JP5360638B2 - Superconducting magnetic field generator, method of magnetizing superconducting magnetic field generator, and nuclear magnetic resonance apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconducting magnetic field generating apparatus capable of magnetic field being formed, as uniform as possible, over a wide range, in an in-cylinder space of a superconducting body, and to provide a method for magnetizing for the superconducting magnetic field generating apparatus, and a nuclear magnetic resonance apparatus which uses the superconducting magnetic field generating apparatus. <P>SOLUTION: This superconducting magnetic field generating apparatus comprises the cylindrical superconducting body 1 that generates a magnetic field by catching a magnetic field, at a temperature which is not higher than the superconducting transition temperature and has an in-cylinder space 10; a cooling apparatus for cooling the superconducting body 1; a vacuum insulation vessel 3 accommodating the superconducting body 1, and a correction coil 4 that corrects a magnetic field distribution in the in-cylinder space 10 of the superconducting body 1 and has a length L in the extending direction of the virtual center axis 11 of the superconducting body 1, the length L which is set to be not larger than the length of the superconducting body 1. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a superconducting magnetic field generator, a magnetization method for the superconducting magnetic field generator, and a nuclear magnetic resonance apparatus.

  Patent Document 1 discloses an NMR analyzer that magnetizes a cylindrical high-temperature superconductor to generate a magnetic field in a hollow portion thereof, and arranges a sample and a detection coil in the magnetic field to detect an NMR signal. . Magnetization is performed by generating a uniform magnetic field with a superconducting magnet, inserting a high-temperature superconductor into the magnetic field, cooling the superconductor below the superconducting transition temperature with a refrigerator, and then stopping the generated magnetic field of the superconducting magnet. The magnetic field is captured by the high-temperature superconductor. According to this technique, since a magnetic field is generated by magnetizing a bulk high-temperature superconductor, the magnet of the NMR analyzer is smaller and simpler than the conventional superconducting coil.

  Patent Document 2 uses a control method of a superconductor magnetic field application apparatus that controls a magnetic field intensity and distribution by magnetizing a high-temperature superconductor and then raising the temperature to a temperature lower than the superconducting transition temperature and then cooling it. A nuclear magnetic resonance apparatus and a superconducting magnet apparatus are disclosed. According to this, the magnitude and distribution of the generated magnetic field can be controlled to a desired magnitude and kept constant.

  Patent Document 3 discloses a magnetic field generator and a nuclear magnetic resonance apparatus in which the critical current density at both ends of a cylindrical superconducting bulk body is higher than that at the center. Here, a magnetic field generator having a wide uniform magnetic field in the vicinity of the central portion of the superconducting bulk can be provided, and a small, high-sensitivity and high-resolution nuclear magnetic resonance apparatus can be used.

  Patent Document 4 discloses a superconducting magnetic field generator in which the magnetic susceptibility of the end of a cylindrical superconducting bulk body is smaller than that at the center, a magnetizing method thereof, and a nuclear magnetic resonance apparatus. By setting the magnetic susceptibility and shape of the superconducting bulk so as to satisfy certain conditions, a uniform magnetic field space can be formed near the center of the superconducting bulk.

In Patent Document 5, a bias magnet is coaxially arranged on the outer peripheral side of a high temperature superconductor having a pinning effect, and the high temperature superconductor is formed by a bias magnet so that a space surrounded by the high temperature superconductor has a desired magnetic field distribution. An MRI apparatus that forms a magnetic field from the periphery of the substrate, then cools the high-temperature superconductor to maintain a high-temperature superconducting state, transfers a desired magnetic field distribution, and removes the magnetic field around the high-temperature superconductor after the transfer, and An MRI apparatus manufacturing method is disclosed. A permanent magnet or a solenoid is employed as the bias magnet. The axial length of the cylindrical bias magnet is set to be considerably longer than the axial length of the cylindrical high-temperature superconductor. Accordingly, the axial end of the cylindrical bias magnet protrudes outward in the axial direction from the axial end of the cylindrical high-temperature superconductor.
JP 2002-006021 A JP 2002-008917 A JP 2007-129158 A JP 2006-207857 A JP-A-9-2013347

  Incidentally, high magnetic field uniformity (for example, 1 ppm or less) is required for a magnetic device typified by a magnet or the like of an NMR device. Usually, a correction coil is added to a room temperature bore (cylindrical space) of a magnet body, and a target is obtained. To achieve magnetic field uniformity. In the magnet of the NMR apparatus of Patent Document 1 using a superconducting bulk, a magnetic field captured by the superconductor by magnetization is used. However, the in-cylinder space of the bulk superconductor is narrow, and the size of the correction coil for correcting the magnetic field distribution Since the number is limited, it is difficult to obtain a high magnetic field uniformity by inserting a correction coil in the in-cylinder space. In order to improve the magnetic field uniformity, it is necessary to lengthen the length of the cylindrical superconductor and limit the size and number of correction coils that can be placed in the space inside the cylinder. The advantage is impaired, and the cost is disadvantageous.

  According to Patent Document 2, after superconducting bulk is magnetized, the temperature and the distribution of the magnetic field are adjusted by changing the temperature of the superconducting bulk. However, it is difficult to partially change the temperature of the superconducting bulk, and the fine magnetic field distribution. It was not possible to correct.

  According to Patent Document 3, the phenomenon (magnetic flux creep) in which the magnetic field escapes from the end after magnetization is suppressed by making the critical current density at both ends of the superconducting bulk higher than the center. According to this, although the temporal change of magnetic field distribution can be suppressed, the spatial correction regarding magnetic field uniformity cannot be performed.

  According to Patent Document 4, the magnetic field distribution is not corrected after the magnetization, but how to apply and capture a uniform magnetic field to the superconductor at the time of magnetization is devised. When magnetizing a superconducting bulk, a uniform magnetic field is applied in the order of ppm, but the applied magnetic field is disturbed by the magnetization of the superconductor itself, and as a result, the uniformity of the magnetic field distribution after magnetization cannot be obtained. It is an essential problem. On the other hand, by setting the magnetic susceptibility at both ends of the superconducting bulk to be smaller than the central part and setting the magnetic susceptibility and external dimensions so as to satisfy certain conditions, the influence of the superconducting bulk magnetization is minimized and the space inside the cylinder is reduced. The magnetic field uniformity at the center of the is improved. However, with this technique, the distribution of the applied magnetic field is determined by the configuration of the superconducting bulk. Therefore, once the bulk configuration is determined, it is difficult to increase the uniformity of the applied magnetic field. In addition, when the thickness of the superconducting bulk is increased, the applied magnetic field distribution in the central axis direction at the center of the cylinder space is affected by the magnetization and changes from a convex shape downward to a convex shape. Since the magnetic field is made uniform by making the bulk thickness of the central part coincide with the dimension of the boundary, the dimensional condition is severe and there is a possibility that the magnetic field uniformity greatly changes due to the deviation of the thickness. In addition, the range in which a uniform magnetic field can be obtained in principle is limited, and it is difficult to expand the uniform magnetic field space beyond that.

  According to Patent Document 5, as described above, the axial length of the cylindrical bias magnet is set to be longer than the axial length of the cylindrical high-temperature superconductor. Accordingly, the axial end of the cylindrical bias magnet protrudes outward in the axial direction from the axial end of the cylindrical high-temperature superconductor. In this case, there is a limit in obtaining a wide magnetic field uniform region in the in-cylinder space of the superconductor. Furthermore, when the bias magnet is a solenoid, the Joule heat generation per unit time increases.

  The present invention has been made in view of the above circumstances, and a superconducting magnetic field generator capable of generating a magnetic field as uniform as possible in the in-cylinder space of the superconductor in a wide range, a magnetization method thereof, and a superconducting magnetic field generator It is an object of the present invention to provide a nuclear magnetic resonance apparatus using the above-mentioned.

A superconducting magnetic field generator according to aspect 1 contains a cylindrical superconductor that generates a magnetic field by capturing a magnetic field at or below the superconducting transition temperature and has a space inside the cylinder, a cooling device that cools the superconductor, and a superconductor The length of the superconductor in the direction in which the virtual central axis extends is the length of the superconductor in order to correct the magnetic field distribution in the in-cylinder space of the superconductor magnetized from the outer peripheral side by the heat insulating container and the external magnetic field application device. characterized in that it comprises a correction coil disposed outside the set Rutotomoni superconductor below.

  In this case, since the cylindrical superconductor, cooling device, heat insulating container, and correction coil are provided, when the magnetic field is applied to the superconductor by the external magnetic field application device, the correction coil is energized. If the magnetic field is corrected by the correction coil, the magnetic field distribution actually applied to the superconductor can be corrected by the magnetic field by the correction coil. Therefore, a superconducting magnetic field generator capable of generating a magnetic field as uniform as possible in the space inside the cylinder of the superconductor can be obtained.

  Further, the length of the correction coil in the direction in which the virtual central axis of the superconductor extends is set to be equal to or shorter than the length of the superconductor (the length in the direction along the virtual central axis of the superconductor). For this reason, when it corrects with a correction coil, the Joule heat by energization of a correction coil is reduced, and the calorific value of a correction coil per unit time is controlled. Therefore, the load applied to the cooling device can be reduced. Here, “below” means that the length of the superconductor in the direction in which the virtual central axis extends is the same as the length of the superconductor (the length in the direction along the virtual central axis of the superconductor). This means that it may be less or less.

  Here, the cylindrical superconductor includes not only the shape defined by the inner diameter, the outer diameter, and the height, but also the shape of a rotating body that is axisymmetric with respect to the virtual central axis of the superconductor. The term “cylindrical shape” means to include a cylindrical shape and a rectangular tube shape, and any cross-sectional shape along the direction perpendicular to the axis of the imaginary central axis may be used. The correction coil means a conductive material that generates a magnetic field for correcting the magnetic field distribution in the in-cylinder space of the superconductor. Therefore, the correction coil only needs to be arranged along the superconductor that generates a magnetic field that corrects the magnetic field distribution in the cylinder space of the superconductor, and the shape of the correction coil is limited to the spiral winding structure. However, the present invention can be changed by various modes for correcting the magnetic field applied to the superconductor.

