TAPE TYPE SUPERCONDUCTOR WITH A PLURALITY OF ELONGATED BARRIER STRUCTURES

Abstract

A tape type superconductor (1), extending in longitudinal direction (LD), includes a substrate tape (2), at least one buffer layer (3), a superconductor layer (4), and plural elongated barrier structures (5, 5a, 5b). The superconductor layer has a width W.sub.SL in a direction (WD) that is perpendicular to the longitudinal direction and runs parallel to a flat side (8) of the substrate tape. The tape type superconductor has a longitudinal length L.sub.TTS t, and the elongated barrier structures are oriented in parallel with the longitudinal direction. A respective barrier structure has a longitudinal length L.sub.BS, with L.sub.BS0.20*W.sub.SL and L.sub.BS0.20*L.sub.TTS. The barrier structures are distributed longitudinally, are located at least partially in the superconductor layer, and impede a superconducting current flow in width direction across a respective barrier structure. This tape type superconductor achieves high critical currents simply and over extended tape lengths with suppressed magnetization.

Claims

1. A tape type superconductor, extending along a longitudinal direction, and comprising: a substrate tape, at least one buffer layer, a superconductor layer, wherein the superconductor layer has a width W.sub.SL in a width direction, that is perpendicular to the longitudinal direction and is parallel to a flat side of the substrate tape, wherein the tape type superconductor has a length L.sub.TTS in the longitudinal direction, and a plurality of elongated barrier structures which are oriented in parallel with the longitudinal direction, wherein a respective one of the barrier structures has a length L.sub.BS in the longitudinal direction, with L.sub.BS0.20*W.sub.SL and L.sub.BS0.20*L.sub.TTS, wherein the barrier structures are arranged distributed along the longitudinal direction, and wherein the barrier structures are located at least partially in the superconductor layer and impede a superconducting current flow in the width direction across a respective barrier structure.

2. A tape type superconductor according to claim 1, wherein the superconductor layer has a complete height H.sub.SL, and a respective one of the barrier structures extends across the complete height H.sub.SL of the superconductor layer in a height direction, wherein the height direction extends perpendicularly to the longitudinal direction and extends perpendicularly to the flat side of the substrate tape.

3. A tape type superconductor according to claim 1, wherein the barrier structures are non-superconducting or exhibit a critical current density j.sub.c.sup.BS in the width direction which is less than 1/100 of a critical current density j.sub.c.sup.SL in the width direction of a superconducting material of the superconductor layer.

4. A tape type superconductor according to claim 1, wherein the barrier structures are spaces filled with a non-superconducting material of a chemical composition that differs from a chemical composition of a superconducting material of the superconductor layer.

5. A tape type superconductor according to claim 4, wherein the spaces are filled with a non-superconducting metal.

6. A tape type superconductor according to claim 1, wherein the barrier structures have a chemical composition that is the same as a chemical composition of a superconducting material of the superconductor layer, and wherein the chemical compositions of the barrier structures versus the superconducting material exhibit deviations in phase composition and/or exhibit disturbances in crystalline structure.

7. A tape type superconductor according to claim 1, wherein at least 80% of the length L.sub.TTS of the tape type superconductor is overlapped by the barrier structures.

8. A tape type superconductor according to claim 1, wherein at least 80% of the length L.sub.TTS of the tape type superconductor is overlapped by at least n of the barrier structures which are sequent in the width direction, with n2.

9. A tape type superconductor according to claim 1, wherein, for an average barrier density ABD, which is defined as a local barrier density of the tape type superconductor averaged along the complete length L.sub.TTS, with the local barrier density being the number of barrier structures intersected by a cross section of the tape type superconductor perpendicular to the longitudinal direction at a local position in longitudinal direction:
ABD0.80.

10. A tape type superconductor according to claim 9, wherein: ABD2.5 and W.sub.SL/(2*ABD)L.sub.BS, and/or ABD250 and L.sub.BS(50/ABD)*W.sub.SL, and/or ABD5 and W.sub.SL/ABDL.sub.BS, and/or ABS125 and L.sub.BS(25/ABD)*W.sub.SL.

