WO2015015892A1 - Magnetic field-generating device, magnetic resonance imaging apparatus using same, and magnetization unit for high temperature superconducting bulks - Google Patents

Magnetic field-generating device, magnetic resonance imaging apparatus using same, and magnetization unit for high temperature superconducting bulks Download PDF

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Publication number
WO2015015892A1
WO2015015892A1 PCT/JP2014/064569 JP2014064569W WO2015015892A1 WO 2015015892 A1 WO2015015892 A1 WO 2015015892A1 JP 2014064569 W JP2014064569 W JP 2014064569W WO 2015015892 A1 WO2015015892 A1 WO 2015015892A1
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magnetic field
temperature superconducting
superconducting bulk
bulk body
temperature
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PCT/JP2014/064569
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French (fr)
Japanese (ja)
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松田　和也
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株式会社日立製作所
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Publication of WO2015015892A1 publication Critical patent/WO2015015892A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/381—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets
    • G01R33/3815—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using electromagnets with superconducting coils, e.g. power supply therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/387—Compensation of inhomogeneities
    • G01R33/3875—Compensation of inhomogeneities using correction coil assemblies, e.g. active shimming

Definitions

  • the present invention relates to a magnetic field generator capable of generating a spatially and temporally uniform high magnetic field, a magnetic resonance imaging apparatus using the same, and a high-temperature superconducting bulk magnetizer.
  • Nuclear Magnetic Resonance (NMR) equipment can obtain useful data for structural analysis of all organic compounds such as chemical shift amounts and spin-spin coupling constants of each atom.
  • a magnet (magnetic field generator) using a superconducting material is used because analysis in detail and with a large amount of information is possible.
  • An NMR apparatus is composed of a magnet (magnetic field generator) that generates a static magnetic field, a coil that generates a high-frequency pulse and detects an NMR signal, a receiver that receives the NMR signal, a system controller, and the like.
  • a superconducting magnet is a magnetic field. It is advantageous in terms of strength, stability and uniformity.
  • a chemical reaction occurring in a tissue or organ is traced as it is, and for example, a magnetic resonance imaging (MRI) apparatus that obtains a brain tomogram is an NMR.
  • MRI magnetic resonance imaging
  • the MRI apparatus is used not only for the medical field but also for industrial materials and components / structure analysis of agricultural products.
  • the MRI apparatus is a magnet that is a static magnetic field generating means, a gradient magnetic field for giving spatial information to a signal, a high-frequency electromagnetic wave irradiation system, an NMR signal detection system, a probe that surrounds an inspection object such as a human body and performs high-frequency electromagnetic wave irradiation and signal detection.
  • This MRI apparatus is safe because it does not use radiation, has a sufficient resolution, and has a very high practical value.
  • Patent Document 1 Japanese Patent Laid-Open No. Hei 11-1990. No. 248810
  • the high-temperature superconducting bulk body makes a superconducting transition at a higher temperature than the conventional helium-cooled superconducting magnet, the operating temperature of the refrigerator can be increased. For this reason, compared with a helium-cooled superconducting magnet, there are advantages in that the heat insulating structure can be simplified and a small refrigerator can be employed.
  • the magnetic field generator can be made smaller and lower in operating cost than a helium-cooled superconducting magnet.
  • a magnetic field generator is arranged inside a vacuum heat insulation container and the vacuum heat insulation container, and a superconducting current flows inside by being cooled and applied with a magnetic field.
  • a high-temperature superconducting bulk body that captures the magnetic field and supplies the supplemented magnetic field; and a refrigerator that cools the high-temperature superconducting bulk body to a cryogenic temperature, and the high-temperature superconducting bulk body includes the high-temperature superconducting bulk body.
  • Magnetization is performed using a magnetizing apparatus that applies a magnetic field and a detachable magnetic field adjusting apparatus that adjusts the magnetic field in the vicinity of the high-temperature superconducting bulk body.
  • the magnetic resonance imaging apparatus generates a static magnetic field in a measurement space in which the subject is set by the magnetic field adjustment device, and acquires a magnetic resonance signal from the subject, thereby obtaining an image of the subject. It is characterized by obtaining.
  • a magnetizing apparatus for a high-temperature superconducting bulk body includes a static magnetic field generating apparatus for generating a static magnetic field and applying a static magnetic field to the high-temperature superconducting bulk body, and the high-temperature superconducting bulk body by the applied static magnetic field. And a magnetic field adjusting device for adjusting magnetic field disturbance caused by the magnetized high-temperature superconducting bulk body.
  • the present invention it is possible to provide a magnetic field generator having high magnetic field uniformity with a small and simple configuration, a magnetic resonance imaging apparatus using the same, and a high temperature superconducting bulk magnetizer.
  • FIG. 3 is a cross-sectional view of the magnetic field generation device, the magnetic field adjustment device, and the magnetization device of the first embodiment taken along line BB. It is a flowchart which shows the magnetization operation
  • FIG. 1 is a configuration diagram of an MRI apparatus S including a magnetic field generation apparatus 1 according to the first embodiment.
  • the MRI apparatus S includes a magnetic field generator 1 that generates a magnetic field in a space 6 to be measured, a coil group 2 having a gradient magnetic field coil (not shown) and an RF (Radio Frequency) coil (not shown), and a system control unit 3, an output device 4, and a refrigerator power supply unit 5.
  • a magnetic field generator 1 that generates a magnetic field in a space 6 to be measured
  • a coil group 2 having a gradient magnetic field coil (not shown) and an RF (Radio Frequency) coil (not shown)
  • a system control unit 3 an output device 4, and a refrigerator power supply unit 5.
  • the magnetic field generator 1 includes high-temperature superconducting bulk bodies 11a and 11b (see FIG. 2) and a refrigerator 13 (see FIG. 2) that act as superconducting permanent magnets by cooling, and the magnetic field generator from the refrigerator power supply unit 5 is provided. By supplying electric power to one refrigerator 13 (see FIG. 2), the high-temperature superconducting bulk bodies 11a and 11b (see FIG. 2) are cooled.
  • the magnetic field generator 1 generates a spatially and temporally uniform magnetic field (static magnetic field) in the measurement space 6 by magnetizing the high-temperature superconducting bulk bodies 11a and 11b (see FIG. 2), which will be described later. It is supposed to let you.
  • a coil group 2 composed of a gradient magnetic field coil (not shown) and an RF coil (not shown) is disposed in a measured space 6 in the measurement space of the magnetic field generator 1.
  • the coil group 2 (gradient magnetic field coil, RF coil) is connected to the system control unit 3.
  • the system control unit 3 generates a gradient magnetic field in the space to be measured 6 by a gradient magnetic field coil (not shown) of the coil group 2 and performs phase encoding and frequency encoding to give signal position information.
  • the system control unit 3 uses an RF coil (not shown) of the coil group 2 to generate an RF signal in a direction perpendicular to the direction of the magnetic field (static magnetic field) generated by the magnetic field generator 1 in the measured space 6.
  • the NMR signal of the object to be measured (not shown) is received by the RF coil (not shown).
  • the RF coil (not shown) may be provided separately with a signal transmitting RF coil (not shown) and a receiving RF coil (not shown), or one RF coil (not shown). May be used for signal transmission and reception.
  • the system control unit 3 maps the NMR signal received by the RF coil (not shown) as MRI, outputs it to the output device 4, and displays it.
