A plurality of superconducting filaments

Abstract

A method (100) for forming a plurality of filaments (242) is presented, where each filament is a superconductor. The method includes providing a substrate (230), the substrate having a first side (231) and a second side (232), the substrate including a plurality of grooves (234) on the first side of the substrate; applying (108) a coating (238) on the substrate (230), the coating including a superconducting material, and for each groove of the plurality of grooves, a first portion of the coating on the first side of the groove feature is separated from a second portion of the coating on the second side of the groove feature, the second side of the groove feature being opposite the first side of the groove feature; removing (112) the substrate from the second side, removing at least a portion of the substrate to remove at least the connection from the first portion of the coating to the second portion of the coating through the substrate.

Description

Technical Field

[0001] The present invention relates to a method for fabricating a plurality of conductive filaments, and more particularly to a plurality of superconducting filaments, and still more particularly to a plurality of filaments and their use.

Background Art

[0002] Superconducting structures are considered advantageous because they can conduct current, such as direct current, without electrical loss due to resistance. For this reason, superconducting structures such as superconducting tapes are used in some applications such as electromagnets, generators, and transformers. However, the method of fabricating a superconducting structure is complex and may not be realistically applicable to industrial-scale manufacturing. Also, although a superconducting structure may have excellent properties when conducting direct current, it may exhibit high energy losses when used in alternating current (AC) applications.

[0003] Therefore, a method for fabricating a superconducting structure that can reduce, minimize, or eliminate losses when used in alternating current (AC) applications, is simpler, and / or has higher applicability to industrial-scale manufacturing is desirable.

Summary of the Invention

[0004] An object of the present invention is to provide a method for fabricating a plurality of filaments, corresponding plurality of filaments, and their use, such as enabling reduction, minimization, or elimination of energy loss when used, for example, in alternating current (AC) applications, a simpler manufacturing method, and / or a manufacturing method with higher applicability to industrial-scale manufacturing. Also, a further object of the present invention is to provide an alternative to the prior art.

[0005] Therefore, the above object and several other objects are intended to be achieved in a first aspect of the present invention by providing a method for fabricating a plurality of filaments in which each filament is a superconductor, such as a high-temperature superconductor (HTS), and the method sequentially includes, for example, the following steps. · A step of providing a substrate, for example, the substrate is made of metal, for example, the substrate is a planar metal substrate, the substrate has a first side and a second side, for example, the first side is on the opposite side of the second side, and the substrate has a plurality of grooves on the first side of the substrate. · A step of applying a coating to the substrate, the coating includes a superconducting material, for example, the coating is a multilayer structure including a superconducting material optionally containing rare earth barium copper oxide (also called REBCO), for example, the coating is a superconductor stack, for example, the coating is a high-temperature superconductor stack, whereby for each of the plurality of grooves, i. The first portion of the coating on the first side of the feature such as the groove is ii. A second portion of the coating on the second side of the feature such as the groove, wherein the second side of the groove feature is on the opposite side of the first side of the groove feature, a step of being physically cut, such as being cut, such as being separated. · Removing at least a part of the substrate from the second side of the substrate through electrolytic polishing and / or etching, etc., removing at least the connection from the first portion of the coating through the substrate to the second portion of the coating, so as to provide a plurality of filaments, for example, such that the portion of the substrate where the filaments were previously joined is removed.

[0006] The present invention is particularly, but not exclusively, useful for providing a method of forming a plurality of filaments, enabling reduction, minimization, or elimination of energy losses, improvement of magnetic field stability, reduction of magnetic field-related forces, etc. when used in alternating current (AC) applications, and being simpler and / or more applicable to industrial-scale manufacturing. As another advantage, twistable filaments as shown in FIG. 9 of the peer-reviewed review article "Multifilamentary coated conductors for high magnetic field applications" (Anders Christian Wulff et al., Supercond. Sci. Technol. 34 (2021) 053003) may be provided. The filaments can be twisted individually, in pairs, or in bundles containing two or more filaments.

[0007] In an embodiment, the method includes the step of twisting the filaments individually, in pairs, or in bundles containing two or more filaments. Advantages include minimizing energy losses, transposition (see, e.g., the article "How filaments reduce the AC losses of HTS coated conductors: A review", by Francesco Grilli, Anna Kario, Supercond. Sci. Technol. 29 (2016) 083002 (15pp), which is hereby incorporated by reference in its entirety), and spatially (and statistically) dispersing the joints.

[0008] The present invention may be particularly advantageous for providing a method of making a wire or cable having narrow or thin filaments made from high-temperature superconductors and / or ceramic-based superconductors.

[0009] Providing a superconducting element in the form of a filament may reduce AC losses and stabilize the magnet. This is based on the method described in the peer-reviewed review article "Multifilamentary coated conductors for high magnetic field applications" (Anders Christian Wulff et al., Supercond. Sci. Technol. 34 (2021) 053003, which is hereby incorporated by reference in its entirety), and / or the method described in the peer-reviewed paper published in the academic journal "How filaments reduce the AC losses of HTS coated conductors: A review", by Francesco Grilli, Anna Kario, Supercond. Sci. Technol. 29 (2016) 083002 (which is hereby incorporated by reference in its entirety).

[0010] Another advantage of fabricating thin superconducting filaments is that effective capping or stabilization of the filaments becomes possible, for example, when the proportion of capping material or stabilization material on the side surface of the filaments becomes large or relatively large (compared to the width of the filaments). For example, compared to a wide flat tape having a width of usually several millimeters, for example, a width of 2 to 12 millimeters, the proportion of the stabilization material in the cross-section relative to the proportion of the stabilization material in the superconducting layer can be increased, resulting in a superconducting tape / wire structure with a higher proportion of stabilization material per unit side area of the superconducting material. As a result, the resistance to quenching such as local heating and loss of local superconducting properties may be enhanced. By adding a stabilization material such as a material selected from the group consisting of silver, copper, nickel, tin, and / or zinc to the first side and the second side of the superconducting material, the thermal and electrical stability of the superconducting material such as a composite material can be enhanced. Even if a stabilization material is added to the edge of a standard wide tape, the proportion of the stabilization material in a wide tape such as 4 mm or 12 mm will not be significantly increased relative to the proportion of the superconducting material. For example, in the case of a narrower tape such as a tape with a width of 70 μm and a thickness of 50 μm, and a 1 μm HTS layer, when 10 μm of stabilization material is added to the entire surface of the tape, the aspect ratio of the stabilization material to the width of the HTS layer is about 40, which is twice (2) higher than that of a tape with a width of 12 mm and a thickness of 50 μm having the same thickness of the stabilization material.

[0011] In one embodiment, the method further includes adding a cap layer and / or a stabilization material as part of and / or on the coating. The "cap layer" and the "stabilization material" are understood as is well-known in the art.

[0012] This method depends on, and / or exclusively depends on in embodiments, such a method. That is, the method according to embodiments of the present method is realistically applicable to industrial-scale manufacturing. For example, the provision of a substrate such as a tape provided in a reel-to-reel manner, the optional application of grooves (the application of grooves in a rolling process and / or a lithography process (such as photolithography and subsequent etching)), the application of a coating, the optional provision and removal of a resist (such as etching from the back side), etc., are all steps that can be realistically applied on an industrial scale.

[0013] It is considered to be the insight of the inventor that the process for providing a plurality of superconducting filaments can be realized by method steps applicable industrially, for example, exclusively by method steps applicable industrially.

[0014] Furthermore, since the method according to embodiments of the present invention is relatively simple and / or efficient, it is considered to have the advantage of being particularly suitable for large-scale manufacturing. For example, long filaments can be obtained, optionally in large numbers, by a relatively fast method and / or a method that requires relatively few resources, such as relatively few facilities, personnel, energy, and / or materials. Therefore, large-scale manufacturing is made possible by embodiments of the present invention, and this is made possible while minimizing resources such as the amount of resources used.

[0015] Also, embodiments of the present invention can be regarded as effective in that they make it possible to provide a substrate for a superconducting structure that facilitates a relatively large critical current because it is possible to obtain a substrate with few or no damage zones (a damage zone is a part where a part of the superconducting material ceases to function, and as a result, the critical current may decrease).

[0016] "Filament" means an optionally flexible, elongated element, such as a solid, elongated element, as generally understood in the art. "Elongated" means having a greater dimension in a first direction (e.g., the direction called the length direction), e.g., 2, 5, 10, 100, 1000, 10000, or 100000 times longer than the dimensions in the other two directions (e.g., the directions called width and height), and may refer to being longer than the dimension in one or both of the other two directions (such as the directions called width and height). "Solid element" may refer to an element comprising a solid phase, such as an element comprising a solid phase.

[0017] "Superconductivity" is understood, as generally understood in the art, optionally, as the ability of a material to conduct an electric current with substantially zero, e.g., zero, electrical resistance when cooled below a characteristic transition temperature.

[0018] "Superconducting material" is understood, as generally understood in the art, e.g., in the context of "superconductivity" described above. A superconducting material may be composed of, for example, rare earth barium copper oxide (REBCO).

[0019] "High-temperature superconductivity (HTS)" (or high T c ) is understood, as generally understood in the art, e.g., as the ability of a material to become superconducting at a temperature above the temperature corresponding to the boiling point of liquid nitrogen (about 77 Kelvin).

[0020] "Substrate" means "a substrate suitable for supporting a superconducting element", which means a solid element on which a superconducting material is disposed, such as by deposition, whereby the substrate and the superconducting element are integrated to form a superconducting element. The substrate may be composed of one or more metallic elements (metal, metalloid, semiconductor, and / or metal semiconductor) or alloys. The substrate may be composed of one or more non-metals such as polymers. The substrate may be composed of a substantially planar surface.

[0021] The solid element may have an arbitrary shape, where the shape is understood as the geometric shape seen in a cross-section in a plane orthogonal to the longitudinal axis (for example, the axis corresponding to the axis parallel to the direction in which current flows). For example, it may be any of arbitrary shapes, such as a tape shape, a rectangular shape (for example, a square shape), a triangular shape, an elliptical shape (for example, a circular shape).

[0022] According to one embodiment, the method includes forming a Rutherford cable from a plurality of filaments.

[0023] Optionally, the substrate has a shape that enables twisting pitching, such as a single element twist, such a pair twist, for example, a ROEBEL structure (see "Supercond. Sci. Technol. 22 (2009) 034003". This reference is incorporated herein by reference in its entirety.), for example, a conductor on round core (see "Supercond. Sci. Technol. 27 (2014) 125008" (the reference "Supercond. Sci. Technol. 27 (2014) 125008" is incorporated herein by reference in its entirety) or a geometric shape that enables transposition of the superconducting element disposed on the substrate, etc. This shaping may be given by a segmented linear shape such as a zigzag shape.