11. A tape type superconductor according to claim 9, wherein the barrier structures are arranged distributed over at least m different positions in the width direction, with m>2*ABD or m>3*ABD.

12. A tape type superconductor according to claim 11, wherein on average over the length L.sub.TTS, the barrier structures are at least approximately equally distributed over the at least m different positions in the width direction.

13. A tape type superconductor according to claim 1, wherein a superconducting material of the superconductor layer is a high temperature superconductor.

14. A tape type superconductor according to claim 13, wherein the high temperature superconductor is REBCO or BiSCCO or MgB.sub.2.

15. A tape type superconductor according to claim 1, wherein between respective two barrier structures subsequent in width direction there is an intermediate region belonging to the superconductive layer, wherein the intermediate region has a length L.sub.IR in longitudinal direction, and wherein L.sub.IRW.sub.SL.

16. A tape type superconductor according to claim 1, wherein between respective two barrier structures subsequent in width direction there is an intermediate region belonging to the superconductive layer, wherein the intermediate region has a length L.sub.IR in longitudinal direction, and wherein L.sub.IR0.25*W.sub.SL/(m+1) and L.sub.IR4*W.sub.SL/(m+1), with m: number of positions in width direction over which the barrier structures are distributed.

17. Method for producing a tape type superconductor according to claim 4, comprising: depositing at least one continuous one of the buffer layers on the substrate tape, depositing superconducting material forming a continuous superconductor layer on the at least one continuous buffer layer, at locations predetermined for the barrier structures, locally removing the superconducting material of the continuous superconductor layer, to form grooves reaching at least to the at least one continuous buffer layer, and filling the grooves with a non-superconducting material of a chemical composition that differs from the chemical composition of the superconducting material of the superconductor layer.

18. Method according to claim 15, wherein the superconducting material is locally removed by laser etching, to form grooves reaching at least to the at least one continuous buffer layer.

19. Method for producing a tape type superconductor according to claim 4, comprising: depositing at least one continuous one of the buffer layers on the substrate tape, depositing superconducting material forming a continuous superconductor layer on the at least one continuous buffer layer, at locations predetermined for the barrier structures, locally converting the superconducting material of the continuous superconductor layer into the non-superconducting material of the chemical composition that differs from the chemical composition of the superconducting material of the superconductor layer.

20. Method according to claim 19, wherein the superconducting material is locally converted by ion bombardment.

21. Method for producing a tape type superconductor according to claim 6, wherein: at locations predetermined for barrier structures, a) locally disturbing a surface of a buffer layer deposited on the substrate tape, to form a disturbance pattern, or b) locally disturbing a surface of a substrate tape, to form a disturbance pattern, and depositing a buffer layer on the substrate tape, and depositing material on the buffer layer such that the superconducting material of the superconductor layer forms everywhere on the buffer layer except on the disturbance pattern.

22. Method according to claim 21, wherein the surface of the buffer layer or the surface of the substrate tape is locally disturbed by scratching or laser etching.

23. Method for producing a tape type superconductor according to claim 6, comprising: depositing at least one continuous one of the buffer layers on the substrate tape, depositing superconducting material forming a continuous superconductor layer on the at least one continuous buffer layer, at locations predetermined for the barrier structures, locally treating the superconducting material of the continuous superconductor layer to impose a new phase composition and/or crystalline structure disturbances without changing a chemical composition of the superconducting material.

24. Method for producing the tape type superconductor according to claim 23, wherein the local treating of the superconducting material comprises local heating of the superconducting material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The invention is shown in the drawing.

[0064] FIG. 1A shows a schematic top view of a first embodiment of an inventive tape type superconductor, with barrier structures at one width position, subsequent along the longitudinal direction;

[0065] FIG. 1B a schematic cross-section of the superconductor of FIG. 1A at plane IB;

[0066] FIG. 1C a schematic cross-section of the superconductor of FIG. 1A at plane IC;

[0067] FIG. 2A shows a schematic top view of a second embodiment of an inventive tape type superconductor, with barrier structures at two width positions, subsequent along the longitudinal direction;

[0068] FIG. 2B a schematic cross-section of the superconductor of FIG. 2A at plane IIB;

[0069] FIG. 2C a schematic cross-section of the superconductor of FIG. 2A at plane ITC;

