Jointless superconducting multi-coils

Abstract

A method of manufacturing a jointless superconducting multi-coil (1, 1') comprises the steps of providing a superconducting element (2) and winding a first part (2b1) around at least part of a first mandrel (3) so as to form a first pre-coil (4) of a first coil (5), winding at least part around at least part of the first mandrel (3) so as to form the first coil (5), and i) winding a second part (2b2) around at least part of a second mandrel (6) so as to form a second pre-coil (7) of a second coil (8) and winding at least part around at least part of the second mandrel (6) so as to form the second coil (8), or ii) winding a second part (2b2) around at least part of the first mandrel (3) so as to form a second pre-coil (7') of a second coil (8') and winding at least part around at least part of the first mandrel (3) so as to form the second coil (8'). The multi-coil (1, 1') comprises the first coil (5) and the second coil (8, 8') being arranged above one another with respect to a longitudinal direction (Lc, Lc') of the multi-coil (1, 1').

Description

[0001] TITLE

[0002] JOINTLESS SUPERCONDUCTING MULTI-COILS

[0003] TECHNICAL FIELD

[0004] The present invention relates to a method of manufacturing a jointless superconducting multi-coil according to claim 1 , and to a superconducting magnet comprising such a multicoil according to claim 12.

[0005] PRIOR ART

[0006] High magnetic fields are important for the applications of nuclear magnetic resonances spectroscopy, accelerators, and fusions. Conventional magnets have large inner diameters. The disadvantage of large-inner-diameter magnets is that the amount of material required for high magnetic field is huge. Another way to improve the magnetic field is to reduce the bore size. However, bore size smaller than 10 mm requires the implementation of a solder joint between the coils, or use of narrower tapes. Heat generated from solder joints reduces the critical current of the magnet, and narrow tapes have worse mechanical stability and lower critical current than wide tapes, limiting the maximum field that can be achieved. Owing to the advancement of high temperature superconducting (HTS) materials, high magnetic fields up to 45.5 Tesla can be achieved within relatively compact HTS magnets. A common way employed in HTS magnets to increase the magnetic field is by stacking more and larger coils. However, this drastically increases the cost of the HTS tapes and the design complexity.

[0007] SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide a method of manufacturing jointless superconducting multi-coils in a simple and cost-effective way.

[0009] This object is achieved with the method according to claim 1. That is, a method of manufacturing a jointless superconducting multi-coil is provided that comprises the steps of i) providing a superconducting element defining a first element-region, a second elementregion, and a middle element-region being arranged between the first element-region and the second element-region, ii) winding a first part of the middle element-region around at least part of a first mandrel so as to form a first pre-coil of a first coil, iii) winding at least part of the first element-region around at least part of the first mandrel so as to form the first coil, and iv) either a) winding a second part of the middle element-region around at least part of a second mandrel so as to form a second pre-coil of a second coil and winding at least part of the second element-region around at least part of the second mandrel so as to form the second coil, or b) winding a second part of the middle element-region around at least part of the first mandrel so as to form a second pre-coil of a second coil and winding at least part of the second element-region around at least part of the first mandrel so as to form the second coil. The multi-coil comprising the first coil and the second coil preferably being arranged above one another with respect to a longitudinal direction of the multi-coil is formed.

[0010] Hence, the method according to the invention enables the manufacturing of a multi-coil comprising at least the first coil and the second coil, wherein said first and second coils are in connection with one another in a jointless-manner.

[0011] To this end the present invention is based on the insight that a multi-coil comprising two or more coils can be manufactured in a jointless manner by forming pre-coils, and wherein said pre-coils enable a jointless connection between the coils in different winding methods.

[0012] In particular, and as will be explained in greater detail below, the first and second coils are preferably in connection with one another via the middle-element region.

[0013] In the event that the multi-coil comprises a first coil and a second coil only, said multi-coil can be referred to as a double-coil. However, it should be noted that the multi-coil can comprise more than two coils. Hence, explanations made herein regarding a first coil, a second coil and a double-coil preferably likewise apply to more than two coils or a multi-coil comprising more than two coils, respectively, and vice versa.