[0024] In an embodiment, the substrate is a "tape", that is, an element having a thickness (length along the first dimension) that is significantly smaller than the width (length along the second dimension), for example, 10, 100, or 1000 times smaller, where the width is significantly smaller than the length (length along the third dimension), for example, 10, 100, or 1000 times smaller.

[0025] The solid element may be composed of any material selected from the group consisting of nickel-based alloys, copper-based alloys, chromium-based alloys, iron, aluminum, silicon, titanium, tungsten (also known as wolfram (W)), silver, Hastelloy, Inconel®, and stainless steel.

[0026] "Hastelloy" refers to an alloy whose main alloying component is nickel and contains one or more (including all) of elements such as molybdenum, chromium, cobalt, iron, copper, manganese, titanium, zirconium, aluminum, carbon, tungsten, etc. in various proportions. In certain embodiments, Hastelloy is an alloy containing the elements Ni, Cr, Fe, Mo, Co, W, C. In a more specific embodiment, this alloy also contains one or more of the elements Ni, Cr, Fe, Mo, Co, W, C, and Mn, Si, Cu, Ti, Zr, Al, B. In a more specific embodiment, this alloy contains approximately 47 wt% Ni, 22 wt% Cr, 18 wt% Fe, 9 wt% Mo, 1.5 wt% Co, 0.6 wt% W, 0.10 wt% C, less than 1 wt% Mn, less than 1 wt% Si, and less than 0.008 wt% B. Hastelloy may be referred to as "superalloy" or "high-performance alloy" in the art.

[0027] "Stainless steel" is generally known in the art. In certain embodiments, for example, stainless steel containing nickel and / or chromium is provided so as to provide corrosion resistance and / or oxidation resistance, mechanical stability, and non-magnetism at the operating temperature of the superconducting layer.

[0028] As generally understood in the art, a "groove" is understood as an elongated depression such as a depression regarding adjacent portions of a substrate, for example. A groove may serve to separate a portion of the surface of a substrate into portions on both sides of the groove such that, for example, by deposition of material onto the substrate as in the line-of-site method, material portions separated at both sides of the groove are obtained. An advantage of such separation is that the distance from a first side surface to a second side surface (any plane) of the substrate varies depending on the position of the first side surface. Thereby, by removing material from the second side surface of the substrate in a spatially non-specific manner (for example, a method in which material is removed in substantially equal amounts from any location on any planar surface) by a method such as etching or electropolishing, for example, there is an advantage that the total thickness of the material from the first side surface to the second side surface of the substrate can first be removed at the position of the groove. For example, by removing material from the second side surface of the substrate by etching or electropolishing, it becomes possible first at the position of the groove to remove the total thickness of the material from the first side surface to the second side surface of the substrate. That is, portions with grooves can be separated from each other by a relatively simple spatially non-specific removal step such as etching or electropolishing.

[0029] The "line-of-sight" process means a process of depositing a material only at positions on a substrate that are visible along a straight line from another position, such as above the substrate. Therefore, the "line-of-sight" process is interpreted to broadly include a process in which the deposited material follows a straight line before deposition and deposition processes having a similar effect. In a particular embodiment, the "line-of-sight" process is any one of die coating, bubble jet coating, and ink jet coating. In a particular embodiment, the "line-of-sight" is understood to be a process in which the deposited material is generated from a source and moves linearly from there to the position where it is deposited. In other words, the deposited material can only exist at positions where a straight line can be drawn to the source without crossing an obstacle. As an advantage of using the line-of-sight process, it becomes possible to deposit the deposited material on both sides of each groove while utilizing groove features that shadow a part such as the bottom of the groove, whereby deposition is not performed on that part and a segmentation strip is formed in the deposited material. A "segmentation strip" is a line of absence of a coating material, and may refer to something that separates the coating material into elongated strips on both sides of the segmentation strip. The segmentation strip can be regarded as a gap in an otherwise consistent coating material. For example, when a continuous coating material, such as a layer of continuous coating material, is traversed by a segmentation strip, the continuity of the continuous coating material is divided into two separate (layered) materials, such as two portions of coating material.

[0030] The grooves may be parallel to each other. "Parallel" means parallel within 0 degrees, 1 degree, 2 degrees, 3 degrees, 4 degrees, 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, 10 degrees. The grooves may be partially parallel, and the grooves themselves may not be straight, but may be curved or partially straight, but adjacent grooves may still be parallel.

[0031] "Coating" is understood in its general meaning in the relevant technical field and is, for example, a layer of material applied to a substrate, such as a thin layer. The application of the coating can be carried out in several ways, such as a line-of-sight process, such as dip coating, bubble jet coating, inkjet coating, or the like. The coating can optionally form a second-generation high-temperature superconducting coated conductor together with at least a part of the substrate.

[0032] The structure and / or texture of the superconducting material in the coating may be imparted to the superconducting layer through another layer in the coating, such as the substrate and / or buffer layer.

[0033] "Buffer (layer)" is as generally understood in the relevant technical field and is understood to be, for example, something that may optionally impart structure and / or texture to the superconducting layer or may optionally impart an inert chemical barrier.

[0034] "Superconductor stack" means a layered structure, such as a multilayer structure optionally including distinct layers, including a buffer layer (e.g., 0.1 to 2 micrometers) and a superconducting layer (e.g., a rare-earth-based barium copper oxide (REBCO) with a thickness of 1 to 5 micrometers). The superconductor stack may be a high-temperature superconductor stack.

[0035] "The first side of the groove feature" means the region of only one side of the groove feature.

[0036] "Features of the groove" means part or all of the groove. For example, the entire groove may serve to separate, i.e., physically cut, the portion of the coating material applied from directly above the groove in the viewing direction process (in this example, there are portions on both sides of the groove, neither of which is composed of the material within the groove). In another example, the edge of the groove or the side surface of the groove may serve to separate, e.g., physically separate, a part of the coating material applied in the line-of-sight direction process from a position outside the plane perpendicular to the surface constituting the groove and parallel to the groove (in this example, a part of the coating may be composed of the material of the groove. For example, the bottom of the groove, etc.).

[0037] "Separated" means that the separated elements are spatially separated. For example, it applies when the elements are separated by a material different from the material of the elements, e.g., when there is a non-solid material between the elements. In an embodiment, the separated elements may be connected to each other via the same material as the material of the elements (e.g., the portions of the elements on the protrusions / hills on each side of the groove may be separated from each other, but may be connected via the same material as the material of the element extending from one protrusion / hill to the other through the groove). In an embodiment, the separated elements may not be connected to each other, e.g., physically, due to the absence of the same material as the material of the elements between the elements (e.g., the elements on the protrusions / hills on both sides of the groove may be separated from each other and not physically connected due to the absence of the same material as the material of the element extending from one protrusion / hill to the other).

[0038] "Separation" means being physically and / or electrically separated. For example, it includes cases where the separated elements are not electrically connected by an electrically conductive material and / or are not physically connected by the material of the elements.

[0039] "Removing from the second side of the substrate" means that the material is removed from the surface of the second side of the substrate, for example, removed from the back side with respect to the front side consisting of grooves, for example, removing the outermost layer of material. Further, removing the material from the second side of the substrate may be understood to include removing the material from the second side of the substrate before removing the material from the first side of the substrate and / or while the material remains on the first side of the substrate. When removing the material from the second side of the substrate, the position of the surface of the second side of the substrate moves towards the first side of the substrate and / or the coated portion.

[0040] "At least removing the connection from the first part of the coating to the second part of the coating through the substrate" means that the material of the substrate is removed, and as a result, the physical connection from the first part of the coating to the second part of the coating through the substrate is eliminated, for example, the first part and the second part of the coating are separated or peeled from each other, and / or the first part and the second part of the coating are no longer connected through the substrate, for example, for any part of the substrate, in at least a cross-section orthogonal to the longitudinal direction of one or more filaments, there is no path through the substrate from the first part of the coating to the second part.

[0041] In an embodiment, "at least removing the connection part from the first part of the coating to the second part of the coating via the substrate" includes dividing, breaking, cutting, or rupturing at least the connection part from the first part of the coating to the second part of the coating via the substrate.

[0042] The removal of the material may be performed, for example, by electropolishing and / or etching (e.g., electrolytic etching), a polishing process, a cutting process, or a laser process.

[0043] The step of "removing at least a part of the substrate from the second side of the substrate" may be performed by electropolishing and / or etching, such as electrolytic etching. Electropolishing and / or etching are established techniques, applicable on an industrial scale, and have the advantage that they can be applied to remove some materials (such as the substrate) without imposing a burden on the remaining materials (especially coatings when the remaining materials are covered by a protective cover).

[0044] "Etching", "electrolytic etching", or "electropolishing" may mean the removal of (substrate) materials by etching with an etching solution, etc., electrolytic etching, or electropolishing. The etching solution may be in any state of plasma, liquid, or gas in certain embodiments. In certain embodiments, reactive ion etching (RIE) is employed.

[0045] "Polishing process" means that a part of the (substrate) material is removed by the polishing process or the polishing process, for example, repeatedly scraping off a part of the (substrate) material to be removed. The "polishing process" is understood to be the same as the "grinding process" in this context.

[0046] "Cutting process" means a process in which the material is not removed but moved. This can be achieved using a relatively sharp tool.

[0047] The step of "removing at least a part of the substrate from the second side of the substrate" can be carried out by a laser process such as any one of laser marking, laser engraving, laser etching, laser annealing.

[0048] For example, by a method such as laser marking in a spatially specific, or spatially clearly defined, or spatially clearly definable way (for example, a method in which material is removed, or can be removed, at a spatially clearly defined position, for example, a method in which material at two positions with similar topography on a planar surface is removed at significantly different rates, for example, the removal rate at one position is non-zero and the removal rate at the other position is substantially zero), a groove is formed such that the distance from the first side surface to the second side surface (the position corresponding to the bottom of the groove) is shortened, and as a result, the amount of substrate material that must be removed to penetrate the substrate is reduced (compared to the case without the groove).

[0049] According to one embodiment, a method is presented that further includes the following steps before removing at least a part of the substrate from the second side surface of the substrate. · A step of applying a protective coating, such as a resist, for example a protective coating layer, on a part or all of the first part of the coating and a part or all of the second part of the coating, for example on the first part and / or the second part of the coating, wherein the protective coating layer partially or entirely fills the voids in the groove.