[0070] FIG. 2D a schematic cross-section of the superconductor of FIG. 2A at plane IID;

[0071] FIG. 3 shows a schematic top view of a third embodiment of an inventive tape type superconductor, with barrier structures at three width positions, with periodically arranged barrier structures;

[0072] FIG. 4 shows a schematic top view of a fourth embodiment of an inventive tape type superconductor, with barrier structures at three width positions, with barrier structures of variable length arranged in a random pattern;

[0073] FIG. 5 shows a schematic top view of a fifth embodiment of an inventive tape type superconductor, with barrier structures at five width positions, with barrier structures of fixed length arranged in a random pattern;

[0074] FIG. 6A-6F show schematically, through six cross-sections, a sequence illustrating a first variant of a method for producing an inventive tape type superconductor, including a laser etching of grooves in a superconductor layer;

[0075] FIG. 7A-7C show schematically, through three cross-sections, a sequence illustrating a second variant of a method for producing an inventive tape type superconductor, including an ion bombardment of regions of a superconductor layer;

[0076] FIG. 8A-8D show schematically, through four cross-sections, a sequence illustrating a third variant of a method for producing an inventive tape type superconductor, including scratching of a buffer layer;

[0077] FIG. 9A-9C show schematically, through three cross-sections, a sequence illustrating a fourth variant of a method for producing an inventive tape type superconductor, including local heating of regions of a superconductor layer.

DETAILED DESCRIPTION

[0078] It should be noted that the figures are schematic in nature, and some features may be shown in an exaggerated or understated way, in order to show particular features of an inventive tape type superconductor or an inventive production method more clearly.

[0079] FIG. 1A shows a first embodiment of an inventive tape type superconductor 1 in a schematic top view. FIGS. 1B and 1C illustrate cross-sectional views of the tape type superconductor 1 perpendicular to the longitudinal direction LD at positions of planes IB and IC.

[0080] The tape type superconductor 1 comprises a substrate tape 2, which is flexible so it can be wound for example into a solenoid type coil, further at least one buffer layer 3 deposited on a flat side 8 of the substrate tape 2, and a superconductor layer 4 deposited on top of the at least one buffer layer 3. Typically, the superconductor layer 4 is further covered with a metallic protection layer or shunt layer (not shown), for example made of a noble metal such as silver or made of copper. The superconductor layer 4 is made of a superconducting material, typically a high temperature superconductor material of ceramic type such as YBCO.

[0081] Further, the tape type superconductor 1 includes a plurality of barrier structures 5 extending in parallel (within the manufacturing accuracy) to the longitudinal direction LD. The barrier structures 5 extend over the complete height H.sub.SL of the superconductor layer 4 in a height direction HD (which runs perpendicular to the flat side 8). The barrier structures 5 are filled with a material that is non-superconducting, such as a metal, or filled with a material with significantly worse superconducting characteristics as compared to the superconducting material of the superconductor layer 4, for example with a critical current density lower by a factor of more than 100 (at the same temperature and magnetic field strength during operation). Note that preferably, the material of the barrier structures 5 is normally conductive, with an electrical conductivity corresponding to the conductivity of copper or better (at operating temperature, such as at 4.2 K). The barrier structures 5 are separate from each other, such that in general, each barrier structure 5 is surrounded by superconducting material of the superconductor layer 4 in width direction WD and longitudinal direction LD (with the exception of end faces of barrier structures 5 at an end of the tape type superconductor 1, see here right end in FIG. 1A).

[0082] The tape type superconductor 1 is intended for transporting an electric current superconductingly along the longitudinal direction LD.

[0083] In the example shown, the barrier structures 5 have a uniform length L.sub.BS in longitudinal direction LD, the overall tape type superconductor 1 has a length L.sub.TTS in longitudinal direction LD, and the superconductor layer 4 has a constant width W.sub.SL (which is here identical to a width of the tape type superconductor 1 in general) in width direction WD. The barrier structures 5 are arranged subsequent in longitudinal direction LD, and are all arranged at the same position 6a (m=1) in width direction, such that the position 6a is in the middle of the tape type superconductor 1 with respect to the width direction WD. Between each two neighboring barrier structures 5 in the sequence, there is an intermediate region 7 belonging to the superconductive layer 4, and therefore with the superconductive characteristics of the superconducting material of the superconductor layer 4. At the intermediate regions 7, a superconducting current may flow between an (in FIG. 1A) upper part and a lower part of the superconductor layer 4. The intermediate regions 7 here have a uniform length of L.sub.IR in longitudinal direction LD. In other words, the barrier structures 5 here form a regular dashed line pattern in the superconductor layer 4.