  The cooling device may be anything as long as it can cool the superconductor, and a regenerative refrigerator such as a GM (Gifford-McMahon) refrigerator, a Stirling refrigerator, or a pulse tube refrigerator can be used. When using an NMR magnet, a pulse tube refrigerator with less vibration is preferable.

  According to aspect 1 described above, the correction coil is a coil that corrects the magnetic field in the direction in which the virtual central axis of the superconductor extends, and the length in the direction in which the virtual central axis extends is equal to or less than the length of the superconductor. Is set to In this case, when used as a magnetic device such as an NMR magnet, it is preferable to make the applied magnetic field as uniform as possible in the space inside the superconductor, particularly at the place where the measurement sample is to be placed.

  Here, when correcting the applied magnetic field in the direction in which the virtual central axis of the in-cylinder space extends, if the length of the correction coil in the axial length direction is long, it is possible to correct a large change in the magnetic field distribution in the virtual central axis direction. It is. However, it is difficult to correct distribution distortion (distortion with a small radius of curvature) in a narrow range of the sample installation location.

  Further, when a current necessary for correction is applied to the correction coil, the longer the axial length of the correction coil, the greater the Joule heat generated by the correction coil. Therefore, there is a possibility that the heat load of the cooling device when the correction coil is cooled by the refrigerator becomes large and the superconductor cannot be cooled to a predetermined temperature. In this case, there is a possibility that a problem arises that a large cooling device is required to cool the superconductor to a predetermined temperature. In this regard, according to the superconducting magnetic field generator according to the present invention, since the length dimension of the correction coil in the axial length direction is set to be equal to or less than the axial length (height) of the superconductor, distortion in a narrow range of distribution can be reduced. At the same time that correction can be performed, heat generation of the correction coil can be suppressed, which is advantageous for downsizing the cooling device.

According to aspect 1, since the correction coil is arranged outside the superconductor, the magnetic field applied to the entire superconductor can be corrected satisfactorily, and the magnetic field can be corrected more effectively for the superconductor. This is advantageous. The correction coil can be arranged coaxially with respect to the superconductor. According to aspect 2, the length of the correction coil in the direction in which the virtual central axis of the superconductor extends is set to be less than the length of the superconductor .

  According to aspect 3, in the above aspect, the correction coil is composed of a plurality of coils. In this case, since the correction coil is formed of a plurality of coils, it is possible to correct a complicated applied magnetic field distribution with respect to the superconductor. As the number of correction coils increases, an advantage that more complicated correction is possible is obtained.

  According to aspect 4, in the above aspect, the correction coil is arranged inside the heat insulating container. In this case, the correction coil is disposed inside the heat insulating container. Since the correction coil can be wound in the vicinity of the superconductor, the distortion of the magnetic field distribution having a smaller radius of curvature can be corrected. In addition, since no protrusion is generated by the correction coil on the outer wall surface of the heat insulating container, there is an advantage that the inner diameter of a magnetizing magnet such as a superconducting magnet used when magnetizing the superconductor can be reduced.

  According to aspect 5, in the above aspect, the correction coil is arranged to be cooled by the cooling device. In this case, since the correction coil is cooled by the cooling device, the electric resistance of the correction coil is reduced. Therefore, the disturbance of the magnetic field of the superconductor can be corrected with a small amount of power. Further, since the correction coil is effectively cooled by the cooling device, the correction coil generates less heat, and the superconductor can be cooled stably.

  According to aspect 6, in the above aspect, the correction coil is a superconducting correction coil formed of a superconducting material, and the superconducting transition temperature of the superconducting correction coil is higher than that of the superconductor. In this case, since the correction coil is formed of a superconducting material, the correction coil has a higher superconducting transition temperature than the magnetized superconductor. This allows current to flow through the correction coil with low electrical resistance (substantially zero), and can increase the magnetic field generated by the correction coil even when the magnetic field of the superconductor is greatly disturbed. The magnetic field of the superconductor can be corrected well. Further, since the Joule heat generation of the correction coil is substantially eliminated, there is an advantage that the cooling can be stably performed without thermal influence on the magnetized superconductor.

  According to aspect 7, in the above aspect, the correction coil is used for correcting the magnetic field distribution when the superconductor is magnetized by the external magnetic field application device. Since the correction coil is used for correcting the magnetic field distribution when the superconductor is magnetized by the external magnetic field application device, the disturbance of the applied magnetic field can be corrected. Therefore, a superconducting magnetic field generator capable of generating a magnetic field as uniform as possible over a wide range can be obtained.

  According to aspect 8, in the above aspect, the superconductor has a magnetic susceptibility different from the magnetic susceptibility of the first part forming at least one end in the direction in which the virtual central axis of the superconductor extends. And the magnetic susceptibility of the first part of the superconductor is set smaller than the magnetic susceptibility of the second part. In this case, since a superconductor having a smaller susceptibility at the end than the susceptibility at the center is used, the magnetic field distribution determined by the configuration of the superconducting bulk can be corrected more uniformly, and a more uniform magnetic field can be obtained over a wide range. An apparatus for generating a superconducting magnetic field is generated.

  According to the aspect 9, the superconductor is composed of portions having different critical current densities, and the critical current density of at least one end in the direction along the virtual central axis of the superconductor is higher than the critical current density of the central portion. Is also set large. In this case, a superconductor having a critical current density at the end of the superconductor larger than that at the center is used, so that a superconducting magnetic field generator capable of generating a uniform magnetic field stably over time in a wide range can be obtained.

According to aspect 10, the main component of the superconductor is RE-Ba-Cu-O (RE is one or more of Y, La, Nd, Sm, Eu, Gd, Er, Yb, Dy, and Ho). It has the composition represented by these. In this case, a superconductor whose main component is represented by RE-Ba-Cu-O (RE is one or more of Y, La, Nd, Sm, Eu, Gd, Er, Yb, Dy, and Ho) In particular, a large magnetic field can be captured by manufacturing by a melting method. The melting method is a method in which a material constituting a superconductor is melted and then solidified to form a superconductor. In this case, it is possible to form a structure in which the insulating phase is finely dispersed in the parent phase that becomes superconducting. In this case, since the finely dispersed insulating phase serves as a pinning point for the magnetic field, a superconductor having a large trapping magnetic field can be obtained. For example, regarding the composition of the superconducting bulk constituting the superconductor, the main components are RE ₁ Ba ₂ Cu ₃ O _7-X (RE123 phase), RE ₂ BaCuO ₅ (RE211 phase), and / or RE _4. Ba ₂ Cu ₂ O ₁₀ (RE422 phase). As an additive component of the superconducting bulk, for example, one or more of Pt, Ag, and Rh can be contained in the form of a simple substance or a compound. However, it is not limited to this, A well-known superconducting material can be used.

The magnetization method of the superconducting magnetic field generator according to aspect 11 includes a cylindrical superconductor that emits a magnetic field by capturing a magnetic field at a superconducting transition temperature or lower and has an in-cylinder space, a cooling device that cools the superconductor, In a magnetization method for magnetizing a superconductor in a superconducting magnetic field generator comprising a heat insulating container containing a superconductor, a magnetic field is applied to the superconductor from the outer circumference side of the superconductor at a temperature higher than the superconducting transition temperature of the superconductor. (B) a magnetic field correction step of correcting the magnetic field distribution in the in-cylinder space of the superconductor by an external correction coil provided near and outside the superconductor in the heat insulating container, and (C) A cooling process in which the superconductor is cooled below the superconducting transition temperature by a cooling device in a state corrected by applying a magnetic field, and (D) a magnetic field applied by an external magnetic field application device or a correction coil. And the magnetic field stopping step of releasing the, characterized in that the implement in order.

  The external magnetic field application device described above is generally disposed outside the superconductor. Examples of the external magnetic field application device include a superconducting magnet. In this case, in addition to the conventional (A) magnetic field application step, (C) cooling step, and (D) magnetic field stop step, (B) a magnetic field correction step using an external correction coil is newly added. For this reason, the magnetic field applied to the superconductor can be corrected in the magnetic field correction step. As a result, the superconductor of the superconducting magnetic field generator can be magnetized so as to generate a uniform magnetic field as widely as possible. The magnetic field application step (A) and the magnetic field correction step by the correction coil (A) can be performed while being shifted in time. However, in some cases, they may be performed simultaneously in time. “Simultaneously in time” means that the magnetic field application process and the magnetic field correction process overlap completely in time and the magnetic field application process and the magnetic field correction process partially overlap in time. Including forms. The external correction coil means a correction coil arranged outside the heat insulating container of the superconducting magnetic field generator.

The superconducting magnetic field generator according to aspect 12 is magnetized by a cylindrical superconductor having an in-cylinder space that generates a magnetic field by capturing the magnetic field at a superconducting transition temperature or lower, a cooling device that cools the superconductor, In order to correct the magnetic field distribution in the heat insulating container that accommodates the superconductor and the space inside the cylinder of the superconductor disposed in the heat insulating container, the length in the direction in which the virtual central axis of the superconductor extends is equal to or less than the length of the superconductor. In the magnetization method of the superconducting magnetic field generator comprising a correction coil that is set and arranged outside the superconductor,
(A) A magnetic field application step of applying a magnetic field to the superconductor from the outer periphery side of the superconductor at a temperature equal to or higher than the superconducting transition temperature of the superconductor, and (B) a magnetic field in the in-cylinder space of the superconductor by the correction coil. A magnetic field correction step for correcting the distribution, (C) a cooling step for cooling the superconductor to a superconducting transition temperature or lower by a cooling device in a state corrected by applying a magnetic field, and (D) an external magnetic field application device or a correction coil. And a magnetic field stopping step for releasing the applied magnetic field in order.