  • FIG. 2 is a perspective view of the magnetic field generator 1 of the first embodiment.
  • FIG. 3 is a cross-sectional view taken along line AA of the magnetic field generator 1 of the first embodiment.
  • the coil group 2 (see FIG. 1) is omitted.
  • the magnetic field generator 1 includes high-temperature superconducting bulk bodies 11a and 11b, a heat conducting member 12 (see FIG. 3), a refrigerator 13, and a vacuum heat insulating container 14 (14a, 14b, and 14c). It is equipped with.
  • the refrigerator 13 is connected to a vacuum heat insulating container 14.
  • the vacuum heat insulating container 14 includes a vacuum heat insulating container 14a disposed so as to surround the high temperature superconducting bulk body 11a, a vacuum heat insulating container 14b disposed so as to surround the high temperature superconducting bulk body 11b, and the heat conducting member 12 (FIG. 3) and a vacuum heat insulating container 14c disposed inside.
  • the cold head 131 of the refrigerator 13 (see FIG. 2) is thermally connected to the high-temperature superconducting bulk bodies 11 a and 11 b via the heat conducting member 12. Thereby, the high-temperature superconducting bulk bodies 11a and 11b are cooled by the refrigerator 13 (see FIG. 2) via the heat conducting member 12.
  • the heat conducting member 12 is made of a material having a high heat conductivity, such as oxygen-free copper.
  • the heat conducting member 12 is fixed so as not to be in direct contact with the vacuum heat insulating container 14, but in order to avoid contact with the vacuum heat insulating container 14 due to deflection of the heat conducting member 12, the vacuum heat insulating container 14 and the heat conducting member 12 are arranged. May be indirectly supported and fixed by a load support (not shown) made of a material having a low thermal conductivity, for example, a fiber-reinforced plastic (FRP).
  • FRP fiber-reinforced plastic
  • alumina, glass fiber, or carbon fiber can be used as the FRP fiber.
  • the refrigerator 13 can downsize the magnetic field generator 1 by using, for example, a compressor-integrated Stirling refrigerator.
  • a compressor separation type GM cycle refrigerator a Solvay cycle refrigerator, a Stirling refrigerator, a pulse tube refrigerator, or the like.
  • the compressor heat radiation part of the refrigerator 13 is radiated by an air cooling or a water cooling device (not shown).
  • the high-temperature superconducting bulk bodies 11a and 11b of the magnetic field generator 1 are inserted into a magnetizing device 30 (see FIG. 4) that generates a high magnetic field.
  • a magnetizing device 30 see FIG. 4
  • the refrigerator 13 is operated by the leakage magnetic field from the magnetizing device 30.
  • the heat conducting member 12 and the vacuum heat insulating container 14c of the magnetic field generator 1 are appropriately lengthened and frozen from the magnetic field generating portion of the magnetizing device 30 to the magnetic field strength at which the refrigerator 13 can operate. It is necessary to increase the distance of the machine 13.
  • the inside of the vacuum heat insulation container 14 is exhausted from an exhaust port (not shown) provided in the vacuum heat insulation container 14.
  • an exhaust port not shown
  • the high-temperature superconducting bulk bodies 11 a and 11 b, the heat conducting member 12 and the cold head 131 disposed inside the vacuum heat insulating container 14 and the vacuum heat insulating container 14 are vacuum insulated.
  • the high temperature superconducting bulk body 11a, 11b, the heat conduction member 12, the cold head 131, and the vacuum heat insulating container 14 are laminated with a super insulator (heat insulating sheet) to suppress intrusion heat due to radiation.
  • a super insulator heat insulating sheet
  • the high-temperature superconducting bulk bodies 11a and 11b are processed into a cylindrical shape as shown in FIG.
  • the pair of high-temperature superconducting bulk bodies 11a and 11b are arranged inside the vacuum heat insulating containers 14a and 14b so as to have the measured space 6 on the opposing surfaces.
  • RE represents yttrium (element symbol Y), samarium (Sm), lanthanum (La), neodymium (Nd), europium (Eu), gadolinium (Gd), erbium (Er), ytterbium (Yb), Of these, at least one type or two or more types are combined.
  • the raw material When synthesizing yttrium-based, neodymium-based, and samarium-based oxide superconductors having a superconducting transition temperature of 90 K or higher in absolute temperature, the raw material is heated to a temperature higher than the melting point and then melted and then solidified again.
  • a high-temperature superconducting bulk body oxide superconducting bulk body in which coarse crystals are grown and formed is obtained.
  • a structure in which the insulating phase is finely dispersed In the parent phase that becomes superconducting, a structure in which the insulating phase is finely dispersed is obtained. The pinning point due to the presence of this dispersed layer captures the magnetic flux, and the high-temperature superconducting bulk body (oxide superconducting bulk body) is Works as a pseudo permanent magnet.
  • silver (Ag) may be added to the synthesis of the high-temperature superconducting bulk body (oxide superconducting bulk body).
  • Silver (Ag) is dispersed in the structure without significantly degrading the performance of the superconducting phase, suppressing the propagation of cracks in the sample to improve the mechanical strength, or lowering the melting point to accelerate crystal growth. By giving a temperature difference from the seed crystal, the melting point can be suppressed and the crystal orientation can be contributed.
  • a high-temperature superconducting bulk body (oxide superconducting bulk body) has anisotropy in superconducting characteristics depending on the crystal orientation, and has a higher critical current density in the direction perpendicular to the c-axis of the crystal axis than other crystal orientations. For this reason, when the c-axis of the crystal axis is oriented in one direction, an excellent magnetic field can be captured. Therefore, excellent trapping magnetic field characteristics can be obtained by orienting the c-axis in the direction of the magnetic field in which the high-temperature superconducting bulk (oxide superconducting bulk) is magnetized.
  • Another material for the high-temperature superconducting bulk material 11 (11a, 11b) is, for example, magnesium diboride (MgB 2 ). Since the high-temperature superconducting bulk body using magnesium diboride has a superconducting transition temperature of about 39 K in absolute temperature, the superconducting transition temperature is lower than that of the oxide superconducting bulk body described above, and the high-temperature superconducting bulk body 11 ( 11a, 11b) must be cooled to a lower temperature, that is, there is a demerit that a refrigerator 13 having a high refrigerating capacity is required.
  • MgB 2 magnesium diboride
  • the high-temperature superconducting bulk body using magnesium diboride has only to be heat-treated after mixing the raw material powder and forming the bulk body in the process of manufacturing the bulk body. Compared to the body, there are advantages that it is easy to produce a large bulk body, that it does not have a complicated crystal structure, and that a metal is a light substance.
  • the high-temperature superconducting bulk body 11 when magnetizing the high-temperature superconducting bulk body 11 (11a, 11b), a Lorentz force acts on the bulk body due to the current flowing inside and the external magnetic field.
  • the high-temperature superconducting bulk body 11 may be impregnated with a resin or an epoxy adhesive, and the high-temperature superconducting bulk body 11 is made of a metal ring such as stainless steel or aluminum. The periphery of (11a, 11b) may be fixed.
  • FIG. 4 is a perspective view showing a state where the magnetic field adjustment device 20 is mounted on the magnetic field generator 1 of the first embodiment and inserted into the magnetizing device 30.
