering, but also prevents tearing when wrapping around the tape end.

[0036] As mentioned above, in some embodiments, the method further comprises the step of sequentially helically winding a plurality of layers of metal foil around the high temperature superconducting tape conductor, offset from one another, the amount of offset being preferably at least 20% of the line width of the metal foil, more preferably substantially half the line width of the metal foil, particularly in this case where each layer can be soldered separately.

[0037] This can significantly improve the quality of the reinforcement and / or hermetic seal.

[0038] In a further embodiment, multiple HTS tape conductors can be stacked or longitudinally spliced ​​together and then the spliced ​​HTS tape conductors can be wound. In this way, the above-mentioned advantages of the invention can be applied to superconductors with substantially higher current carrying capacity without significant changes to the manufacturing methods and / or machines required.

[0039] In particular, in some embodiments, multiple high temperature superconducting tape conductors are stacked together to form a multi-layer composite or connected in an overlapping manner at their ends, wrapped together in metal foil, and soldered.

[0040] In some embodiments, the adhesive strength of the metal foil on the high temperature superconducting tape conductor is greater than 10 MPa when the metal foil is peeled off in a direction perpendicular to the surface of the high temperature superconducting tape conductor.

[0041] The adhesive strength can be determined by an adhesive peel measurement, preferably according to DIN EN ISO4624:2016. This measurement method can also be modified for high-temperature superconducting tape conductors if the line width requires a deviation from the prescribed dolly diameter (7 mm). For example, for a line width of 4 mm, a narrower dolly can be used, whereas for a line width of 12 mm, the dolly specified in the standard can be used.

[0042] As mentioned above, a reliable adhesion of the winding can preferably be ensured by an adhesion peel measurement. For this purpose, the wound tape conductor piece is glued parallel to the planar substrate on its back side. Similarly, the end face of a cylindrical dolly is glued parallel to the metal coating on the front side. The opposite side of the dolly is clamped in a tensile tester so that a tensile force acts axially on the cylinder on the tape conductor surface and the dolly is not tilted. The adhesion strength of the metal foil on the insert measured in this way is preferably above 10 MPa (10 N / mm 2) is greater. Because the high-temperature superconducting tape conductor is wound in a spiral, the adhesion is not only determined by the soldering, but part of the force is also distributed in the metal foil, whose mechanical tensile strength contributes to the adhesion as well. Thus, the winding results in a mechanically very robust configuration.

[0043] Furthermore, to improve the quality of the seal and reinforcement, the or the joined high temperature superconducting tape conductors may be wrapped with at least one further layer of metal foil, whereby the joints of the turns of the first layer are covered by the further layer; and / or The high temperature superconducting tape conductor or the connected high temperature superconducting tape conductors may include a surrounding copper or silver layer having a thickness of more than 2 μm, preferably between 2 μm and 5 μm.

[0044] As described above, the present invention provides a sealed superconductor with significantly improved mechanical, electrical and thermal properties. This superconductor can be easily and reliably manufactured in a variety of sizes and shapes. Therefore, the present invention is an important contribution to making high temperature superconducting tape conductor technology suitable for practical use.

[0045] Certain aspects of the present invention will now be described with reference to the accompanying drawings. [Brief description of the drawings]

[0046] [Figure 1a] FIG. 2 is a schematic cross-sectional view of a high temperature superconducting tape conductor structure prior to winding. [Figure 1b] 2 is a schematic cross-sectional view of a high temperature superconducting tape conductor structure after wrapping according to one embodiment of the present invention; [Diagram 2] FIG. 2 is an illustration of a foil wrapped high temperature superconducting tape conductor according to one embodiment of the present invention. [Diagram 3] FIG. 2 is an illustration of an offset double-wrap high temperature superconducting tape conductor according to one embodiment of the present invention. [Figure 4] FIG. 2 is an illustration of a double-layered high temperature superconducting tape conductor wrapped with metal foil according to one embodiment of the present invention. [Diagram 5] FIG. 2 is an illustration of a foil wrapped multi-layer composite tape conductor according to one embodiment of the present invention. [Figure 6] FIG. 2 is a flow diagram of method steps for manufacturing a reinforced high temperature superconducting tape conductor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] In the following, some exemplary feature combinations will be described with reference to some exemplary embodiments of the present invention. Of course, not all features of the described embodiments must be present to implement the present invention. Moreover, the embodiments can be modified by combining a specific feature of one embodiment with one or more features of another embodiment, if technically compatible and reasonable, without departing from the disclosure and protection scope of the present invention, which is defined only by the claims.