[0014] The method according to the invention is based on two winding approaches with respect to the manufacturing of the second pre-coil and the second coil. That is, in a first winding approach of the method according to the invention, the first pre-coil and the first coil are manufactured by winding the first part of the middle element-region around a first mandrel, and wherein the second pre-coil and the second coil are manufactured by winding the second part of the middle element-region around a second mandrel. In a second winding approach of the method according to the invention, the first pre-coil, the first coil, the second pre-coil and the second coil are all wound around the same mandrel, herein called the first mandrel.

[0015] The manufacturing of the first pre-coil and the first coil is however the same for both winding approaches. Many other aspects relating to the manufacture of the multi-coil are also preferably the same for both aspects. Hence, unless otherwise stated, explanations apply to both winding approaches.

[0016] As will be explained in greater detail further below, the multi-coil being manufactured according to the first winding approach comprises a first coil and a second coil that can be arranged such, that a bottom side of the first coil facing away from the first mandrel is facing a bottom side of the second coil facing away from the second mandrel. That is, it is preferred to first wind the first coil and the second coil separately from one another, i.t. to wind single coils and to then arrange the separately wound or single coils above one another, whereby the multi-coil is formed. The two coils can be arranged above each other so that their respective bottom side are facing each other. In the assembled state, i.e. , when the multicoil comprises the first coil and the second coil being arranged above one another, a longitudinal direction of the first mandrel and a longitudinal direction of the second mandrel preferably run along the longitudinal direction of the multi-coil. To achieve a high magnetic field it is preferred to stack these coils tightly, preferably in the bottom-to-bottom manner as just described. However, it is likewise conceivable that a spacing is present in between, depending on the intended use or purpose of the multi-coil.

[0017] In the multi-coil manufactured according to the second winding approach, it is also preferred that the first coil and the second coil are formed separately. However, here the first coil is preferably formed first, and then the second coil is formed above the first coil with respect to the longitudinal direction of the multi-coil, wherein the bottom side of the second coil preferably faces the top side of the first coil. In the assembled state, i.e., when the multicoil comprises the first coil and the second coil being arranged above one another, a longitudinal direction of the first mandrel preferably runs along the longitudinal direction of the multi-coil. Various geometrical dimensions of the first and second mandrel and of the superconducting element are conceivable and are preferably determined based on a design of the superconducting magnet implementing the multi-coil, see also further below.

[0018] Superconductors are a kind of material where the electrical resistance vanishes and magnetic fields are expelled from the material. High-temperature superconductors (HTS) have critical temperature (the temperature below which the material behaves as a superconductor) above 77 K (-196.2 °C; -321.1 °F), the boiling point of liquid nitrogen. They are only "high-temperature" relative to previously known low temperature superconductors (LTS), which function at even colder temperatures, close to absolute zero. The main class of high-temperature superconductors is copper oxides combined with other metals, especially the rare-earth barium copper oxides (REBCOs) such as yttrium barium copper oxide (YBCO). They are usually produced as a tape shape, which consists of a substrate, buffer, REBCO, and stabilizer in layer forms.

[0019] Superconductor material classes include chemical elements (e.g. mercury or lead), alloys (such as niobium-titanium, germanium-niobium, and niobium nitride), ceramics (YBCO and magnesium diboride), superconducting pnictides (like fluorine-doped LaOFeAs) or organic superconductors (fullerenes and carbon nanotubes). However, other superconducting materials are likewise conceivable and are well-known in the art such as iron-based compounds, etc.

[0020] The superconducting element preferably has the shape of a superconducting tape and / or of a superconducting wire.

[0021] The first pre-coil is preferably formed by winding the first part of the middle element-region in a spiral about a longitudinal direction of the first mandrel. Additionally or alternatively, a pitch between successive turns of the first pre-coil is preferably gradually reduced with respect to a longitudinal direction of the first mandrel and in particular is zero in the region of the first coil. Additionally or alternatively, the first coil is preferably formed in a region of a bottom end of the first mandrel.