  • FIG. 5 is a cross-sectional view of the magnetic field generation device 1, the magnetic field adjustment device 20, and the magnetizing device 30 according to the first embodiment taken along line BB.
  • the magnetizing device 30 is a device that generates a spatially and temporally uniform magnetic field (static magnetic field).
  • the magnetizing device 30 includes magnetizing coil groups 301a and 301b made of a superconducting wire, and an arrow shown in FIG. A uniform magnetic field is generated in the direction of B 0 .
  • the magnetizing coil groups 301a and 301b are cooled to a superconducting transition temperature or lower by a cooling system (not shown) to maintain superconductivity.
  • a cooling system not shown
  • a coil and a refrigerator may be connected by a heat conducting member and cooled by heat conduction similarly to the magnetic field generator 1, and magnetized by liquid nitrogen or liquid helium.
  • the coil groups 301a and 301b may be immersed.
  • the magnetizing device 30 includes an external power supply device (not shown) for controlling the current flowing in the magnetizing coil groups 301a and 301b, and can generate a static magnetic field having a predetermined magnetic field strength. In order to make the generated magnetic field spatially uniform, it is preferable to adjust the magnetic field with a superconducting shim coil. Since the high-temperature superconducting bulk material 11 (11a, 11b) of the magnetic field generator 1 is magnetized with a uniformity equal to or less than the magnetic field of the magnetizing device 30, the magnetic field uniformity of the magnetizing device 30 is better. For example, it is desirable that the distribution in the space in which the magnetic field generator 1 is inserted with respect to the set magnetic field intensity is about several ppm or less.
  • the magnetic field adjustment device 20 is a device that adjusts (corrects) this turbulent magnetic field, and includes a magnetic field adjustment device 20a that can be attached to the vacuum heat insulation container 14a, a magnetic field adjustment device 20b that can be attached to the vacuum heat insulation container 14b, and a magnetic field correction.
  • System controller (not shown).
  • the magnetic field adjustment devices 20a and 20b each include magnetic field adjustment coil groups 201a and 201b.
  • the material of the magnetic field adjustment coil groups 201a and 201b may be copper used in a normal electromagnet, and is cooled to a superconducting transition temperature or lower by a cooling system (not shown), similarly to the magnetizing device 30.
  • a superconducting wire may be used.
  • the magnetic field correction system control unit (not shown) can control the magnetic field (adjusted magnetic field) generated in the magnetic field adjustment coil groups 201a and 201b by controlling the current flowing in the magnetic field adjustment coil groups 201a and 201b. .
  • FIG. 6 is a flowchart showing the magnetizing operation of the magnetic field generator 1.
  • step S101 the magnetizing operator sets the magnetic field strength to be magnetized and inputs it to the magnetizing device 30.
  • the magnetizing device 30 excites until the set magnetic field strength is reached.
  • step S102 the magnetizing operator attaches the magnetic field adjustment device 20 (20a, 20b) to the magnetic field generator 1. Further, as a preparation for step S103 to be described later, the coil group 2 and a dummy sample (not shown) are arranged in the measured space 6 of the magnetic field generator 1. Then, the magnetic field generator 1 equipped with the magnetic field adjusting device 20 is inserted into the magnetic field region of the magnetizing device 30 (see FIGS. 4 and 5). Here, as shown in FIG. 5, by attaching the magnetic field adjusting devices 20a and 20b to the vacuum heat insulating containers 14a and 14b (see FIG. 2) of the magnetic field generator 1, a magnetic field is formed in the vicinity of the high-temperature superconducting bulk bodies 11a and 11b. Adjustment coil groups 201a and 201b are arranged.
  • the magnetic field generator 1 When the magnetic field generator 1 is inserted into the magnetic field region of the magnetizing device 30, the center between the high temperature superconducting bulk body 11a and the high temperature superconducting bulk body 11b of the magnetic field generating device 1 comes to the magnetic field center of the magnetizing device 30. Thus, the magnetic field generator 1 is inserted (arranged). Moreover, the magnetic field generator 1 is fixed to the magnetizing device 30 with a non-magnetic (for example, aluminum or FRP) support jig (not shown) as required. As a result, after the cooling of the high-temperature superconducting bulk body 11 (11a, 11b) is completed and the magnetic flux is trapped in the bulk body, the magnetic field of the magnetizing device 30 is demagnetized (step S106 described later). It is possible to prevent the magnetic field generator 1 from moving toward the center of the magnetic device 30.
  • a non-magnetic for example, aluminum or FRP
  • the high-temperature superconducting bulk body 11 is magnetized by the magnetic field of the magnetizing device 30 depending on the components of the high-temperature superconducting bulk body 11. For this reason, the magnetic high-temperature superconducting bulk body 11 disturbs the spatial uniformity of the magnetic field of the magnetizing device 30.
  • the degree of magnetization at this time increases in the order of Y, Sm, Eu, and Gd depending on the RE element component of the high-temperature superconducting bulk body 11. Therefore, for example, by using a Y-type high-temperature superconducting bulk body 11, the influence of magnetization can be reduced.
  • Y-based high-temperature superconducting bulk bodies have demerits that the trapping magnetic field characteristics are poor compared to other oxide superconducting bulk bodies, and that it is difficult to manufacture large materials.
  • step S103 the system control unit 3 uses the coil group 2 arranged in the measured space 6 of the magnetic field generator 1 to set the magnetic field set for the dummy sample (not shown) arranged in the measured space 6.
  • An NMR signal at the intensity (see S101) is acquired.
  • light and shade is generated in the obtained image.
  • the magnetic field correction system control unit (not shown) of the magnetic field adjustment device 20 makes the magnetic field so as to eliminate the shading in the image based on the shading of the acquired image, that is, so as to eliminate the disturbance of the magnetic field.
  • the current flowing through the magnetic field adjustment coil groups 201a and 201b of the adjustment devices 20a and 20b is controlled to adjust and equalize the magnetic field. If necessary, the NMR signal may be acquired again to check the magnetic field uniformity.
  • step S104 the high-temperature superconducting bulk body 11 is cooled by the refrigerator 13.
  • the high-temperature superconducting bulk body 11 becomes superconducting, and the pinning force works to trap the magnetic flux entering the inside.
  • step S105 it is determined whether the high-temperature superconducting bulk body 11 has been cooled to a predetermined temperature. When cooling to a predetermined temperature is completed (S105 / Yes). Proceed to step S106. When cooling to the predetermined temperature is not completed (No at S105). Returning to step S103, steps S103 and S104 are repeated.
  • the cooling temperature is sufficiently low and the magnetic field adjustment by the magnetic field adjusting device 20 becomes difficult due to the diamagnetism of the high-temperature superconducting bulk body 11, the cooling of the high-temperature superconducting bulk body 11 is stopped and the temperature is raised to a necessary temperature. After breaking the superconducting state, the magnetic field adjustment device 20 adjusts the magnetic field again, and then cooling is resumed.
  • the magnetizing device 30 After completing the cooling of the high-temperature superconducting bulk body 11 to a predetermined temperature, the magnetizing device 30 is demagnetized in step S106.
  • the temperature at this time is preferably about several K to 10K higher than the lowest temperature reached by the high-temperature superconducting bulk body 11. This can suppress time fluctuation of the magnetic field of the high-temperature superconducting bulk body 11 by supercooling the high-temperature superconducting bulk body 11 that has been magnetized from a predetermined temperature to the lowest temperature.