[0048] Figure 1a shows the structure of a high temperature superconducting tape conductor 10 based on a thin metal substrate 11, preferably made of a NiCr alloy such as Hastelloy C276, an alloy of Ni with W or Mo, or a fully alloyed stainless steel. The thickness is preferably 30 to 150 µm, particularly preferably 50 to 100 µm. At least one main surface of the metal substrate is coated with a thin metal layer, for example with MgO, CeO 2 , Y 2 O 3 , LaMnO 3 and / or LaZrO 3 , and then a HTS functional layer 13 is deposited on top of it. 2 Cu 3 O 7 (R represents an element or a mixture of elements selected from the group consisting of rare earths (e.g., Gd, Eu, Dy, Hf) or yttrium (Y). In order to increase the magnetic field strength of the HTS layer, metal oxides other than impurities, such as BaMO 3(M represents an element such as Zr, Hf, Ce, Sn, etc.) may also be added. The high-temperature superconducting tape conductor may be surrounded by a thin layer of silver. This may be reinforced by a surrounding copper layer as well. These two surrounding metal layers 14 function as contact layers for supplying the current and also provide adhesion to the ends and backside of the substrate, allowing the high-temperature superconducting tape conductor to be soldered. The surrounding silver layer and / or the surrounding copper layer have a total thickness of 2 μm or more, preferably 2 to 5 μm, so that they do not alloy with the solder in the subsequent soldering process and do not melt completely. The high-temperature superconducting tape conductor may also be provided with a thin solder layer, for example PbSn, InAg, SAC solder, or other soft solder layer with a melting point below 280° C., which improves wettability during subsequent soldering.

[0049] To hermetically seal the HTS tape conductor, it is tightly wrapped with a preferably ductile metal foil 16, as detailed above and shown in Figures 1b and 2. Metals such as copper, aluminium, silver, nickel, tin, lead, indium or bronze are very suitable for this. In particular, copper, aluminium and silver, optionally with small amounts of alloying additives, and with a thin layer 15 of soft solder having a melting point below 280°C, preferably below 250°C, are preferred.

[0050] The tensile stress with which the metal strip is wound during the manufacture of the superconductor is in the range of 10-150 MPa, depending on the material, and the pitch angle φ is preferably less than 45°, particularly preferably in the range of 20°-30°. The wound high-temperature superconducting tape is then passed over a hot roller or hot caterpillar, melting the solder material 15 and compacting the composite. Alternatively or additionally, melting can also be performed by a hot air blower or infrared radiators. As before, it is preferable to use contact pressure here.

[0051] The winding and soldering steps can also be repeated several times in succession to bring the composite to a certain target thickness. An example of this configuration is shown in Figure 3. Preferably, the second or further layer of metal foil is wound in the same direction with an offset between layers of at least 20% of the line width B, particularly preferably about half the line width B, to ensure that the connection points of the turns of the layer below are covered. A further embodiment relates to a high temperature superconducting tape conductor (insert) with connections.

[0052] Very long tape conductors with high current carrying capacity, for example lengths of hundreds or even thousands of meters, are preferably manufactured by splicing together short pieces of tape. Ideally, these should be practically invisible to the end user and behave like normal simple HTS tape conductors. Suitable splicing methods are described, for example, in US Pat. No. 7,701,144 and EP-A-2,835,838, the latter also describing the repair of defects similar to those described in EP-A-2,689,477. When splicing, the HTS tape conductor is first mechanically connected to the substrate, for example by welding or soldering. To ensure that the current flows through the splice or localized defect, a second tape conductor facing the HTS side is soldered as a patch to the HTS side of the tape conductor surface.

[0053] This configuration is shown in Figure 4. The bridge structure is generally much thicker than the individual HTS tape conductors. Therefore, EP 2 835 838 A describes a method of selectively detaching the substrate from the patch in order to keep the bridge as thin as possible. In either case, however, the joints and repairs represent sensitive areas whose mechanical properties differ significantly from those of conventional HTS tape conductors.

[0054] The stiffness increases with the cube of the tape thickness, and when conveyed by rollers, such points tend to bend, tear or peel due to the sudden change in bending stiffness. The present invention makes it possible to encase or cover such patches or connections, thus providing an additional mechanical reinforcement that can withstand strong bending, reliably seal the connections and make such points virtually invisible from the outside, as shown in Figure 4.

[0055] Further embodiments relate to inserts having multiple high temperature superconducting tape conductors 10 connected, e.g., by soldering, either face to face with the HTS layer side or back to back, or having a combination of high temperature superconducting tape conductors and metal foil soldered together via the major surfaces 17.

[0056] In the first case, the superconducting current carrying capacity increases and the fluctuations in the current carrying capacity become smaller (current sharing).

[0057] Properties such as normal electrical conductivity or heat capacity can be further tailored by the composite of the high temperature superconducting tape conductor and additionally introduced metal foils or intermediate layers 18, as shown diagrammatically in Figure 5. The composite can be mechanically reinforced and hermetically sealed simply with metal foils, or multiple times as shown in Figure 3.

[0058] 6 is a flow diagram of a manufacturing method according to an embodiment of the present invention. In a first step 610, at least one layer of metal foil is wrapped around a high temperature superconducting tape conductor or a number of connected high temperature superconducting tape conductors as described above. Next, the metal foil is heated 620 above the melting point of the solder coating. Finally, the metal foil is cooled again below the melting point of the solder coating and the metal foil is connected to the high temperature superconducting tape conductor, forming a reinforcement that seals the high temperature superconducting tape conductor 630.