[0022] The first part of the middle element-region is preferably wound around the first mandrel along a longitudinal direction of the first mandrel and / or from a top end of the first mandrel towards an opposed bottom end of the first mandrel. In particular, the first pre-coil is preferably formed by spirally winding the first part of the middle element-region along the longitudinal direction of the first mandrel starting from the top end of the first mandrel towards the bottom end of the first mandrel. The first coil is preferably formed at the bottom end of the first mandrel. A pitch, i.e. distance, between successive turns of the first pre-coil is preferably reduced along the longitudinal direction Lm1 of the first mandrel and when seen from the top end of the first mandrel towards the bottom end of the first mandrel.

[0023] In the region of the bottom end of the first mandrel, i.e., in the region of the first coil, the pitch between successive turns of the first pre-coil is preferably zero.

[0024] The distance between consecutive turns in the area of the upper end of the first mandrel can be, for example, smaller than a width of the superconducting element, for instance 12 millimeter or smaller. However, other distances are likewise conceivable.

[0025] Various number of turns of the pre-coils along the mandrel(s) are conceivable and depend, for instance, on the width of the superconducting element, a diameter of the mandrel, and the pitch.

[0026] For example, a number of turns of the first part of the middle element-region forming the first pre-coil and / or of the second part of the middle element-region forming the second precoil can be in the range of 1 to 10'000, for instance between 1 to 100 such as between 5 to 20 in a 47 T magnet. A number of turns of the first element region forming the first coil and / or of the second element region forming the second coil can be in the range of 1 to 10'000, for instance between 100 and 1000 such as about 640 in a 47 T magnet. An outer diameter of the first coil and / or an outer diameter of the second coil can be in the range of 5 millimeter to 2 meter, for instance 64 millimeter in a 47 T magnet.

[0027] An inner diameter of the first coil and / or an inner diameter of the second coil can be in the range of 1 millimeter to 1 meter, for instance 3.5 millimeter in a 47 T magnet. However, as mentioned initially, these values are just examples wherein a variety of other turns and geometrical dimensions are conceivable.

[0028] In the first winding approach, the second pre-coil is preferably formed by winding the second part of the middle element-region in a spiral about a longitudinal direction of the second mandrel. Additionally or alternatively, a pitch between successive turns of the second pre- coil is preferably gradually reduced with respect to a longitudinal direction of the second mandrel and preferably is zero in the region of the second coil. Additionally or alternatively, the second coil is preferably formed in a region of a bottom end of the second mandrel.

[0029] That is, in the first winding approach of the method according to the invention, the second pre-coil is preferably formed on the second mandrel analogous to the first pre-coil being formed on the first mandrel, and the second coil is preferably formed on the second mandrel analogous to the first coil being formed on the first mandrel, respectively.

[0030] In fact, the second pre-coil is preferably formed by winding the second part of the middle element-region around the second mandrel along a longitudinal direction of the second mandrel and / or from a top end of the second mandrel towards an opposed bottom end of the second mandrel.

[0031] The second coil is preferably formed at the bottom end of the second mandrel. A pitch, i.e., distance, between successive turns of the second pre-coil is preferably reduced along the longitudinal direction of the second mandrel and when seen from the top end of the second mandrel towards the bottom end of the second mandrel.

[0032] In the region of the bottom end of the second mandrel, i.e., in the region of the second coil, the pitch between successive turns of the second pre-coil is preferably zero.

[0033] As a result, the winding of the second part of the middle element-region preferably transitions successively from the spiral or helical shape of the second pre-coil along the second mandrel to the coil shape of the second coil.

[0034] In the first winding approach, the first coil and the second coil after being wound are preferably arranged above one another such, that a bottom side of the first coil facing away from the first mandrel faces a bottom side of the second coil facing away from the second mandrel.

[0035] In the first winding approach, part of the first part of the middle element-region and / or part of the second part of the middle element-region preferably extends freely and / or unwound between the first pre-coil and the second pre-coil.

[0036] The first pre-coil, the second pre-coil, and the middle element-region that extends freely and / or unwound between can together also be referred as jointless connection between two coils. Said "unwound" part preferably remains as a free element form.

[0037] In the second winding approach, the second part of the middle element-region is preferably wound around the first mandrel after the first part of the middle element-region that has already been wound about the first mandrel.

[0038] To this end, the second part of the middle element-region is preferably at least partially overlapping the first part of the middle element-region.