  • an induced current is generated in the high-temperature superconducting bulk body 11 so as to maintain the magnetic flux trapped by electromagnetic induction (see S104), and this induced current becomes a superconducting current at a high temperature.
  • the superconducting bulk body 11 continues to flow, and the high-temperature superconducting bulk body 11 functions as a superconducting permanent magnet.
  • the magnetizing operator After demagnetization of the magnetizing device 30, the magnetizing operator removes the magnetic field generating device 1 from the magnetizing device 30 and the magnetic field adjusting device 20 in step S107, and completes the magnetization of the magnetic field generating device 1.
  • the high-temperature superconducting bulk body 11 can trap the magnetic flux as if the original magnetic field was copied if the current flowing through the high-temperature superconducting body 11 was less than the critical current value.
  • the magnetic field generator 1 according to the first embodiment can be magnetized with a uniform magnetic field corrected by the magnetizing device 30 and the magnetic field adjusting device 20.
  • the magnetic field adjusting device 20 is configured to be detachable from the magnetic field generating device 1, so that the magnetic field adjusting coil groups 201a and 201b are arranged in the vicinity of the high temperature superconducting bulk bodies 11a and 11b, and the high temperature superconducting bulk bodies 11a and 11b are arranged.
  • the nearby magnetic field can be suitably adjusted.
  • the magnetic field generator 1 having the high-temperature superconducting bulk body 11 can be used as a magnetic field generator that requires a spatially and temporally uniform high magnetic field like the MRI apparatus S.
  • the magnetic field generation source of the magnetic field generator 1 can be comprised only by the high-temperature superconducting bulk body 11, and as shown in FIGS. 1-3, the magnetic field generator 1 can be reduced in size. For this reason, even if the place where the magnetic field adjusting device 20 and the magnetizing device 30 are provided and the place where the MRI apparatus S is installed are separated from each other, the magnetic field can be obtained using the magnetizing device 30 and the magnetic field adjusting device 20. After magnetizing the generator 1, the magnetic field generator 1 can be transported to the installation location of the MRI apparatus S together with a transport refrigerator power supply unit (not shown) for supplying power to the refrigerator 13.
  • a transport refrigerator power supply unit not shown
  • FIG. 7 is a perspective view of the magnetic field generator 1C of the second embodiment.
  • FIG. 8 is a cross-sectional view taken along the line CC of the magnetic field generator 1C of the second embodiment.
  • the magnetic field generator 1 includes a pair of high-temperature superconducting bulk bodies 11a and 11b processed into a cylindrical shape, whereas the magnetic field generation according to the second embodiment.
  • the apparatus 1 ⁇ / b> C is different in that the high-temperature superconducting bulk body 11 c is processed into a ring shape and a magnetic field is generated in a hollow portion (measurement space 6) at the center of the ring.
  • the ring-shaped high-temperature superconducting bulk body 11c can also have a structure in which a plurality of rings are stacked, for example, for the purpose of extending the axial length of the cavity that generates the magnetic field.
  • the high-temperature superconducting bulk body 11c may be composed of a plurality of high-temperature superconducting bulk bodies, such as using a plurality of high-temperature superconducting bulk bodies stacked in the thickness direction.
  • the circumferential direction of the space to be measured 6 can be covered with the ring-shaped high-temperature superconducting bulk body 11c.
  • the structure is easy to magnetize a uniform magnetic field.
  • the vacuum heat insulating container 14 has a space to be measured 6 in which a static magnetic field from the high-temperature superconducting bulk body 11c is generated at the center of the tip. What is necessary is just to make it the cylindrical shape which has the room temperature bore which becomes, and can be made into a simple structure compared with the vacuum heat insulation container 14 of 1st Embodiment.
  • the heat conducting member 12 is made of a material having a high heat conductivity, such as oxygen-free copper, and is mainly processed and used in a rod shape.
  • the first embodiment is used. Compared to the above, since the ring-shaped high-temperature superconducting bulk body 11c and the refrigerator cold head 131 may be configured to be connected coaxially, a simpler structure can be achieved.
  • magnetizing apparatus 30c for inserting the magnetic field generator. 1C, for generating a magnetic field in the axial direction of the high-temperature superconducting bulk body 11c (the direction of arrow B 0 in FIG. 10),
  • the leakage magnetic field from the magnetizing device 30c is larger than that in the first embodiment.
  • the length of the heat conductive member 12 and the vacuum heat insulation container 14 of the magnetic field generator 1C is lengthened, and the magnetic field of the magnetizing device 30c to the magnetic field intensity which can operate the refrigerator 13 is obtained. It is necessary to separate the refrigerator 13 from the generation part.
  • the vacuum heat insulation container 14 and the heat conduction member 12 are connected to the FRP so that the vacuum heat insulation container 14 and the high-temperature superconducting bulk body 11c, the heat conduction member 12, and the refrigerator cold head 131 are not in direct contact with each other.
  • the support may be indirectly supported and fixed by a load support (not shown) made of a material having a low thermal conductivity such as the like.
  • FIG. 9 is a perspective view showing a state where the magnetic field adjustment device 20c is mounted on the magnetic field generation device 1C of the second embodiment and is inserted into the magnetization device 30c.
  • FIG. 10 is a cross-sectional view taken along the line DD of the magnetic field generator 1C, the magnetic field adjusting device 20c, and the magnetizing device 30c of the second embodiment.
  • the magnetic field adjustment coil group 201c of the magnetic field adjustment device 20c it is necessary to arrange the magnetic field adjustment coil group 201c of the magnetic field adjustment device 20c in the vicinity of the high-temperature superconducting bulk body 11c of the magnetic field generation device 1.
  • the high-temperature superconducting bulk body 11 c has a ring shape
  • the vacuum heat insulating container 14 also has a cylindrical shape. Therefore, only one magnetic field adjustment device 20 c needs to be attached to the magnetic field generation device 1. .
  • the magnetizing coils 301c of magnetizing apparatus 30c is to generate a uniform magnetic field in the axial direction of the ring-shaped high-temperature superconducting bulk body 11c (the direction of arrow B 0).
  • a more uniform magnetic field distribution can be obtained.
  • the magnetization procedure is the same as that in the first embodiment (see FIG. 6), and a description thereof will be omitted.
  • the magnetic field generator 1C according to the second embodiment can surround the circumference of the space 6 to be measured with the high-temperature superconducting bulk body 11c and obtain a more uniform magnetic field distribution.
  • the heat conductive member 12 and the vacuum heat insulation container 14 can be made into a simple structure.

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  • Condensed Matter Physics & Semiconductors (AREA)
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Abstract

The purpose of the present invention is to provide a magnetic field-generating device that has a small and simple configuration and high magnetic field homogeneity, a magnetic resonance imaging apparatus using same, and a magnetization unit for high temperature superconducting bulks. The present invention is provided with: a thermally insulated vacuum container (14); a high temperature superconducting bulk (11), which is disposed inside the thermally insulated vacuum container (14), through which a superconducting current flows and which traps a magnetic field by being cooled and said magnetic field being applied, and which supplies the supplemented magnetic field; and a refrigerator (13) for cooling the high temperature superconducting bulk (11) to a very low temperature. The high temperature superconducting bulk (11) is magnetized using a magnetization unit (30) for applying a magnetic field on the high temperature superconducting bulk (11), and a detachable magnetic field-adjusting unit (20) for adjusting the magnetic field near the high temperature superconducting bulk (11).