[0059] Further embodiments of such manufacturing methods are detailed above, particularly in section 3. [Explanation of symbols]

[0060] 10 High-temperature superconducting tape conductor (insert) 11 Metal Substrate 12 Buffer layer 13 HTS layer 14. Enveloping Metallic Layer 15 Solder layer between high temperature superconducting tape conductor and metal foil 16, 16a First wrapped layer of metal foil 16b Second wrapped layer of metal foil 17 Solder layer between high temperature superconducting tape conductors 18 Interlayer of Composite Conductor W: Width of high-temperature superconducting tape conductor B Metal foil width Φ Pitch angle of the metal foil circumference

Claims

1. A superconductor, a high-temperature superconducting tape conductor (10); and at least one layer of metal foil (16) wrapped helically around the high temperature superconducting tape conductor in multiple turns and soldered to form a reinforcement that hermetically seals the high temperature superconducting tape conductor.

2. the metal foil comprises pure copper, pure aluminum, low-alloy copper, or low-alloy aluminum, and / or the metal foil has a thickness of 10 μm to 100 μm, preferably 20 μm to 50 μm, and / or 2. The superconductor according to claim 1, wherein a solder layer having a melting point of 280°C or less, preferably 250°C or less, and a thickness of 2 μm to 30 μm, preferably 5 μm to 15 μm, is provided on at least one surface of the metal foil.

3. the metal foil is wrapped around the high temperature superconducting tape conductor at an angle of less than 45°, preferably between 20° and 30°, relative to the width of the high temperature superconducting tape conductor; and / or 3. The superconductor according to claim 1, wherein the turns of at least one layer of said metal foil are arranged in contact with each other without overlapping.

4. 3. The superconductor according to claim 1 or 2, wherein the adhesive strength of the metal foil on the high temperature superconducting tape conductor is greater than 10 MPa when the metal foil is peeled off in a direction perpendicular to the surface of the high temperature superconducting tape conductor, preferably the adhesive strength is determined by adhesive peel measurement according to DIN EN ISO 4624:2016.

5. 3. The superconductor of claim 1, further comprising a plurality of high temperature superconducting tape conductors, said plurality of high temperature superconducting tape conductors being stacked together to form a multilayer composite or connected by overlapping ends thereof, wrapped together with said metal foil, and soldered.

6. the high temperature superconducting tape conductor or the connected high temperature superconducting tape conductors are wound with at least one further layer of metal foil, whereby the connection points of the turns of the at least one layer are covered by the further layer; and / or 3. The superconductor according to claim 1, wherein the high temperature superconducting tape conductor or the plurality of connected high temperature superconducting tape conductors has a surrounding copper layer or surrounding silver layer having a total thickness of more than 2 μm, preferably 2 μm to 5 μm.

7. A method for producing a superconductor, comprising: spirally wrapping at least one layer of solder-coated metal foil around a high temperature superconducting tape conductor; heating the metal foil above the melting point of the solder coating; thereafter cooling below the melting point of the solder coating and connecting the metal foil to the high temperature superconducting tape conductor to form a reinforcement that hermetically seals the high temperature superconducting tape conductor.

8. 8. The method of claim 7, wherein the heating and / or cooling is performed under the action of contact pressure, preferably by introducing the wound high temperature superconducting tape conductor into a hot roller or a hot caterpillar.

9. 9. The method according to claim 7 or 8, wherein the number of revolutions and the feed rate of the winding are set so that the circumferential portions of at least one layer of the metal foil are arranged in contact with each other without overlapping each other during the winding.

10. 9. The method according to claim 7 or 8, wherein the number of revolutions and the feed rate during winding are set so that the pitch angle of the winding portion is less than 45°, preferably 20° to 30°.

11. 9. The method of claim 7 or 8, wherein during wrapping, at least one layer of the metal foil is held under a tensile stress of 10 MPa to 100 MPa.

12. 9. The method according to claim 7 or 8, further comprising the step of sequentially winding a plurality of layers of metal foil around the high temperature superconducting tape conductor with an offset to each other, the amount of offset preferably being 20% ​​or more of the line width of the metal foil, more preferably being substantially half the line width of the metal foil.

13. 13. The method of claim 12, wherein each layer is individually soldered.

14. stacking or longitudinally connecting a plurality of high temperature superconducting tape conductors together; 9. The method of claim 7 or 8, further comprising the step of subsequently winding the spliced ​​high temperature superconducting tape conductor.

15. the metal foil comprises pure copper, pure aluminum, low-alloy copper, or low-alloy aluminum, and / or the metal foil has a thickness of 10 μm to 100 μm, preferably 20 μm to 50 μm, and / or 9. The method according to claim 7 or 8, wherein the solder coating is provided on at least one surface of the metal foil, the solder coating having a melting point of 280°C or less, preferably 250°C or less, and a thickness of 2 μm to 30 μm, preferably 5 μm to 15 μm.

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