[0039] As mentioned earlier, the first part of the middle element-region is preferably wound around the first mandrel along a longitudinal direction of the first mandrel and / or from a top end of the first mandrel towards an opposed bottom end of the first mandrel.

[0040] The second part of the middle element-region is preferably would around the first mandrel along the longitudinal direction of the first mandrel and / or from the top end of the first mandrel towards the opposed bottom end of the first mandrel as well.

[0041] In the second winding approach, the first coil and the second coil are preferably arranged above one another with respect to the longitudinal direction of the multi-coil such, that a bottom side of the second coil faces a top side of the first coil.

[0042] In the second winding approach, the first coil and the second coil can be arranged immediately above one another with respect to the longitudinal direction of the multi-coil. In particular, the first and second coil can be in surface contact with one another. However, it is likewise conceivable that the first and second coil are not in direct or surface contact with one another but that at least one fixation element and / or insulation element such as a copper foil or Kapton insulation is arranged between the first and second coil.

[0043] In the first and second winding approach, the outermost turn of the first coil preferably transitions into a current lead that is configured to input or output current from the multi-coil. Additionally or alternatively, the outermost turn of the second coil preferably transitions into a current lead that is configured to input or output current from a power source into the multicoil. Additionally or alternatively, the multi-coil is preferably configured such that current can flow from the first coil to the second coil and vice versa via the middle element-region. That is, the outermost turn of the first coil (second coil) preferably transitions into an input lead that is configured to input current from a power source into the multi-coil. The input lead is preferably provided by the first element-region (second element region) of the superconducting element. For instance, one or more of the outermost turns of the first coil (second coil) could be unwound into a straight section again, and wherein said straight section provides the input lead that is configured to input current into the multi-coil.

[0044] Likewise, the outermost turn of the second coil (first coil) preferably transitions into an output lead that is configured to output current from the multi-coil. The output lead is preferably provided by the second element-region (first element region) of the superconducting element. For instance, one or more of the outermost turns of the second coil (first coil) could be unwound into a straight section again, and wherein said straight section provides the output lead that is configured to output current from the multi-coil.

[0045] In other words, the multi-coil preferably comprises two leads, one being configured to input current, and one being configured to output current. Terminals of these leads are preferably connected to a power source. Said leads can be cryoleads in the event that the multi-coil is to be used in a cryogenic environment. However, it’s also possible to have more than two leads in the cases where coils are charged with different currents. For example, multiple double or single coils can be assembled but connected to independent power sources.

[0046] In the first and second winding approach, at least one protection element can be at least partially wound about the input lead and / or the output lead. The protection element is configured to mechanically and / or thermally stabilize the input lead and / or the output lead and preferably is a further superconducting element.

[0047] In another aspect, a superconducting magnet for a scientific and / or industrial instrument is provided, wherein the superconducting magnet comprises at least one multi-coil manufactured in the method as described above.

[0048] Any explanations regarding the multi-coil and its method of manufacturing as such preferably likewise apply to the superconducting magnet comprising said multi-coil and vice versa.

[0049] The scientific and / or industrial instrument can be a nuclear magnetic resonance spectrometer, an electron paramagnetic resonance spectrometer, a gyrotron, etc. Moreover, various applications are conceivable, such as in medicine (magnetic resonance imaging), particle accelerators (such as the Large Hadron Collider), fusion devices, etc.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

[0052] Figs. 1a-

[0053] 1e show schematic sketches of the manufacturing of a jointless superconducting multi-coil according to the invention being wound according to a first winding approach;

[0054] Figs. 2a-

[0055] 2e show schematic sketches of the manufacturing of a jointless superconducting multi-coil according to the invention being wound according to a second winding approach;

[0056] Figs. 3a-

[0057] 3c show photographs of a jointless superconducting multi-coil being wound according to the first winding approach;

[0058] Fig. 3d shows a diagram depicting the magnetic fields being measured over time with the jointless superconducting multi-coil of figure 3c.

[0059] DESCRIPTION OF PREFERRED EMBODIMENTS

[0060] Aspects of jointless superconducting multi-coils being wound according to the invention are now illustrated with respect to the figures.