[0050] "Protective coating" refers to a layer of material such as a resist that can protect (for example, protect from mechanical deformation and / or thermal effects) the underlying material such as a coating during the step of removing at least a part of the substrate from the second side surface of the substrate, for example during etching. The advantage of applying a protective coating is that the applied material is not damaged, or is less damaged, during the step of removing at least a part of the substrate from the second side surface of the substrate. As a result, the degradation of the superconducting properties of the resulting filament can be reduced, minimized, or eliminated. The protective coating may be a photoresist such as a liquid photoresist.

[0051] According to one embodiment, following the removal of at least a part of the substrate from the second side surface of the substrate, a method is presented that further includes the following steps. · A step of partially or completely removing a protective coating from a part or all of the coating and the remaining part of the substrate, for example, a step of removing at least a connection from a first part of the coating to a second part of the coating through the protective coating.

[0052] The advantage of removing the protective coating is, for example, to enable the separation and / or processing of filaments for the purpose of constructing (optionally twisted and / or relocated) multifilament superconducting elements or multifilament superconducting wires so that the protective coating does not interfere. (Optionally, individual filaments can be twisted in pairs and / or relocated with respect to adjacent filaments).

[0053] According to one embodiment, a method of "partially removing a protective coating" is presented, which is implemented by electropolishing and / or etching, such as electrolytic etching or physical etching. The advantages include that electropolishing and / or etching are established technologies, applicable on an industrial scale, and can remove some materials (such as the substrate) without imposing a burden on the remaining materials (especially coatings when the remaining materials are covered by a protective coating).

[0054] According to one embodiment, a method is presented that includes the following, namely, a method of providing a substrate as follows. · Providing a substrate without grooves on a first side of the substrate, and · Forming a plurality of grooves on the first side of the substrate.

[0055] "Forming a plurality of grooves" can be implemented in several ways, such as cutting or roll cutting, which is beneficial from the perspective of industrial applicability.

[0056] According to one embodiment, a method of forming a plurality of grooves on a first side of a substrate is presented, in which the plurality of grooves are formed on the first side of the substrate in a reel-to-reel manner. The advantage of this method is that large-scale processing becomes easier.

[0057] According to one embodiment, a method is presented for stopping the removal of at least a portion of a substrate, such as electropolishing and / or etching, from a second side of the substrate while each portion of a coating, e.g., a first portion of the coating and a second portion of the coating, is adjacent to the remaining portion of the substrate. By each portion of the coating being adjacent to the remaining portion of the substrate, there may be an advantage that the remaining portion of the substrate provides mechanical strength to a filament consisting of the coating and the remaining portion of the substrate. In some embodiments, the substrate is a roll-processed substrate, whereby the corresponding increase in strength is greater than, and in some cases may be greater than, the increase in strength provided by adding material to a coating from which the (original) substrate has been completely removed. Another advantage of providing the substrate is that, for example, the step of providing the substrate by deposition is omitted.

[0058] Another possible advantage is that a coating, such as a superconductor stack optionally including a protective cap and / or a stabilizing material, is optionally firmly adhered to a metal substrate. For example, a superconductor stack in coated conductor manufacturing can be epitaxially grown on a metal substrate, thereby providing good mechanical strength between the metal substrate, a buffer layer in the superconductor stack, and the superconducting layer. Good mechanical strength is advantageous for avoiding cracks in the coating and thus for avoiding breakage of the coating.

[0059] According to one embodiment, a method is presented in which electropolishing and / or etching is stopped before the liquid used for the electropolishing and / or etching reaches the first part and / or the second part of the coating. A possible advantage is that the liquid is prevented from reaching the first part and / or the second part of the coating. A reason why this can be advantageous compared to the situation where the liquid reaches the first part and / or the second part of the coating is that when the liquid comes into contact with the first part and / or the second part of the coating, the properties of the first part and / or the second part of the coating, for example, the superconducting material of the first part and / or the second part of the coating, may change such as deteriorating. As a further advantage, if the electropolishing and / or etching is stopped before the liquid used for the electropolishing and / or etching reaches the first part and / or the second part of the coating, the liquid may be prevented from moving within the first part and / or the second part (which may be porous) of the coating. In an embodiment, the undercut of the groove is utilized to form a consistent structure of the superconducting material (the first part and / or the second part of the coating) that does not spread to the side surfaces of the groove and extends from one side surface of the groove to the other side surface. For example, it extends from the upper part (protrusion) of the substrate adjacent to the groove to the side surface of the groove and further to the bottom of the groove. Thus, the consistent structure of the superconducting material having a part of the upper part (protrusion) of the substrate adjacent to the groove may be located at a position further away from the second side surface of the substrate (for example, the distance between the second side surface of the substrate and the point of the consistent structure closest to the second side surface of the substrate). The undercut may serve to provide a physical cut between the superconducting material (sacrificial) at one side surface of the groove shape, for example, at the bottom of the groove, and the superconducting material at the other side surface of the groove shape, for example, at the upper part (protrusion) of the substrate adjacent to the groove).

[0060] According to one embodiment, a method for removing at least a part of a substrate from a second side surface of the substrate is presented, and the removal is performed by grinding and / or laser. The advantages of grinding include being efficient, cost-effective, fast, and / or scalable. The advantages of laser include being cost-effective, controllable, and / or spatially clearly definable.

[0061] According to one embodiment, a method is presented in which each of a plurality of grooves is composed of one or more undercuts. This enables the deposition of superconducting material on the substrate and is beneficial for creating a physical barrier between each part of the superconducting material using one or more undercuts.

[0062] According to one embodiment, a method is presented that further includes the following steps. · A step of forming one or more undercuts in each groove using etching or the like, for example, a step of forming one or more undercuts in a two-step undercut process (2LUPS).

[0063] An undercut may be formed, for example, by etching and / or electropolishing, or may be formed by a method as described in, for example, WO13174380A1, which is hereby incorporated by reference in its entirety. By "undercut" is meant the volume in each groove, which volume may be below the rest of the substrate. Thus, the undercut (volume) may be shadowed by the overhanging portion of the substrate. As an advantage, when depositing material using a process visible from above a substrate consisting of grooves with undercuts, the material is not deposited on the shadowed undercut portions of the substrate. It can be understood that an undercut is provided in the process of constructing a sandwich structure by a two-step undercut profile substrate (2LUPS) process. The break strip is described in more detail, for example, in WO13174380A1 (which is hereby incorporated by reference in its entirety), particularly in FIGS. 3A - 3H and the accompanying description. The 2LUPS process is alternatively or additionally described in the paper "Multifilamentary coated conductors for high magnetic field applications", Anders Christian Wulff et al., Supercond. Sci. Technol. 34 (2021) 053003, which is hereby incorporated by reference in its entirety, particularly in section 4.2 and the like.

[0064] According to one embodiment, a method is presented that further includes the following steps. · A step of twisting a plurality of filaments, or a plurality of sets of filaments, wherein each filament is twisted around its own axis and / or the plurality of filaments are twisted around their common axis, for example, optionally the twisted bundles of filaments are twisted around each other, thereby providing one or more superconducting structures each including a plurality of twisted filaments, for example, a step in which each filament has a helical shape having a central axis within one or more other helical filaments, and / or, ·A step of transposing a plurality of filaments, or an aggregate of a plurality of filaments, thereby providing one or more superconducting structures including the plurality of transposed filaments.

[0065] "Twisting" means that a part such as the end of a filament rotates about the longitudinal axis with respect to another part such as the opposite end, and the rotation is at least a half rotation or π (radians) or 180 degrees, for example, n times π (n is at least 1, for example, at least 2 (corresponding to at least one rotation or at least 360 degrees), for example, at least 5, for example, at least 10, for example, at least 50, for example, at least 100, for example, at least 1000. Twisting can occur when each filament is twisted around its own axis and / or when performed on a plurality of filaments (such as a bundle) that are twisted together. The advantage of twisting is that instability and coupling losses can be reduced, minimized, or eliminated.

[0066] The transposition of the filaments can effectively separate the filaments, which can be achieved by twisting the filaments (for example, the paper "How filaments can reduce the ac loss of HTS coated conductors: a review") by Francesco Grilli and Anna Kario, Supercond. Sci. Technol. 29 (2016) 083002 (15pp) (incorporated herein by reference in its entirety, see especially the end of section 2 on page 3).

[0067] "Transposition" generally refers to arbitrarily and periodically interchanging the positions of the conductors of a transmission line in order to reduce crosstalk and / or improve transmission. See, for example, the paper "How filaments can reduce the ac loss of HTS coated conductors: a review" by Francesco Grilli and Anna Kario, Supercond. Sci. Technol. 29 (2016) 083002 (15pp) (incorporated herein by reference in its entirety).

[0068] Furthermore, it is advantageous to additionally deposit a cap of a metal such as copper or silver before each individual filament is twisted around its own axis (vertical axis, axis of rotation). Capping can also be added after twisting and / or after replacement with and / or twisting with other filaments. The additional capping further enhances the mechanical and thermal stability. The metallization can be performed by electrodeposition such as plating or by sputtering.

[0069] According to one embodiment, a method is presented that further includes the following. · Forming a superconducting wire by providing a core and / or capping to one or more superconducting structures.

[0070] The "core" may be understood as an element of any metal (such as copper, stainless steel, gold, silver, etc.) disposed at the center, and optionally, one or more superconducting structures are twisted around the core. The advantage of the core is to provide mechanical strength to the resulting superconducting wire.

[0071] The "capping" can be understood as a material disposed on the periphery. The advantages of capping include providing mechanical and / or thermal protection to the superconducting portion of the resulting superconducting wire. Another advantage of capping is to provide additional mechanical strength to the resulting superconducting wire. It can also be expected to have the effect of preventing quenching of the superconductor by increasing the heat capacity (see "Multifilamentary coated conductors for high magnetic field applications" Anders Christian Wulff et al., Supercond. Sci. Technol. 34 (2021) 053003, which is hereby incorporated by reference in its entirety).

[0072] "Wire" means an electrically conductive and optionally flexible element composed of a plurality of superconducting filaments and one or more additional elements such as caps and / or cores. The wire may be composed of at least 5 filaments, at least 10 filaments, at least 100 filaments, at least 500 filaments, at least 1000 filaments, at least 10000 filaments, etc. The length of the wire may be at least 0.1 m, for example at least 1 m, at least 10 m, at least 100 m, at least 1000 m.