  In this case, since the correction coil is built in the heat insulating container of the superconducting magnetic field generator, (A) the advantage that the applied magnetic field can be corrected according to the external magnetic field application device used for magnetic field application in the magnetic field application step. Is obtained. The magnetic field application step (A) and the magnetic field correction step using the correction coil (A) can be performed while being shifted in time, but may be performed simultaneously depending on circumstances. “Simultaneously in time” means that the magnetic field application process and the magnetic field correction process overlap completely in time and the magnetic field application process and the magnetic field correction process partially overlap in time. Including forms.

  According to aspect 13, the magnetic field correction step is performed in a temperature region between the superconducting transition temperature of the superconductor and + 10 ° C. above the superconducting transition temperature. In this case, when the superconducting transition temperature of the superconductor is Tc, the magnetic field correction step is performed between Tc and (Tc + 10 ° C.). When magnetizing in the above temperature range, the distribution of the magnetic field applied at the superconducting transition temperature is basically captured by the superconductor. In general, the magnetization of a superconductor depends on temperature, and changes with temperature. As a result, the disturbance of the magnetic field distribution due to the magnetization of the superconductor itself also depends on the temperature and changes from the temperature. In this regard, the magnetic field correction step (B) is performed in a temperature region between the superconducting transition temperature and + 10 ° C. above the superconducting transition temperature, so that more accurate magnetic field correction can be performed.

  According to aspect 14, the correction coil is a superconducting correction coil having a higher superconducting transition temperature than the superconductor, and the magnetic field correcting step is performed at a temperature lower than the superconducting transition temperature of the superconducting correction coil and higher than the superconducting transition temperature of the superconductor. It is characterized by performing. In this case, the correction coil is made of a superconductor having a higher superconducting transition temperature than the superconductor to be magnetized, and (B) the magnetic field correction step is performed from the transition temperature of the superconductor magnetized lower than the superconducting transition temperature of the correction coil. Since it is performed at a high temperature, a current can be passed through the correction coil when the electrical resistance is substantially zero, and a large magnetic field disturbance can be corrected. Further, since the Joule heat generation of the correction coil is suppressed, there is no thermal influence on the magnetized superconductor, and the cooling can be stably performed.

  According to the aspect 15, the magnetic field application step and the magnetic field correction step are performed simultaneously. In this case, since the (A) magnetic field application step and the (B) magnetic field correction step are performed simultaneously in time, there is an advantage that magnetization can be performed in a shorter time. Simultaneously means that the magnetic field application step and the magnetic field correction step are completely or partially overlapped in time.

  The nuclear magnetic resonance apparatus according to the aspect 16 includes the superconducting magnetic field generation apparatus according to the aspect described above as a magnet. In this case, a small and high-performance nuclear magnetic resonance apparatus can be obtained by using the superconducting magnetic field generation apparatus according to the above aspect as a magnet.

  According to the present invention, it is possible to generate a magnetic field as uniform as possible in the in-cylinder space of the superconductor over a wide range, and to generate a superconducting magnetic field that has an effect of reducing the amount of heat generated by the correction coil per unit time. The apparatus can provide a magnetizing method thereof. Furthermore, it is possible to provide a nuclear magnetic resonance apparatus that uses a superconducting magnetic field generator having the above-described effects.

  Embodiments of the present invention will be described below.

<Embodiment 1>
FIG. 1 shows a first embodiment. The superconducting magnetic field generator according to the present embodiment generates a magnetic field by capturing a magnetic field at a superconducting transition temperature or lower, and is a cylinder formed of a superconducting bulk having a virtual center axis 11 (virtual center line) having an in-cylinder space 10. -Shaped (cylindrical) superconductor 1, a cooling device 2 (cooler) for cooling the superconductor 1, and a vacuum heat insulating container 3 having a heat insulating chamber 30 for accommodating the superconductor 1 (material: non-magnetic such as aluminum alloy) Material) and a correction coil 4 for correcting the magnetic field distribution in the in-cylinder space 10 of the superconductor 1. The heat insulation chamber 30 is maintained in a high vacuum state.

  A cooling mechanism 20 for cooling the cold head 22 is provided between the cold head 22 where the cold occurs and the cooling device 2. The vacuum heat insulating container 3 has a tip wall 3a and a peripheral wall 3b, and has a pipe 35 inserted into the in-cylinder space 10 from the tip wall 3a. The pipe 35 has a bottom wall 36 for maintaining a vacuum in the heat insulating chamber 30. The interior of the pipe 35 is a space 10c where an inspection object can be placed. Since the inspection object is inserted into the space 10c in the pipe 35 inserted into the in-cylinder space 10 in this way, it is preferable to make the magnetic field in the in-cylinder space 10 of the superconductor 1 as uniform as possible.

  The correction coil 4 is a coil having a cylindrical shape having a coil axis 40 extending along the virtual central axis 11 of the superconductor 1, and is arranged substantially coaxially with the superconductor 1. In the correction coil 4, the length L of the superconductor 1 in the direction in which the virtual central axis 11 extends is set to be equal to or less than the height H of the superconductor 1 (corresponding to the length of the superconductor 1 in the axial length direction). Yes. Therefore, the relationship of L ≦ H is set. The correction coil 4 is disposed at the center of the superconductor 1 in the axial length direction. However, it is not limited to this.

The correction coil 4 described above is composed of a single coil that coaxially surrounds the outer peripheral side of the superconductor 1, and is disposed on the outer peripheral side of the superconductor 1. In the correction coil 4, current flows around the coil axis 40. As shown in FIG. 1, the correction coil 4 is disposed inside the heat insulating chamber 30 of the vacuum heat insulating container 3. As a result, the correction coil 4 is arranged to be cooled by the cooling device 2. The correction coil 4 is used for correcting the magnetic field distribution when the superconductor 1 is magnetized. The superconductor 1 has a composition whose main component is represented by RE-Ba-Cu-O (RE is one or more of Y, La, Nd, Sm, Eu, Gd, Er, Yb, Dy, and Ho). Have Specifically, according to the present embodiment, the superconducting bulk constituting the superconductor ₁ is RE ₁ Ba ₂ Cu ₃ O _7-X (RE123 phase), RE ₂ BaCuO ₅ (RE211 phase), Pt, Ag _2. Each raw material powder of O is blended in a predetermined ratio and formed by a melting method. The superconducting bulk can form a structure in which the insulating phase is finely dispersed in the parent phase that becomes superconducting. In this case, since the finely dispersed insulating phase serves as a pinning point of the magnetic field, the superconductor 1 having a large trapping magnetic field can be obtained.

  Further explanation will be added. As shown in FIG. 1, a correction coil 4 that corrects an applied magnetic field distribution in a direction in which a virtual central axis 11 of a superconductor 1 formed of a cylindrical superconducting bulk extends is provided. The correction coil 4 is held by a cylindrical sample holder 5 (material: aluminum alloy) for fixing the superconductor 1 to the cold head 22 of the cooling device 2. Here, the correction coil 4 is cooled together with the superconductor 1 by the cold bed 22 of the cooling device. For this reason, the electric resistance of the correction coil 4 is reduced, and the disturbance of the magnetic field can be corrected with a small amount of power. The correction coil 4 may be made of a superconducting wire or may be made of a conductive material other than the superconducting wire. When the correction coil 4 is made of a superconducting wire, the electrical resistance is substantially zero and heat generation in the correction coil 4 is suppressed, so that there is a thermal effect on the superconductor 1 formed of the superconducting bulk. It is suppressed. That is, when the correction coil 4 is a superconducting correction coil made of a superconducting material, the superconducting transition temperature of the superconducting correction coil is preferably higher than that of the superconductor 1. In this case, since the correction coil 4 is made of a superconducting material, the correction coil 4 has a higher superconducting transition temperature than the superconductor 1 to be magnetized. For this reason, it is possible to pass a current through the correction coil 4 with low electrical resistance (substantially zero), and even when the magnetic field of the superconductor 1 is greatly disturbed, the magnetic field generated by the correction coil 4 The magnetic field of the superconductor 1 can be corrected well. Further, since the Joule heat generation of the correction coil 4 is substantially eliminated, there is an advantage that there is no thermal influence on the magnetized superconductor 1 and that the cooling can be stably performed.

  According to this embodiment, the cold head 22, the superconductor 1, the sample holder 5, and the correction coil 4 are accommodated in the vacuum heat insulating container 3 that forms the heat insulating chamber 30 whose inside is evacuated. The vacuum heat insulating container 3 and the sample holder 5 are made of an aluminum alloy (nonmagnetic material) so as not to disturb the magnetic field distribution. Instead of aluminum alloy, austenitic stainless steel or ceramics may be used. A bottomed pipe 35 having a closed bottom 36 is coaxially attached in the in-cylinder space 10 to the upper part of the vacuum heat insulating container 3 forming the heat insulating chamber 30. As a result, a space 10c that communicates with the atmosphere and is maintained at atmospheric pressure is formed on the inner peripheral side of the cylindrical superconductor 1. For example, when the present apparatus is used as the magnet 6 of the NMR apparatus, the NMR analysis can be performed by placing an object to be measured in the space 10 c in the in-cylinder space 10.

  According to this embodiment, since the correction coil 4 is disposed inside the vacuum heat insulating container 3, the correction coil 4 can be disposed in the vicinity of the superconductor 1, and a magnetic field distribution having a smaller radius of curvature. Can be corrected. In addition, since the projection by the correction coil 4 does not occur on the outer wall surface of the vacuum heat insulating container 3, there is an advantage that the inner diameter of a magnetizing magnet such as a superconducting magnet used when the superconductor 1 is magnetized can be reduced. . The correction coil 4 is arranged to be cooled by the cooling device 2. For this reason, since the correction coil 4 is cooled by the cooling device 2, the electric resistance of the correction coil 4 is lowered. Therefore, the disturbance of the magnetic field of the superconductor 1 can be corrected with a small amount of power. Further, since the correction coil 4 is effectively cooled by the cooling device 2, the heat generation of the correction coil 4 is reduced.

