JP6607120B2 - Superconducting magnetic field generator and nuclear magnetic resonance apparatus - Google Patents

Description

  The present invention relates to a superconducting magnetic field generator and a nuclear magnetic resonance apparatus.

  Nuclear magnetic resonance (NMR) is a resonance phenomenon of energy of nuclear spin (magnetic moment) generated when an electromagnetic wave is applied to a sample placed in a strong magnetic field. A nuclear magnetic resonance apparatus (NMR apparatus) is an instrument that analyzes the structure of a sample using such a resonance phenomenon. Since the sensitivity and resolution of the NMR signal increase as the magnetic field strength increases, the NMR apparatus is provided with a magnetic field generator for generating a strong magnetic field.

  As a magnetic field generator that generates a strong magnetic field, a superconducting magnetic field generator that generates a magnetic field by magnetizing a superconductor has been developed. As the superconductor provided in the superconducting magnetic field generator, a high-temperature superconductor having a high superconducting transition temperature and relatively easy cooling is preferably used.

  In analyzing the molecular structure of the sample by the NMR apparatus, the sample is placed in a magnetic field. At this time, if the magnetic field intensity varies greatly depending on the location, the obtained NMR spectrum becomes broad and the molecular structure of the sample cannot be properly identified. Therefore, the superconducting magnetic field generator used in the NMR apparatus is configured to generate a strong magnetic field and to form a magnetic field having a uniform magnetic field intensity (uniform magnetic field) in the measurement space of the sample. Is preferred.

  For high-resolution NMR measurement, a magnetic field uniformity of 1 ppm or less is required. A highly uniform magnetic field of 1 ppm or less can usually be achieved by adding a plurality of shim coils (magnetic field correction coils) to the superconducting magnetic field generator. In other words, the uniformity of the magnetic field generated by the superconducting magnetic field generator must be at least on the order of ppm that can be corrected by the shim coil.

  The superconductor provided in the superconducting magnetic field generator used in the NMR apparatus is formed in a cylindrical shape, for example. In this case, a magnetic field (applied magnetic field) is applied to the superconductor by the external magnetic field generator so that a magnetic field through which the magnetic flux passes in the axial direction is generated in the inner circumferential space (bore) of the cylindrical superconductor. Then, the superconductor is cooled to a temperature not higher than the superconducting transition temperature while the magnetic field is applied. After the cooling is completed, the applied magnetic field generated by the external magnetic field generator is removed. Then, the superconductor is magnetized so as to maintain the applied magnetic field, and a superconducting current is induced in the superconductor. As a result of the superconducting current flowing in the superconductor in this way, a magnetic field (capture magnetic field) through which the magnetic flux passes in the axial direction is formed in the bore of the superconductor. A space (room temperature bore space) in which the sample is placed is formed in the bore of the superconductor where the trapping magnetic field is formed. By applying electromagnetic waves to the sample placed in the room temperature bore space, weak electromagnetic waves are emitted from the sample. An NMR spectrum is obtained by detecting this electromagnetic wave.

  In order to improve the analysis accuracy of the sample, the trapped magnetic field formed in the bore of the cylindrical superconductor has an axisymmetric magnetic field strength distribution (that is, perpendicular to the central axis of the cylindrical superconductor) as shown in FIG. It is preferable that the magnetic field strength is uniform in the central portion (the space in which the sample is placed). In order to obtain such a trapping magnetic field, the superconducting current flowing in the magnetized superconductor must be a circular current flowing in the circumferential direction around the central axis of the cylindrical superconductor. In other words, the superconducting current loop that is concentric with the ring shape represented by the cross section perpendicular to the axial direction of the superconductor is formed in the superconductor. This is necessary in order to form a trapped magnetic field with a uniform magnetic field strength. However, when the material structure or superconducting characteristics of the superconductor used is not uniform, the superconducting current loop is formed in a distorted shape different from the concentric shape. That is, the superconducting current loop is disturbed. When the superconducting current loop is disturbed, the axial symmetry of the magnetic field in the bore of the superconductor is broken and the uniformity is deteriorated, so that the magnetic field intensity distribution is axisymmetric and the trapped magnetic field with a uniform magnetic field strength in the central part is obtained. It cannot be formed in the bore of a superconductor. Therefore, the material structure and superconducting characteristics of the superconductor should be uniform.

By the way, as a high-temperature superconductor, a RE-Ba-Cu-O-based superconducting bulk (RE is a rare earth element including Y) manufactured by a melting method is well known. However, such a superconducting bulk has the following characteristics (hereinafter referred to as non-uniform characteristics) that disturb the superconducting current loop.
(1) Since the superconducting bulk is produced by growing a single crystal from a seed crystal placed on the superconductor, it has a crystal growth boundary. For example, when a superconducting bulk is produced by growing a crystal from a seed crystal placed so that the c-plane of the crystal structure is in contact with the superconductor, the crystal grows in a cross shape around the seed crystal as viewed from above. A cross-shaped crystal growth boundary is formed in the superconducting bulk. When the superconducting bulk formed in this manner is magnetized, the shape of the superconducting current loop formed in the superconducting bulk becomes a quadrangular shape that connects adjacent crystal growth boundaries. That is, when the superconducting current flows so as to swell outward at the crystal growth boundary portion, the superconducting current loop is disturbed and a concentric superconducting current loop is not formed. As a result, the axial symmetry of the trapped magnetic field formed in the bore of the superconductor is broken and the uniformity is deteriorated.
(2) A superconducting bulk as a high-temperature superconductor has a structure in which a non-superconducting phase is finely dispersed in a single crystal superconducting phase. The non-superconducting phase forms a pinning point that captures a strong magnetic field, but the size and distribution of the non-superconducting phase varies, and such variation disturbs the superconducting current loop formed in the superconducting bulk.
(3) The superconducting bulk has non-uniform material structure such as vacancies, unnecessary precipitates, the presence of microcracks, and disorder of crystallinity. Such non-uniformity in material structure disturbs the superconducting current loop formed in the superconducting bulk.
(4) The superconducting bulk has local variations in superconducting characteristics (superconducting transition temperature Tc, critical current density Jc, etc.). This also disturbs the superconducting current loop.

  Therefore, when a superconducting bulk is used for the high-temperature superconductor provided in the superconducting magnetic field generator, the superconducting current loop is disturbed by the above-mentioned non-uniform characteristics. It is difficult to form a uniform trapping magnetic field.

  Patent Document 1 discloses an outer superconductor formed in a cylindrical shape by a high-temperature superconducting material, and an inner superconductor formed in a cylindrical shape by a high-temperature superconducting material and arranged coaxially with the outer superconductor on the inner peripheral side of the outer superconductor. Disclosed is a superconducting magnetic field generating device comprising: a body; and a cooling device that generates cold for cooling the outer superconductor and the inner superconductor to a temperature equal to or lower than a superconducting transition temperature. The inner superconductor provided in this superconducting magnetic field generator is configured such that the uniformity of the critical current density in the cylindrical circumferential surface is higher than the uniformity of the critical current density of the outer superconductor in the cylindrical circumferential surface. The Here, the cylindrical peripheral surface is a surface parallel to the outer peripheral surface and inner peripheral surface of the cylindrical superconductor, that is, a circle that forms the outer periphery and inner periphery of the cylindrical superconductor when viewed from the axial direction. It is a surface forming a coincident circle or a concentric circle.

  According to the superconducting magnetic field generator described in Patent Document 1, the superconductor (upper conductor) is formed by compensating the disturbance of the superconducting current loop formed in the outer superconductor with the superconducting current loop formed in an arbitrary direction in the inner superconductor. The axial symmetry and uniformity of the trapping magnetic field formed in the bore of the inner superconductor) is maintained.

JP 2006-006825 A

(Problems to be solved by the invention)
Patent Document 1 shows an example in which a cylindrical base material having a cylindrical portion is provided on the inner peripheral side of an inner superconductor (see FIG. 8 of Patent Document 1). An inner superconductor made of a superconducting ribbon (superconducting tape wire) is wound around the outer peripheral surface of the cylindrical portion of the cylindrical base material. The cylindrical base material is connected to the cold head of the cooling device. Therefore, the cold generated by the cold head is transmitted to the inner superconductor via the cylindrical base material. In this case, in order to improve the transmission efficiency of the cold heat from the cylindrical base material to the inner superconductor, generally, the inner superconductor is bonded to the entire outer peripheral surface of the cylindrical base material with an adhesive. Accordingly, the cold heat generated in the cold head is transmitted to the inner superconductor through the cylindrical portion of the cylindrical base material and the adhesive.

  As shown in FIG. 8 of the above-mentioned Patent Document 1, when the inner superconductor is formed in a cylindrical shape in a state where the inner superconductor is adhered to the entire outer peripheral surface of the cylindrical portion of the cylindrical base material with an adhesive, Thermal stress acts on the inner superconductor due to the difference between the heat shrinkage rate of the inner superconductor and the heat shrinkage rate of the inner superconductor. There is a risk of damage to the inner superconductor due to such thermal stress.

  In particular, when the inner superconductor is composed of a superconducting ribbon, there is a high possibility that the inner superconductor will be damaged due to thermal stress acting during cooling. This is because a superconducting ribbon manufactured using a high-temperature superconductor, particularly a RE-Ba-Cu-O-based high-temperature superconductor, is a multilayer in which a plurality of films including a superconducting film are laminated on a metal thin film substrate. Because it has a structure, it is weak to the tensile stress acting in the thickness direction (stacking direction), and if the tensile stress acts as a thermal stress on the inner superconductor during cooling, the superconducting ribbon constituting the inner superconductor is easily peeled off Because it does.

  The present invention relates to a superconducting magnetic field generator comprising an outer superconductor and an inner superconductor, the inner superconductor being wound around a cylindrical portion of a cylindrical base material, and the inner superconductor caused by thermal stress acting during cooling. It is an object of the present invention to provide a superconducting magnetic field generator having a structure in which body damage is suppressed, and a nuclear magnetic resonance apparatus having such a superconducting magnetic field generator.

(Means for solving the problem)
The present invention provides an outer superconductor (2) that generates a trapped magnetic field by capturing an applied magnetic field in a state of being formed into a cylindrical shape by a high-temperature superconducting material and cooled to a temperature equal to or lower than the superconducting transition temperature, And is arranged coaxially with the outer superconductor on the inner peripheral side of the outer superconductor, and the uniformity of the critical current density in the cylindrical peripheral surface is the criticality of the outer superconductor in the cylindrical peripheral surface. An inner superconductor (3) having a higher current density uniformity, and a cooling device (5) for generating cold for cooling the outer superconductor and the inner superconductor to temperatures below the superconducting transition temperature, respectively, The cooling device includes a cylindrical substrate (53) having a cylindrical portion (531) disposed coaxially with the outer superconductor in the inner peripheral space of the outer superconductor, and the inner superconductor is a peripheral surface of the cylindrical portion. Wrapped around One, in a state of being partially adhered to the peripheral surface of the cylindrical portion, provided on the inner peripheral side of the outer superconductors are arranged outside superconductor coaxial with, the superconducting magnetic field generating apparatus (100, 101).

  According to the present invention, the cylindrical inner superconductor arranged coaxially with the outer superconductor is provided on the inner peripheral side of the cylindrical outer superconductor. The inner superconductor is formed in a cylindrical shape by being wound around the peripheral surface of the cylindrical portion of the cylindrical base material. Further, the inner superconductor is not bonded to the entire circumferential surface of the cylindrical portion, but is partially bonded to the circumferential surface of the cylindrical portion. Therefore, when the inner superconductor is cooled, there is a region where the inner superconductor is subjected to thermal stress (for example, tensile stress) from the cylindrical portion through the bonding portion due to the difference between the thermal contraction rate of the cylindrical portion and the thermal shrinkage rate of the inner superconductor. Small compared to the case of full adhesion. That is, by partially bonding the inner superconductor to the cylindrical portion, thermal stress (for example, tensile stress) acting on the inner superconductor from the cylindrical portion is reduced. As a result, damage to the inner superconductor due to thermal stress generated during cooling, for example, peeling of the superconducting ribbon constituting the inner superconductor due to tensile stress generated during cooling is suppressed.

  In the present invention, the peripheral surface of the cylindrical portion around which the inner superconductor is wound may be an outer peripheral surface or an inner peripheral surface. Further, the inner superconductor may have any original shape as long as it can be formed in a cylindrical shape. For example, the inner superconductor may be configured by winding a sheet-shaped superconductor (superconducting sheet) around the circumferential surface of the cylindrical portion and deforming it into a cylindrical shape. More preferably, the inner superconductor is constituted by a long superconducting thin ribbon (superconducting tape wire) (3A). This is because the superconducting ribbon is easy to handle among existing superconducting materials and can be easily deformed into a desired shape (for example, a cylindrical shape). Here, the superconducting ribbon means a material having a tape shape (that is, a shape that is very thin and formed long in one direction) and can exhibit superconducting properties.

  When a superconducting thin ribbon is used as the inner superconductor, the aspect for forming it into a cylindrical shape may be any form. For example, the inner superconductor may be formed in a cylindrical shape by connecting the superconducting ribbons formed in a ring shape with both ends connected in the axial direction. More preferably, the inner superconductor is formed in a cylindrical shape by winding a superconducting ribbon in a spiral shape around the circumferential surface of the cylindrical portion. In other words, the inner superconductor is preferably formed in a cylindrical shape by a long superconducting ribbon that is spirally wound around the circumferential surface of the cylindrical portion with the axial direction of the cylindrical portion as the translation direction. The inner superconductor formed in a cylindrical shape is preferably partially bonded to the peripheral surface of the cylindrical portion at a plurality of spaced positions. In other words, the bonding position of the inner superconductor to the cylindrical portion may be a plurality of spaced bonding positions. According to this, a cylindrical inner superconductor can be easily produced by spirally winding a single long superconducting ribbon on the peripheral surface of the cylindrical portion.