[0073] According to one embodiment, a method is presented that further includes winding one or more filaments, superconducting structures, and / or superconducting wires to form a coil. The advantage of providing a coil is that such a coil may be useful for a number of applications, such as the generation of magnetic fields used in, for example, nuclear magnetic resonance (NMR) scanners, magnetic resonance imaging (MRI) scanners, fusion reactor toroidal or poloidal field magnets, central solenoid magnets, toroidal, solenoid, accelerator magnets, or racetrack coil magnets.

[0074] According to one embodiment, a method is presented in which a superconducting wire includes a reinforcing element, for example a reinforcing element made of Hastelloy and / or carbon fiber, and the reinforcing element is optionally embedded in a cap. The advantage of an improved strength of the resulting superconducting wire is considered. The reinforcing element may be a fibrous material (optionally with a diameter of 50 to 500 micrometers, for example 100 to 300 micrometers, for example 150 to 250 micrometers, for example substantially 200 micrometers). For example, Hastelloy fibers or carbon fibers are wound around one or more filaments, wound, optionally embedded in capping, optionally plated on capping, such as copper capping produced by copper plating.

[0075] According to one embodiment, the distance between the surface of the first side of the substrate, the plane parallel to the surface, the protruding portion, and the groove, and the surface in contact with the bottom of the plurality of grooves, for example, the depth of the groove measured in a direction perpendicular to the plane of the first side of the substrate, is at least 1 μm, for example, at least 10 μm, for example, at least 25 μm, for example, at least 50 μm, for example, at least 100 μm. By having the minimum distance (depth), the tolerance for subsequent removal of the substrate becomes correspondingly larger. As a result, the removal step is simplified and / or the risk of failure or damage to the remaining elements is reduced.

[0076] According to one embodiment, a method is presented for providing a substrate, which includes providing the substrate, for example, a tape, in a reel-to-reel configuration. A possible advantage is that large-scale processing becomes easier.

[0077] According to one embodiment, a method is presented for coating a substrate, which includes coating the substrate, such as a tape, in a reel-to-reel manner. A possible advantage is that large-scale processing becomes easier.

[0078] According to one embodiment, a method is presented for removing at least a part of the substrate from the second side of the substrate, which includes removing at least a part of the substrate, for example, a tape, from the second side of the substrate in a reel-to-reel manner (for example, removing it through any one or more of electrolytic polishing, etching, grinding, and / or laser). A possible advantage is that large-scale processing becomes easier.

[0079] According to a second aspect of the present invention, a plurality of filaments are presented, each filament being superconducting, such as high-temperature superconductivity (HTS), and each filament is not connected to one or more other filaments through a substrate, for example, each filament is physically separated from one or more other parts of the substrate (for example, when each filament constitutes a part of the substrate, for example, the (original) substrate).

[0080] According to another second aspect alternative to the second aspect of the present invention, a plurality of filaments are presented, each filament being superconducting, for example high-temperature superconducting (HTS), and each filament is not connected to one or more other filaments via a substrate, for example each filament is physically cut off from one or more other parts of the substrate.

[0081] According to one embodiment, a plurality of filaments are presented, and each filament constitutes a substrate. Thereby, there is a possibility of obtaining the advantage that the strength and / or robustness of the filament is improved. This can be utilized, for example, when the filament is integrated into a wire.

[0082] According to one embodiment, a plurality of filaments are presented, and the substrate is a solid element on which a superconducting material is disposed. For example, by being deposited, the substrate and the superconducting element together form a superconducting element.

[0083] According to one embodiment, a plurality of filaments are presented, and the solid element is made of a material selected from the group consisting of nickel-based alloys, copper-based alloys, chromium-based alloys, iron, aluminum, silicon, titanium, tungsten (also known as wolfram (W)), silver, Hastelloy, Inconel®, and stainless steel.

[0084] According to one embodiment, a plurality of filaments are presented, and each filament includes a rare earth barium copper oxide and is made of, for example, a superconducting material composed of a rare earth barium copper oxide.

[0085] According to one embodiment, a plurality of filaments are presented, and each filament includes a superconducting material such as a high-temperature superconducting (HTS) material, and further includes a part of the substrate adjacent to the superconducting material (for example, after the step of removing at least a part of the substrate from the second side of the substrate is completed), and optionally further includes a buffer layer and / or one or more metal layers (which can be regarded as forming a superconductor stack, for example an HTS stack together).

[0086] According to one embodiment, a plurality of filaments are presented, and each filament includes a superconducting material that partially or entirely covers each of two or more sides of a substrate, such that when each side is observed in a cross-sectional view orthogonal to the longitudinal direction of each filament, each side is non-parallel and orthogonal to at least one other side within the two or more sides. A possible advantage is that a larger area (not just the upper surface) of each filament is utilized for carrying the superconducting material, and as a result, each filament can carry more current.

[0087] According to one embodiment, each filament includes a superconducting material, and the angular range of the superconducting material observed in a cross-sectional view orthogonal to the longitudinal direction of each filament around the geometric center of the substrate is 90° or more, for example at least 135°, for example 180° or more, for example 181° or more, for example 185° or more, for example 190° or more, for example 200° or more, for example at least 225°, for example at least 270°, for example at least 315°. As an example, in the case of a filament having a two-dimensional cross-section where the superconducting material exists on only one side, the angular range is 90°. As another example, in the case of a filament having a circular cross-section where the superconducting material exists on only one side (for example, referring to the upper side, for example, the northern hemisphere in a cross-section passing through the center of the earth), the angular range is 180°. The advantage of a relatively large angular range is that a larger portion of the surface of the filament is utilized for carrying the superconducting material, and as a result, there is a possibility of carrying a larger current. In an embodiment, the angular range is less than 360° (for example, not completely surrounding, for example less than 355°).

[0088] According to one embodiment, a plurality of filaments with a substrate roll-processed are presented. Here, the substrate is a metal or a metal alloy, such as Hastelloy, stainless steel, an austenitic nickel-chromium-based superalloy, such as Inconel® or nickel tungsten. The advantages of a roll-processed metal or metal alloy, such as warm rolling or cold rolling, are, for example, having high strength against materials deposited by, for example, electron beam evaporation, thermal evaporation, sputter deposition, or electrochemical deposition, such as a metal or a metal alloy. In one embodiment, the substrate is annealed, such as by being heat-treated, after roll processing. The roll-processed (substrate) material has a characteristic grain structure observable by, for example, a scanning electron microscope (SEM).

[0089] According to one embodiment, a plurality of filaments are presented where the plurality of filaments are connected by a protective coating and the protective coating only partially covers each filament, for example, covers a superconducting coating but does not cover all of the remaining part of the filament. The advantages of having a protective coating are, for example, being able to protect a part of the filament, such as a superconducting coating, during storage and transportation. Another advantage is that the protective coating can hold the filaments together in a fixed spatial relationship and continue to control the relative spatial arrangement of the filaments.

[0090] According to one embodiment, the width, such as the maximum dimension in a direction orthogonal to the longitudinal direction of each filament and optionally further the maximum dimension in a direction parallel to the interface between the superconducting material and the substrate material, is 2 mm or less, for example 1 mm or less, for example 750 micrometers or less, for example 500 micrometers or less, 400 micrometers or less, 300 micrometers or less, 250 micrometers or less, 200 micrometers or less, 150 micrometers or less, 100 micrometers or less, etc. The advantage of a relatively narrow width is that a plurality of filamentary superconductors can be arranged in the superconducting structure, whereby the strength of the shielding magnetic field and / or the hysteresis energy loss (Q h) There may be a possibility of reducing or minimizing it. Also, there is an advantage that mechanical bending, such as applying torsion around the longitudinal axis of the filament, becomes easier as the width of the filament becomes narrower. The advantages of applying torsion include that in-plane bending is reduced, minimized, or zero compared to a wider filament (in-plane bending may generally have an adverse effect, such as reducing superconducting properties), enabling transposition. Another advantage is that the ratio of the metal cap per individual filament increases, improving thermal stability. Also, if the filament becomes smaller, there is an advantage that the amount of Joule heating decreases when a single filament breaks or fails.

[0091] It can be understood that the width of the filament is a dimension in a direction orthogonal to the longitudinal direction of each filament and parallel to the interface between the superconducting material and the substrate material.

[0092] According to one embodiment, the width, such as the maximum dimension in a direction orthogonal to the longitudinal direction of each filament, is 200 micrometers or less, for example 150 micrometers or less, for example 100 micrometers or less, for example 50 micrometers or less, for example 25 micrometers or less, for example 10 micrometers or less.

[0093] According to one embodiment, the width, which is the maximum dimension in a direction orthogonal to the longitudinal direction of each filament and optionally further the maximum dimension in a direction parallel to the interface between the superconducting material and the substrate material, is 1 micrometer or more, for example 10 micrometers or more, 100 micrometers or more, 200 micrometers or more, 500 micrometers or more, etc. This minimum width has the advantage of being advantageous for overcoming the problem that the grain size (for example, REBCO with a grain size of about 50 nm) becomes equal to the width. Another advantage is that current can be dissipated to surrounding materials such as the copper matrix.

[0094] According to one embodiment, the length of each filament, for example, the maximum dimension in the longitudinal direction of each filament, is 1 m or more, for example, 10 m or more, for example, 100 m or more, for example, 1 km or more, for example, 10 km or more, for example, 100 km or more, 1000 km or more, etc., and a plurality of filaments are presented. The length of each filament can be understood as the maximum dimension of the filament. The length can be understood as being measured along the filament and / or with respect to the configuration of the filament where the length is maximum (for example, the length of the filament is not the length or diameter of a coil composed of the wound filament, but the length of the unwound filament). In a specific embodiment, the length can be 1 m, for example, 100 m, for example, 1 km, for example, 20 km, for example, 100 km, for example, more than 100 km, for example, within 1 m to 30 km, for example, within 1 km to 30 km.

[0095] According to one embodiment, a plurality of filaments are presented in which the length of each filament, for example, the maximum dimension in the longitudinal direction of each filament, is 1 km or less, for example, 100 m or less, for example, 25 m or less, for example, 10 m or less.