  According to the present embodiment, the correction coil 4 is used for magnetic field distribution correction when the superconductor 1 is magnetized by an external magnetic field application device. Since the correction coil 4 is used for correction of the magnetic field distribution when the superconductor 1 is magnetized by the external magnetic field application device, the disturbance of the applied magnetic field can be corrected. Therefore, a superconducting magnetic field generator capable of generating a magnetic field as uniform as possible over a wide range can be obtained.

  According to this embodiment, the magnetic field correction step is performed in a temperature region between the superconducting transition temperature of the superconductor 1 and + 10 ° C. above the superconducting transition temperature. In this case, assuming that the superconducting transition temperature of the superconductor 1 is Tc, the magnetic field correction step is performed between Tc and (Tc + 10 ° C.). When magnetizing in the above temperature range, the distribution of the magnetic field applied at the superconducting transition temperature is basically captured by the superconductor 1. In general, the magnetization of the superconductor 1 depends on the temperature and changes depending on the temperature. As a result, the disturbance of the magnetic field distribution due to the magnetization of the superconductor 1 itself also depends on the temperature and changes from the temperature. In this regard, the magnetic field correction step (B) is performed in a temperature region between the superconducting transition temperature and + 10 ° C. above the superconducting transition temperature, so that more accurate magnetic field correction can be performed.

<Embodiment 2>
FIG. 2 shows a second embodiment. This embodiment has basically the same configuration and effects as the first embodiment. In the following, different parts will be mainly described. The cooling device 2 is a two-stage refrigerator. The cryogenic cooling temperature of the second cold head 22s is lower than the cryogenic cooling temperature of the first-stage first cold head 22f. In this case, as shown in FIG. 2, a radiation shield 24 (heat transfer member) is disposed between the first cold head 22 f and the correction coil 4. The first cold head 22 f is in thermal contact with the correction coil 4 via the cylindrical radiation shield 24 and cools the correction coil 4. The base end 24a of the radiation shield 24 is in thermal contact with the first cold head 22f. The tip 24 c of the radiation shield 24 is approaching the tip wall 3 a of the vacuum heat insulating container 3 while facing it. The radiation shield 24 is disposed on the outer peripheral side of the superconductor 1 and the sample holder 5 and on the inner peripheral side of the correction coil 4. The correction coil 4 may be held by the radiation shield 24 or may be held by another member.

  The superconductor 1 is cooled by the second cold head 22s of the second stage. The difference from the first embodiment is that the correction coil 4 is in thermal contact with the radiation shield 24 (material: a non-magnetic and thermally conductive material such as a copper alloy) and is cooled to a low temperature by the radiation shield 24. Yes. Therefore, the cooling of the correction coil 4 is separated from the cooling of the superconductor 1. Thereby, even when the correction coil 4 is energized, even when the correction coil 4 generates Joule heat, there is an advantage that the temperature rise of the superconductor 1 by the correction coil 4 can be suppressed. In addition, since the cylindrical radiation shield 24 can be attached almost coaxially to the superconductor 1 to the first cold head 22f in the first stage, the entire superconductor 1 can be uniformly cooled to a low temperature.

<Embodiment 3>
3 and 4 show the third embodiment. The present embodiment has basically the same configuration and effects as the first and second embodiments. In the following, different parts will be mainly described. As the superconductor 1, a Gd—Ba—Cu—O-based superconducting bulk synthesized by a melting method (critical current density at 40 K Jc = 6 × 10 ⁸ A / m ² , relative permeability at 100 K μr = 1.01) ) Is used. Hereinafter, the critical current density is based on 40K. The relative permeability μr is based on 100K.

  FIG. 3 shows the generated magnetic field distribution of the superconducting magnetic field generator. As shown in FIG. 3, the superconductor 1 has an outer diameter Do 60 mm, an inner diameter Di 16 mm, and a height (a dimension in the direction in which the virtual central axis 11 of the superconductor 1 extends) H 60 mm. The correction coil 4 has an outer diameter Eo80 mm, an inner diameter Ei76 mm, and a length L26 mm. In FIG. 3, the direction in which the virtual central axis 11 of the superconductor 1 extends is shown as the z direction. The radial direction (perpendicular to the axis) of the superconductor 1 is shown as the r direction. Here, a predetermined position in the z direction in the in-cylinder space 10 (the center in the axial length direction of the superconductor 1) is defined as a zero point in the z direction. A point on the virtual central axis 11 in the in-cylinder space 10 is set as a zero point in the r direction.

  FIG. 4 shows a form in which the superconductor 1 is magnetized using an external magnetic field application device and the correction coil 4 (L = 26 millimeters). As shown in FIG. 4, a commercially available NMR superconducting magnet 6 that generates a magnetic field as uniform as possible at 1 ppm or less is used as a magnetizing magnet (external magnetic field applying device). The superconducting magnet 6 is accommodated in a vacuum heat insulating container 3a having a heat insulating chamber 30a, and coaxially surrounds the superconductor 1 of the superconducting magnetic field generator from the outer peripheral side. The magnetization procedure is as follows (see Tables 1 and 2). Table 1 shows a case where correction is performed by the correction coil. Table 1 shows a case where correction is not performed by the correction coil.

  (A) Magnetic field application step: As shown in Table 1, the temperature T of the superconductor 1 is set to a temperature exceeding the superconducting transition temperature Tc (T> Tc). In this state, (1) a current is passed through the superconducting magnet 6 (see FIG. 4) in the direction shown. Thereby, a predetermined magnetic field (5T) is applied upward in the direction in which the virtual central axis 11 of the superconductor 1 extends. At this time, the magnetic field of the superconducting magnet 6 has a uniformity of 1 ppm or less. However, under the influence of the magnetization of the superconductor 1 itself, the actual applied magnetic field has a distorted distribution.

  (B) Magnetic field correction step: As shown in Table 1, (1) With the magnetic field of the superconducting magnet 6 applied, (2) The correction coil 4 faces away from the superconducting magnet 6 (the direction in which the virtual central axis 11 extends) Current) is applied to the correction coil 4 so as to generate a magnetic field of a downward direction. As a result, the distribution of the applied magnetic field is corrected to a predetermined shape (T> Tc). The magnetic field application step (A) and the magnetic field correction step (B) are performed with a time interval, but the present invention is not limited to this, and the magnetic field application step (A) and the magnetic field correction step (B) may be performed at the same time or overlapping in time. Good.

  (C) Cooling step: As shown in Table 1, the temperature T of the superconductor 1 is cooled to less than Tc while both the magnetic field by the superconducting magnet 6 and (2) the magnetic field by the correction coil 4 are applied. (T <Tc).

  (D) Magnetic field stopping step: As shown in Table 1, with the temperature T of the superconductor 1 kept below the critical temperature Tc (T <Tc), (1) the magnetic field by the superconducting magnet 6 and (2) correction Both the magnetic field by the coil 4 is made zero. At this time, as shown in FIG. 3, a superconducting current is induced inside the superconductor 1 having a cylindrical shape so as to maintain the corrected applied magnetic field distribution. As a result, a uniform magnetic field space is formed in the in-cylinder space 10 of the superconductor 1. If the temperature T of the superconductor 1 is less than Tc (T <Tc), the magnetic field may be stopped during the cooling process. Further, after stopping the magnetic field, the superconductor 1 may be further cooled.

According to the present embodiment, a magnetic field of 5T is applied to the superconductor 1 by the superconducting magnet 6 in the above-described (A) magnetic field application step, and (B) in the magnetic field correction step, the current density of the coil current flowing through the correction coil 4 is set. 16 A / mm ² is set. Thereby, the magnetic field by the correction coil 4 is applied so as to be opposite to the direction of the magnetic field by the superconducting magnet 6 (see FIG. 4). Note that the current density of the magnetic field and coil current by the superconducting magnet 6 is not limited to these.

  The magnetic field correction process described above was performed by simulation analysis processing. The simulation analysis process was performed using magnetic field analysis software. In Table 1, the simulation analysis was performed from (A) magnetic field application step to (D) magnetic field stop step.

  FIG. 5 shows the distribution of the applied magnetic field and the trapped magnetic field (magnetic field distribution in the Z direction) in the in-cylinder space 10 of the superconductor 1. In FIG. 5, the horizontal axis indicates the distance in the z direction, and the vertical axis indicates ΔBz / Bo (ppm). Bo represents the magnetic flux density at z = 0 millimeter (0 point). ΔBz represents a difference between magnetic flux density B (z) and Bo at a distance z on the virtual central axis, that is, B (z) −Bo.

In FIG. 5, in “H60Gdt0”, “H60” indicates that the height (axial length dimension) of the superconductor 1 in the direction along the virtual central axis 11 is 60 millimeters. “Gd” indicates that a Gd-based superconducting bulk is used as the superconductor 1. “T0” indicates that the superconducting magnet 6 is applying a magnetic field. In “H60Gd-16A / mm ² ”, “H60” indicates that the axial length of the superconductor 1 is 60 mm. “16 A / mm ² ” indicates that a current is supplied to the correction coil 4 at the time of correction, and the current density of the supplied current is 16 A / mm ² .

  FIG. 6 shows the distribution (magnetic field distribution in the r direction) between the applied magnetic field and the trapped magnetic field in the in-cylinder space 10 of the superconductor 1. In FIG. 6, the horizontal axis indicates the distance in the r direction, and the vertical axis indicates ΔBz / Bo (ppm). Here, in FIG. 5 and Table 1, although the magnetic field is applied to the superconductor 1 by the superconducting magnet 6, the applied magnetic field distribution when the magnetic field is not corrected by the correction coil 4 is shown as ◯ (white circle, characteristic line A1). The generated magnetic field distribution (captured magnetic field distribution) after the magnetic field stop process without being corrected by the correction coil 4 is shown as ▲ (black triangle, characteristic line A2). Although the magnetic field is applied to the superconductor 1 by the superconducting magnet 6, the applied magnetic field distribution when the applied coil 4 is energized to correct the applied magnetic field is shown as ◇ (white rhombus, characteristic line A3). The generated magnetic field distribution (captured magnetic field distribution) after the magnetic field stop process is shown as ■ (black square, characteristic line A4).