  When the inner superconductor is formed in a cylindrical shape by spirally winding the superconducting ribbon on the circumferential surface of the cylindrical portion, the inner superconductor is cylindrical at both end positions in the longitudinal direction of the superconducting ribbon constituting it. It may be partially bonded to the peripheral surface of the part. That is, the bonding position of the inner superconductor to the peripheral surface of the cylindrical portion is preferably the both end positions in the longitudinal direction of the superconducting ribbon constituting the cylindrical superconductor. In other words, the inner superconductor formed in a cylindrical shape by spirally winding the superconducting ribbon around the peripheral surface of the cylindrical portion is bonded to the peripheral surface of the cylindrical portion at both end positions in the axial direction of the cylindrical portion. It is good to have. According to this, the minimum necessary region for fixing the superconducting ribbon spirally wound around the circumferential surface of the cylindrical portion to the cylindrical portion, that is, the position of the beginning of winding of the superconducting ribbon on the circumferential surface of the cylindrical portion and The inner superconductor is bonded to the circumferential surface of the cylindrical portion only at the winding end position. By reducing the bonding area as much as possible in this way, thermal stress (for example, tensile stress) acting on the inner superconductor during cooling is further reduced. Therefore, damage such as peeling of the superconducting ribbon constituting the inner superconductor is further suppressed. In addition, after applying an adhesive on both ends of the cylindrical portion in the axial direction, a superconducting ribbon is spirally wound around the peripheral surface of the cylindrical portion, so that the inner superconductor can be easily partly provided on the peripheral surface of the cylindrical portion. Can be glued.

  In addition, the inner superconductor formed in a cylindrical shape by a superconducting ribbon spirally wound around the cylindrical portion is a plurality of linear regions that are separated in the circumferential direction and extend linearly in a direction including an axial component. You may adhere | attach partially on the surrounding surface of a cylindrical part. That is, the bonding position of the inner superconductor to the peripheral surface of the cylindrical portion may be a plurality of linear regions that are separated in the circumferential direction and linearly extend in the direction including the axial component. In this case, each linear region may be a region extending linearly in a direction including an axial component so as to straddle each spiral winding of the superconducting ribbon spirally wound on the peripheral surface of the cylindrical portion. According to this, since the adhesion region of the inner superconductor to the peripheral surface of the cylindrical portion extends linearly in the direction including the axial direction of the cylindrical inner superconductor, the cylindrical inner superconductor is cooled during cooling. Is cooled substantially uniformly along the axial direction through an adhesive extending linearly in a direction including the axial direction. In addition, by applying an adhesive so as to extend in a direction including the axial component at a plurality of positions spaced apart in the circumferential direction of the cylindrical portion, it is easy to spirally wind a superconducting ribbon around the cylindrical portion. In addition, the inner superconductor can be partially bonded to the peripheral surface of the cylindrical portion.

  Further, the inner superconductor is formed in a cylindrical shape by a long superconducting ribbon that is spirally wound around the circumferential surface of the cylindrical portion with the axial direction of the cylindrical portion as a translation direction, and a plurality of spaced apart positions. The first inner superconductor (31) partially bonded to the peripheral surface of the cylindrical portion and the peripheral surface of the first inner superconductor are spirally wound around the axial direction of the cylindrical portion as a translation direction. A second inner superconductor (32) which is formed in a cylindrical shape by a long superconducting ribbon and is partially bonded to the peripheral surface of the first inner superconductor at a plurality of spaced positions. , May be provided. In this case, the position of the side edge of each spiral winding of the superconducting ribbon constituting the second inner superconductor is the position of the side edge of each spiral winding of the superconducting ribbon constituting the first inner superconductor. It is good that it is wound around the peripheral surface of the first inner superconductor so as not to coincide with.

  When the inner superconductor is formed into a cylindrical shape by spirally winding the superconducting ribbon, a superconducting current loop is formed at the position straddling the side edge of each spiral winding of the superconducting ribbon constituting the inner superconductor. Can not do it. On the other hand, as described above, the position of the side edge of each spiral winding of the superconducting ribbon constituting the first inner superconductor and the side of each spiral winding of the superconducting ribbon constituting the second inner superconductor When superconducting ribbons that make up each superconductor are spirally wound so that the positions of the edges do not match, they are formed across the side edges of the spiral winding of the superconducting ribbon that constitutes one inner superconductor The superconducting current loop to be performed can be formed in the superconducting ribbon constituting the other inner superconductor. For this reason, the number of superconducting current loops that can be formed increases, and as a result, the uniformity of the magnetic field in the inner space (room temperature bore space) of the inner superconductor is further enhanced.

  In this case, the bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion and the bonding position of the second inner superconductor to the circumferential surface of the first inner superconductor are different with the first inner superconductor interposed therebetween. It should be a position (ie not the same position). In other words, the position where the first inner superconductor is bonded to the cylindrical portion and the position where the first inner superconductor is bonded to the second inner superconductor are the superconductivity constituting the first inner superconductor. The same position in the direction perpendicular to the front and back surfaces (tape surface) of the ribbon should not be. According to this, the bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion and the bonding position of the second inner superconductor to the circumferential surface of the first inner superconductor are on the front and back surfaces of the first inner superconductor. Deviation from the vertical direction. For this reason, the first inner superconductor does not receive thermal stress (for example, tensile stress) from both sides at the same position during cooling. Therefore, damage such as peeling of the superconducting ribbon constituting the first inner superconductor can be further suppressed.

  The first inner superconductor is partially bonded to the peripheral surface of the cylindrical portion at both end positions in the longitudinal direction of the superconducting ribbon constituting the first inner superconductor, and the second inner superconductor is superconducting thin film constituting the first inner superconductor. You may adhere | attach partially on the surrounding surface of a 1st inner superconductor in the both ends position in the longitudinal direction of a belt | band | zone. That is, the bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion is the position of both ends in the longitudinal direction of the superconducting ribbon constituting the first inner superconductor, and the first inner superconductor is positioned on the circumferential surface of the first inner superconductor. The bonding positions of the two inner superconductors may be both end positions in the longitudinal direction of the superconducting ribbon constituting the second inner superconductor. In other words, the first inner superconductor formed in a cylindrical shape by spirally winding a superconducting ribbon on the circumferential surface of the cylindrical portion is formed on the circumferential surface of the cylindrical portion at both end positions in the axial direction of the cylindrical portion. The second inner superconductor formed in a cylindrical shape by being bonded and spirally wound around the peripheral surface of the first inner superconductor is at both end positions in the axial direction of the first inner superconductor, It is good to adhere to the peripheral surface of the first inner superconductor. According to this, the first inner superconductor is bonded to the circumferential surface of the cylindrical portion at the minimum necessary region only at the winding start position and winding end position of the superconducting ribbon spirally wound around the cylindrical portion, The second inner superconductor is bonded to the peripheral surface of the first inner superconductor in the minimum necessary region only at the winding start position and the winding end position of the superconducting ribbon spirally wound around the one inner superconductor. By reducing the bonding area as much as possible in this way, thermal stress (for example, tensile stress) acting on the inner superconductor during cooling is further reduced. Therefore, damage such as peeling of the superconducting ribbons constituting the first inner superconductor and the second inner superconductor is further suppressed. In addition, the first inner superconductor and the second inner superconductor can be partially bonded easily.

  Further, the bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion is a plurality of linear regions that are separated in the circumferential direction and linearly extend in the direction including the axial component, and the first inner superconductor The bonding position of the second inner superconductor to the peripheral surface of the plurality of linear regions may be a plurality of linear regions that are separated in the circumferential direction and linearly extend in a direction including the axial component. In this case, the bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion and the bonding position of the second inner superconductor to the circumferential surface of the first inner superconductor are preferably shifted in the circumferential direction. Furthermore, in this case, each adhesion region of the first inner superconductor to the circumferential surface of the cylindrical portion includes an axial component so as to straddle each helical winding of the superconducting ribbon spirally wound on the circumferential surface of the cylindrical portion. It is preferable that the region extends linearly in the direction. Similarly, each adhesion region of the second inner superconductor to the circumferential surface of the first inner superconductor straddles each spiral winding of the superconducting ribbon spirally wound on the circumferential surface of the first inner superconductor, It may be a region extending linearly in a direction including the axial component.

  According to this, since the adhesion region of the first inner superconductor to the cylindrical portion extends linearly in a direction including the axial direction of the cylindrical first inner superconductor, the cylindrical first The inner superconductor is cooled substantially uniformly along the axial direction through an adhesive extending linearly in a direction including the axial direction. Similarly, the adhesion region of the second inner superconductor to the first inner superconductor extends linearly in the direction including the axial direction of the cylindrical second inner superconductor. The two inner superconductors are substantially uniformly cooled along the axial direction via an adhesive extending linearly in a direction including the axial direction. In addition, the first inner superconductor and the second inner superconductor can be partially bonded easily. Further, since the bonding position of the first inner superconductor and the bonding position of the second inner superconductor are shifted in the circumferential direction, the first inner superconductor is thermally stressed from both sides at the same position during cooling (for example, tensile stress). Not receive. For this reason, damage such as peeling of the first inner superconductor is effectively suppressed.

  In addition, the elastic modulus of the material used for bonding is part or all of the gap between the cylindrical portion and the first inner superconductor and the gap between the first inner superconductor and the second inner superconductor. It is preferable that a filler having a smaller elastic modulus is filled. According to this, the gap formed between the cylindrical portion and the first inner superconductor in the unbonded region, and the unbonded region between the first inner superconductor and the second inner superconductor. Since some or all of the gaps formed in the filler are filled with a filler that is more easily deformed than the adhesive, the thermal stress (for example, tensile stress) acting on the filler filling area is reduced during cooling. It is weaker than the thermal stress (for example, tensile stress) acting on the region. Therefore, damage such as peeling of the superconducting ribbon during cooling is suppressed as compared with the case of full adhesion. In addition, at the time of cooling, the first inner superconductor and / or the second inner superconductor are also cooled through the filler, so that the first inner superconductor and / or the second inner superconductor can be efficiently and uniformly provided. Can be cooled.

  Any filler may be used as long as the elastic modulus is smaller than the elastic modulus of the adhesive. For example, when an epoxy adhesive is used, grease, wax, silicone, or the like is suitably used as the filler.

  Also, a cover portion formed in a cylindrical shape so as to face the peripheral surface of the second inner superconductor and opposite to the surface partially bonded to the peripheral surface of the first inner superconductor May be provided. In this case, the cover part may be connected to the cylindrical base material. According to this, the 2nd inner superconductor can be cooled also from the cover part connected to the cylindrical base material. Therefore, the cooling efficiency is further improved.

  Furthermore, in this case, a part or the whole of the gap between the second inner superconductor and the cover portion may be filled with a filler having an elastic modulus smaller than that of the material used for bonding. According to this, at the time of cooling, the second inner superconductor is cooled via the filler. Therefore, the cooling efficiency is further improved.

  In addition, the cooling device according to the present invention includes a cold head disposed to face one end surface of the outer superconductor, and the cylindrical base member has one end of the cylindrical portion closed so as to close one end of the cylindrical portion. It is good to have a fixed part connected to the part. And it is good for the fixing | fixed part to be fixed to the cold head. According to this, since the cylindrical base material is directly fixed to the cold head, heating of the cylindrical base material due to heat generation of the outer superconductor when magnetizing the outer superconductor and the inner superconductor is suppressed. For this reason, the inner superconductor is efficiently and uniformly cooled through the cylindrical portion of the cylindrical base material.

  The present invention also provides a nuclear magnetic resonance apparatus including the superconducting magnetic field generation apparatus having the above-described configuration. According to this, it is possible to provide a nuclear magnetic resonance apparatus including a superconducting magnetic field generator having a structure in which damage to the inner superconductor due to thermal stress acting during cooling of the outer superconductor and the inner superconductor is suppressed. .