[0096] Advantages of the relatively short length of the filament section include, for example, the ability to join short manufactured products of coated conductors such as HTS tapes with a width of 4 mm or 12 mm and a length of 100 m. The joint can span a length of several meters, such as 1 to 100 cm, for example 10 cm or 50 cm, or 1 to 10 m, for example 1 m or 5 m. The joint can be industrially manufactured by electroplating, such as copper plating, such as silver plating, or soldering, such as Sn soldering. The filaments can be mechanically twisted to form a transposed matrix, and then, for example, copper plating or soldering can be performed to adhere to the filaments. The longer the joint portion, the lower the electrical resistance of the entire joint. This solution generally solves the problems related to the joining of superconducting (SC) tapes such as high-temperature superconducting (HTS) tapes, which are usually soldered and joined only at a very short portion at the end of the tape. By using short pieces of superconductors such as HTS, it becomes possible to completely or partially overlap the joint portions over several meters, and the joint portion no longer becomes a so-called weak point. By using short pieces of HTS, the manufacturing of coated conductors is simplified and the performance of superconductors is improved. Because multifilaments can be interchanged over the entire length of superconducting wires and cables, when filaments with low, medium, or high performance such as Ic and Tc are evenly distributed, that is, when they are statistically evenly distributed over the entire length of the wire or cable, even if there are variations in the quality of individual filaments such as superconducting performance, by combining the fragments generated in the manufacturing process of superconducting wire materials, the manufacturing of coated conductors is simplified and superconducting performance can be exhibited over a wider range.

[0097] That is, multifilament transposed wires or cables can generally be manufactured to low HTS manufacturing standards, and by using HTS tapes from different vendors, advantages such as averaging the variations in superconducting performance levels over the entire wire can be obtained.

[0098] According to one embodiment, a plurality of filaments are presented, where the maximum dimension in a direction orthogonal to the longitudinal direction of each filament, and the thickness such as the maximum dimension in a direction optionally further orthogonal to the interface between the superconducting material and the substrate material, for example, when this dimension is orthogonal to one or both of the dimensions in which the width and length are measured, is at least 1 μm, for example at least 10 μm, for example at least 25 μm, for example at least 50 μm, for example at least 100 μm. It is at least 1 μm, for example at least 10 μm, for example at least 25 μm, for example at least 50 μm, for example at least 100 μm, for example at least 200 μm, for example at least 500 μm. Such dimensions have the advantage of obtaining strength and / or robustness. Such dimensions may be provided by a method with a corresponding depth of the groove and a first side having homogeneous etching. Alternatively, such dimensions may be provided by a method with a first side having spatially limited etching.

[0099] The thickness of the filament may be understood as the dimension in a direction orthogonal to the longitudinal direction of each filament and orthogonal to the interface between the superconducting material and the substrate material.

[0100] According to one embodiment, the engineering current density J of each filament at a temperature of 77 Kelvin and in a zero applied magnetic field E is at least 10 5 A / cm 2 , for example at least 3×10 5 A / cm 2 , for example at least 5×10 5 A / cm 2 , for example at least 10 6 A / cm 2 , for example at least 3×10 6 A / cm 2 , for example at least 10 7 A / cm 2and here, the engineering current density is defined as the current density of a cross-sectional area including the superconducting material, a substrate including a buffer layer or buffer stack and a stabilization layer when present, and each filament is optionally 500 micrometers or less, for example 400 micrometers or less, for example 300 micrometers or less, for example 250 micrometers or less, for example 200 micrometers or less, for example 150 micrometers or less, for example 100 micrometers or less. The "engineering current density" is as generally understood in the art.

[0101] An example of the width of the superconducting filament is 20 μm.

[0102] According to one embodiment, a plurality of filaments are presented in which the distance from an end such as the side surface of a filament in which the superconducting characteristics of the superconducting material have deteriorated into the filament, for example, the average distance, is 100 micrometers or less, for example 50 micrometers or less, for example 25 micrometers or less, for example 20 micrometers or less, for example 15 micrometers or less, for example 10 micrometers or less, for example 1 micrometer or less. "Deterioration" means a change in characteristics that adversely affects superconducting characteristics such as peeling, phase change and / or cracking. This distance can be observed and measured, for example, from a scanning electron microscope (SEM) image, for example, one obtained from above the superconducting coating portion, or a cross-sectional image obtained from a cross-sectional plane orthogonal to the longitudinal direction of the filament. An advantage is that a relatively high engineering current density can be maintained even if the deterioration distance is relatively small.

[0103] It is considered advantageous that there are no cracks or as few as possible. This is because if there are cracks, the coating may break, such as when the coating is composed of a high-temperature superconducting (HTS) layer.

[0104] According to one embodiment, a ratio t / w of the thickness t of a substrate adjacent to a superconducting material (the thickness is measured in a direction orthogonal to the longitudinal direction and a direction orthogonal to the interface between the superconducting coating and the substrate) to the width w (the width is in a direction orthogonal to the longitudinal direction, a direction orthogonal to the thickness direction, and / or a direction orthogonal to the interface between the superconducting material and the substrate material) is at most 20:1 or less, for example 10:1 or less, for example 5:1 or less, for example 2:1 or less, and a plurality of filaments are shown. For example, since a lower ratio makes it easier to integrate the filaments into the superconducting structure, it is advantageous for the ratio t / w of the thickness to the width to be relatively low.

[0105] According to a third aspect of the present invention, it is proposed to use a plurality of filaments provided according to the first aspect and / or the second aspect for passing an electric current. For example, it is for conduction of an electric current in a superconducting state and the like.

[0106] According to a fourth aspect of the present invention, a wire (such as a cable composed of a plurality of wires) such as a power cable (a cable capable of transmitting power at at least 10 kV and / or capable of transmitting a current of at least 100 amperes) composed of a plurality of filaments provided according to the first aspect and / or the second aspect is proposed. "Cable" means a conductive structure including a plurality of wires, and the wires are twisted around their own axis and / or a common axis. The length of the cable may be at least 0.1 m, for example at least 1 m, for example at least 10 m, for example at least 100 m, for example at least 1000 m. The cable may include at least 5 filaments, for example at least 10 filaments, for example at least 100 filaments, for example at least 500 filaments, for example at least 1000 filaments, for example at least 10000 filaments.

[0107] According to an alternative according to a further aspect of the present invention, there is provided a coil, an electric generator, a transformer, a nuclear magnetic resonance (NMR) scanner, a magnetic resonance imaging scanner, a nuclear fusion reactor poloidal or toroidal magnetic field magnet, a central column solenoid magnet, a toroidal, solenoid, accelerator magnet, or a racetrack coil magnet, comprising a plurality of filaments provided according to the first corresponding and / or second aspect.

Brief Description of the Drawings

[0108] Hereinafter, with reference to the accompanying drawings, the first, second, and third aspects according to the present invention will be described in more detail. The figures are illustrative of one way of implementing the invention and should not be construed as limiting other possible embodiments that fall within the scope recited in the appended claims.

[0109]

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DETAILED DESCRIPTION OF THE INVENTION

[0110] FIG. 1 is a flowchart showing a method according to an embodiment of the present invention. The method is Method 100 which forms a plurality of filaments where each filament is superconducting such as high temperature superconducting (HTS), and further forms a superconducting structure to provide a superconducting wire. The method sequentially includes the following. · Step 102 of providing a substrate which is a planar metal substrate, the substrate having a first side and a second side, the first side facing the second side, and the step of providing the substrate is as follows: i. Providing a substrate without grooves on the first side of the substrate, ii. Forming a plurality of grooves on the first side of the substrate 104, and, iii. Perform via etching and / or electrolytic polishing to form one or more undercuts in each groove, optionally in a two-step undercut process (2LUPS) (note that alternative embodiments are also conceivable. For example, embodiments that are similar to this embodiment in other respects but have no or no formed undercuts), A process including, · Step 108 of coating the substrate, where the coating includes a high-temperature superconductor stack, and each groove in the plurality of grooves, i. A first portion of the coating on the first side of a feature such as a groove, ii. A second portion of the coating on the second side of a feature such as a groove, where the second side of the feature such as a groove is on the opposite side of the first side of the feature such as a groove, from the second portion of the coating on the second side, Step 108 of being physically separated, such as being cut, etc., · Step 110 of applying a protective coating such as a resist on a part or all of the first portion of the coating and a part or all of the second portion of the coating, for example on the first portion and / or the second portion of the coating, where the protective coating partially or entirely fills the voids in the grooves, · Step 112 of removing at least a part of the substrate from the second side of the substrate by electrolytic polishing and / or etching, and removing at least the connection from the first portion of the coating to the second portion of the coating through the substrate to provide, for example, a plurality of filaments, where, for example, the part of the substrate that previously joined the filaments is removed, · Step 114 of stopping the removal of at least a part from the second side of the substrate while each part of the coating, for example the first portion and the second portion of the coating, is adjacent to the remaining part of the substrate, · Step 116 of partially or entirely removing the protective cover from a part or all of the coating and the remaining part of the substrate, for example removing at least the connecting part between the first portion and the second portion of the coating through the protective cover, ·Step 118 of twisting a plurality of filaments, or a multiplicity of plural filaments, where each filament is twisted around its own axis and / or the plural filaments are twisted around their common axis, for example, an arbitrarily twisted bundle of arbitrarily twisted filaments that are optionally twisted together are twisted together, thereby providing one or more superconducting structures including a plurality of twisted filaments, for example, Step 118 where each filament has a spiral shape with a central axis within one or more other spiral filaments. ·Step 120 of forming a superconducting wire by providing one or more superconducting structures with cores and caps.

[0111] Figures 2 - 7 are schematic diagrams showing the steps of a method according to an embodiment of the present invention. The method is Method 100, which forms a plurality of filaments where each filament is a superconductor such as a high-temperature superconductor (HTS), further forms a superconducting structure, and provides a superconducting wire.

[0112] Figure 2 shows, at 102, that the substrate 228 is a planar metal substrate without grooves on the first side. The substrate has a first side 231 and a second side 232. For example, the first side faces the second side.

[0113] Figure 3 shows the substrate 230 after Step 104 of forming a plurality of grooves 234 on the first side of the substrate and after Step 106 of forming one or more undercuts 236 in each groove (indicated by the dashed lines separating the shaded undercut portions of each groove).