Description

磁場発生装置、それを用いた磁気共鳴イメージング装置、および、高温超電導バルク体の着磁装置Magnetic field generator, magnetic resonance imaging apparatus using the same, and magnetizing apparatus for high-temperature superconducting bulk material
　本発明は、空間的、時間的に均一な高磁場を発生可能な磁場発生装置、それを用いた磁気共鳴イメージング装置、および、高温超電導バルク体の着磁装置に関する。 The present invention relates to a magnetic field generator capable of generating a spatially and temporally uniform high magnetic field, a magnetic resonance imaging apparatus using the same, and a high-temperature superconducting bulk magnetizer.
　核磁気共鳴（Nuclear Magnetic Resonance：ＮＭＲ）装置は、各原子の化学シフト量やスピン－スピン結合定数等、あらゆる有機化合物の構造解析上有用なデータを得ることができるもので、強磁界を使うほど詳細で情報量の多い分析が可能なことから、超電導材料を用いた磁石（磁場発生装置）が利用されている。ＮＭＲ装置は、静磁場を作る磁石（磁場発生装置）、高周波パルスを発生しＮＭＲ信号を検出するコイル、ＮＭＲ信号を受ける受信機およびシステムコントローラ等から構成され、前記磁石としては、超電導磁石が磁場の強度および安定性と均一性の点から優位である。また、ＮＭＲ現象を利用して、組織や器官の中で起きている化学反応をそのままの状態で追跡し、例えば脳透視断層図を得る磁気共鳴イメージング（Magnetic Resonance Imaging：ＭＲＩ）装置は、このＮＭＲの医療への応用の代表例である。また、ＭＲＩ装置は、医療分野だけでなく、工業用素材や農作物の成分・構造分析等にも利用されている。 Nuclear Magnetic Resonance (NMR) equipment can obtain useful data for structural analysis of all organic compounds such as chemical shift amounts and spin-spin coupling constants of each atom. A magnet (magnetic field generator) using a superconducting material is used because analysis in detail and with a large amount of information is possible. An NMR apparatus is composed of a magnet (magnetic field generator) that generates a static magnetic field, a coil that generates a high-frequency pulse and detects an NMR signal, a receiver that receives the NMR signal, a system controller, and the like. As the magnet, a superconducting magnet is a magnetic field. It is advantageous in terms of strength, stability and uniformity. In addition, by using the NMR phenomenon, a chemical reaction occurring in a tissue or organ is traced as it is, and for example, a magnetic resonance imaging (MRI) apparatus that obtains a brain tomogram is an NMR. It is a representative example of application to medical treatment. In addition, the MRI apparatus is used not only for the medical field but also for industrial materials and components / structure analysis of agricultural products.
　ＭＲＩ装置は、静磁場発生手段である磁石、空間情報を信号に与えるための傾斜磁場、高周波電磁波照射系、ＮＭＲ信号検出系、人体等の検査対象を取り巻き高周波の電磁波照射や信号検出を行うプローブコイル、これらを制御しかつ得られた信号を処理するコントローラ等から構成され、静磁場存在下に置かれた検査対象に高周波電磁波を照射し、得られたＮＭＲ信号により信号を発生している核種の空間分布を映像化するものである。このＭＲＩ装置は、放射線を使用しないことから安全であり、かつ、十分な解像度が得られ、実用価値が極めて高いものである。 The MRI apparatus is a magnet that is a static magnetic field generating means, a gradient magnetic field for giving spatial information to a signal, a high-frequency electromagnetic wave irradiation system, an NMR signal detection system, a probe that surrounds an inspection object such as a human body and performs high-frequency electromagnetic wave irradiation and signal detection. A nuclide composed of a coil, a controller for controlling these signals, and a controller for processing the obtained signals, irradiating a test object placed in the presence of a static magnetic field with high-frequency electromagnetic waves, and generating a signal based on the obtained NMR signals The spatial distribution of is visualized. This MRI apparatus is safe because it does not use radiation, has a sufficient resolution, and has a very high practical value.
　従来の核磁気共鳴を用いたＮＭＲ分析装置やＭＲＩ装置において、精度の高い分析を必要とする場合、被測定物体を配置する被測定空間の磁場を、高い磁場強度、かつ、空間・時間的に均一にする必要がある。このため、従来のＮＭＲ分析装置やＭＲＩ装置は、主磁場の形成に、ニオブ・チタンなどの金属系超電導線材による超電導コイルを使用した超電導磁石が用いられている。この超電導コイルは液体ヘリウムを使って極低温に冷却して利用するため、高価な液体ヘリウムが多量に必要であり、運転コストが高くなるという問題があった。 In a conventional NMR analysis apparatus or MRI apparatus using nuclear magnetic resonance, when high-precision analysis is required, the magnetic field in the measurement space in which the object to be measured is placed has a high magnetic field strength, spatially and temporally. It needs to be uniform. For this reason, in conventional NMR analyzers and MRI apparatuses, a superconducting magnet using a superconducting coil made of a metallic superconducting wire such as niobium / titanium is used to form a main magnetic field. Since this superconducting coil is used after being cooled to a very low temperature using liquid helium, a large amount of expensive liquid helium is required, and there has been a problem that the operating cost becomes high.
　一方で、核磁気共鳴装置ほど空間・時間的に高い均一度が必要ない、例えば磁気分離装置向けの磁場発生装置では、上記金属系超電導線材による超電導コイルを使用した超電導磁石を冷凍機で直接冷却する場合もある。この冷却方式では、液体ヘリウムが不要のために液溜めを除くことができ、冷凍機との熱伝導構造によっては装置を小型化することが可能である。しかし、冷凍機により超電導コイルを液体ヘリウム温度まで冷却する必要があるために、冷凍機が大型、かつ大量の電力を消費し、結果として冷凍機を含めた装置全体の大型化や運転コストが増加するという問題があった。 On the other hand, high uniformity in space and time is not required as much as nuclear magnetic resonance devices. For example, in magnetic field generators for magnetic separation devices, superconducting magnets using superconducting coils made of the above metal-based superconducting wires are directly cooled by a refrigerator. There is also a case. In this cooling method, since liquid helium is not required, the liquid reservoir can be removed, and the apparatus can be downsized depending on the heat conduction structure with the refrigerator. However, since the superconducting coil needs to be cooled to the liquid helium temperature by the refrigerator, the refrigerator is large and consumes a large amount of power, resulting in an increase in the size and operating cost of the entire device including the refrigerator. There was a problem to do.