It is the schematic showing the cross section which cut | disconnected the superconducting magnetic field generator which concerns on 1st embodiment by the plane containing the centerline along an up-down direction. It is the schematic which shows the cross section which cut | disconnected the superconducting thin ribbon which comprises an inner superconductor by the plane containing a longitudinal direction and thickness direction. It is a figure which shows the state by which the superconducting thin ribbon was spirally wound by the outer peripheral surface of the cylindrical part. It is a figure which shows schematic structure of a nuclear magnetic resonance apparatus. It is a figure which shows typically the superconducting current which is flowing into the outer superconductor when the trapping magnetic field is generated in the bore of the superconductor by the superconducting magnetic field generator. It is a figure which shows typically the correction | amendment electric current loop formed in an inner superconductor. It is the schematic showing the cross section which cut | disconnected the superconducting magnetic field generator which concerns on 2nd embodiment by the plane containing the center line along the up-down direction. It is a figure which shows the state by which the inner side superconductor which concerns on 3rd embodiment is wound around the cylindrical part of the cylindrical base material which concerns on 2nd embodiment. It is a figure which shows the 1st inner superconductor and 2nd inner superconductor which concern on 3rd embodiment separately. In 4th embodiment, it is a figure which shows the adhesion position of the 1st inner superconductor to the outer peripheral surface of a cylindrical part. In 4th embodiment, it is a figure which shows the adhesion position of the 2nd inner superconductor to the outer peripheral surface of a 1st inner superconductor. It is a perspective view which shows the state which the adhesion | attachment of the 1st inner superconductor which concerns on 4th embodiment, and the adhesion | attachment of the 2nd inner superconductor were completed. It is the schematic which shows the adhesion state of the 1st inner superconductor which concerns on 4th embodiment, and the adhesion state of the 2nd inner superconductor from the cross section containing the central axis line of a cylindrical part. It is the schematic which shows the adhesion state of the 1st inner side superconductor which concerns on 5th embodiment, and the adhesion state of the 2nd inner side superconductor from the cross section containing the center axis line of a cylindrical part. It is the schematic which shows the adhesion state of the inner side superconductor which concerns on 6th embodiment from the cross section containing the central axis of a cylindrical part. It is the schematic which shows the state by which the inner side superconductor which concerns on 7th embodiment is adhere | attached on the cylindrical part of the cylindrical base material from the cross section containing the central axis of a cylindrical part. In 8th embodiment, it is a figure which shows the adhesion position of the 1st inner superconductor to the outer peripheral surface of a cylindrical part. In 8th embodiment, it is a figure which shows the adhesion position of the 2nd inner superconductor to the outer peripheral surface of a 1st inner superconductor. It is the schematic which shows the adhesion state of the 1st inner superconductor which concerns on 8th embodiment, and the adhesion state of the 2nd inner superconductor from the cross section perpendicular | vertical to the axial direction of a cylindrical part. It is the schematic which shows the adhesion state of the 1st inner superconductor which concerns on 8th embodiment, and the adhesion state of the 2nd inner superconductor from the cross section perpendicular | vertical to the axial direction of a cylindrical part. It is II sectional drawing of FIG. It is II-II sectional drawing of FIG. FIG. 3 is a diagram showing a trapped magnetic field formed in a bore of a superconductor, wherein the magnetic field strength distribution is axisymmetric and the central portion has a uniform magnetic field strength.

(First embodiment)
First, the first embodiment will be described. FIG. 1 is a schematic diagram illustrating a cross section of the superconducting magnetic field generation device 100 according to the first embodiment cut along a plane including a center line along the vertical direction. As shown in FIG. 1, a superconducting magnetic field generation device 100 includes a superconductor 1, a holder 4, a cooling device 5, a vacuum heat insulating container 6, and an external magnetic field generation coil 7 (external magnetic field generation device).

  The cooling device 5 may be any device as long as it generates a low temperature not higher than the superconducting transition temperature Tc (for example, 90K) of the high-temperature superconductor, for example, a low temperature (cool) of about 50K. Examples of the cooling device 5 include a pulse tube refrigerator, a GM refrigerator, and a Stirling refrigerator. The cooling device 5 is preferably a device that generates cold by performing a refrigeration cycle operation, but is a substance that can provide a temperature lower than the superconducting transition temperature Tc of a high-temperature superconductor, such as liquid nitrogen. Also good.

  In the present embodiment, the cooling device 5 includes a mechanism for generating a low temperature inside. The cooling device 5 includes a cold head 52 and a cylindrical base material 53. The cold head 52 is cooled by the operation of the mechanism inside the cooling device 5. The cold head 52 is formed of a nonmagnetic material having high thermal conductivity, such as copper. The cold head 52 includes a columnar column portion 52a and a disk-shaped stage portion 52b. In FIG. 1, the column part 52 a is provided in the upper part of the cooling device 5. The upper end (the other end) of the column part 52a is connected to one end face of the disc-shaped stage part 52b. The column part 52a and the stage part 52b may be integrally formed.

  The holder 4 and the cylindrical base material 53 are placed on the other surface (upper surface) of the stage portion 52b. The cylindrical base material 53 has a cylindrical portion 531 formed in a cylindrical shape and having an outer peripheral surface 531 a and an inner peripheral surface 531 b, and a flange portion 532 formed at one end of the cylindrical portion 531. Then, the flange portion 532 is placed on the stage portion 52 b of the cold head 52. The cylindrical base material 53 is formed of a nonmagnetic metal having a high thermal conductivity. For example, examples of the material of the cylindrical base material 53 include copper, aluminum, and sapphire (alumina single crystal).

  The superconductor 1 includes an outer superconductor 2 and an inner superconductor 3 as shown in FIG. The outer superconductor 2 is formed in a cylindrical shape by stacking a plurality of ring-shaped superconducting bulks 2a along the axial direction. The cylindrical outer superconductor 2 may be constituted by one superconducting bulk. One end face (lower end face) of the cylindrical outer superconductor 2 is placed on the flange portion 532 of the cylindrical base material 53 placed on the stage portion 52 b of the cold head 52. At this time, the outer superconductor 2 is placed on the flange portion 532 so that the cylindrical portion 531 of the cylindrical base material 53 is coaxially disposed with the outer superconductor 2 in the inner circumferential space of the outer superconductor 2.

  An inner superconductor 3 is disposed on the inner peripheral side of the outer superconductor 2. The inner superconductor 3 is also formed in a cylindrical shape like the outer superconductor 2. However, the length (thickness) in the radial direction of the inner superconductor 3 is very thin compared to the length (thickness) in the radial direction of the outer superconductor 2. The inner superconductor 3 is wound around the outer peripheral surface 531 a of the cylindrical portion 531 of the cylindrical base material 53 and is partially bonded to the outer peripheral surface 531 a of the cylindrical portion 531. Since the cylindrical portion 531 and the outer superconductor 2 are coaxially arranged as described above, the inner superconductor 3 wound around the outer peripheral surface 531 a of the cylindrical portion 531 is arranged on the inner peripheral side of the outer superconductor 2. Will be arranged coaxially. The outer peripheral surface of the inner superconductor 3 may or may not be in contact with the inner peripheral surface of the outer superconductor 2.

  The outer superconductor 2 and the inner superconductor 3 are type 2 superconductors and are formed of a high-temperature superconducting material. In the present embodiment, the outer superconductor 2 is a RE-Ba-Cu-O (RE is a rare earth element including Y) series superconductor, and is formed by a well-known melting method. The outer superconductor 2 is a high-temperature superconductor having a layered crystal structure in which the c-axis direction is a stacking direction (a direction perpendicular to the layer), and the c-axis direction of the crystal structure coincides with the axial direction of the outer superconductor 2 Thus, it is formed by crystal growth from a seed crystal. The inner superconductor 3 is a high-temperature superconductor having a layered crystal structure in which the c-axis direction is the stacking direction (direction perpendicular to the layer), and the c-axis direction of the crystal structure coincides with the radial direction of the inner superconductor 3. Formed as follows.

  In the present embodiment, the inner superconductor 3 is composed of a superconducting ribbon (superconducting tape wire). A superconducting ribbon is a material that is very thin, is formed long in one direction, and can exhibit superconducting properties. FIG. 2 is a schematic view showing a cross section of the superconducting ribbon 3A constituting the inner superconductor 3 taken along a plane including the longitudinal direction and the thickness direction. As shown in FIG. 2, the superconducting ribbon 3A includes an intermediate layer 3b, a superconducting film 3c composed of a RE-BBa-Cu-O based superconductor, a protective layer on a thin film metal substrate 3a composed of Hastelloy or the like. The stabilization layer 3e composed of the layer 3d, Cu or the like has a multilayer structure laminated in this order. The superconducting film 3c is formed so that the c-axis direction of the crystal structure coincides with the direction perpendicular to the tape surface, that is, the surface perpendicular to the thickness direction of the superconducting ribbon (the direction of arrow A in FIG. 2).

  Since the superconducting ribbon 3A has a multilayer structure as described above, the superconducting film 3c is easily peeled off when a tensile stress acts in the stacking direction (thickness direction). That is, it is easy to peel off by a tensile stress perpendicular to the tape surface (surface perpendicular to the thickness direction). Therefore, it is preferable that a large tensile stress does not act on the superconducting ribbon 3A in a direction perpendicular to the tape surface.

  In the present embodiment, the inner superconductor 3 is formed by winding a long superconducting thin ribbon 3A having the structure shown in FIG. 2 around the outer peripheral surface 531a of the cylindrical portion 531 of the cylindrical base 53 in a spiral shape. It is formed in a cylindrical shape. FIG. 3 is a view showing a state in which the superconducting ribbon 3A is spirally wound around the outer peripheral surface 531a of the cylindrical portion 531. In FIG. 3, the cylindrical portion 531 is indicated by a one-dot chain line, and the superconducting ribbon 3A spirally wound is indicated by a solid line. As shown in FIG. 3, the superconducting ribbon 3A is spirally wound around the outer peripheral surface 531a of the cylindrical portion 531 with the axial direction (vertical direction in FIG. 3) of the cylindrical portion 531 as the translation direction. In this case, the superconducting ribbon 3A is such that the inner peripheral surface side of the cylindrical inner superconductor 3 is on the thin metal substrate 3a side of the superconducting ribbon 3A and the outer peripheral surface is on the stabilizing layer 3e side of the superconducting ribbon 3A. Is spirally wound. Note that both end portions in the translation direction of the superconducting thin ribbon 3 </ b> A wound spirally are cut obliquely along the axial end portion of the cylindrical portion 531.

  When the cylindrical inner superconductor 3 is formed by spiral winding of the superconducting ribbon 3A, the direction perpendicular to the tape surface of the superconducting ribbon 3A, that is, the c-axis direction of the crystal structure is the diameter of the cylindrical inner superconductor 3. Match the direction. Therefore, the inner superconductor 3 is formed so that the c-axis direction of the crystal structure coincides with the radial direction.

  Further, before the superconducting ribbon 3A is spirally wound around the outer peripheral surface 531a of the cylindrical portion 531, it is partially bonded to the outer peripheral surface 531a of the cylindrical portion 531 at a plurality of spaced positions as shown by, for example, black circles in FIG. The agent 9 is applied, and the superconducting ribbon 3A is spirally wound around the outer peripheral surface 531a of the cylindrical portion 531 after the adhesive 9 is applied. Thus, the inner peripheral surface of the inner superconductor 3 is partially bonded to the outer peripheral surface 531a of the cylindrical portion 531 at a plurality of spaced positions. The adhesive is not particularly limited as long as it can adhere the inner peripheral surface of the inner superconductor 3 (superconducting ribbon 3A) to the outer peripheral surface 531a of the cylindrical portion 531. For example, an epoxy-based adhesive Can be used.

  As shown in FIG. 1, the holder 4 has a cylindrical main body 41 having an inner diameter substantially the same as the outer diameter of the outer superconductor 2, and extends radially outward from the lower end of the main body 41 in FIG. 1. 1 and the end surface portion 43 formed in a ring shape by extending radially inward from the upper end of the main body portion 41 in FIG. It has a bottomed cylindrical shape. When the fixing portion 42 of the holder 4 is placed on the stage portion 52b, the holder 4 is fixed to the stage portion 52b. The superconductor 1 (the outer superconductor 2 and the inner superconductor 3) is disposed in the inner circumferential space of the main body 41 of the holder 4. In the state where the holder 4 is fixed on the stage portion 52b, the outer peripheral surface of the outer superconductor 2 contacts the inner peripheral surface of the main body portion 41 of the holder 4, and the upper end surface of the outer superconductor 2 in FIG. It contacts the lower surface of the end surface portion 43 of the holder 4. In this way, the outer superconductor 2 is held by the holder 4. Similarly to the cold head 52, the holder 4 is also made of a nonmagnetic material having a high thermal conductivity such as copper or aluminum.

  The vacuum heat insulating container 6 has a cylindrical main body 61 having an inner diameter larger than the outer diameter of the main body 41 of the holder 4, and extends radially outward from the lower end in FIG. 1 of the main body 61. A fixing portion 62 formed in a ring shape and an upper surface portion 63 formed in a ring shape by extending radially inward from the upper end in FIG. Further, the fixing portion 62 is airtightly fixed to the cooling device 5. The superconductor 1, the holder 4, the cold head 52, and the cylindrical base material 53 are accommodated in the inner peripheral space of the main body 61.

  As shown in FIG. 1, the cylindrical container 8 is inserted into the inner peripheral space of the vacuum heat insulating container 6 from a circular opening surrounded by the inner peripheral wall of the upper surface portion 63 of the vacuum heat insulating container 6. The cylindrical container 8 includes a bottomed cylindrical container portion 81 and a lid portion 82 that extends radially outward from the opening end of the container portion 81, and the lid portion 82 is an upper surface of the vacuum heat insulating container 6. The part 63 is placed on the upper surface in FIG. The container portion 81 enters the bore (inner peripheral space) of the superconductor 1 so as to face the inner peripheral surface 531 b of the cylindrical portion 531 of the cylindrical base material 53. That is, the container part 81 is disposed in the bore of the superconductor 1. For example, a sample to be analyzed by an NMR apparatus is placed in the space in the container portion 81. The space in the container portion 81 is provided in the approximate center of the bore of the superconductor 1. This space is called a room temperature bore space. In the present embodiment, the room temperature bore space has a cylindrical shape.