  According to the characteristic line A2 shown in FIG. 5, before the correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the z direction is 0.75 millimeters from 0 point to one side. Therefore, considering both sides in the z direction, 0.75 millimeters × 2 = 1.5 millimeters, which is a narrow range. On the other hand, according to the characteristic line A4 shown in FIG. 5, after the correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the z direction is 7.5 on the one side from the zero point. Mm. Therefore, considering both sides in the z direction, 7.5 mm × 2 = 15 mm, which is a wide range.

  According to the characteristic line A2 shown in FIG. 6, before the correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the r direction is 1 millimeter from the 0 point to one side. Therefore, considering both sides in the r direction, 1 mm × 2 = 2 mm, which is a narrow range. On the other hand, according to the characteristic line A4 shown in FIG. 6, after correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the r direction is 5 millimeters from 0 point to one side. is there. Therefore, considering both sides in the r direction, 5 millimeters × 2 = 10 millimeters, which is a wide range.

  As shown in FIG. 5 and FIG. 6 described above, when there is no correction of the magnetic field by the correction coil 4 (before correction), the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained is approximately φ2 mm × LA1.5 mm. There is a narrow range. On the other hand, by correcting the applied magnetic field, the uniform magnetic field space becomes φ10 mm × LA15 mm, which is a wide range, and it can be seen that the superconductor 1 can generate a uniform magnetic field in a wide range.

According to this embodiment, as shown in FIG. 3, the direction of the magnetic field by the correction coil 4 is opposite to the magnetic field of the superconducting magnet 6. However, the direction of the current flowing through the correction coil 4 is not limited to this, and both may be set in the same direction as necessary. The Gd—Ba—Cu—O-based superconducting bulk forming the superconductor 1 is, for example, 0.5 mass% Pt, 10 mass% Ag with respect to Gd123: Gd211 = 3: 1 (molar ratio). _It can be formed by adding ₂ O. However, the composition of the superconducting bulk is not limited to this.

<Embodiment 4>
7 to 9 show a fourth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. The apparatus shown in Embodiment 1 was used. In this case, instead of the Gd-based superconductor 1, an Eu-based bulk superconductor 1 (Eu-Ba-Cu-O-based bulk superconductor 1 (Jc = 6 × 10 ⁸ A / m ² , μr = 1.001) is used as the superconductor 1. The dimensions of the superconductor 1 are an outer diameter Do 60 mm, an inner diameter Di 16 mm, and a height H 60 mm. In this embodiment, according to the simulation analysis, the current density of the coil current flowing through the correction coil 4 (L = 26 millimeters, L <H) is set to 2 A / mm ^{2 in} the magnetic field correction step. The magnetic field by the coil 4 is applied so as to be opposite to the direction of the magnetic field by the superconducting magnet 6 (see FIG. 7).

8 and 9 show the correction results by simulation analysis. Characteristic line A1 (◯), characteristic line A2 (▲), characteristic line A3 (◇), and characteristic line A4 (■) are the same as described above. In this case, as described above, the current density of the current of the correction coil 4 was set to 2 A / mm ² at the time of correction. Then, a magnetic field opposite to the magnetic field applied by the superconducting magnet 6 is applied to the superconductor 1 by the correction coil 4.

  According to the characteristic line A2 shown in FIG. 8, before the correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the z direction is 2 millimeters from 0 point to one side. Therefore, considering both sides in the z direction, 2 millimeters × 2 = 4 millimeters. On the other hand, according to the characteristic line A4 shown in FIG. 8, after the correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the z direction is 6 millimeters from 0 point to one side. is there. Therefore, considering both sides in the z direction, 6 mm × 2 = 12 mm, which is a wide range.

  According to the characteristic line A2 shown in FIG. 9, before the correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the r direction is 3 millimeters from 0 point to one side. Therefore, considering both sides in the r direction, 3 millimeters × 2 = 6 millimeters. On the other hand, according to the characteristic line A4 shown in FIG. 9, after correction by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less is obtained in the r direction is 7 millimeters from 0 point to one side. is there. Therefore, considering both sides in the r direction, 7 millimeters × 2 = 14 millimeters.

As a result, the uniform magnetic field space of 1 ppm or less was φ6 mm × LA4 mm without correction by the correction coil 4. On the other hand, when the correction coil 4 is energized and corrected, it can be seen that it can be enlarged to φ14 mm × LA12 mm. In addition, as Eu-Ba-Cu-O-based superconducting bulk forming the superconductor 1 described above, for example, with respect to Eu123: Eu211 = 100: 35 (molar ratio), 0.5 mass% Pt, 20 mass% Ag _It can be formed by adding ₂ O. However, the composition of the superconducting bulk is not limited to this.

<Embodiment 5>
10 to 12 show the fifth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. In this case, the superconductor 1 includes a cylindrical (cylindrical) end portion 121 (first portion) that forms both ends in the direction in which the virtual central axis 11 of the superconductor 1 extends, and an end portion 121 (first portion). ) And a cylindrical (cylindrical) central portion 120 (second portion) having a magnetic susceptibility different from the magnetic susceptibility in the stacking direction (direction in which the virtual central axis 11 extends). Here, the magnetic susceptibility of the end portion 121 (first portion) of the superconductor 1 is set smaller than the magnetic susceptibility of the central portion 120 (second portion).

  Further, paying attention to the critical current density Jc, the superconductor 1 is composed of portions having different critical current densities Jc in the stacking direction of the superconductor 1 and both ends of the superconductor 1 in the direction along the virtual central axis 11. Part 121 and a central part 120 sandwiched between end parts 121. The current density Jc at the end portion 121 is set to be larger than the critical current density Jc at the central portion 120.

  In other words, the central portion 120 formed of the Gd—Ba—Cu—O-based superconductor 1 is replaced with two end portions 121 formed of the Sm—Ba—Cu—O-based superconductor 1 in the axial length direction. In FIG. 2, the sheet is sandwiched while being crimped by a holder (not shown). Thereby, the superconducting laminate shown in FIG. 10 is formed. The outer diameter Do and inner diameter Di of the superconducting laminate are 60 mm and 16 mm, respectively. The height H1 of the central portion 120 of the Gd system is 40 mm, and the height H2 of the end portion of the Sm system is 10 mm.

The relative permeability μr at 100 K is 1.01 at the central portion 120 formed of the Gd-based superconducting bulk and 1.00035 at the end portion 121 formed of the Sm-based superconducting bulk. Therefore, the relative magnetic permeability μr at the ends disposed at both ends in the stacking direction is set to be smaller than the relative magnetic permeability μr at the center disposed at the center in the stacking direction. Regarding the critical current density Jc at 40K, the central portion formed by the Gd-based superconductor 1 is 6 × 10 ⁸ A / m ² , and the end portion 121 formed by the Sm-based superconductor 1 is 1 × 10 ⁹ A / m ² . Therefore, in the stacking direction of the superconductor 1, Jc at the end portions 121 at both ends is set to be larger than Jc at the center portion 120. In this case, it is advantageous to generate a uniform magnetic field stably over time in a wide range.

11 and 12 show simulation analysis results. FIG. 11 shows the distribution of the applied magnetic field and the trapped magnetic field (distribution in the Z direction) in the in-cylinder space 10 of the superconductor 1. FIG. 12 shows the distribution (distribution in the r direction) of the applied magnetic field and the trapped magnetic field in the in-cylinder space 10 of the superconductor 1. In this case, the current density of the current of the correction coil 4 in the correction characteristic is 2 A / mm ² . Here, the applied magnetic field distribution when the applied magnetic field is not corrected by the correction coil 4 is shown as ◯ (characteristic line A1). The generated magnetic field distribution (captured magnetic field distribution) is shown as ▲ (characteristic line A2). The applied magnetic field distribution when the correction coil 4 is energized to correct the applied magnetic field is shown as ◇ (characteristic line A3). The generated magnetic field distribution (captured magnetic field distribution) after the magnetic field stop process is indicated by (characteristic line A4).

  As shown in FIGS. 11 and 12, when the applied magnetic field was not corrected by the correction coil 4, the uniform magnetic field space in which the magnetic field uniformity of 1 ppm or less was obtained was approximately φ3 mm × LA3 mm. In contrast, by correcting the magnetic field with the correction coil 4, the uniform magnetic field space becomes φ5 mm × LA7 mm, and a uniform magnetic field can be generated over a wide range.

According to this embodiment, the direction of the magnetic field by the correction coil 4 is opposite to the magnetic field of the superconducting magnet 6. However, the direction of the current flowing through the correction coil 4 is not limited to this, and both may be set in the same direction as necessary. In addition, as Sm-Ba-Cu-O-based superconducting bulk forming the superconductor 1 described above, for example, 0.5 mass% Pt, 20 mass% Ag with respect to Sm123: Sm211 = 3: 1 (molar ratio). _It can be formed by adding ₂ O. However, the composition of the superconducting bulk is not limited to this.

<Embodiment 6>
13 to 15 show the sixth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. In the present embodiment, as the superconductor 1, the Eu-Ba-Cu-O-based cylindrical central portion 120 is stacked in the stacking direction (of the superconductor 1 with the Sm-Ba-Cu-O-based cylindrical end portion 121). A superconducting laminate sandwiched in the direction in which the virtual central axis 11 extends is used. In other words, as shown in FIG. 13, the superconductor 1 includes a cylindrical end 121 (first portion) that forms both ends in the direction in which the virtual central axis 11 of the superconductor 1 extends, and an end 121 ( A cylindrical central part 120 (second part) having a magnetic susceptibility different from that of the first part) is laminated. The magnetic susceptibility of the end 121 (first part) of the superconductor 1 is set smaller than the magnetic susceptibility of the central part 120 (second part).