[0114] FIG. 3 also shows the dimensions of the groove 234. In FIG. 3, the distance 223a between a plane parallel to the upper surface (shown by the upper horizontal broken line) of the first side surface of the substrate (in the figure), for example, the plane in contact with the protrusion between the grooves, the plane (shown by the lower horizontal broken line), and the plane in contact with the bottom of the plurality of grooves, that is, the depth of the groove measured in the direction perpendicular to the plane of the first side surface of the substrate (that is, the depth measured in the vertical / up-and-down direction of the paper of the figure) is shown. The distance 233a or the depth is not zero, for example, at least 100 nm, for example, at least 1 μm, for example, at least 10 μm, for example, at least 25 μm, for example, at least 50 μm, for example, at least 100 μm. The distance 233a or the depth may be further at most 4 mm, at most 2 mm, at most 1 mm. The distance 233a or the depth may be within ]10 nm; 4 mm[, for example, ]1 μm; 2 mm[, for example, ]10 μm; 1 mm[ (the parentheses "]x; y[" indicate that neither x nor y is included in the interval, but all numerical values between them are included). Further, the dimension or width 233b of the groove, that is, the distance from the end of the protrusion on one side of the groove (for example, the end of the end such as the end of the flat portion of the substrate outside the groove) to the end of the protrusion on the other side of the groove measured in the direction perpendicular to the plane of the first side surface of the substrate (that is, the distance measured in the horizontal and left-right directions of the paper of the figure) is shown. The dimension or width 233b may be at least 1 μm, for example, at least 2 μm, for example, at least 5 μm, for example, at least 10 μm, for example, at least 30 μm, for example, at least 100 μm, for example, at least 200 μm. The dimension or width 233b may be at most 1 mm, for example, at most 500 μm, for example, at most 200 μm, for example, at most 100 μm. The dimension or width 233b may be in the range of 1 μm to 1 mm, for example, 10 μm to 500 μm. FIG. 3 further shows the distance 233c between adjacent grooves, and this distance is measured in the same direction as the width 233b. The distance 233c may be at least 100 μm. The distance 233c may be at most 2 mm. The distance 233c may be within ]100 μm; 2 mm[, for example, ]200 μm; 1 mm[.

[0115] FIG. 4 shows the state after step 108 of applying a coating 238 consisting of a high-temperature superconductor stack to the substrate 230. For each of the plurality of grooves, a first portion of the coating on the first side of the groove is physically separated from a second portion of the coating on the second side of the groove. Here, the second side of the groove feature is on the opposite side of the first side of the groove feature. Further, a part of the coating material is found in the groove.

[0116] FIG. 5 shows step 110 of applying a protective coating 240, which is a resist, to the substrate on a part or all of the first portion of the coating and a part or all of the second portion of the coating, for example, on the first portion and / or the second portion of the coating. Here, the protective coating partially or entirely fills the voids in the grooves.

[0117] FIG. 6 shows a plurality of filaments 242 (the substrate 230 is no longer present, and the dotted rectangle 244 indicates the position previously occupied by the substrate 230) after step 112 of removing the substrate from the second side. By electropolishing and / or etching at least a part of the substrate, at least the connection from the first portion of the coating to the second portion of the coating through the substrate is removed. For example, a part of the substrate that previously joined the filaments is removed, for example, through a superconducting coating, so as to provide a plurality of filaments 242 where each filament is superconducting. FIG. 6 also shows the result of step 114 of stopping the removal from the second side of the substrate at least on a part of the substrate with each part of the coating, for example, the first portion and the second portion of the coating, adjacent to the remaining part 246 of the substrate.

[0118] FIG. 7 shows a plurality of filaments 242 after step 116 of partially or completely removing the protective coating 240 from a part or all of the coating and the remaining part of the substrate. For example, at least the connection from the first portion of the coating to the second portion of the coating through the protective coating is removed. FIG. 7 also shows the width 248 and thickness 250 of the filaments. The length is a dimension orthogonal to the plane of the paper.

[0119] FIG. 8 shows a plurality of groups of filaments, each filament being twisted around its own axis, and the plurality of filaments within each group of filaments being twisted around their common axis, thereby providing a plurality of superconducting structures 256. Each filament is helical, and these superconducting structures are provided in a superconducting wire 252 having a core 254 and a cap 258.

Example

[0120] Example According to one embodiment, a method of forming a plurality of filaments is presented, each filament being a superconductor, and the method includes steps 1-9, which are described in detail below and schematically shown in FIG. 9.

[0121] In steps 1-5, a substrate including a plurality of grooves is provided, and in steps 2-5, a plurality of grooves are formed on a first side of the substrate (such as the overside, topside, or front side), where the first side is opposite to a second side such as the underside, bottom side, or back side.

[0122] Step 1: Start with a polished Hastelloy tape that is 4 mm wide, 100 μm thick, and 50 m long, and has no grooves with a surface roughness of 10 nm or less (where the surface roughness is the arithmetic surface roughness value in an atomic force microscope scan of 10×10 μm 2 ). This surface quality is suitable for coated conductor (CC) chemical vapor deposition (CVD) / metalorganic chemical vapor deposition (MOCVD), physical vapor deposition (PVD), or chemical vapor deposition of buffer layers and superconducting layers. Polishing can be performed by electrochemically polishing in a mixed solution of phosphoric acid and sulfuric acid according to standard procedures described in the literature. See, for example, page 2, section 2 of Wulff et al. 2015, Supercond. Sci. Technol. 28 (2015) 072001.

[0123] Sub - figure (a) of FIG. 9 shows a cross - sectional view of the tape in a plane orthogonal to the longitudinal direction of the tape.

[0124] Step 2: Apply a masking material as described in section 2, page 2 of Wulff et al., 2015, Supercond. Sci. Technol. 28 (2015) 072001.

[0125] This is, for example, a Kapton® film, a photoresist, or a similar masking tape. It is understood that "Kapton® film" refers to the well - known product of DuPont® which is a film of poly(4,4'-oxydiphenylene - pyromellitimide).

[0126] Sub - figure (b) of FIG. 9 shows a cross - sectional view of the tape in a plane orthogonal to the longitudinal direction of the tape with the masking material applied.

[0127] Step 3: Remove a part of the masking material by mechanical scribing, wet / dry chemical lithography process, or laser scribing. Here, standard lithography steps are used to completely remove the masking material in the area where the grooves are to be etched.

[0128] Sub - figure (c) of FIG. 9 shows a cross - sectional view of the tape in a plane orthogonal to the longitudinal direction of the tape with a part of the masking material removed.

[0129] Step 4: Etch the substrate using a mixture of phosphorus and sulfuric acid while applying a current density of 0.01 - 1 A / cm 2 until grooves are formed.

[0130] Sub - figure (d) of FIG. 9 shows a cross - sectional view of the tape in a plane orthogonal to the longitudinal direction of the tape with grooves formed by etching.

[0131] Step 5: Remove the masking material using a release agent such as an organic solvent (e.g., acetone) or sodium hydroxide.

[0132] A coating (coated conductor (CC) stack) that is a high-temperature superconductor stack is applied to a substrate. For each of the plurality of grooves, while the first portion of the coating on the first side of the groove remains physically connected (e.g., as depicted in FIG. 9(e), separated but still physically connected), the first portion of the coating on the first side of the groove is separated from the second portion of the coating on the second side of the groove.

[0133] Step 6: Deposit a superconducting coated conductor (CC) stack on the material. See, for example, page 2, section 2 of Wulff et al 2015, Supercond. Sci. Technol. 28 (2015) 072001, or page 2, section 2 of Insinga et al 2018, IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 28, NO. 4, JUNE 2018.

[0134] Subfigure (e) of FIG. 9 shows a cross-sectional view of the tape in a plane perpendicular to the longitudinal direction of the tape, where the remaining portion of the masking material has been removed and the superconducting CC stack has been deposited on the tape.

[0135] In step 7, a protective cover (protective material) that partially or entirely fills the voids in the grooves is applied to a part or all of the first portion of the coating and a part or all of the second portion of the coating.

[0136] Step 7: Apply a protective material such as a liquid photoresist to cover the tape and the top of the CC stack (and in this embodiment also the sides, avoiding etching of the sides of the substrate and / or the sides of the outer CC stack) to protect the superconducting stack. Also cover the trenches, either completely or partially, with the protective material. The protective material can be applied in several ways. For example, a liquid photoresist applied by inkjet (e.g., while firmly pressing the opposite side of the tape against the solid element so that the photoresist does not adhere to the opposite side), a brush, or dip coating (e.g., temporarily covering the opposite side of the tape with Scotch tape (registered trademark) and then dip coating).

[0137] Sub - figure (f) of FIG. 9 shows a cross - sectional view of the tape in a plane perpendicular to the longitudinal direction of the tape to which the protective material has been applied.

[0138] From the second side (e.g., the back or bottom surface) of the substrate, remove at least a part of the substrate by etching such as electrochemical etching or electrolytic polishing, and through the substrate, remove at least a part of the connection from the first part of the coating to the second part of the coating, for example, by providing a plurality of filaments, such that the part where the filaments of the substrate were joined is removed in Step 8.

[0139] Step 8: Etch from the back surface of the tape structure using a mixture of phosphorus and sulfuric acid. The etching can continue until they are only physically connected through the protective material.

[0140] Sub - figure (g) of FIG. 9 shows a cross - sectional view of the resulting plurality of filaments connected in a plane perpendicular to the longitudinal direction of the plurality of filaments by the protective coating after a part of the substrate has been removed from the back surface (the same figure as sub - figure (g) of FIG. 9).

[0141] The protective coating is partially or completely removed from part or all of the coating and the remaining part of the substrate, for example, by removing at least the connection from the first part of the coating to the second part of the coating through the protective coating, which is performed in step 9.

[0142] Step 9: The protective material is removed by mechanically peeling the material or dissolving it in an organic solvent such as ethanol or acetone, or a stripping solvent such as sodium hydroxide.

[0143] Sub - figure (h) of FIG. 9 shows a cross - sectional view of the resulting plurality of filaments, showing a state where they are no longer connected by the protective coating, that is, the state after the protective coating has been removed, in a plane perpendicular to the longitudinal direction of the plurality of filaments.

[0144] FIG. 10 shows a state where a CC stack 1038 (without undercut) is formed on a Hastelloy substrate 1030 in which grooves are formed by the 2LUPS process. FIG. 10 can be regarded as corresponding to the schematic diagram of FIG. 4 and / or sub - figure (e) of FIG. 9.

[0145] FIG. 11 shows an enlarged view of FIG. 10.

[0146] FIG. 12 shows a single filament 1242 cut out by etching, and also shows the remaining part 1246 of the substrate. Here, the width (i.e., the dimension in the left - right direction in the plane of the paper, i.e., about 500 μm) represents a filament 1242 about 500 mm wide having a CC stack. The thickness of the filament (the dimension in the up - down direction in the plane of the paper) is about 80 μm. FIG. 12 can be regarded as corresponding to the schematic diagram of FIG. 7 and / or sub - figure (h) of FIG. 9.