  Further, the gap between the outer peripheral surface of the upper portion of the container 81 and the inner peripheral surface of the ring-shaped upper surface portion 63 is hermetically sealed by a sealing means (not shown). Thereby, the opening formed in the upper surface portion 63 is closed. Further, as described above, the fixing portion 62 of the vacuum heat insulating container 6 is airtightly fixed to the cooling device 5. Therefore, a sealed space partitioned by the vacuum heat insulating container 6, the cooling device 5, and the cylindrical container 8 is formed above the cooling device 5 in FIG. 1. In this sealed space, superconductor 1 (outer superconductor 2, inner superconductor 3), holder 4, cold head 52, and cylindrical base material 53 are disposed. The vacuum heat insulating container 6 is formed of a nonmagnetic material such as an aluminum alloy.

  Moreover, as shown in FIG. 1, the external magnetic field generation coil 7 is provided so that the outer periphery of the cylindrical main-body part 61 of the vacuum heat insulation container 6 may be enclosed. A magnetic field is generated by energizing the external magnetic field generating coil 7. Hereinafter, the magnetic field generated by energizing the external magnetic field generating coil 7 may be referred to as an applied magnetic field. The applied magnetic field is formed at least in the inner space of the external magnetic field generating coil 7. Accordingly, a magnetic field is applied to the superconductor 1 by the operation of the external magnetic field generating coil 7. At this time, a magnetic field is formed in the bore of the superconductor 1 so that the magnetic flux passes along the axial direction of the outer superconductor 2 and the inner superconductor 3.

  The operation of the superconducting magnetic field generation apparatus 100 having the above configuration will be described. First, the inside of the sealed space formed in the inner peripheral space of the main body 61 of the vacuum heat insulating container 6 is exhausted using an exhaust device (not shown). Thereby, the pressure in the sealed space is reduced so as to be in a vacuum state (for example, 0.1 Pa or less). Thereafter, the applied magnetic field is generated by operating the external magnetic field generating coil 7. In this case, as described above, a magnetic field through which magnetic flux passes along the axial direction of the outer superconductor 2 and the inner superconductor 3 is formed in the space in the bore of the superconductor 1. A magnetic field is applied to the space in the bore of the superconductor 1 so that the magnetic field strength distribution is axisymmetric and the magnetic field strength in the room temperature bore space is uniformly distributed in the radial direction and the axial direction. (Magnetic field application process).

  The cooling device 5 is operated while the magnetic field is applied to the superconductor 1 by the operation of the external magnetic field generating coil 7. As a result, the cold head 52 is cooled, and the cylindrical base material 53 and the holder 4 placed on the stage portion 52b of the cold head 52 are cooled. The inner superconductor 3 is wound around the outer peripheral surface 531 a of the cylindrical portion 531 of the cylindrical base material 53 via the adhesive 9. Therefore, the inner superconductor 3 is cooled via the cylindrical portion 531 and the adhesive. Further, the outer superconductor 2 is cooled via the flange portion 532 and the holder 4 of the cylindrical base material 53. In this case, the outer superconductor 2 and the inner superconductor 3 are cooled to temperatures below their respective superconducting transition temperatures (cooling step).

  During the cooling process, up to a temperature slightly higher than the higher one of the superconducting transition temperature Tco of the outer superconductor 2 and the superconducting transition temperature Tci of the inner superconductor 3 (temperature Ts> Tco, Tci immediately before superconducting), When the outer superconductor 2 and the inner superconductor 3 are cooled, the external magnetic field generating coil 7 is controlled so that the axial direction of the superconductor 1 (the outer superconductor 2 and the inner superconductor 3) and the room temperature bore space The applied magnetic field is adjusted so that a uniform magnetic field with a uniform magnetic field strength distribution in the radial direction is formed (magnetic field adjusting step). By this magnetic field adjustment step, the influence of the change in magnetization that has occurred in the superconductor 1 so far on the applied magnetic field is canceled.

  When the temperature of the outer superconductor 2 and the temperature of the inner superconductor 3 are lowered to temperatures below the respective superconducting transition temperatures due to cooling by the cooling device 5, the outer superconductor 2 and the inner superconductor 3 are brought into a superconducting state. At this time, that is, when the temperature of the outer superconductor 2 and the temperature of the inner superconductor 3 are equal to or lower than the superconducting transition temperature, the operation of the external magnetic field generating coil 7 is stopped and the applied magnetic field is removed. Then, in response to the change in the magnetic field strength accompanying the removal of the applied magnetic field, a superconducting current is induced in the outer superconductor 2 so as to restore the state of the magnetic field. A magnetic field is generated by the superconducting current thus induced flowing in the outer superconductor 2. That is, the outer superconductor 2 is magnetized. The magnetic field generated by the magnetization of the outer superconductor 2 is basically the same as the applied magnetic field generated by the operation of the external magnetic field generating coil 7. That is, when the superconducting current flows through the outer superconductor 2, the outer superconductor 2 captures the applied magnetic field generated by the operation of the external magnetic field generating coil 7 (magnetic field capturing step). When the outer superconductor 2 captures the applied magnetic field, a magnetic field is generated in the bore of the superconductor 1. A magnetic field generated by capturing a magnetic field is sometimes called a captured magnetic field.

  Next, a nuclear magnetic resonance apparatus using the trapped magnetic field generated by the superconducting magnetic field generator 100 will be briefly described. FIG. 4 is a diagram showing a schematic configuration of the nuclear magnetic resonance apparatus 110. The nuclear magnetic resonance apparatus 110 includes a superconducting magnetic field generation apparatus 100, a detection coil 120, and analysis means 130. The detection coil 120 is disposed in the container portion 81 (in the room temperature bore space) of the cylindrical container 8 disposed in the bore of the superconductor 1. A sample P to be measured is disposed on the inner peripheral side of the detection coil 120. The analysis means 130 includes a high frequency generator 131, a pulse programmer (transmitter) 132, a high frequency amplifier 133, a preamplifier (signal amplifier) 134, a phase detector 135, an analog-digital (A / D) converter 136, and a computer. 137.

  When the superconducting magnetic field generator 100 is operated, a trapping magnetic field is formed in the bore of the superconductor 1 as described above. Next, the uniformity of the magnetic field strength of the captured magnetic field is improved by adjusting the captured magnetic field with a shim coil (not shown). At this time, the captured magnetic field is adjusted by the shim coil so that the uniformity of the magnetic field strength in the room temperature bore space is 1 ppm or less. Then, the sample P is placed in the room temperature bore space. In this state, the high frequency generator 131 is operated. Then, the high frequency pulse generated by the high frequency generator 131 is energized to the detection coil 120 through the pulse programmer 132 and the high frequency amplifier 133, and the sample P is irradiated with a pulse electromagnetic wave (radio wave). Due to nuclear magnetic resonance that occurs when the sample P placed in a magnetic field is irradiated with radio waves, a minute current flows through the detection coil 120 provided around the sample P. A signal (NMR signal) representing this minute current is passed to the computer 137 via the preamplifier 134, the phase detector 135, and the A / D converter 136. The computer 137 calculates an NMR spectrum based on the delivered NMR signal. The molecular structure of the sample P is analyzed from the obtained NMR spectrum.

  As will be described later, when the superconducting magnetic field generator 100 according to this embodiment is used, the uniformity of the trapped magnetic field generated in the room temperature bore space is high. Therefore, the peak of the NMR spectrum obtained from the minute current detected by the detection coil 120 is clear. Therefore, the analysis accuracy of the molecular structure of the sample P is improved.

  Next, the superconducting current flowing in the outer superconductor 2 when the trapping magnetic field is generated by the superconducting magnetic field generator 100 will be described. FIG. 5 is a diagram schematically showing a superconducting current flowing in the outer superconductor 2 when a trapped magnetic field is generated in the bore of the superconductor 1 by the operation of the superconducting magnetic field generator 100. As described above, the applied magnetic field is formed so that the magnetic flux flows in the space in the bore of the superconductor 1 along the axial direction of the outer superconductor 2 and the inner superconductor 3, so that the trapped magnetic field is the same. It is formed so that the magnetic flux flows through. Such a trapping magnetic field is maintained by the superconducting current continuously flowing around the central axis of the outer superconductor 2 along the circumferential direction. At this time, the superconducting current forms a circular superconducting current loop that goes around the central axis of the outer superconductor 2. By forming a circular superconducting current loop, a trapping magnetic field is formed such that magnetic flux flows in the bore of the superconductor 1 in the axial direction.

  In general, the superconducting current starts to flow from the outside of the diameter of the cylindrical superconductor. As the superconducting current increases, the superconducting current also flows inwardly of the superconductor. The magnitude of the superconducting current is proportional to the magnitude of the trapped magnetic field. Therefore, when the trapping magnetic field is very large, the superconducting current for forming the trapping magnetic field flows not only in the outer superconductor 2 but also in the inner superconductor 3. However, in the present embodiment, a trapping magnetic field having the same magnitude as the applied magnetic field is theoretically configured so that a superconducting current flows only in the outer superconductor 2. In other words, the applied magnetic field is set smaller than the magnitude of the magnetic field formed when the theoretically maximum superconducting current can flow through the outer superconductor 2.

  When a magnetic field is applied by the external magnetic field generating coil 7 in the bore of the superconductor 1 such that the magnetic field strength distribution is axisymmetric and the magnetic field strength is uniform in the central portion (room temperature bore space). The superconducting current loop formed in the outer superconductor 2 in order to obtain the same trapping magnetic field as the applied magnetic field is within the cross section perpendicular to the central axis of the outer superconductor 2 and around the outer superconductor 2 around the central axis. A circle concentric with the outer peripheral shape (or inner peripheral shape) of the outer superconductor 2 is drawn along the direction. FIG. 5 shows such an ideal superconducting current loop R.

  If the material properties and superconducting properties of the outer superconductor 2 are completely uniform, an ideal superconducting current loop R as shown in FIG. 5 should be formed. However, since the outer superconductor 2 is formed of a superconducting bulk, the outer superconductor 2 has the above-described non-uniform characteristics, and there are a portion where current easily flows and a portion where current does not easily flow. Since the superconducting current flows while avoiding a portion where current does not easily flow, if the superconductor has non-uniform characteristics, the superconducting current loop is likely to be formed in a distorted shape instead of the concentric circle described above. That is, the superconducting current loop is likely to be disturbed. Therefore, even if the applied magnetic field formed in the bore of the superconductor 1 has an axisymmetric distribution and the magnetic field strength at the center portion (room temperature bore portion) is uniform, Due to the uniform properties, the superconducting current loop actually formed in the outer superconductor 2 is disturbed. In FIG. 5, the turbulent superconducting current loop R 'is shown in dotted lines. The magnetic field obtained by a turbulent superconducting current loop is inhomogeneous. This impairs the axial symmetry and uniformity of the captured magnetic field.

  In the present embodiment, the inner superconductor 3 is coaxially provided inside the outer superconductor 2. When the axial symmetry and uniformity of the trapped magnetic field are impaired by the disturbance of the superconducting current loop formed in the outer superconductor 2, the loop of the superconducting current (correction current) for correcting the trapped magnetic field is the inner superconductor. 3 is formed. By forming such a correction current loop in the inner superconductor 3, a magnetic field that returns the non-uniform trapping field formed by the turbulent superconducting current loop formed in the outer superconductor 2 to the uniform trapping field. Is formed. As a result, the axial symmetry and uniformity of the captured magnetic field are maintained. Therefore, a trapping magnetic field in which the magnetic field strength distribution is axisymmetric and the magnetic field strength at the central portion is uniform is formed in the bore of the superconductor 1.

  FIG. 6 is a diagram schematically showing a correction current loop formed in the inner superconductor 3. Since the correction current loop is formed according to the disturbance of the superconducting current loop formed in the outer superconductor 2, its shape changes variously. For example, as shown in correction current loops L1 and L2 in FIG. 6, a correction current loop formed by a superconducting current flowing only in a partial region in the circumferential direction in the cylindrical peripheral surface can be formed. That is, the inner superconductor 3 is formed with a correction current loop having an arbitrary shape within the cylindrical circumferential surface. When the cylindrical inner superconductor 3 is formed by spirally winding the superconducting ribbon 3A as in this embodiment, the correction current loop is a spirally wound superconducting ribbon. A correction current loop having an arbitrary shape is formed in a region that does not cross the boundary between adjacent windings of 3A.

  The reason why a correction current loop having an arbitrary shape is formed on the cylindrical peripheral surface of the inner superconductor 3 will be described. The critical current density Jc of the cylindrical superconductor is represented by the critical current density Jcz in the axial direction, the critical current density Jcr in the radial direction, and the critical current density Jcθ in the circumferential direction. Further, at a certain point, the direction of Jcz, the direction of Jcr, and the direction of Jcθ are orthogonal. Therefore, a plane orthogonal to Jcθ is defined by Jcz and Jcr, a plane orthogonal to Jcz is defined by Jcr and Jcθ, and a plane orthogonal to Jcr is defined by Jcθ and Jcz. A surface orthogonal to Jcr is a cylindrical peripheral surface. That is, the cylindrical peripheral surface is defined by Jcθ and Jcz. Here, the cylindrical peripheral surface is a surface parallel to the outer peripheral surface and inner peripheral surface of the cylindrical superconductor, that is, a circle that forms the outer periphery and inner periphery of the cylindrical superconductor when viewed from the axial direction. It is a surface forming a coincident circle or a concentric circle.

  Further, as described above, the inner superconductor 3 is formed so that the c-axis direction of the crystal structure coincides with the radial direction. In general, in a superconductor having a layered crystal structure in which the c-axis direction is the stacking direction (direction perpendicular to the layer), the critical current density in the c-axis direction is low and the critical current density in the direction orthogonal to the c-axis direction is high. . Furthermore, the critical current density in the plane orthogonal to the c-axis direction is substantially equal. From this, in the inner superconductor 3, it can be said that the critical current density Jcr1 in the radial direction is low, the critical current density Jcz1 in the axial direction and the critical current density Jcθ1 in the circumferential direction are high, and Jcz1 and Jcθ1 are substantially equal. That is, the relationship of Jcθ1≈Jcz1> Jcr1 is established.