　小型かつ簡単な構成で強磁界を発生する手段として、従来の低温超電導体コイルによる超電導磁石にかえて、冷凍機で直接冷却する高温超電導バルク体を使用する装置が特許文献１（特開平１１－２４８８１０号公報）に開示されている。高温超電導バルク体は、従来のヘリウム冷却型の超電導磁石に比べて高い温度で超電導遷移するために、冷凍機の運転温度を高くすることが可能である。このため、ヘリウム冷却型の超電導磁石に比べ、断熱構造の簡易化や小型冷凍機が採用できるメリットがある。また、低い冷凍能力でも冷却可能なため、ヘリウム冷却型の超電導磁石に比べて小型かつ運転コストの低い磁場発生装置にすることができる。 As means for generating a strong magnetic field with a small and simple configuration, an apparatus using a high-temperature superconducting bulk body that is directly cooled by a refrigerator instead of a conventional superconducting magnet by a low-temperature superconducting coil is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. Hei 11-1990). No. 248810). Since the high-temperature superconducting bulk body makes a superconducting transition at a higher temperature than the conventional helium-cooled superconducting magnet, the operating temperature of the refrigerator can be increased. For this reason, compared with a helium-cooled superconducting magnet, there are advantages in that the heat insulating structure can be simplified and a small refrigerator can be employed. In addition, since cooling is possible even with a low refrigerating capacity, the magnetic field generator can be made smaller and lower in operating cost than a helium-cooled superconducting magnet.
特開平１１－２４８８１０号公報Japanese Patent Laid-Open No. 11-248810
　ところで、高温超電導バルク体を超電導磁石として用いるためには、永久磁石と同様に、着磁を行う必要がある。すなわち、高温超電導バルク体とは別に、高温超電導バルク体が必要とするだけの磁場を発生させることができる着磁装置により、高温超電導バルク体に磁場を印加しなければならない。 By the way, in order to use the high-temperature superconducting bulk body as a superconducting magnet, it is necessary to perform magnetization similarly to the permanent magnet. That is, apart from the high-temperature superconducting bulk body, a magnetic field must be applied to the high-temperature superconducting bulk body by a magnetizing apparatus that can generate a magnetic field required by the high-temperature superconducting bulk body.
　しかしながら、着磁装置により高温超電導バルク体に着磁を行う際、仮に着磁装置が発生する磁場が均一であったとしても、着磁装置から発生する磁場により高温超電導バルク体自身が磁化するため、磁化した高温超電導バルク体の影響で磁場の空間均一性が乱れた状態となる。このため、高温超電導バルク体は、磁場の空間均一性が乱れた状態で着磁されるために、着磁装置で設定した磁場均一性を維持して高温超電導バルク体を着磁することができないという問題があった。 However, when magnetizing a high-temperature superconducting bulk body with a magnetizing device, even if the magnetic field generated by the magnetizing device is uniform, the high-temperature superconducting bulk body itself is magnetized by the magnetic field generated from the magnetizing device. The spatial uniformity of the magnetic field is disturbed due to the influence of the magnetized high-temperature superconducting bulk material. For this reason, since the high-temperature superconducting bulk material is magnetized in a state where the spatial uniformity of the magnetic field is disturbed, the high-temperature superconducting bulk material cannot be magnetized while maintaining the magnetic field uniformity set by the magnetizing device. There was a problem.
　そこで、本発明は、小型かつ簡単な構成で高い磁場均一性を有する磁場発生装置、それを用いた磁気共鳴イメージング装置、および、高温超電導バルク体の着磁装置を提供することを課題とする。 Therefore, it is an object of the present invention to provide a magnetic field generator having high magnetic field uniformity with a small and simple configuration, a magnetic resonance imaging apparatus using the same, and a high temperature superconducting bulk magnetizer.
　このような課題を解決するために、本発明に係る磁場発生装置は、真空断熱容器と、前記真空断熱容器の内部に配置され、冷却され磁場を印加されることにより超電導電流が内部を流れて前記磁場を捕捉し、補足した前記磁場を供給する高温超電導バルク体と、前記高温超電導バルク体を極低温に冷却する冷凍機と、を備え、前記高温超電導バルク体は、該高温超電導バルク体に磁場を印加する着磁装置と、該高温超電導バルク体の近傍の磁場を調整する着脱可能な磁場調整装置と、を用いて着磁されることを特徴とする。 In order to solve such a problem, a magnetic field generator according to the present invention is arranged inside a vacuum heat insulation container and the vacuum heat insulation container, and a superconducting current flows inside by being cooled and applied with a magnetic field. A high-temperature superconducting bulk body that captures the magnetic field and supplies the supplemented magnetic field; and a refrigerator that cools the high-temperature superconducting bulk body to a cryogenic temperature, and the high-temperature superconducting bulk body includes the high-temperature superconducting bulk body. Magnetization is performed using a magnetizing apparatus that applies a magnetic field and a detachable magnetic field adjusting apparatus that adjusts the magnetic field in the vicinity of the high-temperature superconducting bulk body.
　また、本発明に係る磁気共鳴イメージング装置は、磁場調整装置により被検体を設置する被測定空間に静磁場を発生させ、前記被検体からの磁気共鳴信号を取得することにより、前記被検体の画像を得ることを特徴とする。 Further, the magnetic resonance imaging apparatus according to the present invention generates a static magnetic field in a measurement space in which the subject is set by the magnetic field adjustment device, and acquires a magnetic resonance signal from the subject, thereby obtaining an image of the subject. It is characterized by obtaining.
　また、本発明に係る高温超電導バルク体の着磁装置は、静磁場を発生させ、高温超電導バルク体に静磁場を印加する静磁場発生装置と、印加された前記静磁場により前記高温超電導バルク体が磁化し、磁化した該高温超電導バルク体による磁場の乱れを調整する磁場調整装置と、を備えることを特徴とする。 Further, a magnetizing apparatus for a high-temperature superconducting bulk body according to the present invention includes a static magnetic field generating apparatus for generating a static magnetic field and applying a static magnetic field to the high-temperature superconducting bulk body, and the high-temperature superconducting bulk body by the applied static magnetic field. And a magnetic field adjusting device for adjusting magnetic field disturbance caused by the magnetized high-temperature superconducting bulk body.
　本発明によれば、小型かつ簡単な構成で高い磁場均一性を有する磁場発生装置、それを用いた磁気共鳴イメージング装置、および、高温超電導バルク体の着磁装置を提供することができる。 According to the present invention, it is possible to provide a magnetic field generator having high magnetic field uniformity with a small and simple configuration, a magnetic resonance imaging apparatus using the same, and a high temperature superconducting bulk magnetizer.
第１実施形態に係る磁場発生装置を備えるＭＲＩ装置の構成図である。It is a block diagram of an MRI apparatus provided with the magnetic field generator which concerns on 1st Embodiment. 第１実施形態の磁場発生装置の斜視図である。It is a perspective view of the magnetic field generator of 1st Embodiment. 第１実施形態の磁場発生装置のＡ－Ａ線断面図である。It is an AA line sectional view of the magnetic field generator of a 1st embodiment. 第１実施形態の磁場発生装置に磁場調整装置を装着し、着磁装置に挿入した状態を示す斜視図である。It is a perspective view which shows the state which equipped the magnetic field generator of 1st Embodiment with the magnetic field adjustment apparatus, and was inserted in the magnetizing apparatus. 第１実施形態の磁場発生装置、磁場調整装置および着磁装置のＢ－Ｂ線断面図である。FIG. 3 is a cross-sectional view of the magnetic field generation device, the magnetic field adjustment device, and the magnetization device of the first embodiment taken along line BB. 磁場発生装置の着磁作業を示すフローチャートである。It is a flowchart which shows the magnetization operation | movement of a magnetic field generator. 第２実施形態の磁場発生装置の斜視図である。It is a perspective view of the magnetic field generator of 2nd Embodiment. 第２実施形態の磁場発生装置のＣ－Ｃ線断面図である。It is CC sectional view taken on the line of the magnetic field generator of 2nd Embodiment. 第２実施形態の磁場発生装置に磁場調整装置を装着し、着磁装置に挿入した状態を示す斜視図である。It is a perspective view which shows the state which equipped the magnetic field generator of 2nd Embodiment with the magnetic field adjustment apparatus, and was inserted in the magnetizing apparatus. 第２実施形態の磁場発生装置、磁場調整装置および着磁装置のＤ－Ｄ線断面図である。It is the DD sectional view taken on the line of the magnetic field generator of 2nd Embodiment, a magnetic field adjustment apparatus, and a magnetizing apparatus.