[0084] In the example shown, the following roughly applies:

a) L.sub.BS=0.20*L.sub.TTS; note that typically L.sub.TTS is much longer than shown in the example, so often L.sub.BS0.001*L.sub.TTS, for example;
b) L.sub.BS=0.92*W.sub.SL;
c) L.sub.IR=0.17*L.sub.BS; note that this means here that about 86% of the entire length L.sub.TTS is overlapped by barrier structures 5, and an average barrier density ABD is about 0.86 in this case.

[0085] The barrier structures 5 separate the superconductor layer 4 into an (in FIG. 1A) upper part and a lower part where areas for particular shielding currents are reduced. When m>1, they are even more reduced with consequent suppression of shielding currents and related magnetization. Thus, in case shown in FIG. 1A, the invention provides a decoupling of regions in the superconductor layer 4 at opposing sides of a respective barrier structure 5 (adjacent areas). On the other hand, at the intermediate regions 7 a current exchange (i.e. partial coupling) may take place. This coupling represents a non-linear effect which allows more homogeneous distribution of the entire transport current in the entire cross-section (width) of the tape.

[0086] In the following, further embodiments of inventive tape type superconductors 1 are explained, and only the major differences with respect to the embodiment shown in FIGS. 1A-1C are discussed in more detail.

[0087] FIG. 2A in top view and FIGS. 2B, 2C and 2D in cross-sectional views at the positions of planes IIB, IIC and IID show a second embodiment of an inventive tape type superconductor 1. Note that the end at the right hand side of the tape type superconductor 1 is shown abbreviated in FIG. 2A here.

[0088] In this embodiment, barrier structures 5 of uniform length L.sub.BS are located at two positions 6a, 6b (m=2) in width direction WD; note that in general, embodiments wherein the barrier structures 5 are distributed over a plurality of positions in width direction WD (i.e. m2) are generally preferred, so shielding currents may be more limited in space in width direction WD, in order to achieve a lower magnetization. At each position 6a, 6b, barrier structures 5 are arranged subsequent in longitudinal direction LD, with intermediate regions 7 of uniform length L.sub.IR between barrier structures 5 neighboring in longitudinal direction LD.

[0089] The intermediate regions 7 of positions 6a and 6b are displaced in longitudinal direction such that they do not mutually overlap. Seen the other way, the barrier structures 5 of positions 6a and 6b are displaced in longitudinal direction such that they do mutually overlap, here at both ends. As a result, all of the length L.sub.TTS, i.e. 100%, are overlapped by at least one barrier structure 5. FIGS. 2C, 2D illustrate the situations with one barrier structure 5 in cross-section, which here applies over about 35% of the length L.sub.TTS. FIG. 2B illustrates the situation with two barrier structures 5 in cross-section, which here applies about 65% of the length L.sub.TTS. This results in an average barrier density ABD of (0.35*1)+(0.65*2)=1.59 for the illustrated tape type superconductor 1. In the example shown, approximately L.sub.BS=1.07*W.sub.SL and further L.sub.IR=0.21*L.sub.BS applies.

[0090] In general it is preferred that

L.sub.IR0.25*W.sub.SL/(m+1) and/or L.sub.IR4*W.sub.SL/(m+1),
preferably L.sub.IR0.5*W.sub.SL/(m+1) and/or L.sub.IR2*W.sub.SL/(m+1), with m: number of positions in width direction over which the barrier structures 5 are distributed. Often L.sub.IRW.sub.SL is also preferred, and often L.sub.IRW.sub.SL/4 or even L.sub.IRW.sub.SL/10 also applies.