  The c-axis direction of the crystal structure of the outer superconductor 2 coincides with the axial direction of the outer superconductor 2 as described above. Therefore, the critical current density Jcz2 of the superconducting current flowing in the axial direction of the outer superconductor 2 is larger than the critical current density Jcr2 of the superconducting current flowing in the radial direction of the outer superconductor 2 and the critical current density Jcθ2 of the superconducting current flowing in the circumferential direction. small. Jcr2 and Jcθ2 are substantially equal. That is, the relationship of Jcr2≈Jcθ2> Jcz2 is established.

  The uniformity of the critical current density on the cylindrical peripheral surface of the cylindrical superconductor can be expressed by the ratio of the critical current density Jcθ in the circumferential direction to the critical current density Jcz in the axial direction (Jcθ / Jcz), and the ratio (Jcθ / It can be said that the closer Jcz) is to 1, the more uniform the critical current density on the cylindrical peripheral surface. Here, in the inner superconductor 3, since Jcz1 and Jcθ1 are substantially equal, the ratio (Jcθ1 / Jcz1) is close to 1. On the other hand, in the outer superconductor 2, since Jcz2 is smaller than Jcθ2, the ratio (Jcθ2 / Jcz2) is considerably larger than 1. That is, the ratio of the critical current density of the inner superconductor 3 (Jcθ1 / Jcz1) is closer to 1 than the ratio of the critical current density of the outer superconductor 2 (Jcθ2 / Jcz2). In short, the uniformity of the critical current density on the cylindrical peripheral surface of the inner superconductor 3 is higher than the uniformity of the critical current density on the cylindrical peripheral surface of the outer superconductor 2.

  When the critical current density in the plane is high and the critical current density in the plane is uniform, the superconducting current easily flows in the plane. That is, the superconducting current easily flows in the cylindrical peripheral surface of the inner superconductor 3. Therefore, a superconducting current loop (correction current loop) having an arbitrary shape is formed in the cylindrical peripheral surface of the inner superconductor 3.

  By forming a correction current loop of an arbitrary shape in the cylindrical peripheral surface of the inner superconductor 3, the magnetic field strength distribution is axisymmetric and the magnetic field strength at the central portion is uniformly captured in the bore of the superconductor 1. Mention why the magnetic field can be formed. When the magnetic field strength distribution of the applied magnetic field formed in the bore of the superconductor 1 is axisymmetric and the magnetic field strength of the applied magnetic field in the central portion is uniform, the applied magnetic field is present in the outer superconductor 2. A superconducting current loop should be formed such that the same trapping magnetic field is formed. However, when a superconducting current loop that cannot form the same magnetic field as the applied magnetic field due to the non-uniform characteristics of the outer superconductor 2 is formed in the outer superconductor 2, a magnetic field that is the difference between the applied magnetic field and the trapped magnetic field. Is captured by a correction current loop formed in the inner superconductor 3. Here, as described above, the inner superconductor 3 can form a superconducting current loop (corrected current loop) having an arbitrary shape in the cylindrical peripheral surface thereof. Therefore, by forming one or more superconducting current loops of any shape at any position within the region of the inner circumferential surface of the superconductor 3 where the superconducting current loop can be formed, It is possible to form a magnetic field having an arbitrary intensity through which a magnetic flux passes in an arbitrary direction. That is, regardless of the magnetic field of the difference, a superconducting current loop (corrected current loop) having an arbitrary shape is formed in the cylindrical peripheral surface of the inner superconductor 3 so that a magnetic field corresponding to the magnetic field is formed. Is formed. As a result, the non-uniform trapping magnetic field is compensated to maintain the axial symmetry and uniformity of the trapping magnetic field. For this reason, it is possible to form a trapped magnetic field in the bore of the superconductor 1 in which the magnetic field strength distribution is axisymmetric and the central portion has a uniform magnetic field strength. Therefore, it is possible to form a trapped magnetic field having a uniform magnetic field strength in the axial direction and along the radial direction in the room temperature bore space arranged in the central portion of the bore of the superconductor 1.

  In the present embodiment, as described above, the c-axis direction of the crystal structure of the cylindrical outer superconductor 2 coincides with the axial direction, while the c-axis direction of the crystal structure of the cylindrical inner superconductor 3. Corresponds to the radial direction. The direction of the applied magnetic field (the direction in which the magnetic flux flows) is the axial direction of the superconductor 1. That is, a magnetic field is applied to the outer superconductor 2 so that a magnetic flux flows in the c-axis direction, and a magnetic field is applied to the inner superconductor 3 so that a magnetic flux flows perpendicularly to the c-axis direction. Here, the superconductor has a property that the critical current density is decreased by application of a magnetic field, but the superconductor also has a property that the amount of decrease in the critical current density is changed depending on the application direction of the magnetic field. The amount of decrease in critical current density when a magnetic field is applied so that magnetic flux flows perpendicularly to the c-axis direction is less than the amount of decrease in critical current density when magnetic field is applied so that magnetic flux flows in the c-axis direction. Few. That is, the amount of decrease in critical current density in the inner superconductor 3 is smaller than the amount of decrease in critical current density in the outer superconductor 2. Therefore, even when the outer superconductor 2 and the inner superconductor 3 have the same material composition, the critical current density of the inner superconductor 3 is larger than the critical current density of the outer superconductor 2 due to the difference in the c-axis direction. Become. As described above, since the critical current density of the inner superconductor 3 is large, it is possible to prevent the correction current loop from being limited by the critical current density. Therefore, an appropriate correction current loop corresponding to the disturbance of the superconducting loop formed in the outer superconductor 2 can be formed in the inner superconductor 3, and as a result, the magnetic field strength distribution is more axisymmetric. In addition, it is possible to form a trapping magnetic field having a uniform magnetic field strength in the central portion.

  Incidentally, as described above, in order to form a supplementary magnetic field in the room temperature bore space, the superconductor 1 (the outer superconductor 2 and the inner superconductor 3) is cooled to a temperature equal to or lower than the superconducting transition temperature in the cooling step. In addition, the inner superconductor 3 is bonded to the outer peripheral surface 531 a of the cylindrical portion 531 of the cylindrical base material 53 via the adhesive 9. Therefore, in the cooling process, the inner superconductor 3 is cooled via the cylindrical portion 531 and the adhesive.

  Further, at the time of cooling, the inner superconductor 3, the cylindrical portion 531 and the adhesive 9 are thermally contracted. In this case, when each of the inner superconductor 3, the adhesive 9, and the cylindrical portion 531 has a different heat shrinkage rate, thermal stress acts on the inner superconductor 3 due to the difference in heat shrinkage rate. In particular, when the thermal contraction rate of the cylindrical portion 531 is larger than the thermal contraction rate of the inner superconductor 3, a tensile stress is received from the cylindrical portion 531 that causes the inner superconductor 3 to be pulled radially inward during cooling.

  The tensile stress described above acts on the inner superconductor 3 via the adhesive 9. That is, a tensile stress acts on the adhesion region of the inner superconductor 3 to the outer peripheral surface 531 a of the cylindrical portion 531. Therefore, when the adhesion area by the adhesive 9 is large, a large tensile stress acts on the inner superconductor 3. For example, when the entire surface of the inner superconductor 3 is bonded to the outer peripheral surface 531 a of the cylindrical portion 531 by the adhesive 9, a very large tensile stress acts on the inner superconductor 3.

  Such tensile stress acts in a direction perpendicular to the tape surface of the superconducting ribbon 3A constituting the inner superconductor 3. Therefore, when the tensile stress is large, there is a high possibility that damage such as peeling of the superconducting ribbon 3A occurs.

  In this regard, in this embodiment, the inner superconductor 3 is partially bonded to the outer peripheral surface 531a of the cylindrical portion 531 with an adhesive. Therefore, the adhesion area is small compared to the case of full adhesion. Therefore, the tensile stress acting on the inner superconductor 3 from the cylindrical portion 531 due to the difference in thermal shrinkage during cooling is also small. Therefore, the occurrence of damage such as peeling of the superconducting ribbon 3A constituting the inner superconductor 3 is suppressed.

  As described above, the superconducting magnetic field generation apparatus 100 according to the present embodiment is formed in a cylindrical shape from a high-temperature superconducting material, and captures an applied magnetic field while being cooled to a temperature equal to or lower than the superconducting transition temperature. The outer superconductor 2 is formed in a cylindrical shape by a high-temperature superconducting material, and is arranged coaxially with the outer superconductor 2 on the inner circumferential side of the outer superconductor 2 and has a uniform critical current density in the circumferential surface of the cylinder. For cooling the inner superconductor 3, and the outer superconductor 2 and the inner superconductor 3 to a temperature lower than the superconducting transition temperature, which are higher than the uniformity of the critical current density of the outer superconductor 2 in the cylindrical circumferential surface. And a cooling device 5 that generates cold heat. Further, the cooling device 5 includes a cylindrical substrate 53 having a cylindrical portion 531 disposed coaxially with the outer superconductor 2 in the inner circumferential space of the outer superconductor 2. The inner superconductor 3 is wound around the outer peripheral surface 531a of the cylindrical portion 531 and is partially bonded to the outer peripheral surface 531a of the cylindrical portion 531 so that the outer superconductor is disposed on the inner peripheral side of the outer superconductor 2. 2 and coaxial.

  According to the present embodiment, since the inner superconductor 3 is partially bonded to the outer peripheral surface 531a of the cylindrical portion 531, the thermal contraction rate of the cylindrical portion 531 and the inner superconductor 3 are reduced when the inner superconductor 3 is cooled. The region where the inner superconductor 3 receives thermal stress (tensile stress) from the cylindrical portion 531 through the bonding site due to the difference from the thermal contraction rate is small compared to the case of full-surface bonding. That is, by partially bonding the inner superconductor 3 to the cylindrical portion 531, thermal stress (tensile stress) acting on the inner superconductor 3 from the cylindrical portion 531 is reduced. As a result, damage to the inner superconductor 3 due to thermal stress (tensile stress) generated during cooling, for example, peeling of the superconducting ribbon 3A constituting the inner superconductor 3 is suppressed.

  The inner superconductor 3 is formed in a cylindrical shape by a long superconducting thin ribbon 3A wound spirally around the outer peripheral surface 531a of the cylindrical portion 531 with the axial direction of the cylindrical portion 531 as the translation direction. The inner superconductor 3 thus formed in a cylindrical shape is partially bonded to the peripheral surface of the cylindrical portion at a plurality of spaced positions. For this reason, the cylindrical inner superconductor 3 can be easily produced from one long superconducting ribbon 3A.

(Second embodiment)
Next, a second embodiment will be described. The superconducting field generator according to this embodiment is basically the above except for the structure of the cooling device, more specifically, the configuration of the cold head and the cylindrical base material. The configuration is the same as that of the superconducting magnetic field generator 100 according to the first embodiment. Therefore, with respect to the configuration other than the configuration described below, the same reference numerals as those in the first embodiment are used, and a specific description thereof will be omitted. Hereinafter, differences will be mainly described.

  FIG. 7 is a schematic diagram showing a cross section of the superconducting magnetic field generation apparatus 101 according to the present embodiment cut along a plane including a center line along the vertical direction. As shown in FIG. 7, the cooling device 5 provided in the superconducting magnetic field generation device 101 according to the present embodiment is similar to the cooling device 5 according to the first embodiment, and includes a cold head 52 having a column portion 52a and a stage portion 52b. And a cylindrical substrate 53.

  In the present embodiment, a concave portion 52c having a circular cross section perpendicular to the vertical direction in FIG. 7 is formed at the center of the surface (upper surface in FIG. 7) of the stage portion 52b of the cold head 52. The cylindrical base material 53 includes a cylindrical cylindrical portion 531 having an outer peripheral surface 531a and an inner peripheral surface 531b, and one end of the cylindrical portion 531 so as to close one end surface (lower end surface in FIG. 7) of the cylindrical portion 531. And a disk-shaped fixing portion 533 connected to the end face of the. The diameter of the fixing portion 533 is slightly smaller than the diameter of the concave portion 52c formed on the surface of the stage portion 52b.

  Then, the fixing portion 533 of the cylindrical base material 53 is fitted in a recess 52 c formed on the surface of the stage portion 52 b of the cold head 52. The fixing part 533 fitted in the recess 52c is fixed to the stage part 52b of the cold head 52 by a bolt BT. Thereby, the fixing | fixed part 533 of the cylindrical base material 53 is directly fixed to the cold head 52 (stage part 52b) in the state embedded at the stage part 52b. The outer superconductor 2 is directly placed on the stage portion 52 b of the cold head 52. Other configurations are the same as those in the first embodiment.

  According to this embodiment, since the fixing portion 533 of the cylindrical base material 53 is fixed in an embedded state in the stage portion 52b of the cold head 52, the amount of cold heat transmitted from the cold head 52 to the cylindrical base material 53 is increased. be able to. For this reason, the cooling process time can be shortened. Furthermore, heating of the cylindrical base material 53 due to heat generation of the outer superconductor 2 when the outer superconductor 2 and the inner superconductor 3 are magnetized is suppressed. For this reason, the inner superconductor 3 is efficiently and uniformly cooled through the cylindrical portion 531 of the cylindrical base material 53.