  Further, focusing on the critical current density Jc, as shown in FIG. 13, the superconductor 1 is formed by stacking portions having different critical current densities, and the direction along the virtual central axis 11 of the superconductor 1 Are provided with two end portions 121 and a central portion 120 sandwiched between the two end portions. Here, the critical current density Jc of the end portion 121 is set to be larger than the critical current density Jc of the central portion 120.

  In other words, the superconductor 1 is sandwiched in the axial length direction (lamination direction) between the two end portions 121 formed of the Sm-based superconducting bulk with the central portion 120 formed of the Eu-based superconducting bulk. A superconducting laminate B is formed. In this case, it is advantageous to generate a uniform magnetic field stably over time in a wide range.

The outer diameter Do and inner diameter Di of the superconducting laminate are 60 mm and 16 mm, respectively. The height H1 of the Eu-based central portion 120 is 40 mm, and the height H2 of the Sm-based end portion 121 is 15 mm. The current density Jc is 6 × 10 ⁸ A / m ^{2 at} the Eu-based central portion 120 and 1 × 10 ⁹ A / m ² at the end portion 121 of the Sm system, and the current density Jc at the end portions 121 at both ends is It is larger than the current density Jc of the central portion 120.

The relative permeability μr is 1.001 at the Eu-based end portion 121 and 1.00035 at the Sm-based end portion 121, and the relative permeability μr at the end portions 121 at both ends is larger than the μr at the central portion 120. small. 14 and 15 show the simulation analysis results. According to this embodiment, the current density of the current of the correction coil 4 is set to 0.4 A / mm ² . Thereby, it can be seen that the uniform magnetic field space of 1 ppm or less can be expanded from φ9 mm × LA8 mm without correction to φ13 mm × LA15 mm.

<Embodiment 7>
FIG. 16 shows a seventh embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. About the superconductor 1 (outer diameter Do 60 mm, inner diameter Di 16 mm, height H 60 mm, relative permeability μr = 1.01) formed of the Gd—Ba—Cu—O based superconducting bulk used in Embodiment 3 shown in FIG. The applied magnetic field was corrected by changing the length L of the correction coil 4 (outer diameter 80 mm, inner diameter 76 mm) using the apparatus configuration of the first embodiment (see FIG. 17). The applied magnetic field distribution (FIG. 17) and the heat generation amount per unit time of the correction coil 4 (FIG. 18) at this time were examined by simulation analysis.

  In FIG. 17, “L10” indicates a case where the length of the correction coil 4 is 10 millimeters, that is, a case where the length is shorter than the axial length (height) of the superconductor 1. “L60” indicates a case where the length of the correction coil 4 is 60 millimeters, that is, a case where the length is equal to the axial length (height) of the superconductor 1. “L140” indicates a case where the length of the correction coil 4 is 140 millimeters, that is, a case where the length is longer than the axial length of the superconductor 1.

  In FIG. 17, “H60Gdt0” indicates that the superconductor 1 formed of a Gd-based superconducting bulk having a height of 60 mm is used. “To indicates that a magnetic field is being applied by a superconducting magnet.” “L10J20.5” indicates that the length L of the correction coil 4 is 10 millimeters and the current density J of the correction coil 4 is 20. It shows that it is 5A / mm2.

As shown in FIG. ^{17, L10mm: 20.5A / mm 2} , L20mm: 11.5A / mm 2, L30mm: 9.22A / mm 2, L40mm: 8.8A / mm 2, L50mm: 9.3A / mm ^{2, L60mm: 10.55A / mm 2} , L70mm: 12.5A / mm 2, L80mm: 15.1A / mm 2, L90mm: 18.5A / mm 2, L100mm: 22.8A / mm 2, L110mm: 28 .3 A / mm ² , L120 mm: 35.1 A / mm ² , L130 mm: 43.2 A / mm ² , L140 mm: 53 A / mm ² were examined. The result is shown in FIG. As shown in FIG. 17, as indicated by ●, when the correction by the correction coil 4 is not performed, the magnetic field uniform region of 1 ppm or less is a narrow range. On the other hand, when correction by the correction coil 4 is performed, when the length of the correction coil 4 is in the range of L10 (10 millimeters) to L60 (60 millimeters), the magnetic field uniform region of 1 ppm or less can be widened. I understand.

  That is, as shown in FIG. 17, when the length L of the correction coil 4 is 60 millimeters or less, the shorter the length L of the correction coil 4, the 1 ppm region of the applied magnetic field after correction is in the z direction. It turns out that it becomes wide. When the length L of the correction coil 4 is longer than the superconducting bulk height of 60 mm, the effect of increasing the region of the uniform magnetic field space of 1 ppm in the z direction is mitigated, but the correction coil 4 per unit time is reduced. The calorific value increases exponentially (see FIG. 18).

  According to the characteristic line W1 shown in FIG. 18, when the height H of the superconductor 1 is 60 millimeters, the heat generation amount per unit time of the correction coil 4 forms a minimum range of L20 to 40 millimeters. Shows the minimum at around L30mm. From the above results, in the superconductor 1, the amount of heat generation is reduced when the length L of the correction coil 4 is shorter than the height H of the superconductor 1 formed of the superconducting bulk. Therefore, it can be seen that the thermal load on the cooling device is reduced, and the applied magnetic field distribution can be uniformly corrected in a wider region. In other words, when the height H of the superconductor 1 is displayed relative to 100, the length L of the correction coil 4 can be set to about 33 to 66, or about 40 to 50. However, it is good also as 10-90 and 20-80 by a relative display as needed.

<Eighth embodiment>
19 and 20 show an eighth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. In the same manner as in the seventh embodiment, a superconductor 1 (outer diameter Do 60 mm, outer diameter Do 60 mm, formed of an Sm—Ba—Cu—O based superconducting bulk having a property of having a magnetic susceptibility (permeability) smaller than that of a Gd based superconducting bulk. The length L of the correction coil 4 when using an inner diameter Di16 mm, a height H80 mm, and a relative permeability μr = 1.00035), an applied magnetic field distribution, and a heat generation amount per unit time of the correction coil 4 (see FIG. 20) The relationship was investigated by simulation analysis.

In this ^{case, L10mm: 0.52A / mm 2,} L20mm: 0.285A / mm 2, L30mm: 0.225A / mm 2, L40mm: 0.21A / mm 2, L50mm: 0.22A / mm 2, L60mm: ^{0.24A / mm 2, L70mm: 0.27A} / mm 2, L80mm: 0.33A / mm 2, L90mm: 0.4A / mm 2, L100mm: 0.49A / mm 2, L110mm: 0.61A / mm ^{2, L120mm: 0.76A / mm 2} , L130mm: 0.94A / mm 2, L140mm: was examined 1.15A / mm ^2. Even in this case, the magnetic field uniform region is widened by the correction.

  Further, the heat generation amount per unit time of the correction coil 4 increases exponentially (FIG. 20). When the height H of the superconductor 1 is 80 millimeters, the heat generation amount per unit time of the correction coil 4 shows a minimum range at L20 to 40 millimeters. In particular, when the length L of the correction coil 4 is 30 mm, the heat generation amount is minimized. In other words, when the height H of the superconductor 1 is displayed relative to 100, the length L of the correction coil 4 can be about 25 to 50, or about 30 to 40. However, it is good also as 10-90 and 20-80 by a relative display as needed. As described above, also for the superconductor 1 formed of the Sm-based superconducting bulk having a low magnetic susceptibility, the heat load on the cooling device becomes smaller when the length L of the correction coil 4 is shorter than the height H of the superconducting bulk. It can be seen that the applied magnetic field distribution can be uniformly corrected in a wider region.

<Ninth Embodiment>
21 and 22 show the ninth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. In the present embodiment, as the superconductor 1, the Eu-Ba-Cu-O-based cylindrical central portion 120 is stacked in the stacking direction (of the superconductor 1 with the Sm-Ba-Cu-O-based cylindrical end portion 121). A superconducting laminate sandwiched in the direction in which the virtual central axis 11 extends is used as the superconductor 1. In other words, as shown in FIG. 21, the superconductor 1 includes a cylindrical end 121 (first portion) that forms both ends in the direction in which the virtual central axis 11 of the superconductor 1 extends, and an end 121 ( A cylindrical central part 120 (second part) having a magnetic susceptibility different from that of the first part) is laminated. The magnetic susceptibility of the end 121 (first part) of the superconductor 1 is set smaller than the magnetic susceptibility of the central part 120 (second part). In this case, as will be described later, it is advantageous to provide a superconducting magnetic field generator that generates a uniform magnetic field stably over time in a wide range. Here, the critical current density Jc of the end portion 121 is set to be larger than the critical current density Jc of the central portion 120.

  Here, Sm-based end portion 121 (height 15 mm), Eu-based central portion 120 (height 40 mm), and Sm-based end portion 120 (height 15 mm) are stacked in the stacking direction. When a laminate (outer diameter 60 mm, inner diameter 16 mm, overall height 70 mm) was used and the length L of the correction coil 4 was changed, the applied magnetic field distribution and the heat generation amount per unit time of the correction coil 4 were examined by simulation analysis. . Even in this case, the magnetic field uniform region can be widened. When the height H of the superconductor 1 is 70 millimeters, a minimum area is obtained with the length L20 to 40 millimeters of the correction coil 4 with respect to the heat generation amount per unit time of the correction coil 4. In particular, it can be seen that the heat generation amount is exponentially increased when the heat generation amount is minimum at L30 millimeters and the length L of the correction coil 4 is longer than the height of the superconducting bulk 70 mm (FIG. 22). As described above, also in the superconductor 1 formed of a laminated bulk of Sm / Eu / Sm, the heat load on the cooling device 2 is greater when the length L of the correction coil 4 is shorter than the height H of the superconductor 1. It can be seen that the applied magnetic field distribution can be uniformly corrected more efficiently. When the height H of the superconductor 1 is displayed relative to 100, the central portion 120 can be set to 30 to 90 and 40 to 80. Each end 120 can be 5-30.