[0091] The positions 6a, 6b are basically equally distributed over the width W.sub.SL of the superconductor layer 4 or of the tape type superconductor 1, respectively. The barrier structures 5 have an aspect ratio AR.sub.BS=L.sub.BS/W.sub.BS, with W.sub.BS being the width of the barrier structure 5 in width direction WD, and with here approximately AR.sub.BS=14; note that in general, aspect ratios AR.sub.BS of 10 or more, or even 20 or more are preferred.

[0092] FIG. 3 illustrates a third embodiment of an inventive tape type superconductor 1, wherein the barrier structures 5 having a uniform length L.sub.BS are distributed equally over three positions 6a, 6b, 6c (i.e. m=3) in width direction WD. Again, the barrier structures 5 at each position 6a-6c are arranged one behind the other, separated by intermediate regions 7 of uniform length L.sub.IR.

[0093] In the example shown, the following approximately applies:

a) L.sub.BS=2.38*W.sub.SL;
b) L.sub.IR=0.11*L.sub.BS; since the intermediate regions 7 do not overlap, this results in an average barrier density ABD of [3*0.11*2+(1.113*0.11)*3]/(1.11)=2.70.

[0094] In this embodiment, the barrier structures 5 are arranged periodically with respect to the longitudinal direction LD, here with a period P corresponding to the entirety of one barrier structure 5 and one adjacent intermediate region 7, and here with approximately P=2.63*W.sub.SL.

[0095] FIG. 4 illustrates in a fourth embodiment a tape type superconductor 1 similar to the embodiment shown in FIG. 3, so only the major differences are discussed.

[0096] In the fourth embodiment, the barrier structures 5 have a variable length L.sub.BS. However, intermediate regions 7 between barrier structures subsequent in longitudinal direction at the same position 6a-6c have a uniform length L.sub.IR in longitudinal direction LD.

[0097] In the example shown, the barrier structure 5a has the shortest length L.sub.BS.sup.short, for which applies here approximately L.sub.BS.sup.short=1.0*W.sub.SL, and the barrier structure 5b has the longest length L.sub.BS.sup.long; for which applies here approximately L.sub.BS.sup.long=2.9*W.sub.SL. The lengths L.sub.BS of all barrier structures 5 are randomly distributed between L.sub.BS.sup.short and L.sub.BS.sup.long, and said barrier structures 5 are randomly arranged at the positions 6a-6c in random sequences.

[0098] However, as a border condition, an overlap of intermediate regions 7 should not be allowed for neighboring positions 6a-6c, and preferably should not be allowed for any positions 6a-6c (as shown here). Please note that in case of long enough (average) lengths L.sub.BS as compared to the length L.sub.IR, for example for (average) L.sub.BS50*L.sub.IR, an overlap of intermediate regions 7 for neighboring positions 6a-6c in random arrangements becomes so rare that it does not need to be considered any more.

[0099] A random arrangement of barrier structures 5 along the tape type superconductor 1, as shown for example in FIG. 4 (see above) and FIG. 5 (see below), may help to prevent congeneric behavior at different sections of the tape type superconductor 1 which may add up or cause self-enforcing effects, in particular resulting in a quench or the built up of undesired magnetic field components. This is particularly true if the tape type superconductor 1 is wound in such a way that sections of the tape type superconductor 1 are arranged neighboring in width direction WD and/or neighboring in a direction perpendicular to the tape plane (i.e. one above the other section).

[0100] FIG. 5 illustrates in a top view a fifth embodiment of the inventive tape type superconductor 1.

[0101] In this embodiment, the barrier structures 5 have a uniform length L.sub.BS in longitudinal direction LD and are distributed equally over five positions 6a-6e (i.e. m=5) in width direction WD, with said positions 6a-6e also being equally distributed along the width direction WD.

[0102] In the example shown, each barrier structure 5 has an overlap with two other barrier structures 5a, 5b, with each of the other barrier structures 5a, 5b overlapping with half of the length of said barrier structure 5 at the end and at the front, respectively. As a result, an average barrier density ABD=2 is established.