(Third embodiment)
Next, although the third embodiment will be described, the superconducting magnetic field generator according to this embodiment basically generates the superconducting magnetic field according to the first embodiment or the second embodiment except for the configuration of the inner superconductor 3. The same as the devices 100 and 101. Hereinafter, different points will be mainly described.

  In this embodiment, the inner superconductor includes two superconductors formed in a cylindrical shape by spirally winding a superconducting ribbon. These two cylindrical superconductors are superposed to form an inner superconductor.

  FIG. 8 is a diagram illustrating a state in which the inner superconductor 3 according to the present embodiment is wound around the cylindrical portion 531 of the cylindrical base material 53 according to the second embodiment. In FIG. 8, the cylindrical portion 531 is indicated by a one-dot chain line. As shown in FIG. 8, the inner superconductor 3 according to this embodiment includes a first inner superconductor 31 and a second inner superconductor 32. Both the first inner superconductor 31 and the second inner superconductor 32 are cylindrical. The first inner superconductor 31 is provided on the outer peripheral side of the cylindrical portion 531, and the second inner superconductor 32 is provided on the outer peripheral side of the first inner superconductor 31.

  FIG. 9 is a diagram showing the first inner superconductor 31 and the second inner superconductor 32 separately. FIG. 9A shows the first inner superconductor 31 and FIG. 9B shows the second inner superconductor. A superconductor 32 is shown. As can be seen from FIG. 9A, the first inner superconductor 31 is a long superconducting thin film that is spirally wound around the outer peripheral surface 531 a of the cylindrical portion 531 with the axial direction of the cylindrical portion 531 as the translation direction. It is formed in a cylindrical shape by the band 3A. 9B, the second inner superconductor 32 is formed on the outer peripheral surface 31a of the first inner superconductor 31 formed in a cylindrical shape in the axial direction of the cylindrical portion 531 (that is, the first inner superconductor). It is formed in a cylindrical shape by a long superconducting thin ribbon 3A wound spirally with the axial direction of the body 31 as the translation direction.

  Further, as shown in FIG. 9A, among the spiral windings of the spirally wound superconducting ribbon 3A constituting the first inner superconductor 31, the side edges of the windings adjacent to each other in the axial direction are gaps. I ’ll be dating. For this reason, a boundary line B1 between adjacent side edges is formed in a spiral shape. Similarly, as shown in FIG. 9B, among the spiral windings of the spirally wound superconducting ribbon 3A constituting the second inner superconductor 32, the side edges of the windings adjacent in the axial direction are adjacent to each other. Dating without gaps. Therefore, a boundary line B2 between adjacent side edges is formed in a spiral shape.

  Further, as can be seen by comparing FIG. 9A and FIG. 9B, the formation position of the spiral boundary line B1 formed on the first inner superconductor 31 (that is, the first inner superconductor 31 is The position of the side edge of each spiral winding of the spirally wound superconducting ribbon 3A and the position where the spiral boundary line B2 formed on the second inner superconductor 32 is formed (that is, the second inner superconductor 32). The boundary line B1 and the boundary line B2 are shifted in the axial direction of the cylindrical portion 531 so that the spiral winding superconducting ribbon 3A constituting the spiral winding 3A does not coincide with each other. Therefore, among the correction current loops formed in the inner superconductor 3 when the magnetic field is captured, the correction current loop L6 straddling the spiral boundary B2 formed in the second inner superconductor 32 is the first inner superconductor. A correction current loop L 7 formed in the first inner superconductor 31 and straddling the boundary line B 1 formed in the first inner superconductor 31 is formed in the second inner superconductor 32.

  Thus, the first inner superconductor 31 and the second inner superconductor 32 are wound by spirally winding two long superconducting ribbons so that the positions of the respective side edges are different from each other. By configuring the inner superconductor 3 provided with a correction current loop to be formed at a position straddling one side edge, the other superconducting ribbon is formed. That is, the induced correction current loop is always formed in one of the superconducting ribbons. Therefore, a correction current loop having an arbitrary shape can be formed in the inner superconductor 3 in the inner superconductor 3.

  The first inner superconductor 31 is partially bonded to the outer peripheral surface 531 a of the cylindrical portion 531 with an adhesive, and the second inner superconductor 32 is bonded to the outer peripheral surface 31 a of the first inner superconductor 31. Are partially bonded. In FIG. 8, the adhesion position A of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 is represented by a black circle, and the second inner superconductor 32 is bonded to the outer peripheral surface 31a of the first inner superconductor 31. Position B is represented by a white circle. As can be seen from FIG. 8, the bonding position A and the bonding position B are at different positions.

  Here, the bonding position A is a position where the first inner superconductor 31 is bonded to the cylindrical portion 531, and the bonding position B is a position where the second inner superconductor 32 is bonded to the first inner superconductor 31. is there. The position where the bonding position A and the bonding position B are different means that the bonding position A and the bonding position B are different with respect to the first inner superconductor 31, that is, the direction perpendicular to the tape surface of the first inner superconductor 31. That is, it is not the same position in (radial direction). For this reason, the first inner superconductor 31 is not bonded on both sides in the direction perpendicular to the tape surface.

  In this way, in the cooling process, the first inner superconductor is adjusted by adjusting the adhesion position A and the adhesion position B so that the adhesion position A and the adhesion position B are different from each other with the first inner superconductor 31 interposed therebetween. 31 can be prevented from being pulled from both sides at the same position. For this reason, it is prevented that a big tensile stress acts on the 1st inner superconductor 31 locally, As a result, damages, such as peeling of the 1st inner superconductor 31, are suppressed effectively.

(Fourth embodiment)
Next, although the fourth embodiment will be described, the superconducting magnetic field generator according to the fourth embodiment includes an adhesion position of the first inner superconductor to the outer peripheral surface of the cylindrical portion, and an outer peripheral surface of the first inner superconductor. The configuration is basically the same as that of the superconducting magnetic field generator according to the third embodiment except for the bonding position of the second inner superconductor. Hereinafter, the difference will be mainly described.

  Also in the present embodiment, as in the third embodiment, the inner superconductor includes a first inner superconductor and a second inner superconductor. Further, the first inner superconductor is formed in a cylindrical shape by a superconducting thin ribbon spirally wound around the outer peripheral surface of the cylindrical portion with the axial direction of the cylindrical portion as a translation direction. The second inner superconductor is formed in a cylindrical shape by a superconducting thin ribbon spirally wound around the outer peripheral surface of the first inner superconductor with the axial direction of the cylindrical portion as the translation direction. Further, the first inner superconductor is partially bonded to the outer peripheral surface of the cylindrical portion, and the second inner superconductor is partially bonded to the outer peripheral surface of the first inner superconductor.

  FIG. 10A is a diagram illustrating a bonding position of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 in the fourth embodiment. Moreover, FIG. 10B is a figure which shows the adhesion position of the 2nd inner superconductor 32 to the outer peripheral surface 31a of the 1st inner superconductor 31 in 4th embodiment. The bonding position in FIG. 10A and the bonding position in FIG.

  As shown in FIG. 10A, adhesion positions U1 and D1 of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 are both end positions in the axial direction of the cylindrical portion 531. Here, one end of the elongated superconducting ribbon constituting the first inner superconductor 31 faces one end of the cylindrical portion 531, and the other end of the cylindrical portion 531 The other end portion in the longitudinal direction of the elongated superconducting ribbon constituting the first inner superconductor 31 faces. Therefore, it can be said that the adhesion positions U1 and D1 of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 are both end positions in the longitudinal direction of the superconducting ribbon constituting the first inner superconductor 31. The superconducting ribbon constituting the first inner superconductor 31 starts to be wound from one end portion of the outer peripheral surface 531a of the cylindrical portion 531 and ends at the other end portion. Therefore, in other words, the bonding positions U1 and D1 are a winding start position and a winding end position when the superconducting ribbon is spirally wound around the outer peripheral surface 531a of the cylindrical portion 531.

  As shown in FIG. 10B, the bonding positions U2 and D2 of the second inner superconductor 32 to the outer peripheral surface 31a of the first inner superconductor 31 are both end positions in the axial direction of the first inner superconductor 31. One end portion of the elongated superconducting ribbon constituting the second inner superconductor 32 faces one end portion of the first inner superconductor 31 and the other end of the first inner superconductor 31 The other end portion in the longitudinal direction of the long superconducting ribbon constituting the second inner superconductor 32 faces the end portion. Therefore, it can be said that the adhesion positions U2 and D2 of the second inner superconductor 32 to the outer peripheral surface 31a of the first inner superconductor 31 are both end positions in the longitudinal direction of the superconducting ribbon constituting the second inner superconductor 32. . The superconducting ribbon constituting the second inner superconductor 32 starts to be wound from one end portion of the outer peripheral surface 31a of the first inner superconductor 31 and finishes winding at the other end portion. Therefore, in other words, the bonding positions U2 and D2 are a winding start position and a winding end position when the superconducting ribbon is spirally wound around the outer peripheral surface 31a of the first inner superconductor 31.

  FIG. 11 is a perspective view showing a state where the bonding of the first inner superconductor 31 and the bonding of the second inner superconductor 32 according to the present embodiment are completed. FIG. 12 is a schematic view showing the bonding state of the first inner superconductor 31 and the bonding state of the second inner superconductor 32 according to the present embodiment from a cross section including the central axis of the cylindrical portion 531.

  As shown in FIG. 12, the bonding position U1 of the first inner superconductor 31 to the outer circumferential surface 531a of the cylindrical portion 531 and the bonding position U2 of the second inner superconductor 32 to the outer circumferential surface 31a of the first inner superconductor 31. Are the same positions with the first inner superconductor 31 in between, the bonding position D1 of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 and the first position of the first inner superconductor 31 to the outer peripheral surface 31a. The adhesion position D2 of the two inner superconductors 32 is the same position with the first inner superconductor 31 in between.

  Further, there is no wide area between the outer peripheral surface 531a of the cylindrical portion 531 and the inner peripheral surface of the first inner superconductor 31 and between the bonding positions U1 and D1 located at both ends in the axial direction of the cylindrical portion 531. It is an adhesion area. Similarly, bonding positions U2 and D2 located between the outer peripheral surface 31a of the first inner superconductor 31 and the inner peripheral surface of the second inner superconductor 32 and at both ends in the axial direction of the first inner superconductor 31. The wide area between is the unbonded area.

  In this embodiment, the bonding positions of the inner superconductors 31 and 32 are thus limited to both end positions (both end positions in the longitudinal direction of the superconducting ribbon) that are the minimum positions necessary for fixing the inner superconductors. In addition, by reducing the bonding area as much as possible, the tensile stress acting on the inner superconductors 31 and 32 during cooling can be further reduced. As a result, damage to the inner superconductors 31 and 32 during cooling is further suppressed. In addition, after applying an adhesive to both ends of the outer peripheral surface 531 a of the cylindrical portion 531, a superconducting ribbon is spirally wound around the outer peripheral surface 531 a of the cylindrical portion 531, so The inner superconductor 31 can be easily bonded. Similarly, after applying an adhesive to both ends of the outer peripheral surface 31a of the first inner superconductor 31, the first inner superconductor 31 is spirally wound around the outer peripheral surface 31a of the first inner superconductor 31, thereby The second inner superconductor 32 can be easily bonded to the outer peripheral surface 31 a of the superconductor 31.

(Fifth embodiment)
Next, a fifth embodiment will be described. A superconducting magnetic field generator according to the present embodiment includes an unbonded region between the cylindrical portion and the first inner superconductor shown in the fourth embodiment, and This is basically the same as the fourth embodiment except that the non-bonded region between the one inner superconductor and the second inner superconductor is filled with a filler. Hereinafter, the difference will be mainly described.

  FIG. 13 is a schematic view showing a bonding state of the first inner superconductor 31 and a bonding state of the second inner superconductor 32 according to the present embodiment from a cross section including the central axis of the cylindrical portion 531. As shown in FIG. 13, the first inner superconductor 31 is bonded to the outer peripheral surface 531 a of the cylindrical portion 531 at bonding positions U <b> 1 and D <b> 1 at both ends in the axial direction of the cylindrical portion 531. The second inner superconductor 32 is bonded to the outer peripheral surface 31a of the first inner superconductor 31 at bonding positions U2 and D2 at both ends in the axial direction of the first inner superconductor 31.

  Also, the filler 10 is filled in a gap (unbonded region) formed between the outer peripheral surface 531a of the cylindrical portion 531 and the inner peripheral surface of the first inner superconductor 31 and formed between the bonding positions U1 and D1. ing. Similarly, a filler is formed between the outer peripheral surface 31a of the first inner superconductor 31 and the inner peripheral surface of the second inner superconductor 32 and between the bonding positions U2 and D2. 10 is filled.

  As the filler 10, a material whose elastic modulus is smaller than that of the adhesive 9 applied to the bonding positions U1, D1, U2, D2 can be adopted. For example, when the adhesive applied to the bonding positions U1, D1, U2, and D2 is an epoxy adhesive, grease, wax, or silicone can be used as the filler 10.

  Thus, in the present embodiment, all of the gap between the cylindrical portion 531 and the first inner superconductor 31 and the gap between the first inner superconductor 31 and the second inner superconductor 32 or Part of the filler 10 is filled with an elastic modulus smaller than that of the adhesive. With this configuration, the inner superconductor 3 can receive cold heat not only from the adhesive applied to each bonding position but also from the filler 10 filled in the gap in the cooling step. For this reason, cooling efficiency can be improved more.