[0061] In particular, figures 1a to 1e schematically depict the manufacturing of a jointless superconducting multi-coil 1 being wound in a first winding approach and figures 2a to 2e schematically depict the manufacturing of a jointless superconducting multi-coil T being wound in a second winding approach. These two types of superconducting multi-coils 1 , T have many features in common, which is why the same reference signs are used for these common features. Features of the superconducting multi-coil T being wound according to the second winding approach, which are not present in the superconducting multi-coil 1 being wound according to the first winding approach, are identified by a reference sign with apostrophe (').

[0062] Aspects of the first winding approach are now discussed with reference to figures 1a to 1e. That is, a jointless superconducting multi-coil 1 is manufactured by providing a first mandrel 3 extending along a longitudinal direction Lm1 and comprising a top end 14 and an opposed bottom end 13 (figure 1a). Moreover, a superconducting element 2 defining a first elementregion 2a, a second element-region 2c, and a middle element-region 2b being arranged between the first element-region 2a and the second element-region 2c is provided. A first part 2b1 of the middle element-region 2b is wound around at least part of the first mandrel 3 so as to form a first pre-coil 4 of a first coil 5 (figure 1 b). At least part of the first elementregion 2a is then wound around at least part of the first mandrel 3 so as to form the first coil 5 (figure 1c). A second part 2b2 of the middle element-region 2b is wound around at least part of a second mandrel 6 so as to form a second pre-coil 7 of a second coil 8 (figure 1d). The second mandrel 6 extends along a longitudinal direction Lm2 and comprises a top end 16 and an opposed bottom end 15 like the first mandrel 3. Then, at least part of the second element-region 2c is wound around at least part of the second mandrel 6 so as to form the second coil 8 (figure 1e). In this way, a multi-coil 1 comprising here two coils 5, 8 is manufactured, and wherein said two coils 5, 8 are connected to one another in a jointless manner via the middle-element region 2b.

[0063] In particular, and as follows from figures 1b and 1c, the first pre-coil 4 is formed by winding the first part 2b1 of the middle element-region 2b in a spiral about a longitudinal direction Lm1 of the first mandrel 3 starting from the top end 14 of the first mandrel 3 toward the bottom end 13 of the first mandrel 3. A pitch between successive turns of the first pre-coil 4 is gradually reduced with respect to the longitudinal direction Lm1 of the first mandrel 3 and is zero in the region of the first coil 5. As a result, the winding of the first part 2b1 of the middle element-region 2b transitions successively from the spiral or helical shape of the first pre-coil 4 along the first mandrel 3 to the coil shape of the first coil 5. The first coil 5 is formed in a region of a bottom end 13 of the first mandrel 3.

[0064] Likewise, and as follows from figures 1d and 1e, the second pre-coil 7 is formed by winding the second part 2b2 of the middle element-region 2b in a spiral about a longitudinal direction Lm2 of the second mandrel 6 starting from the top end 16 towards the bottom end 15 of the second mandrel 6, and wherein a pitch between successive turns of the second pre-coil 7 is gradually reduced with respect to the longitudinal direction Lm2 of the second mandrel 6 and is zero in the region of the second coil 8. As a result, the winding of the second part 2b2 of the middle element-region 2b transitions successively from the spiral or helical shape of the second pre-coil 7 along the second mandrel 6 to the coil shape of the second coil 8. The second coil 8 is formed in a region of a bottom end 15 of the second mandrel 6.

[0065] As best seen in figures 1d and 1e, the jointless connection of the first and second coils 5, 8 is provided by part of the first part 2b1 of the middle element-region 2b and part of the second part 2b2 of the middle element-region 2b that extends freely and unwound between the first pre-coil 4 and the second pre-coil 7.

[0066] Photographs of a jointless superconducting multi-coil 1 being wound according to this winding approach are depicted in figures 3a and 3b. As follows from figure 3c, the first coil 5 and the second coil 8 can be arranged above one another with respect to a longitudinal direction Lc of the multi-coil 1 , such that a double pancake coil is formed. In particular, in this example, the first coil 5 and the second coil 8 are arranged such, that a bottom side 9 of the first coil 5 facing away from the fist mandrel 3 is facing a bottom side 10 of the second coil 8 facing away from the second mandrel 6. In this assembled state, the longitudinal direction Lm1 of the first mandrel and the longitudinal direction Lm2 of the second mandrel run along the longitudinal direction Lc of the multi-coil 1.