[0103] Along the longitudinal direction LD, for a given barrier structure 5, the position 6a-6e at which the next overlapping barrier structure 5b is located is randomly chosen from the positions which are unequal to the positions of said barrier structure 5 and the previous barrier structure 5a. For example, for said barrier structure 5 marked in FIG. 5 at position 6e, which has a previous barrier structure 5a at position 6d, the next barrier structure 5b may be chosen among positions 6a, 6b and 6c, and in the example shown, the next barrier structure 5b happens to be located at position 6c.

[0104] As a consequence of the random arrangement of barrier structures 5, barrier structures 5 at the same width position 6a-6e and subsequent in longitudinal direction LD are separated by intermediate regions 7, with the intermediate regions 7 having random extensions in longitudinal direction.

[0105] When the number m of available positions 6a-6e is relatively big as compared to ABD, for example with m>2*ABD or with m(ABD+2), and here with m=2.5*ABD or m=ABD+3, respectively, a particularly large variety of possible (random) arrangements of the barrier structures 5 is available. In this case, congeneric behavior and self-enforcing effects are even less likely.

[0106] In the illustrated example, approximately L.sub.BS=0.67*W.sub.SL applies; note that for relatively big m as compared to ABD, relatively short lengths L.sub.BS of the barrier structures 5 are preferred, for example with L.sub.BS2*W.sub.SL/(ABS+1).

[0107] FIGS. 6A-6F illustrate a first variant of a method for producing an inventive tape type superconductor; in each case, cross-sections perpendicular to the longitudinal direction are shown.

[0108] The method starts with a substrate tape 2, for example a steel substrate or a Hastelloy substrate, polished at its surface 2a of the flat side 8, see FIG. 6A. On its surface 2a, at least one continuous buffer layer 3 is deposited then, see FIG. 6B. On the surface 3a of the (uppermost) buffer layer 3, a continuous superconductor layer 4 is deposited, see FIG. 6C.

[0109] Then at locations intended for barrier structures, a laser beam 60 originating from a laser device 61 is applied, compare FIG. 6D. The laser beam 60 strongly heats and etches away superconducting material close to the laser spot 62, what results in a groove 63 in the superconductor layer 4, and here also in the buffer layer 3, compare FIG. 6E. The space 65 of the groove 63 is then filled with material, here with a non-superconducting metal such as gold or silver, resulting in a barrier structure 5, compare FIG. 6F. Then the tape type superconductor 1 is finished. Note that typically a protection layer or shunt layer is further deposited on the combined surface 64 of the superconductor layer 4 and the barrier structure 5 (not shown).

[0110] Please note that in FIG. 6F only one barrier structure 5 is included in the cross-section for simplicity, but the tape type superconductor 1 may include other numbers of barrier structures 5 or other arrangements than shown.

[0111] In the second variant of a method for producing a tape type superconductor shown in FIG. 7A-7C, first a semi-finished product with a substrate tape 2, at least one continuous buffer layer 3 and a continuous superconductor layer 4, here of YBCO, is produced (see also FIGS. 6A-6C above), compare FIG. 7A. Then at locations intended for barrier structures, a beam 70 of gallium ions (Ga.sup.+) is directed, with the gallium ions being provided by an ion gun 71, compare FIG. 7B. Note that said ion bombardment should be done under vacuum conditions. In a region 72, the material of the superconductor layer 4 is enriched with gallium, thus locally changing the chemical composition in the corresponding space 65. In the region 72, the superconducting characteristics get lost, what results in a barrier structure 5 of non-superconducting material in the tape type superconductor 1, compare FIG. 7C.

[0112] FIGS. 8A-8D illustrate a third variant of a method for producing a tape type superconductor.

[0113] On a polished surface 2a of a substrate tape 2, see FIG. 8A, a continuous buffer layer 3 is deposited, see FIG. 8B. The surface 3a of said buffer layer 3 is then locally scratched with a scratching tool 80 at locations intended for barrier structures, thus forming a disturbance pattern 81 on or in the buffer layer 3, see FIG. 8C. This is followed by depositing material, here components for YBCO, on the patterned surface 3a, see FIG. 8D. Above the disturbance pattern 81, material growth results in non-superconducting (or poorly superconducting) material in a space 65 forming a barrier structure 5, and lateral of the disturbance pattern 81, superconducting material, here YBCO, of the superconductor layer 4 grows.