  In addition, since the filler 10 is more easily deformed than the adhesive, the tensile stress acting on the filling region of the filler 10 during cooling is weaker than the tensile stress in the bonding region. Therefore, damage such as peeling of the inner superconductor 3 during cooling is effectively suppressed.

(Sixth embodiment)
Next, a sixth embodiment will be described. The superconducting magnetic field generator according to this embodiment is basically the same as the fifth embodiment except that a cover is provided on the outer peripheral side of the second inner superconductor. Are identical. Hereinafter, the difference will be mainly described.

  FIG. 14 is a schematic view showing a bonding state of the first inner superconductor 31 and the second inner superconductor 32 provided in the superconducting magnetic field generator according to the present embodiment from a cross section including the central axis of the cylindrical portion 531. As shown in FIG. 14, the first inner superconductor 31 is bonded to the outer peripheral surface 531a of the cylindrical portion 531 at the bonding positions U1, D1 at both ends in the axial direction of the cylindrical portion 531, and the second inner superconductor 32 is The first inner superconductor 31 is bonded to the outer peripheral surface 31a of the first inner superconductor 31 at bonding positions U2 and D2 at both ends in the axial direction.

  The elastic modulus is bonded to all or part of the gap between the cylindrical portion 531 and the first inner superconductor 31 and the gap between the first inner superconductor 31 and the second inner superconductor 32. Filler 10 smaller than the agent is filled.

  Further, as can be seen from FIG. 14, a cover portion 54 is provided outside the second inner superconductor 32. The cover portion 54 has a cylindrical shape and is formed of a material having good thermal conductivity. Further, the lower end portion of the cover portion 54 in FIG.

  The cover part 54 is provided so as to cover the second inner superconductor 32. That is, the cover portion 54 is formed in a cylindrical shape so as to face the outer peripheral surface 32 a of the second inner superconductor 32. The outer peripheral surface 32a of the second inner superconductor 32 is a peripheral surface opposite to the inner peripheral surface of the second inner superconductor 32 (a peripheral surface partially bonded to the outer peripheral surface 31a of the first inner superconductor 31). It is. That is, the cover portion 54 is a peripheral surface of the second inner superconductor 32 that is opposite to a surface (inner peripheral surface) that is partially bonded to the outer peripheral surface 31 a of the first inner superconductor 31. It is formed in a cylindrical shape so as to face the (outer peripheral surface 32a).

  Further, a gap is formed between the second inner superconductor 32 and the cover portion 54, and the filler 10 is filled in this gap. As described above, the filler 10 has an elastic modulus smaller than the elastic modulus of the adhesive used for bonding the inner superconductors 31 and 32.

  According to this embodiment, the inner superconductor 3 is also cooled from the cover portion 54 side in the cooling step. Therefore, the cooling efficiency is further improved and the inner superconductor 3 can be uniformly cooled.

(Seventh embodiment)
Next, a seventh embodiment will be described. The superconducting magnetic field generator according to this embodiment is basically the same as the superconductor except that the inner superconductor is disposed on the inner peripheral surface side of the cylindrical portion. The same as in the sixth embodiment. Hereinafter, the difference will be mainly described.

  FIG. 15 is a schematic view showing a state in which the inner superconductor 3 according to the present embodiment is bonded to the cylindrical portion 531 of the cylindrical base material 53 from a cross section including the central axis of the cylindrical portion 531. As shown in FIG. 15, the inner superconductor 3 includes a first inner superconductor 31 and a second inner superconductor 32.

  The first inner superconductor 31 is disposed on the inner peripheral surface 531b side of the cylindrical portion 531 of the cylindrical base material 53, and at the bonding positions A and A at both ends of the inner peripheral surface 531b of the cylindrical portion 531, the cylindrical portion Partially glued to 531. The second inner superconductor 32 is disposed on the inner peripheral surface 31 b side of the first inner superconductor 31, and is at bonding positions B and B at both ends of the inner peripheral surface 31 b of the first inner superconductor 31. The first inner superconductor 31 is partially bonded.

  Further, the gap between the inner peripheral surface 531 b of the cylindrical portion 531 and the outer peripheral surface of the first inner superconductor 31 is filled with the filler 10. Similarly, the filler 10 is also filled into the gap between the inner peripheral surface 31b of the first inner superconductor 31 and the outer peripheral surface of the second inner superconductor.

  A cylindrical cover portion 54 is disposed on the inner peripheral side of the second inner superconductor 32. The cover portion 54 is formed of a material having a good thermal conductivity, and the outer peripheral surface thereof is disposed facing the inner peripheral surface of the second inner superconductor 32. Further, the lower end portion of the cover portion 54 in FIG. Further, a gap is provided between the second inner superconductor 32 and the cover portion 54, and the filler 10 is filled in this gap.

  In this embodiment, there exists an effect similar to the said 6th embodiment.

(Eighth embodiment)
Next, an eighth embodiment will be described. The superconducting magnetic field generator according to the present embodiment is basically the third embodiment and the fourth embodiment except that the bonding position of the inner superconductor is different. The form is the same. Hereinafter, the difference will be mainly described.

  Also in this embodiment, the inner superconductor includes a first inner superconductor and a second inner superconductor as in the third embodiment and the fourth embodiment. The first inner superconductor is bonded to the outer peripheral surface of the cylindrical portion, and the second inner superconductor is bonded to the outer peripheral surface of the first inner superconductor.

  FIG. 16A is a diagram showing a bonding position A of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 in the eighth embodiment. FIG. 16B is a diagram showing a bonding position B of the second inner superconductor 32 to the outer peripheral surface 31a of the first inner superconductor 31 in the eighth embodiment. The adhesion position A in FIG. 16A and the adhesion position B in FIG. 16B are each indicated by hatching.

  As shown in FIG. 16A, the adhesion position A of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 is linear in the circumferential direction of the cylindrical portion 531 and along the axial direction of the cylindrical portion 531. A plurality of linear regions extending. Similarly, as shown in FIG. 16B, the bonding position B of the second inner superconductor 32 to the outer peripheral surface 31a of the first inner superconductor 31 is separated in the circumferential direction of the first inner superconductor 31 and the first inner superconductor 31 These are a plurality of linear regions extending linearly along the axial direction of the superconductor 31.

  Each of the plurality of linear regions (bonding position A) where the first inner superconductor 31 is bonded to the outer peripheral surface 531a of the cylindrical portion 531 is the first inner superconductor 31 when the first inner superconductor 31 is bonded. Is straddled between the spiral windings of the spirally wound superconducting thin ribbon that constitutes the cylindrical portion 531. Therefore, each spiral winding is bonded to the cylindrical portion 531 at at least one place. Similarly, each of the plurality of linear regions (adhesion position B) where the second inner superconductor 32 is bonded to the first inner superconductor 31 is the second inner superconductor when the second inner superconductor 32 is bonded. The spiral winding of the spirally wound superconducting ribbon constituting the body 32 is straddled along the axial direction of the cylindrical portion 531. Therefore, each spiral winding is bonded to the first inner superconductor 31 at least at one place.

  FIG. 17 is a schematic view showing a bonding state of the first inner superconductor 31 and a bonding state of the second inner superconductor 32 according to the present embodiment from a cross section perpendicular to the axial direction of the cylindrical portion 531. As shown in FIG. 17, when viewed from the axial direction of the cylindrical portion 531, the adhesion position A of the first inner superconductor 31 to the outer peripheral surface 531 a of the cylindrical portion 531 is to the outer peripheral surface 31 a of the first inner superconductor 31. This is a position different from the bonding position B of the second inner superconductor 32. Specifically, the bonding position A and the bonding position B are different positions in the circumferential direction of the cylindrical portion 531. That is, the bonding position A and the bonding position B are shifted in the circumferential direction of the cylindrical portion 531. For this reason, the bonding position A and the bonding position B do not come to the same position across the first inner superconductor 31.

  According to this embodiment, since the adhesion region (adhesion position A) of the first inner superconductor 31 to the cylindrical portion 531 extends linearly in the axial direction of the first inner superconductor 31, The one inner superconductor 31 is cooled substantially uniformly along the axial direction via an adhesive applied to a bonding region (bonding position A) extending linearly in the axial direction. Similarly, the adhesion region (adhesion position B) of the second inner superconductor 32 to the first inner superconductor 31 extends linearly in the axial direction of the second inner superconductor 32. The inner superconductor 32 is cooled substantially uniformly along the axial direction via an adhesive applied to a bonding region (bonding position B) extending linearly in the axial direction. Also, the first inner superconductor 31 and the second inner superconductor 32 can be partially bonded easily. Furthermore, the position where the first inner superconductor 31 is bonded to the cylindrical portion 531 (bonding position A) and the position where the first inner superconductor 31 is bonded to the second inner superconductor 32 (bonding position B) are Since the inner superconductor 31 is located at different positions (displaced in the circumferential direction), the first inner superconductor 31 is not pulled from both sides at the same position during cooling. For this reason, damage such as peeling of the first inner superconductor 31 is effectively suppressed.

(Ninth embodiment)
Next, a ninth embodiment will be described. The superconducting magnetic field generator according to this embodiment includes a gap between the cylindrical portion and the first inner superconductor, and the first inner superconductor and the second inner superconductor. The superconducting magnetic field generator according to the eighth embodiment is basically the same as the superconducting magnetic field generating apparatus according to the eighth embodiment except that the gaps between them are filled with fillers. Hereinafter, the difference will be mainly described.

  Also in this embodiment, the inner superconductor includes a first inner superconductor and a second inner superconductor as in the eighth embodiment. The first inner superconductor is bonded to the outer peripheral surface of the cylindrical portion, and the second inner superconductor is bonded to the outer peripheral surface of the first inner superconductor.

  The bonding position of the first inner superconductor to the outer peripheral surface of the cylindrical portion and the bonding position of the second inner superconductor to the outer peripheral surface of the first inner superconductor are also the same positions as in the eighth embodiment. . That is, also in this embodiment, as shown in FIG. 16A, the bonding position A of the first inner superconductor 31 to the outer peripheral surface 531a of the cylindrical portion 531 is separated in the circumferential direction of the cylindrical portion 531 and the cylindrical portion 531 A plurality of linear regions extending linearly along the axial direction. Similarly, as shown in FIG. 16B, the bonding position B of the second inner superconductor 32 to the outer peripheral surface 31a of the first inner superconductor 31 is separated in the circumferential direction of the first inner superconductor 31 and the first inner superconductor 31 These are a plurality of linear regions extending linearly along the axial direction of the superconductor 31.

  FIG. 18 is a schematic view showing a bonding state of the first inner superconductor 31 and a bonding state of the second inner superconductor 32 according to the present embodiment from a cross section perpendicular to the axial direction of the cylindrical portion 531. As shown in FIG. 18, when viewed from the axial direction of the cylindrical portion 531, the bonding position A of the first inner superconductor 31 to the outer peripheral surface 531 a of the cylindrical portion 531 is to the outer peripheral surface 31 a of the first inner superconductor 31. This is a position different from the bonding position B of the second inner superconductor 32. Specifically, the bonding position A and the bonding position B are different positions in the circumferential direction of the cylindrical portion 531. That is, the bonding position A and the bonding position B are shifted in the circumferential direction of the cylindrical portion 531.

  Further, as can be seen from FIG. 18, a gap (unbonded region) formed between the outer peripheral surface 531a of the cylindrical portion 531 and the inner peripheral surface of the first inner superconductor 31 except for the bonding position A. Is filled with a filler 10. Similarly, a filler is formed in a gap (unbonded region) formed between the outer peripheral surface 31a of the first inner superconductor 31 and the inner peripheral surface of the second inner superconductor 32 except for the bonding position B. 10 is filled.

  The filler 10 can be selected such that its elastic modulus is smaller than the elastic modulus of the adhesive applied to the bonding positions A and B. For example, when the adhesive applied to the bonding positions A and B is an epoxy adhesive, grease, wax, or silicone can be selected as the filler 10.

  19A is a cross-sectional view taken along the line II in FIG. 18, and FIG. 19B is a cross-sectional view taken along the line II-II in FIG. In the cross section shown in FIG. 19A, the filler 10 is filled between the cylindrical portion 531 and the first inner superconductor 31, while between the first inner superconductor 31 and the second inner superconductor 32. Adhesive is applied. In the cross section shown in FIG. 19B, an adhesive is applied between the cylindrical portion 531 and the first inner superconductor 31, while between the first inner superconductor 31 and the second inner superconductor 32. Is filled with a filler 10.

  According to this embodiment, there exists an effect similar to the said 8th embodiment. In the present embodiment, all or part of the gap between the cylindrical portion 531 and the first inner superconductor 31 and the gap between the first inner superconductor 31 and the second inner superconductor 32. In addition, the filler 10 having an elastic modulus smaller than that of the adhesive is filled. With this configuration, the inner superconductor 3 can receive cold heat not only from the adhesive applied to the bonding positions A and B but also from the filler 10 filled in the gap in the cooling step. For this reason, cooling efficiency can be improved more.

  In addition, since the filler 10 is more easily deformed than the adhesive, the tensile stress acting on the filling region of the filler 10 during cooling is weaker than the tensile stress in the bonding region. Therefore, damage such as peeling of the inner superconductor 3 during cooling is effectively suppressed.

(Reference Example 1)
The subject of the present invention is that, in the superconducting magnetic field generator 100 shown in FIG. 1, the inner superconductor 3 is made of a material whose thermal contraction rate is larger than the thermal contraction rate of the cylindrical portion 531 or the cylindrical portion. The problem can also be solved by forming 531 with a material having a thermal contraction rate smaller than that of the inner superconductor 3.