[0147] Figure 13 shows an I / V setup for characterizing the superconducting performance of filament 1342 in liquid nitrogen, including current leads 1360 and voltage taps 1362. The dimensions can be obtained from scale 1364 (the numbers are in centimeters, and the distance between adjacent small linear markings is 1 mm). Washer 1366 is substantially circular, indicating that the scale markings of the ruler apply both horizontally and vertically.

[0148] Figure 14 shows the I / V setup of Figure 13 immersed in liquid nitrogen. When a test was conducted where the filament was immersed in liquid nitrogen and the current was gradually increased while measuring the voltage drop between the contacts, no transition to normal conduction was observed at 3 A or above at zero applied magnetic field and 77 K. The width of the substrate and CC stack is estimated to be 500 μm, and the total thickness is estimated to be 80 μm. The engineering current density at zero applied magnetic field and 77 K is 9375 A / cm 2 and is estimated to be. For the reference coating conductor sample, the average Ic value at zero applied magnetic field of a 4 mm-wide tape at 77 K, which indicates that the predicted Ic value of a 500-μm-wide filament is 12 A or more, was recorded as 97 A. The engineering current density may be improved by at least 3 to 5 times by changing the superconducting material to another one. Furthermore, by reducing the thickness of the substrate, it may be possible to achieve a value of at least twice. For example, by continuing the etching to remove the substrate from the back surface for a longer time (e.g., making the substrate less than half of the current substrate thickness), reducing the thickness of the substrate by leaving a small amount (about 4 μm) of the substrate, or estimating the situation where the substrate is completely etched, a factor of about 20 can be obtained. Considering both the improvement of the material and the thinning of the substrate, the engineering current density may reach about 1.8 MA / cm 2 at zero magnetic field and 77 K. Also, at lower operating temperatures such as 50 K, 30 K, 20 K, 4.2 K, etc., even higher current densities are expected. On the other hand, as the applied magnetic field increases, a lower current density is expected.

[0149] Figure 15 shows a scanning electron microscope (SEM) image of a 3D-etched Hastelloy substrate (viewpoint from a direction perpendicular to the flat surface of the tape). Figure 15 corresponds to the schematic diagram of Figure 3 (excluding undercuts) and / or the subfigure (d) of Figure 9 (excluding the remaining masking material).

[0150] Figure 16 shows a scanning electron microscope image (perspective view) of a Hastelloy substrate that has been subjected to 3D etching and focused ion beam processing. This figure shows a protrusion (or an elongated "hill") formed between two grooves (on the left and right sides of the protrusion), and the width of the protrusion (in the left-right direction of the paper) is approximately 18 μm. Figure 16 (excluding the cut-out part by focused ion beam processing) corresponds to the schematic diagram of Figure 3 (excluding undercuts) and / or the subfigure (d) of Figure 9 (excluding the remaining masking material).

[0151] Figure 17 shows a scanning electron microscope image of a focused ion beam processed 3D-etched haloteroi substrate with a CC stack where substrate 1771 is Hastelloy C276, buffer layer 1772 with a thickness of 1 - 2 mm is yttria-stabilized zirconia (YSZ) with 50 nm cerium oxide (Wulff et al. 2015, Supercond. Sci. Technol. 28 (2015) 072001), yttrium-barium-copper oxide (YBCO) layer 1773 with a thickness of 1 - 2 μm, and silver layer 1774 with a thickness of 1 - 2 μm. All thicknesses refer to the vertical / up-down dimension in the figure, i.e., the dimension in the direction perpendicular to the plane of each layer. The width of the superconducting filament is approximately 25 μm. Figure 17 corresponds to the schematic diagram of Figure 4 (excluding undercuts) and / or the subfigure (e) of Figure 9.

[0152] Figure 18 shows a collage of two images of filaments (the filament in the right image is held by a human finger), and in a plane perpendicular to the longitudinal direction of the substrate, the substrate is etched from the back surface to remove the connections between the filaments passing through the substrate. The length of the filament, for example the length of the free part of the filament, extends to several centimeters. The (complete) width of the substrate is 4 mm (for example, the complete width shown vertically in the upper right corner of the left sub - figure).

[0153] Figure 19 shows the result of twisting a plurality of filaments. The plurality of filaments are twisted around their common axis, and each filament is thereby also twisted around its own axis. As a result, each filament is twisted around its own axis (by an angular amount corresponding to the twisting of the plurality of filaments), and a structure is provided that includes a plurality of twisted filaments having a helical shape with a central axis within one or more other helical filaments. A wire is provided by providing a core. Kapton (registered trademark) tape is provided at each end, and the distance between the Kapton (registered trademark) tapes is 5 cm.

[0154] The present invention has been described in connection with specific embodiments, but should not be construed as limited to the examples presented. The scope of the present invention is defined by the appended claims. In the context of the claims, the terms "comprising" or "including" do not exclude other possible elements or steps. Also, references such as "a" or "an" should not be construed as excluding a plurality. The use of reference numerals in the claims regarding the elements shown in the figures should not be construed as limiting the scope of the invention. Furthermore, the individual features recited in different claims may be advantageously combined, and the fact that these features are recited in different claims does not exclude the possibility and advantage of combining the features.

[0155] Clause Furthermore, methods of forming a plurality of filaments, a plurality of filaments, and uses of a plurality of filaments according to the following clauses are presented. These clauses can be combined with any of the foregoing embodiments and / or the appended claims.

[0156] 1. A method (100) of forming a plurality of filaments (242), wherein each filament is a superconductor, such as a high-temperature superconductor (HTS), the method comprising, for example, the following steps: · A step (102) of providing a substrate (230), the substrate comprising a metal, such as a substrate that is a planar metal substrate, having a first side (231) and a second side (232), such as a substrate where the first side is on the opposite side of the second side, and providing a substrate where the substrate includes a plurality of grooves (234) on the first side of the substrate: · A step (108) of applying a coating (238) to the substrate, the coating comprising a superconducting material, such as the coating being a high-temperature superconductor stack, and each groove within the plurality of grooves i. A first portion of the coating on the first side of a feature such as a groove ii. A second portion of the coating on the second side of a feature such as a groove, where the second side of the feature such as a groove is on the opposite side of the first side of the feature such as a groove, from being separated, such as being physically cut, such as being cut, etc. · Removing at least a part of the substrate from the second side of the substrate, such as via electropolishing and / or etching, etc., removing at least the connection from the first portion of the coating through the substrate to the second portion of the coating, so as to provide a plurality of filaments, such as making it such that the portion of the substrate that previously joined the filaments is removed, the method (100) comprising.

[0157] 2. The method (100) according to any of the foregoing clauses, further comprising the following steps before removing at least a part from the second side of the substrate: · Applying a protective coating layer (240), such as a resist, to part or all of the first part of the coating and part or all of the second part of the coating (238), for example, the step of the protective coating layer partially or entirely filling the voids in the grooves, is included in the method (100).

[0158] 3. The method (100) according to any of the preceding clauses, wherein the step of removing at least a part of the substrate from the second side surface (232) of the substrate (230) is carried out via electropolishing and / or etching, for example, electrolytic etching.

[0159] 4. The method (100) according to any of the preceding items, wherein the step of removing at least a part of the substrate from the second side surface, such as electropolishing and / or etching, is a step that is stopped (114) while each part of the coating, for example, the first part of the coating and the second part of the coating, is adjacent to the remaining part (246) of the substrate.

[0160] 5. The method (100) according to any of the preceding clauses, wherein the method further includes the following steps: · Twisting (118) a plurality of filaments (242), or a plurality of multiple filaments, wherein each filament is twisted around its own axis and / or the plurality of filaments are twisted around their common axis, for example, optionally, bundles of twisted filaments are twisted together with each other, thereby providing one or more superconducting structures (256), each of which includes a plurality of twisted filaments. For example, each filament has a spiral shape having a central axis within one or more other spiral filaments, and / or · Providing one or more superconducting structures (256) consisting of a plurality of transposed filaments by transposing a plurality of filaments (242) or a plurality of multiple filaments is included in the method (100).

[0161] 6. The method (100) according to item 5, wherein the method further comprises the following steps: · Forming (120) a superconducting wire (252) by providing one or more superconducting structures (256) comprising a core (254) and / or a cap (258).

[0162] 7. A plurality of filaments (242), each filament being a superconductor, such as a high-temperature superconductor (HTS), and each filament not being connected to one or more other filaments via a substrate, for example, each filament being physically separated from one or more other parts of the substrate.

[0163] 8. The plurality of filaments according to item 7, each filament being made of a superconducting material, such as a high-temperature superconducting (HTS) material, and further comprising a part of the substrate adjacent to the superconducting material.

[0164] 9. The plurality of filaments (242) according to any one of items 7 to 8, wherein the substrate is a metal or a metal alloy, such as an austenitic nickel-chromium-based superalloy like Hastelloy, stainless steel, Inconel®, or a rolled product like nickel-tungsten.

[0165] 10. The plurality of filaments (242) according to any one of items 7 to 9, wherein the plurality of filaments are connected by a protective coating (240), and the protective coating only partially covers each filament.

[0166] 11. A plurality of filaments (242) as described in any one of clauses 7 to 10, wherein the maximum dimension in a direction orthogonal to the longitudinal direction of each filament, and optionally further the width (248) which is a dimension parallel to the interface between the superconducting material and the substrate material, is 200 micrometers or less, for example 150 micrometers or less, for example 100 micrometers or less, for example 50 micrometers or less, for example 25 micrometers or less, for example 10 micrometers or less.

[0167] 12. A plurality of filaments (242) as described in any one of clauses 7 to 11, wherein the length of each filament, for example the maximum dimension in the longitudinal direction of each filament, is 1 m or more, for example 10 m or more, 100 m or more, 1 km or more, 10 km or more, 100 km or more, 1000 km or more.

[0168] 13. A plurality of filaments (242) as described in any one of clauses 7 to 12, wherein the engineering current density J of each filament at a temperature of 77 Kelvin and in a zero applied magnetic field E is at least 10 3 A / cm 2 , for example at least 3×10 3 A / cm 2 , for example at least 10 4 A / cm 2 , for example at least 18750 A / cm 2 , at least 3×10 4 A / cm 2 , at least 10 5 A / cm 2 , at least 3×10 5 A / cm 2 , at least 5×10 5 A / cm 2 , at least 10 6 A / cm 2 , at least 3×10 6 A / cm 2 , at least 10 7 A / cm 2, here, the engineering current density is defined as the current density in a cross-sectional area including a superconducting material and a substrate including a buffer layer or a buffer stack and a stabilization layer when present, and each filament optionally has a width of 500 micrometers or less, for example 400 micrometers or less.