　以下、本発明を実施するための形態（以下「実施形態」という）について、適宜図面を参照しながら詳細に説明する。なお、各図において、共通する部分には同一の符号を付し重複した説明を省略する。 Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.
≪第１実施形態≫
＜磁気共鳴イメージング装置（ＭＲＩ装置）＞
　第１実施形態に係る磁気共鳴イメージング装置（ＭＲＩ装置）Ｓについて、図１を用いて説明する。図１は、第１実施形態に係る磁場発生装置１を備えるＭＲＩ装置Ｓの構成図である。 << First Embodiment >>
<Magnetic resonance imaging system (MRI system)>
A magnetic resonance imaging apparatus (MRI apparatus) S according to the first embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram of an MRI apparatus S including a magnetic field generation apparatus 1 according to the first embodiment.
　ＭＲＩ装置Ｓは、被測定空間６に磁場を発生する磁場発生装置１と、傾斜磁場コイル（図示せず）およびＲＦ（Radio Frequency）コイル（図示せず）を有するコイル群２と、システム制御部３と、出力装置４と、冷凍機電源ユニット５と、を備えている。 The MRI apparatus S includes a magnetic field generator 1 that generates a magnetic field in a space 6 to be measured, a coil group 2 having a gradient magnetic field coil (not shown) and an RF (Radio Frequency) coil (not shown), and a system control unit 3, an output device 4, and a refrigerator power supply unit 5.
　磁場発生装置１は、冷却することにより超電導永久磁石として働く高温超電導バルク体１１ａ，１１ｂ（図２参照）および冷凍機１３（図２参照）を備えており、冷凍機電源ユニット５から磁場発生装置１の冷凍機１３（図２参照）に電力を供給することにより、高温超電導バルク体１１ａ，１１ｂ（図２参照）を冷却する。また、磁場発生装置１は、高温超電導バルク体１１ａ，１１ｂ（図２参照）に後述する着磁を行うことにより、被測定空間６に空間的、時間的に均一な磁場（静磁場）を発生させるようになっている。 The magnetic field generator 1 includes high-temperature superconducting bulk bodies 11a and 11b (see FIG. 2) and a refrigerator 13 (see FIG. 2) that act as superconducting permanent magnets by cooling, and the magnetic field generator from the refrigerator power supply unit 5 is provided. By supplying electric power to one refrigerator 13 (see FIG. 2), the high-temperature superconducting bulk bodies 11a and 11b (see FIG. 2) are cooled. The magnetic field generator 1 generates a spatially and temporally uniform magnetic field (static magnetic field) in the measurement space 6 by magnetizing the high-temperature superconducting bulk bodies 11a and 11b (see FIG. 2), which will be described later. It is supposed to let you.
　磁場発生装置１の測定空間内にある被測定空間６には、傾斜磁場コイル（図示せず）およびＲＦコイル（図示せず）からなるコイル群２が配置されている。コイル群２（傾斜磁場コイル、ＲＦコイル）は、システム制御部３と接続されている。 A coil group 2 composed of a gradient magnetic field coil (not shown) and an RF coil (not shown) is disposed in a measured space 6 in the measurement space of the magnetic field generator 1. The coil group 2 (gradient magnetic field coil, RF coil) is connected to the system control unit 3.
　システム制御部３は、コイル群２の傾斜磁場コイル（図示せず）により、被測定空間６に傾斜磁場を発生させ、位相エンコードおよび周波数エンコードを行うことにより、信号の位置情報を与える。次に、システム制御部３は、コイル群２のＲＦコイル（図示せず）により、被測定空間６で磁場発生装置１が発生させる磁場（静磁場）の向きに対して垂直な方向にＲＦ信号を発生させた後、被測定物体（図示せず）のＮＭＲ信号をＲＦコイル（図示せず）により受信する。なお、このＲＦコイル（図示せず）は、信号の送信用ＲＦコイル（図示せず）および受信用ＲＦコイル（図示せず）を分けて設けてもよく、１つのＲＦコイル（図示せず）を信号の送信用および受信用に用いてもよい。そして、システム制御部３は、ＲＦコイル（図示せず）で受信したＮＭＲ信号をＭＲＩとしてマッピングし、出力装置４へ出力し表示する。 The system control unit 3 generates a gradient magnetic field in the space to be measured 6 by a gradient magnetic field coil (not shown) of the coil group 2 and performs phase encoding and frequency encoding to give signal position information. Next, the system control unit 3 uses an RF coil (not shown) of the coil group 2 to generate an RF signal in a direction perpendicular to the direction of the magnetic field (static magnetic field) generated by the magnetic field generator 1 in the measured space 6. Then, the NMR signal of the object to be measured (not shown) is received by the RF coil (not shown). The RF coil (not shown) may be provided separately with a signal transmitting RF coil (not shown) and a receiving RF coil (not shown), or one RF coil (not shown). May be used for signal transmission and reception. Then, the system control unit 3 maps the NMR signal received by the RF coil (not shown) as MRI, outputs it to the output device 4, and displays it.
＜磁場発生装置＞
　次に、第１実施形態に係る磁気共鳴イメージング装置（ＭＲＩ装置）Ｓが備える磁場発生装置１について、図２および図３を用いて更に説明する。図２は、第１実施形態の磁場発生装置１の斜視図である。図３は、第１実施形態の磁場発生装置１のＡ－Ａ線断面図である。なお、図２においては、コイル群２（図１参照）を省略して図示している。 <Magnetic field generator>
Next, the magnetic field generator 1 provided in the magnetic resonance imaging apparatus (MRI apparatus) S according to the first embodiment will be further described with reference to FIGS. FIG. 2 is a perspective view of the magnetic field generator 1 of the first embodiment. FIG. 3 is a cross-sectional view taken along line AA of the magnetic field generator 1 of the first embodiment. In FIG. 2, the coil group 2 (see FIG. 1) is omitted.
　図２に示すように、磁場発生装置１は、高温超電導バルク体１１ａ，１１ｂと、熱伝導部材１２（図３参照）と、冷凍機１３と、真空断熱容器１４（１４ａ，１４ｂ，１４ｃ）と、を備えている。 As shown in FIG. 2, the magnetic field generator 1 includes high-temperature superconducting bulk bodies 11a and 11b, a heat conducting member 12 (see FIG. 3), a refrigerator 13, and a vacuum heat insulating container 14 (14a, 14b, and 14c). It is equipped with.