  That is, the superconducting magnetic field generator according to Reference Example 1 is formed in a cylindrical shape by a high-temperature superconducting material, and captures the applied magnetic field in a state cooled to a temperature equal to or lower than the superconducting transition temperature, thereby generating the outer superconductivity that generates the trapping magnetic field The body 2 and a high-temperature superconducting material are formed in a cylindrical shape, and are arranged coaxially with the outer superconductor 2 on the inner peripheral side of the outer superconductor 2, and the uniformity of the critical current density in the cylindrical peripheral surface is cylindrical. The inner superconductor 3, which is higher than the uniformity of the critical current density of the outer superconductor 2 in the peripheral surface, and the cold for cooling the outer superconductor 2 and the inner superconductor 3 to temperatures below the superconducting transition temperature are generated. The cooling device 5 includes a cylindrical base material 53 having a cylindrical portion 531 disposed coaxially with the outer superconductor 2 in the inner circumferential space of the outer superconductor 2, and the inner superconductor. 3 , The heat shrinkage factor is larger than the heat shrinkage ratio of the cylindrical portion 531, and is provided on the outer peripheral side of the cylindrical portion 531, a superconducting magnetic field generating apparatus.

  According to this example, the inner superconductor 3 is provided on the outer peripheral side of the cylindrical portion 531. That is, the cylindrical portion 531 is provided on the inner peripheral side, and the inner superconductor 3 is provided on the outer peripheral side. Further, the amount of heat shrinkage of the inner superconductor 3 on the outer peripheral side is larger than the amount of heat shrinkage of the cylindrical portion 531 on the inner peripheral side. For this reason, at the time of cooling, the inner superconductor 3 on the outer peripheral side is more thermally contracted than the cylindrical portion 531 on the inner peripheral side, and the inner superconductor 3 is pressed against the cylindrical portion 531. That is, the inner superconductor 3 receives a compressive stress from the cylindrical portion 531 during cooling. In other words, no tensile stress acts on the inner superconductor 3 from the cylindrical portion 531 during cooling. Therefore, damage such as peeling of the inner superconductor 3 due to the tensile stress acting on the inner superconductor 3 is effectively suppressed.

  In this case, the inner superconductor 3 is formed by laminating a first metal film layer, a superconducting film, and a second metal film layer having a thermal contraction rate larger than that of the first metal film layer in this order. It is preferable that it is formed in a cylindrical shape so that the first metal film layer is on the inner peripheral side. According to this, at the time of cooling, the second metal film layer in the inner superconducting ribbon compresses the superconducting film from the outer peripheral side. For this reason, tensile stress does not act on the superconducting film. Therefore, damage such as peeling of the inner superconductor due to the tensile stress acting on the superconducting film is more effectively suppressed.

  In addition, among the configurations of the superconducting magnetic field generation device according to the present example, the description of the superconducting magnetic field generation device 100 according to the first embodiment can be cited for configurations other than the above-described features.

(Reference Example 2)
Further, the problem of the present invention is that in the superconducting magnetic field generator 100 shown in FIG. 1, the inner superconductor 3 is disposed on the inner peripheral side of the cylindrical substrate 53 of the cylindrical portion 531, and the inner superconductor 3 is The problem can also be solved by configuring the material with a thermal contraction rate smaller than that of the cylindrical portion 531 or by configuring the cylindrical portion 531 with a material greater than the thermal contraction rate of the inner superconductor 3. .

  In other words, the superconducting magnetic field generator according to Reference Example 2 is formed in a cylindrical shape by a high-temperature superconducting material, and captures the applied magnetic field in a state cooled to a temperature equal to or lower than the superconducting transition temperature, thereby generating the outer superconducting power The body 2 and a high-temperature superconducting material are formed in a cylindrical shape, and are arranged coaxially with the outer superconductor 2 on the inner peripheral side of the outer superconductor 2, and the uniformity of the critical current density in the cylindrical peripheral surface is cylindrical. The inner superconductor 3, which is higher than the uniformity of the critical current density of the outer superconductor 2 in the peripheral surface, and the cold for cooling the outer superconductor 2 and the inner superconductor 3 to temperatures below the superconducting transition temperature are generated. The cooling device 5 includes a cylindrical base material 53 having a cylindrical portion 531 disposed coaxially with the outer superconductor 2 in the inner circumferential space of the outer superconductor 2, and the inner superconductor. 3 , The heat shrinkage ratio is smaller than the heat shrinkage ratio of the cylindrical portion 531, and are provided on the inner peripheral side of the cylindrical portion 531, a superconducting magnetic field generating apparatus.

  According to this example, the inner superconductor 3 is provided on the inner peripheral side of the cylindrical portion 531. That is, the cylindrical portion 531 is provided on the outer peripheral side, and the inner superconductor 3 is provided on the inner peripheral side. Further, the amount of heat shrinkage of the inner superconductor 3 on the inner peripheral side is smaller than the amount of heat shrinkage of the cylindrical portion 531 on the outer peripheral side. For this reason, during cooling, the outer circumferential cylindrical portion 531 is more thermally contracted than the inner circumferential inner superconductor 3 and the inner superconductor 3 is pressed against the cylindrical portion 531. That is, the inner superconductor 3 receives a compressive stress from the cylindrical portion 531 during cooling. In other words, no tensile stress acts on the inner superconductor 3 from the cylindrical portion 531 during cooling. Therefore, damage such as peeling of the inner superconductor due to the tensile stress acting on the inner superconductor 3 is effectively suppressed.

  In this case, the inner superconductor 3 is formed by laminating a first metal film layer, a superconducting film, and a second metal film layer having a thermal contraction rate larger than that of the first metal film layer in this order. It is preferable that it is formed in a cylindrical shape so that the first metal film layer is on the inner peripheral side. According to this, at the time of cooling, the second metal film layer in the inner superconducting ribbon compresses the superconducting film from the outer peripheral side. For this reason, tensile stress does not act on the superconducting film. Therefore, damage such as peeling of the inner superconductor due to the tensile stress acting on the superconducting film is more effectively suppressed.

  In addition, among the configurations of the superconducting magnetic field generation device according to the present example, the description of the superconducting magnetic field generation device 100 according to the first embodiment can be cited for configurations other than the above-described features.

  As mentioned above, although embodiment of this invention was described, this invention should not be limited to the said embodiment. For example, in the above embodiment, the inner superconductor 3 formed in a cylindrical shape by spirally winding the superconducting ribbon 3A is illustrated, but the superconducting ribbon formed in a ring shape is connected in the axial direction to form a cylinder. A shaped inner superconductor may be configured. Alternatively, a cylindrical inner superconductor may be configured by winding a sheet of superconductor (superconducting sheet) around the cylindrical portion 531 in a roll shape more than one round. Furthermore, a cylindrical inner superconductor may be formed by winding a plurality of superconducting sheets formed in a cylindrical shape around the circumferential surface of the cylindrical portion 531 so that the respective seams do not overlap each other. . In the first embodiment, the example in which the inner superconductor 3 is partially bonded to the cylindrical portion 531 at a plurality of spaced positions is shown. However, the inner superconductor 3 is partially attached to the circumferential surface of the cylindrical portion 531. If bonded, a plurality of bonded portions may be connected. Thus, the present invention can be modified without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 ... Superconductor, 2 ... Outer superconductor, 2a ... Superconducting bulk, 3 ... Inner superconductor, 31 ... First inner superconductor, 31a ... Outer peripheral surface, 31b ... Inner peripheral surface, 32 ... Second inner superconductor, 32a ... outer peripheral surface, 3A ... superconducting ribbon, 5 ... cooling device, 52 ... cold head, 52a ... column portion, 52b ... stage portion, 52c ... concave portion, 53 ... cylindrical substrate, 531 ... cylindrical portion, 531a ... outer peripheral surface, 531b ... inner peripheral surface, 533 ... fixing part, 54 ... cover part, 6 ... vacuum insulation container, 7 ... external magnetic field generating coil, 9 ... adhesive, 10 ... filler, 100,101 ... superconducting magnetic field generator, 110 ... Nuclear magnetic resonance apparatus

Claims (13)

An outer superconductor that generates a trapped magnetic field by capturing an applied magnetic field in a state of being formed into a cylindrical shape by a high-temperature superconducting material and cooled to a temperature equal to or lower than the superconducting transition temperature;
It is formed in a cylindrical shape by a high-temperature superconducting material and is arranged coaxially with the outer superconductor on the inner peripheral side of the outer superconductor, and the uniformity of the critical current density in the cylindrical peripheral surface is An inner superconductor higher than the uniformity of the critical current density of the outer superconductor;
A cooling device that generates cold for cooling the outer superconductor and the inner superconductor to a temperature equal to or lower than the superconducting transition temperature, and
With
The cooling device includes a cylindrical base material having a cylindrical portion disposed coaxially with the outer superconductor in an inner circumferential space of the outer superconductor,
The inner superconductor is wound around the peripheral surface of the cylindrical portion and is partially bonded to the peripheral surface of the cylindrical portion, and is coaxial with the outer superconductor on the inner peripheral side of the outer superconductor. Located in the
Superconducting magnetic field generator. The superconducting magnetic field generator according to claim 1,
The inner superconductor is formed in a cylindrical shape by superconducting ribbons spirally wound around the circumferential surface of the cylindrical portion with the axial direction of the cylindrical portion as a translation direction, and at a plurality of spaced positions. Are partially bonded to the circumferential surface of the cylindrical portion,
Superconducting magnetic field generator. The superconducting magnetic field generator according to claim 2,
The bonding position of the inner superconductor to the peripheral surface of the cylindrical portion is the both end positions in the longitudinal direction of the superconducting ribbon constituting the inner superconductor.
Superconducting magnetic field generator. The superconducting magnetic field generator according to claim 2,
The bonding position of the inner superconductor to the circumferential surface of the cylindrical portion is a plurality of linear regions that are spaced apart in the circumferential direction and extend linearly in a direction that includes an axial component.
Superconducting magnetic field generator. In the superconducting magnetic field generator according to any one of claims 2 to 4,
The inner superconductor is:
The cylindrical portion is formed into a cylindrical shape by a long superconducting thin ribbon that is spirally wound around the circumferential surface of the cylindrical portion with the axial direction of the cylindrical portion as a translation direction, and at a plurality of spaced positions, the cylinder A first inner superconductor partially bonded to the peripheral surface of the part;
Formed in a cylindrical shape by a long superconducting ribbon that is spirally wound around the circumferential surface of the first inner superconductor with the axial direction of the cylindrical portion as a translation direction, and at a plurality of spaced positions. A second inner superconductor partially bonded to the peripheral surface of the first inner superconductor;
With
In the second inner superconductor, the position of the side edge of each spiral winding of the superconducting ribbon constituting the second inner superconductor is set to the position of the side edge of each spiral winding of the superconducting ribbon constituting the first inner superconductor. It is wound around the peripheral surface of the first inner superconductor so as not to match,
Superconducting magnetic field generator. In the superconducting magnetic field generator according to claim 5,
The bonding position of the first inner superconductor to the peripheral surface of the cylindrical portion and the bonding position of the second inner superconductor to the peripheral surface of the first inner superconductor sandwich the first inner superconductor. In different positions,
Superconducting magnetic field generator. In the superconducting magnetic field generator according to claim 5,
The bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion is the positions of both ends in the longitudinal direction of the superconducting ribbon constituting the first inner superconductor,
Bonding positions of the second inner superconductor to the peripheral surface of the first inner superconductor are both end positions in the longitudinal direction of the superconducting ribbon constituting the second inner superconductor.
Superconducting magnetic field generator. In the superconducting magnetic field generator according to claim 5,
The bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion is a plurality of linear regions that are separated in the circumferential direction and linearly extend in a direction including an axial component,
The bonding position of the second inner superconductor to the peripheral surface of the first inner superconductor is a plurality of linear regions that are separated in the circumferential direction and linearly extend in a direction including an axial component,
The bonding position of the first inner superconductor to the circumferential surface of the cylindrical portion and the bonding position of the second inner superconductor to the circumferential surface of the first inner superconductor are shifted in the circumferential direction.
Superconducting magnetic field generator. The superconducting magnetic field generator according to any one of claims 5 to 8,
Of the material used for bonding, part or all of the gap between the cylindrical portion and the first inner superconductor and the gap between the first inner superconductor and the second inner superconductor. Filled with a filler having an elastic modulus smaller than the elastic modulus,
Superconducting magnetic field generator. The superconducting magnetic field generator according to claim 9,
A cover portion formed in a cylindrical shape so as to face the peripheral surface of the second inner superconductor and opposite to the surface partially bonded to the peripheral surface of the first inner superconductor Is provided,
The cover portion is connected to the cylindrical base material,
Superconducting magnetic field generator. The superconducting magnetic field generator according to claim 10,
The filler is filled in a part or all of the gap between the second inner superconductor and the cover part,
Superconducting magnetic field generator. The superconducting magnetic field generator according to any one of claims 1 to 11,
The cooling device includes a cold head disposed facing one end face of the outer superconductor,
The cylindrical base material has a fixed portion connected to the one end portion of the cylindrical portion so as to close one end portion of the cylindrical portion,
The fixing part is fixed to the cold head;
Superconducting magnetic field generator.   A nuclear magnetic resonance apparatus comprising the superconducting generator according to any one of claims 1 to 12.

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