[0067] Figures 2a to 2e depict aspects of the second winding approach. That is, a jointless superconducting multi-coil T can be manufactured by providing a first mandrel 3 extending along a longitudinal direction Lm1 and comprising a top end 14 and an opposed bottom end 13 (figure 2a). Moreover, a superconducting element 2 defining a first element-region 2a, a second element-region 2c, and a middle element-region 2b being arranged between the first element-region 2a and the second element-region 2c is provided. A first part 2b1 of the middle element-region 2b is wound around at least part of the first mandrel 3 so as to form a first pre-coil 4 of a first coil 5 (figure 2b). At least part of the first element-region 2a is then wound around at least part of the first mandrel 3 so as to form the first coil 5 (figure 2c). Also in this second winding approach the first pre-coil 4 is formed by winding the first part 2b1 of the middle element-region 2b in a spiral about a longitudinal direction Lm1 of the first mandrel 3, wherein a pitch between successive turns of the first pre-coil 4 is gradually reduced with respect to the longitudinal direction Lm1 of the first mandrel 3 and is zero in the region of the first coil 5. The first coil 5 is formed in a region of a bottom end 13 of the first mandrel 3. As a result, the winding of the middle element-region 2b, in particular of the first part 2b1 of the middle element-region 2b, transitions successively from the spiral or helical shape of the first pre-coil 4 along the mandrel 3 to the coil shape of the first coil 5. In contrast to the first winding approach, a second part 2b2 of the middle element-region 2b is wound around at least part of the first mandrel 3 again so as to form a second pre-coil 7' of a second coil 8' (figure 2d). That is, the second part 2b2 of the middle element-region 2b is wound around the first mandrel 3 after the first part 2b1 of the middle element-region 2b that has already been wound about the first mandrel 3. In the depicted example, said second part 2b2 of the middle element-region 2b is at least partially overlapping the first part 2b1 of the middle element-region 2b. Then, at least part of the second element-region 2c is wound around at least part of the first mandrel 3 so as to form the second coil 8', wherein the multicoil T comprising the first coil 5 and the second coil 8' being arranged above one another with respect to a longitudinal direction Lc' of the multi-coil T is formed (figure 2e).

[0068] That is, in this second winding approach, the first coil 5 is formed first, and then the second coil 8' is formed above the first coil 5 with respect to the longitudinal direction Lc' of the multi-coil T, wherein the bottom side 10' of the second coil 8' faces the top side 11 of the first coil 5. In the assembled state, i.e. , when the multi-coil T comprises the first coil 5 and the second coil 8' being arranged above one another, a longitudinal direction Lm1 of the first mandrel 3 preferably runs along the longitudinal direction Lc' of the multi-coil T.

[0069] As indicated in figures 1e and 2e, the outermost turn of the first coil 5 transitions into an output lead 21 (input lead) that is configured to output (input) current from the multi-coil 1 ; T. The outermost turn of the second coil 8; 8' transitions into an input lead 22; 22' (output lead) that is configured to input (output) current from a power source into the multi-coil 1 ; T. Moreover, the multi-coil 1 ; T is configured such that current can flow from the first coil 5 to the second coil 8; 8' via the middle element-region 2b and vice versa.

[0070] Various geometrical dimensions of the first and second mandrel 3, 6, the superconducting element 2 and ultimately of the pre-coils 4, 7, 7' and coils 5, 8, 8' are conceivable and are preferably determined based on a design of the superconducting magnet implementing the multi-coil 1 , T.