[0169] 14. A plurality of filaments (242) according to any one of clauses 7 to 13, wherein the distance from an end such as the side surface of the filament into the filament, for example the average distance, is 100 micrometers or less, for example 50 micrometers or less, for example 25 micrometers or less, for example 20 micrometers or less, for example 15 micrometers or less, for example 10 micrometers or less, for example 5 micrometers or less in a portion where the superconducting characteristics of the superconducting material are deteriorated.

[0170] 15. A method of passing an electric current using a plurality of filaments (242) provided according to any one of clauses 1 to 6 and / or according to any one of clauses 7 to 14, for example a method of passing an electric current under superconducting conditions.

Claims

1. A method (100) for forming multiple filaments (242), wherein each filament is a superconductor, for example, a high-temperature superconductor (HTS), comprises the following steps: - A step (102) of providing a substrate (230), wherein the substrate is a substrate containing metal, for example, the substrate is a planar metal substrate, the substrate has a first side surface (231) and a second side surface (232), for example, the first side surface is on the opposite side from the second side surface, and the substrate has a plurality of grooves (234) on the first side surface of the substrate. - A step (108) of applying a coating (238) to a substrate, wherein the coating includes a superconducting material, for example the coating is a high-temperature superconductor stack, and for each groove in a plurality of grooves, i. The first portion of the coating on the first side surface of the groove or other feature is ii. A second portion of the coating on the second side surface of a feature such as a groove, wherein the second side surface of the feature such as a groove extends from the second portion opposite to the first side surface of the feature such as a groove. For example, a process of separation by cutting, such as by physical cutting, - A process in which at least a portion of the substrate is removed from a second side of the substrate by electrolytic polishing and / or etching, etc., thereby removing at least the connection from a first portion of the coating to a second portion of the coating via the substrate, thereby providing multiple filaments, for example, a portion of the substrate to which the filaments were previously joined has been removed. A method (100) that sequentially includes the following.

2. Before removing at least a portion from the second side of the substrate, the following steps are taken: The method according to claim 1 (100), comprising the step (110) of applying a protective coating layer (240) such as a resist to part or all of a first portion of a coating and part or all of a second portion of a coating (238), for example, the first portion and / or second portion of a coating, such that the protective coating layer partially or completely fills the voids in the grooves.

3. The method according to claim 1 or 2 (100), wherein the step of removing at least a portion of the substrate from a second side surface (232) of the substrate (230) is carried out by electropolishing and / or etching, for example, by electrolytic etching.

4. The method according to claim 3 (100), wherein the electrolytic polishing and / or etching is stopped before the liquid used for electrolytic polishing and / or etching reaches a first portion and / or a second portion of the coating.

5. The method according to claim 1 or 2 (100), wherein the step of removing at least a portion of the substrate from a second side surface (232) of the substrate (230) is carried out by grinding and / or laser.

6. The method according to claim 1 or 2 (100), wherein the removal of at least a portion from a second side of the substrate, e.g., electropolishing and / or etching, is stopped (114) while each portion of the coating, e.g., a first portion and a second portion of the coating, are adjacent to the rest of the substrate (246).

7. Furthermore, the following steps: - A step of twisting together (118) multiple filaments (242) or multiple filaments, wherein each filament is twisted around its own axis, and / or multiple filaments are twisted around their common axis, for example, bundles of optionally twisted filaments are twisted around each other, thereby providing one or more superconducting structures (256) each comprising multiple twisted filaments, for example, each filament having a spiral shape with a central axis in one or more other spiral filaments, and / or - A step of transposing multiple filaments (242), or thereby providing one or more superconducting structures (256) each containing multiple transposed filaments. The method according to claim 1 or 2 (100), comprising:

8. Furthermore, the following steps: The method (100) of claim 1 or 2, comprising the step of (120) forming a superconducting wire (252) by providing one or more superconducting structures (256) having a core (254) and / or a cap (258).

9. The method according to claim 1 or 2 (100), wherein the distance (223a) between a surface parallel to the surface of the first side surface of the substrate, for example, a surface in contact with the protrusions between the grooves (234), and a surface in contact with the bottom surfaces of the plurality of grooves, for example, the groove depth measured in a direction perpendicular to the surface of the first side surface of the substrate is at least 1 μm, for example at least 10 μm, for example at least 25 μm, for example at least 50 μm.

10. The method according to claim 1 or 2 (100), wherein the step (102) of providing the substrate (230) includes the step of providing a tape-like substrate in a reel-to-reel manner.

11. The method according to claim 1 or 2 (100), which includes the step of applying a coating (238) to a substrate (108) in a reel-to-reel manner to a substrate such as a tape.

12. The method according to claim 1 or 2 (100), wherein the step of removing at least a portion from the second side surface of the substrate (112) is a reel-to-reel method, and the step of removing at least a portion from the second side surface of a substrate such as a tape (112).

13. The method according to claim 1 or 2 (100), wherein each of the multiple grooves includes one or more undercuts.

14. moreover, - A process of forming one or more undercuts in each groove by etching, etc. The method according to claim 1 or 2 (100), comprising:

15. Multiple filaments (242), each filament being a superconductor such as high-temperature superconductor (HTS), and each filament not connected to one or more other filaments via a substrate, for example, each filament being physically separated from one or more other parts of the substrate.

16. Multiple filaments (242), each filament being a superconductor such as high-temperature superconductor (HTS), and each filament not connected to one or more other filaments via a substrate, for example, each filament being physically separated from one or more other parts of the substrate.

17. A plurality of filaments according to claim 15 or 16, each filament including a substrate.

18. The substrate is a solid element on which a superconducting material is disposed, for example, by vapor deposition, and the substrate and the superconducting element together form a superconducting element, according to claim 15 or 16.

19. The plurality of filaments according to claim 18, wherein the solid element is composed of a material selected from the group including nickel alloys, copper alloys, chromium alloys, iron, aluminum, silicon, titanium, tungsten (also known as Wolfram (W)), silver, Hastelloy, Inconel (registered trademark), and stainless steel.

20. The plurality of filaments according to claim 15 or 16, each filament comprising a superconducting material, for example, a rare-earth barium copper oxide.

21. The plurality of filaments according to claim 15 or 16, each filament comprising a superconducting material, such as a high-temperature superconducting (HTS) material, and further comprising a portion of a substrate adjacent to the superconducting material.

22. The plurality of filaments (242) according to claim 21, each filament comprises a superconducting material that partially or completely covers two or more sides of a substrate, each of which sides is nonparallel and, for example, perpendicular to at least one other side of the two or more sides when viewed in a cross section perpendicular to the longitudinal direction of each filament.

23. The plurality of filaments (242) according to claim 21, wherein, when observed in a cross-section perpendicular to the longitudinal direction of each filament around the geometric center of the substrate, the angular range of the superconducting material is 90° or more, for example, 180° or more.

24. The plurality of filaments (242) according to claim 15 or 16, wherein the substrate is, for example, a metal or metal alloy, such as an austenitic nickel-chromium superalloy such as Hastelloy, stainless steel, Inconel (registered trademark), or nickel-tungsten, which has been rolled.

25. Multiple filaments (242) according to claim 15 or 16, wherein multiple filaments are connected by a protective cover (240), and the protective cover partially covers each filament.

26. For example, the plurality of filaments (242) according to claim 15 or 16, wherein the maximum dimension of each filament in a direction perpendicular to the longitudinal direction of each filament, and optionally further parallel to the interface between the superconducting material and the substrate material, is 200 micrometers, for example 150 micrometers or less, for example 100 micrometers or less, for example 50 micrometers or less, for example 25 micrometers or less, for example 10 micrometers or less.

27. For example, the plurality of filaments (242) according to claim 15 or 16, wherein the maximum dimension of each filament in a direction perpendicular to the longitudinal direction of each filament, and optionally further parallel to the interface between the superconducting material and the substrate material, is 1 micrometer or more, for example 10 μm or more, for example 25 μm or more, for example 50 μm or more, for example 100 μm or more, for example at least 200 μm, for example at least 500 μm.

28. For example, the maximum length of each filament in the longitudinal direction is 1 m or more, for example 10 m or more, for example 100 m or more, for example 1 km or more, for example 10 km or more, for example 100 km or more, for example 1000 km or more, for example 1000 km or more, according to claim 15 or 16 (242).

29. For example, the plurality of filaments (242) according to claim 15 or 16, wherein the maximum dimension in the direction perpendicular to the longitudinal direction of each filament, and optionally further, the thickness perpendicular to the interface between the superconducting material and the substrate material, for example, the dimension perpendicular to one or both of the dimensions of width and length measured along it, is at least 1 μm, for example at least 10 μm, for example at least 25 μm, for example at least 50 μm, for example at least 100 μm, for example at least 200 μm, for example at least 500 μm.

30. The engineering current density J of each filament at a temperature of 77 Kelvin and in a zero applied magnetic field Ｅ is at least 10 ３ A / cm ２ , for example at least 3×10 ３ A / cm ２ , for example at least 10 ４ A / cm ２ , for example at least 18750 A / cm ２ , at least 3×10 ４ A / cm ２ , at least 10 ５ A / cm ２ , at least 3×10 ５ A / cm ２ , at least 5×10 ５ A / cm ２ , at least 10 ６ A / cm ２ , at least 3×10 ６ A / cm ２ , at least 10 ７ A / cm ２ and the engineering current density is defined as the current density of a cross-sectional area including a superconducting material and a substrate including a buffer layer or buffer stack and a stabilization layer if present, and each filament optionally has a width of 500 micrometers or less, for example 400 micrometers or less. The plurality of filaments (242) according to claim 15 or 16

31. For example, the distance from the end of the side surface of the filament to the inside of the filament, for example, the average distance, is 100 micrometers or less, for example 50 micrometers or less, for example 25 micrometers or less, for example 20 micrometers or less, for example 15 micrometers or less, for example 10 micrometers or less, for example 5 micrometers or less, for example 1 micrometer or less, according to claim 15 or 16, wherein the superconducting properties of the superconducting material deteriorate, the plurality of filaments (242).

32. A wire, such as a cable or power cable, comprising a plurality of filaments (242) provided according to claim 1 or 2 and / or claim 15 or 16.

33. A plurality of filaments (242) provided according to claim 1 or 2 and / or claim 15 or 16, for conducting electric current, for example, for conducting electric current under superconducting conditions.

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