[0114] Note that in the tape type superconductor 1, the elemental composition of the material of the superconductor layer 4 and the barrier structure 5 are identical here, but the disturbance pattern 81 causes a different phase composition and/or a different crystallinity, resulting in different characteristics with respect to superconductivity.

[0115] It should be noted that instead of scratching (or otherwise disturbing) the surface 3a of the buffer layer 3, also the polished surface 2a of the substrate tape 2 may be scratched (or otherwise disturbed). The buffer layer (or layers) deposited on top can carry on this disturbance pattern to the surface 3a of the buffer layer 3 then, also resulting in a superconductor layer 4 and barrier structures 5 upon material deposition.

[0116] In the fourth variant of a method for producing a tape type superconductor shown in FIG. 9A-9C, first a semi-finished product with a substrate tape 2, at least one continuous buffer layer 3 and a continuous superconductor layer 4, here of YBCO, is produced (see also FIGS. 6A-6C above), compare FIG. 9A. Then at locations intended for barrier structures, the material of the superconductor layer 4 is locally heated with a heating device 90, compare FIG. 9B. In a region 91, the superconducting material of the superconductor layer 4 degrades and becomes non-superconductive, for example by a non-reversible phase transition. This results in a barrier structure 5 of non-superconducting material in the corresponding space 65 in the tape type superconductor 1, compare FIG. 9C.

[0117] In the illustrated variant, the elemental composition of the originally superconducting material of the superconductor layer 4 does not change upon the heat treatment. However, in another variant, very strong heating may lead to a thermolysis, with elements evaporating into the surrounding; in this case the elemental composition will change in the space 65 or the barrier structure 5 as compared to the superconductor layer 4.

[0118] In summary, the invention proposes a tape type superconductor with a plurality of barrier structures within its superconductor layer. The barrier structures are much shorter than the total length of the tape type superconductor, and the barrier structures are arranged subsequent in longitudinal direction, to which they are parallel. At a particular position in width direction, numerous barrier structures, typically 10 or more, often 100 or more, are arranged subsequently in longitudinal direction, but separated from each other by superconducting intermediate regions. The barrier structures are arranged at at least one position in width direction, but there may be a plurality of positions in width direction over which the barrier structures are distributed. The barrier structures may be distributed in a pattern periodic in longitudinal direction, or may be arranged in a random pattern. The barrier structures are non-superconducting or worse superconducting as compared to the superconductor layer. The separated barrier structures allow for a decoupling of regions in the superconductor layer, but all regions of the superconductor layer are still interconnected superconductingly. This reduces unwanted induced magnetization, without a substantial reduction of the critical current. Inventive tape type superconductors may be used in spools, magnet coils, in particular for NMR magnets, for motors or generators, transformers, fault current limiters or cables, for example.

LIST OF REFERENCE SIGNS

[0119] 1 tape type superconductor [0120] 2 substrate tape [0121] 2a surface (substrate tape) [0122] 2 buffer layer [0123] 3a surface (buffer layer) [0124] 4 superconductor layer [0125] 5, 5a, 5b barrier structures [0126] 6a-6e positions [0127] 7 intermediate region [0128] 8 flat side (substrate tape) [0129] 60 laser beam [0130] 61 laser device [0131] 62 laser spot [0132] 63 groove [0133] 64 surface (combined superconductor layer and barrier structure) [0134] 65 space [0135] 70 beam of ions [0136] 71 ion gun [0137] 72 region (affected by ions) [0138] 80 scratching tool [0139] 81 disturbance pattern [0140] 90 heating device [0141] 91 region (affected by heating) [0142] ABD average barrier density [0143] HD height direction [0144] H.sub.SL height of superconductor layer [0145] L.sub.BS length of barrier structure [0146] L.sub.BS.sup.long length of longest barrier structure [0147] L.sub.BS.sup.short length of shortest barrier structure [0148] LD longitudinal direction [0149] L.sub.IR length of intermediate region [0150] L.sub.TTS length of tape type superconductor [0151] P period [0152] WD width direction [0153] W.sub.BS width of a barrier structure [0154] W.sub.SL width of superconductor layer