[0071] Figures 3a to 3c depict photographs of a superconducting coil 1 corresponding to a 140 m DP. That is, said double pancake coil example here was wound using HTS element with a total length of 140 meter. The element has a width of 12 mm and thickness of 43 urn. The small winding diameters of 3.5 mm to 5 mm benefit greatly from the thin thickness of the element 2. A length of the first element-region 2a is about half of the total length of the superconducting element 2 and thus here is about 70 meter. A length of the second element-region 2c is about half of the total length of the superconducting element 2 thus here is about 70 meter. A length of the middle element-region 2b is much smaller than the length of the first element-region 2a and the second element-region 2c and is here about 1- 2 meter. Moreover, in this example, a length of the first mandrel 3 along the longitudinal direction Lm1 of the first mandrel 3 is here about 5 centimeter. In these depicted examples, a number of turns of the first element region 2a forming the first coil 5 and of the second element region 2c forming the second coil 8, 8' is about 643. An outer diameter d1 of the first coil 5 and an outer diameter d2; d2' of the second coil 8, 8' is in the range of 10 to 100 millimeter such as about 63 mm. An inner diameter di1 of the first coil 5 and an inner diameter di2; di2' of the second coil 8; 8' is in the range of 1 millimeter to 10 millimeter such as about 4.2 mm. However, it is again emphasised that these values are just an example.

[0072] Figure 3d shows helium test data of the 140 m jointless double pancake coil. A magnetic field of 47 T was measured at a maximum current of 1248 A, demonstrating the feasibility of the jointless connection in coil fabrication for small-bore high-field superconducting magnets.

[0073] Hence, the present invention provides manufacturing methods for superconducting-multi- coils 1 , T that can be implemented as high-field small-bore HTS magnets using wide elements without any solder joint. Using the winding approaches according to the invention, a 47 Tesla magnetic field was achieved in an HTS coil with only handheld size.

[0074] LIST OF REFERENCE SIGNS

[0075] 1 , T multi-coil

[0076] 2 superconducting element

[0077] 2a first element-region

[0078] 2b middle element-region

[0079] 2b1 first part of middle element-region

[0080] 2b2 second part of middle element-region

[0081] 2c second element-region

[0082] 3 first mandrel

[0083] 4 first pre-coil

[0084] 5 first coil

[0085] 6 second mandrel

[0086] 7, 7' second pre-coil

[0087] 8, 8' second coil

[0088] 9 bottom side of first coil

[0089] 10, 10' bottom side of second coil

[0090] 11 top side of first coil

[0091] 12 top side of second coil

[0092] 13 bottom end of first mandrel

[0093] 14 top end of first mandrel

[0094] 15 bottom end of second mandrel

[0095] 16 top end of second mandrel

[0096] 17 jointless connection

[0097] 21, 2T output lead

[0098] 22 input lead

[0099] Lc, Lc' longitudinal direction of multi-coil

[0100] Lm1 longitudinal direction of first mandrel

[0101] Lm2 longitudinal direction of second mandrel d1 outer diameter of first coil d2, d2' outer diameter of second coil di1 inner diameter of first coil di2, di2' inner diameter of second coil

Claims

CLAIMS1. A method of manufacturing a jointless superconducting multi-coil (1 , T) comprising the steps of:- Providing a superconducting element (2) defining a first element-region (2a), a second element-region (2c), and a middle element-region (2b) being arranged between the first element-region (2a) and the second element-region (2c);Winding a first part (2b1) of the middle element-region (2b) around at least part of a first mandrel (3) so as to form a first pre-coil (4) of a first coil (5);Winding at least part of the first element-region (2a) around at least part of the first mandrel (3) so as to form the first coil (5); and i) Winding a second part (2b2) of the middle element-region (2b) around at least part of a second mandrel (6) so as to form a second pre-coil (7) of a second coil (8) and winding at least part of the second element-region (2c) around at least part of the second mandrel (6) so as to form the second coil (8), or ii) Winding a second part (2b2) of the middle element-region (2b) around at least part of the first mandrel (3) so as to form a second pre-coil (7') of a second coil (8') and winding at least part of the second element-region (2c) around at least part of the first mandrel (3) so as to form the second coil (8'), and wherein the multi-coil (1 , T) comprising the first coil (5) and the second coil (8, 8') preferably being arranged above one another with respect to a longitudinal direction (Lc, Lc') of the multi-coil (1 , T) is formed.