<Embodiment 10>
FIG. 23 shows the tenth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. As shown in FIG. 23, in the present embodiment, as the superconductor 1, an Eu-Ba-Cu-O-based cylindrical central portion 120 is replaced with an Sm-Ba-Cu-O-based cylindrical end portion 121. A superconducting laminate sandwiched in the stacking direction (the direction in which the virtual central axis 11 of the superconductor 1 extends) is used as the superconductor 1. In other words, as shown in FIG. 23, the superconductor 1 includes a cylindrical end 121 (first portion) that forms both ends in the direction in which the virtual central axis 11 of the superconductor 1 extends, and an end 121 ( A cylindrical central part 120 (second part) having a magnetic susceptibility different from that of the first part) is laminated. The magnetic susceptibility of the end 121 (first part) of the superconductor 1 is set smaller than the magnetic susceptibility of the central part 120 (second part). Here, the critical current density Jc of the end portion 121 is set to be larger than the critical current density Jc of the central portion 120. In this case, as will be described later, it is advantageous to provide a superconducting magnetic field generator that generates a uniform magnetic field stably over time in a wide range.

  Here, according to the present embodiment, the inner diameter Di of the superconductor 1 is set larger than the inner diameter of the ninth embodiment. Superconductivity formed of a stacked bulk in which an Sm-based end portion 121 (height 26 mm), an Eu-based central portion 120 (height 48 mm), and an Sm-based end portion 121 (height 26 mm) are stacked in the stacking direction. Body 1 (outer diameter 60 mm, inner diameter 24 mm, overall height 100 mm). In this case, the calorific value per unit time of the correction coil 4 (FIG. 24) was examined by simulation analysis.

  FIG. 24 shows the result of simulation analysis of the heat generation characteristics of the correction coil 4 when the length L of the correction coil 4 is changed. About the calorific value per unit time of the correction coil 4, the minimum range was obtained in L20-50 vicinity. In particular, when the length L of the correction coil 4 is 30 mm, the amount of heat generated by the correction coil 4 is minimized, and when the length L of the correction coil 4 is longer than the height H (100 mm) of the superconductor 1, It can be seen that it is not desirable because it increases exponentially (FIG. 24). From the above, even in the superconductor 1 formed of a laminated bulk of Sm / Eu / Sm having a large inner diameter, the cooling device is such that the length L of the correction coil 4 is shorter than the height H of the superconductor 1. It can be seen that the applied magnetic field distribution can be uniformly corrected more efficiently with a small thermal load on the.

<Embodiment 11>
FIG. 25 shows the eleventh embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. In the first embodiment, two correction coils 4 (first correction coil 41 and second correction coil 42) are connected in series in the virtual central axis (z-axis) direction of the superconductor 1 and the virtual central axis 11 of the superconductor 1. However, a superconducting magnetic field generator having a structure arranged almost coaxially is used. The first correction coil 41 and the second correction coil 42 have the same size (outer diameter Eo 80 mm, inner diameter Ei 76 mm, length LA 10 mm). The first correction coil 41 and the second correction coil 42 are disposed at positions that are vertically symmetrical with respect to the center point of the superconductor 1 in the height direction (axial length direction) of the superconductor 1 formed of the superconducting bulk. ing. In addition, the first correction coil 41 and the second correction coil 42 are connected to a power source (not shown) so that the directions of currents are opposite to each other. The interval (gap) between the first correction coil 41 and the second correction coil 42 was set to 0, 10, 20, 30, 40, 50, and 60 millimeters, respectively.

FIG. 26 shows a magnetic field distribution (simulation analysis) generated by the correction coil 4 when a current density of 1 A / mm ² is passed through the correction coil 4. A characteristic line C1 indicates when gap is 0 millimeter and L is 20 millimeter. A characteristic line C2 indicates when gap is 10 millimeters and L is 30 millimeters. A characteristic line C3 indicates when gap is 20 millimeters and L is 40 millimeters. A characteristic line C4 indicates when gap is 30 millimeters and L is 50 millimeters. A characteristic line C5 indicates when gap is 40 millimeters and L is 60 millimeters. A characteristic line C6 indicates when gap is 50 millimeters and L is 70 millimeters. A characteristic line C7 indicates when gap is 60 millimeters and L is 80 millimeters.

  If correction is performed by energizing the first correction coil 41 and the second correction coil 42, the uniform magnetic field region can be widened. By reversing the directions of the currents of the two first correction coils 41 and the second correction coils 42, the linear inclination of the applied magnetic field distribution in the direction in which the virtual central axis 11 of the superconductor 1 extends can be corrected. Yes (first order correction).

  As the gap between the first correction coil 41 and the second correction coil 42 increases, the gradient of the magnetic field distribution near z = 0 increases. A larger gradient is better. Therefore, the characteristic lines C2, C3, C4, C5, C6, and C7 are good. As indicated by the characteristic line C5, the gap decreases after it reaches a maximum in the vicinity of 40 mm (L60 mm). As a result, in order to perform the primary correction of the magnetic field distribution with the same current, the optimum coil interval is obtained when the length L at both ends of the first correction coil 4 and the second correction coil 4 is equal to or less than the coil outer diameter. You can see that it exists.

<Twelfth embodiment>
27 and 28 show the twelfth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. A perspective view of the first correction coil 41 and the second correction coil 42 is shown in FIG. As shown in FIGS. 27 and 28, the superconducting magnetic field generator in the case where the first correction coil 41 and the second correction coil 42 are used in parallel in the r direction (x direction) which is the radial direction of the superconductor 1 is used. It has been. A perspective view of the first correction coil 41 and the second correction coil 42 is shown in FIG.

  As shown in FIG. 28, the first correction coil 41 includes an arc portion 41a having a C shape on one side (upper side), an arc portion 41b having a C shape on the other side (lower side), and arc portions 41a and 41b. It has the connection part 41c extended along the axial length direction of the superconductor 1 so that they may be connected. The second correction coil 42 has a symmetric shape with the first correction coil 41, and has an arc portion 42a having a C shape on one side (upper side) and an arc portion 42b having a C shape on the other side (lower side). The connecting portion 42c extends along the axial direction of the superconductor 1 so as to connect the arc portions 42a and 42b.

  In this case, a current is passed through the first correction coil 41 and the second correction coil 42 in the opposite directions. When the currents are passed through the first correction coil 41 and the second correction coil 42 in opposite directions, a correction magnetic field similar to that in FIG. 26 is formed in the r direction (x direction), and the linear inclination of the applied magnetic field distribution is corrected. Yes (first order correction).

<Embodiment 13>
29 and 30 show a thirteenth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. As shown in FIG. 29, the superconducting magnetic field generator in the case where the first correction coil 41 and the second correction coil 42 are used in parallel in the r direction (x direction) which is the radial direction of the superconductor 1 is used. . A perspective view of the first correction coil 41 and the second correction coil 42 is shown in FIG. In this case, a current is passed through the first correction coil 41 and the second correction coil 42 in the same direction. As shown in FIG. 30, the first correction coil 41 includes a circular arc portion 41a having a C shape on one side (upper side), a circular arc portion 41b having a C shape on the other side (lower side), and circular arc portions 41a and 41b. It has the connection part 41c extended along the axial length direction of the superconductor 1 so that they may be connected. The second correction coil 42 has a symmetric shape with the first correction coil 41, and has an arc portion 42a having a C shape on one side (upper side) and an arc portion 42b having a C shape on the other side (lower side). The connecting portion 42c extends along the axial direction of the superconductor 1 so as to connect the arc portions 42a and 42b.

  In the case where currents are passed through the first correction coil 41 and the second correction coil 42 in the same direction, it is possible to correct the applied magnetic field distribution (secondary correction) symmetrical in the r direction (x direction).

  As shown in FIG. 30, although the correction coils 41 and 42 are arranged in parallel in the r direction (x direction), the third correction coil and the fourth correction coil are not shown in the r direction (y direction) perpendicular thereto. By applying a correction coil and changing the direction and magnitude of the current flowing through the first correction coil 41, the second correction coil 42, the third correction coil, and the fourth correction coil, the applied magnetic field in the xy plane Can correct distortion.

<Embodiment 14>
FIG. 31 shows a fourteenth embodiment. This embodiment has basically the same configuration and effects as the above-described embodiment. In this embodiment, the superconducting magnetic field generator described above is incorporated into a nuclear magnetic resonance apparatus.

  The nuclear magnetic resonance apparatus 200 is a nuclear magnetic resonance apparatus including the above-described superconducting magnetic field generation apparatus, and is a small and high-performance nuclear magnetic resonance apparatus. One preferred embodiment is shown in the block diagram of FIG. As shown in FIG. 31, the nuclear magnetic resonance apparatus 200 of the present embodiment includes a superconducting magnetic field generation apparatus 100 and analysis means 300. The cooling device 2 of the superconducting magnetic field generator 100 is connected to the compressor 220, and the vacuum heat insulating container 3 communicates with the vacuum pump 230. M indicated by a broken line is a superconducting magnet (external magnetic field applying device) used only during application. The analysis unit 300 includes a high frequency generator 310, a pulse programmer (transmitter) 320, a high frequency amplifier 330, a preamplifier (signal amplifier) 340, a phase detector (receiver) 350, an analog / digital converter 360, a computer 370, and the like. Become.

  Since the nuclear magnetic resonance apparatus 200 having such a configuration includes the superconducting magnetic field generation apparatus 100 that generates a correctable uniform magnetic field, it is compact and can perform NMR analysis with high accuracy.

(others)
The present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications within a range not departing from the gist. The superconductor 1 is not limited to the composition described above, and can be appropriately selected as necessary. Also in the superconductor having a laminated structure, the composition of the end portion 121 and the central portion 120 is not limited to the above-described composition, and can be appropriately selected as necessary. The nonmagnetic material used in the superconducting magnetic field generator is not limited to the above-described materials, and can be appropriately selected as necessary.