2. The method according to claim 1 , wherein the first pre-coil (4) is formed by winding the first part (2b1) of the middle element-region (2b) in a spiral about a longitudinal direction (Lm1) of the first mandrel (3), and / or wherein a pitch between successive turns of the first pre-coil (4) are gradually reduced with respect to a longitudinal direction (Lm1) of the first mandrel (3) and preferably is zero in the region of the first coil (5), and / or wherein the first coil (5) is formed in a region of a bottom end (13) of the first mandrel (3).

3. The method according to any one of the preceding claims, wherein at least one of:- a number of turns of the first part (2b1) of the middle element-region (2b) forming the first pre-coil (4) and / or of the second part (2b2) of the middle element-region (2b)forming the second pre-coil (7, 7') is in the range of 1 to 10'000,- a number of turns of the first element region (2a forming the first coil (5) and / or of the second element region (2c) forming the second coil (8, 8') is in the range of 1 to 10'000,- an outer diameter (d1) of the first coil and / or an outer diameter (d2; d2') of the second coil (8, 8') is in the range of 100 micrometer to 2 meter,- an inner diameter (di 1 ) of the first coil (5) and / or an inner diameter (di2; di2') of the second coil (8; 8') is in the range of 50 micrometer to 1 meter, or- a number of turns of the first part (2b1) of the middle element-region (2b) forming the first pre-coil (4) and / or a number of turns of the second part (2b2) of the middle element-region (2b) forming the second pre-coil (7; 7') is in the range of 1 to 10'000.

4. The method according to any one of the preceding claims, wherein the second precoil (7) is formed by winding the second part (2b2) of the middle element-region (2b) in a spiral about a longitudinal direction (Lm2) of the second mandrel (6), and / or wherein a pitch between successive turns of the second pre-coil (7) is gradually reduced with respect to a longitudinal direction (Lm2) of the second mandrel (6) and preferably is zero in the region of the second coil (8), and / or wherein the second coil (8) is formed in a region of a bottom end (15) of the second mandrel (6).

5. The method according to any one of the preceding claims, wherein the first coil (5) and the second coil (8) after being wound are arranged above one another such, that a bottom side (9) of the first coil (5) facing away from the first mandrel (3) faces a bottom side (10) of the second coil (8) facing away from the second mandrel (6).

6. The method according to any one of the preceding claims, wherein part of the first part (2b1) of the middle element-region (2b) and / or part of the second part (2b2) of the middle element-region (2b) extends freely and / or unwound between the first pre-coil (4) and the second pre-coil (7).

7. The method according to any one of claims 1 to 3, wherein the second part (2b2) of the middle element-region (2b) is wound around the first mandrel (3) after the first part (2b1) of the middle element-region (2b) that has already been wound about the first mandrel (3).

8. The method according to any one of claims 1 to 3 or 7, wherein the first coil (5) andthe second coil (8') are arranged above one another with respect to the longitudinal direction (Lc1) of the multi-coil (T) such, that a bottom side (10') of the second coil (8') faces a top side (11) of the first coil (5).

9. The method according to any one of claims 1 to 3 or 7 to 8, wherein the first coil (5) and the second coil (8') are arranged immediately above one another with respect to the longitudinal direction (Lc1) of the multi-coil (T).

10. The method according to any one of the preceding claims, wherein the outermost turn of the first coil (5) transitions into an output lead (21) that is configured to input or output current from the multi-coil (1 ; T) and / or wherein the outermost turn of the second coil (8; 8') transitions into a current lead (22; 22') that is configured to input or output current from a power source into the multi-coil (1 ; T) and vice versa, and / or wherein the multi-coil (1 ; T) is configured such that current can flow from the first coil (5) to the second coil (8; 8') and vice versa via the middle element-region (2b).

11. The method according to claim 10, wherein at least one protection element is at least partially wound about the input lead (22; 22') and / or the output lead (21), and wherein the protection element is configured to mechanically and / or thermally stabilize the input lead (22; 22') and / or the output lead (21) and preferably is a further superconducting element.

12. A superconducting magnet for a scientific and / or industrial instrument such as a nuclear magnetic resonance spectrometer, an electron paramagnetic resonance spectrometer, and a gyrotron, comprising at least one multi-coil (1 ; T) manufactured in the method according to any one of the preceding claims.

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