  The superconducting magnetic field generating apparatus having the superconducting magnetic field generating element of the present invention can generate a strong static magnetic field with a uniform distribution, and thus is suitable as a magnetic field generating apparatus for a nuclear magnetic resonance apparatus. In addition, since such a superconducting nuclear magnetic resonance apparatus is highly sensitive, has high resolution and is compact, it can be suitably used for MRI apparatuses in the medical field, or for components and structural analysis of industrial materials and agricultural products. it can.

1 is a cross-sectional view schematically showing a superconducting magnetic field generator according to Embodiment 1. FIG. It is sectional drawing which concerns on Embodiment 2 and shows a superconducting magnetic field generator typically. FIG. 10 is a cross-sectional view schematically showing a superconductor and a correction coil according to the third embodiment. FIG. 10 is a cross-sectional view schematically showing a state in which a magnetic field is applied to a superconductor with a superconducting magnet while being corrected by a correction coil according to the third embodiment. It is a graph which shows the uniform magnetic field space which concerns on Embodiment 3 and can obtain the magnetic field uniformity of 1 ppm or less in az direction. It is a graph which shows the uniform magnetic field space which concerns on Embodiment 3 and can obtain the magnetic field uniformity of 1 ppm or less in the r direction. FIG. 10 is a cross-sectional view schematically showing a superconductor and a correction coil according to the fourth embodiment. It is a graph which shows the uniform magnetic field space which concerns on Embodiment 4 and can obtain the magnetic field uniformity of 1 ppm or less in az direction. It is a graph which shows the uniform magnetic field space which concerns on Embodiment 4 and can obtain the magnetic field uniformity of 1 ppm or less in the r direction. FIG. 10 is a cross-sectional view schematically showing a superconductor and a correction coil according to the fifth embodiment. 10 is a graph showing a uniform magnetic field space according to Embodiment 5 in which a magnetic field uniformity of 1 ppm or less is obtained in the z direction. 10 is a graph showing a uniform magnetic field space according to Embodiment 5 in which a magnetic field uniformity of 1 ppm or less is obtained in the r direction. FIG. 10 is a cross-sectional view schematically showing a superconductor and a correction coil according to the sixth embodiment. It is a graph which shows the uniform magnetic field space which concerns on Embodiment 6 and can obtain the magnetic field uniformity of 1 ppm or less in az direction. It is a graph which shows the uniform magnetic field space which concerns on Embodiment 6 and can obtain the magnetic field uniformity of 1 ppm or less in the r direction. FIG. 10 is a cross-sectional view schematically showing a superconductor and a correction coil according to the seventh embodiment. 10 is a graph showing a uniform magnetic field space in which a magnetic field uniformity of 1 ppm or less is obtained in the z direction according to the seventh embodiment. 18 is a graph illustrating heat generation characteristics when the length L of the correction coil is changed according to the seventh embodiment. FIG. 10 is a cross-sectional view schematically showing a superconductor and a correction coil according to an eighth embodiment. 10 is a graph illustrating heat generation characteristics when the length L of the correction coil is changed according to the eighth embodiment. FIG. 16 is a cross-sectional view schematically showing a superconductor and a correction coil according to the ninth embodiment. 25 is a graph showing heat generation characteristics when the length L of the correction coil is changed according to the ninth embodiment. FIG. 16 is a cross-sectional view schematically showing a superconductor and a correction coil according to the tenth embodiment. 18 is a graph illustrating heat generation characteristics when the length L of the correction coil is changed according to the tenth embodiment. FIG. 16 is a cross-sectional view schematically showing a superconducting magnetic field generator according to Embodiment 11 and including a superconductor and a correction coil in a heat insulating container. 20 is a graph according to Embodiment 11 and showing a relationship with a correction magnetic field when an interval between the first correction coil and the second correction coil is changed. FIG. 16 is a cross-sectional view schematically showing a main part of a superconducting magnetic field generation device according to Embodiment 12 and including a superconductor and a correction coil in a heat insulating container. FIG. 14 is a perspective view schematically showing a correction coil provided in a superconductor according to Embodiment 12. It is sectional drawing which concerns on Embodiment 13 and shows typically the principal part of the superconducting magnetic field generator provided with a superconductor and a correction coil in a heat insulation container. FIG. 20 is a perspective view schematically showing a correction coil provided in a superconductor according to Embodiment 13. FIG. 16 is a configuration diagram illustrating a state in which a superconducting magnetic field generation device is incorporated in a nuclear magnetic resonance apparatus according to a fourteenth embodiment.

Explanation of symbols

  100 is a superconducting magnetic field generator, 1 is a superconductor, 10 is an in-cylinder space, 11 is a virtual central axis, 121 is an end, 120 is a central part, 2 is a cooling device, 22 is a cold head, 3 is a vacuum insulation container, Reference numeral 30 denotes a heat insulating chamber, 4 denotes a correction coil, and 6 denotes a superelectromagnet (external magnetic field applying device).

Claims (15)

A cylindrical superconductor that emits a magnetic field by capturing the magnetic field below the superconducting transition temperature and has an in-cylinder space;
A cooling device for cooling the superconductor;
A heat insulating container for accommodating the superconductor;
In order to correct the magnetic field distribution in the in-cylinder space of the superconductor magnetized from the outer peripheral side by an external magnetic field application device, the length of the superconductor in the direction in which the virtual central axis extends is equal to or less than the length of the superconductor And a correction coil disposed outside the superconductor, and a superconducting magnetic field generator. Oite to claim 1, wherein the correction coils are superconducting magnetic field generating apparatus characterized by being formed by a plurality of coils. 3. The superconducting magnetic field generator according to claim 1, wherein the correction coil is disposed inside the heat insulating container. In any one of claims 1-3, wherein the correction coil, the superconducting magnetic field generating apparatus characterized by being arranged to be cooled by the cooling device. The correction coil according to any one of claims 1 to 4 , wherein the correction coil is a superconducting correction coil formed of a superconducting material, and a superconducting transition temperature of the superconducting correction coil is higher than that of the superconductor. Superconducting magnetic field generator. The superconductivity according to any one of claims 1 to 5 , wherein the correction coil is used for correction of magnetic field distribution when the superconductor is magnetized from outside the heat insulating container by an external magnetic field application device. Magnetic field generator. The superconductor according to any one of claims 1 to 6 , wherein the superconductor includes a first portion that forms at least one end in a direction in which the virtual central axis of the superconductor extends, and the first portion. And a second part having a magnetic susceptibility different from the magnetic susceptibility, wherein the magnetic susceptibility of the first part of the superconductor is set smaller than the magnetic susceptibility of the second part. Magnetic field generator. The superconductor according to any one of claims 1 to 7 , wherein the superconductor includes portions having different critical current densities, and the critical current of at least one end of the superconductor in a direction along the virtual central axis. A superconducting magnetic field generator characterized in that the density is set to be larger than the critical current density at the center of the superconductor. In any one of claims 1-8, wherein the superconductor is its main component RE-Ba-Cu-O ( RE Y, La, Nd, Sm, Eu, Gd, Er, Yb, Dy , Ho), a superconducting magnetic field generator having a composition represented by: Superconductivity comprising a cylindrical superconductor that generates a magnetic field by capturing a magnetic field at or below the superconducting transition temperature and has an in-cylinder space, a cooling device that cools the superconductor, and a heat insulating container that houses the superconductor. In a magnetization method of magnetizing the superconductor in a magnetic field generator,
(A) a magnetic field application step of applying a magnetic field to the superconductor from the outer peripheral side of the superconductor at a superconducting transition temperature of the superconductor by an external magnetic field application device;
(B) a magnetic field correction step of correcting the magnetic field distribution in the in-cylinder space of the superconductor by a correction coil provided near and outside the superconductor in the heat insulating container;
(C) a cooling step of cooling the superconductor to a superconducting transition temperature or lower by the cooling device in a state corrected by applying a magnetic field;
(D) A method of magnetizing a superconducting magnetic field generator, comprising: a magnetic field stopping step of releasing a magnetic field applied by the external magnetic field applying device or the correction coil. A cylindrical superconductor that generates a magnetic field by capturing a magnetic field at a temperature lower than the superconducting transition temperature and has an in-cylinder space, a cooling device that cools the superconductor, a heat insulating container that houses the superconductor, and the heat insulating container In order to correct the magnetic field distribution in the in-cylinder space of the superconductor, the length in the direction in which the virtual central axis of the superconductor extends is set to be equal to or less than the length of the superconductor, and the superconductor In a magnetization method of a superconducting magnetic field generator comprising a correction coil disposed outside,
(A) a magnetic field application step of applying a magnetic field to the superconductor from the outer peripheral side of the superconductor at a superconducting transition temperature of the superconductor by an external magnetic field application device;
(B) A magnetic field correction step of correcting the magnetic field distribution in the in-cylinder space of the superconductor by the correction coil;
(C) a cooling step of cooling the superconductor to a superconducting transition temperature or lower by the cooling device in a state corrected by applying a magnetic field;
(D) A method of magnetizing a superconducting magnetic field generator, comprising: a magnetic field stopping step of releasing a magnetic field applied by the external magnetic field applying device or the correction coil. 12. The method of magnetizing a superconducting magnetic field generator according to claim 10 , wherein the magnetic field correcting step is performed in a temperature region between a superconducting transition temperature of the superconductor and + 10 ° C. above the superconducting transition temperature. The superconducting correction coil according to any one of claims 10 to 12 , wherein the correction coil is a superconducting correction coil having a higher superconducting transition temperature than the superconductor, and the magnetic field correcting step is performed using the superconducting transition temperature of the superconducting correction coil. A method for magnetizing a superconducting magnetic field generator, wherein the method is performed at a temperature lower and higher than a superconducting transition temperature of the superconductor. 14. The method for magnetizing a superconducting magnetic field generator according to claim 10 , wherein the magnetic field applying step and the magnetic field correcting step are performed simultaneously. The nuclear magnetic resonance apparatus, comprising a superconducting magnetic field generating apparatus as a magnet according to one of claims 1 to 9.

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