　冷凍機１３は、真空断熱容器１４と接続されている。真空断熱容器１４は、高温超電導バルク体１１ａを囲むように配置されている真空断熱容器１４ａと、高温超電導バルク体１１ｂを囲むように配置されている真空断熱容器１４ｂと、熱伝導部材１２（図３参照）が内部に配置されている真空断熱容器１４ｃと、から構成されている。 The refrigerator 13 is connected to a vacuum heat insulating container 14. The vacuum heat insulating container 14 includes a vacuum heat insulating container 14a disposed so as to surround the high temperature superconducting bulk body 11a, a vacuum heat insulating container 14b disposed so as to surround the high temperature superconducting bulk body 11b, and the heat conducting member 12 (FIG. 3) and a vacuum heat insulating container 14c disposed inside.
　図３に示すように、冷凍機１３（図２参照）のコールドヘッド１３１は、熱伝導部材１２を介して高温超電導バルク体１１ａ，１１ｂと熱的に接続されている。これにより、高温超電導バルク体１１ａ，１１ｂは、熱伝導部材１２を介して冷凍機１３（図２参照）により冷却される。 As shown in FIG. 3, the cold head 131 of the refrigerator 13 (see FIG. 2) is thermally connected to the high-temperature superconducting bulk bodies 11 a and 11 b via the heat conducting member 12. Thereby, the high-temperature superconducting bulk bodies 11a and 11b are cooled by the refrigerator 13 (see FIG. 2) via the heat conducting member 12.
　熱伝導部材１２は、熱伝導率の大きい材料、例えば無酸素銅等により構成される。熱伝導部材１２は、真空断熱容器１４と直接接触しないよう固定されているが、熱伝導部材１２のたわみによって真空断熱容器１４と接触することを避けるために、真空断熱容器１４と熱伝導部材１２とを熱伝導率の小さい材料、例えば繊維強化プラスチック（Fiber Reinforced Plastics；ＦＲＰ）からなる荷重支持体（図示せず）により間接的に支持固定してもよい。なお、ＦＲＰの繊維には、例えばアルミナ、ガラス繊維、炭素繊維等を用いることができる。 The heat conducting member 12 is made of a material having a high heat conductivity, such as oxygen-free copper. The heat conducting member 12 is fixed so as not to be in direct contact with the vacuum heat insulating container 14, but in order to avoid contact with the vacuum heat insulating container 14 due to deflection of the heat conducting member 12, the vacuum heat insulating container 14 and the heat conducting member 12 are arranged. May be indirectly supported and fixed by a load support (not shown) made of a material having a low thermal conductivity, for example, a fiber-reinforced plastic (FRP). For example, alumina, glass fiber, or carbon fiber can be used as the FRP fiber.
　冷凍機１３は、例えば圧縮機一体型のスターリング冷凍機を用いることにより、磁場発生装置１を小型化することができる。その他に、圧縮機分離型のＧＭサイクル冷凍機、ソルベイサイクル冷凍機、スターリング冷凍機、パルス管冷凍機等を用いても同様の効果が得られる。ちなみに、冷凍機１３の圧縮機放熱部は、空冷や水冷装置（図示せず）により放熱される。 The refrigerator 13 can downsize the magnetic field generator 1 by using, for example, a compressor-integrated Stirling refrigerator. In addition, the same effect can be obtained by using a compressor separation type GM cycle refrigerator, a Solvay cycle refrigerator, a Stirling refrigerator, a pulse tube refrigerator, or the like. Incidentally, the compressor heat radiation part of the refrigerator 13 is radiated by an air cooling or a water cooling device (not shown).
　ちなみに、後述するように、磁場発生装置１の高温超電導バルク体１１ａ，１１ｂは、高磁場を発生する着磁装置３０（図４参照）に挿入される。このため、例えば圧縮機一体型のスターリング冷凍機、ＧＭサイクル冷凍機等の場合、冷凍機１３の内部にモータが組み込まれているため、着磁装置３０からの漏洩磁場により、冷凍機１３が動作しないおそれがある。このため、あらかじめ設計段階で、磁場発生装置１の熱伝導部材１２および真空断熱容器１４ｃの長さを適切に取り、冷凍機１３が動作可能な磁場強度まで着磁装置３０の磁場発生部分から冷凍機１３の距離を離す必要がある。 Incidentally, as will be described later, the high-temperature superconducting bulk bodies 11a and 11b of the magnetic field generator 1 are inserted into a magnetizing device 30 (see FIG. 4) that generates a high magnetic field. For this reason, for example, in the case of a compressor-integrated Stirling refrigerator, GM cycle refrigerator, etc., since the motor is incorporated in the refrigerator 13, the refrigerator 13 is operated by the leakage magnetic field from the magnetizing device 30. There is a risk of not. For this reason, in the design stage in advance, the heat conducting member 12 and the vacuum heat insulating container 14c of the magnetic field generator 1 are appropriately lengthened and frozen from the magnetic field generating portion of the magnetizing device 30 to the magnetic field strength at which the refrigerator 13 can operate. It is necessary to increase the distance of the machine 13.
　真空断熱容器１４の内部は、真空断熱容器１４に設けられた排気ポート（図示せず）から排気される。これにより、真空断熱容器１４の内部に配置される高温超電導バルク体１１ａ，１１ｂ、熱伝導部材１２およびコールドヘッド１３１と、真空断熱容器１４との間が、真空断熱されている。なお、図示は省略するが、常温の真空断熱容器１４から低温の高温超電導バルク体１１ａ，１１ｂ、熱伝導部材１２およびコールドヘッド１３１への輻射熱の侵入を抑制するために、高温超電導バルク体１１ａ，１１ｂ、熱伝導部材１２およびコールドヘッド１３１と、真空断熱容器１４との間に、スーパーインシュレータ（断熱シート）を積層させることにより、輻射による侵入熱を抑制する。これにより、高温超電導バルク体１１ａ，１１ｂを更に低温に維持できる。 The inside of the vacuum heat insulation container 14 is exhausted from an exhaust port (not shown) provided in the vacuum heat insulation container 14. As a result, the high-temperature superconducting bulk bodies 11 a and 11 b, the heat conducting member 12 and the cold head 131 disposed inside the vacuum heat insulating container 14 and the vacuum heat insulating container 14 are vacuum insulated. In addition, although illustration is abbreviate | omitted, in order to suppress the penetration | invasion of the radiant heat from the vacuum heat insulation container 14 of normal temperature to the low temperature high temperature superconducting bulk body 11a, 11b, the heat conductive member 12, and the cold head 131, the high temperature superconducting bulk body 11a, 11b, the heat conduction member 12, the cold head 131, and the vacuum heat insulating container 14 are laminated with a super insulator (heat insulating sheet) to suppress intrusion heat due to radiation. Thereby, the high-temperature superconducting bulk bodies 11a and 11b can be maintained at a lower temperature.
＜高温超電導バルク体＞
　高温超電導バルク体１１ａ，１１ｂは、図２に示すように、円柱形状に加工されている。そして、一対の高温超電導バルク体１１ａ，１１ｂが対向面に被測定空間６を有するように、真空断熱容器１４ａ，１４ｂの内部にそれぞれ配置される。 <High-temperature superconducting bulk material>
The high-temperature superconducting bulk bodies 11a and 11b are processed into a cylindrical shape as shown in FIG. The pair of high-temperature superconducting bulk bodies 11a and 11b are arranged inside the vacuum heat insulating containers 14a and 14b so as to have the measured space 6 on the opposing surfaces.
　冷却することにより超電導永久磁石として働く高温超電導バルク体１１（１１ａ，１１ｂ）の材料として、例えばその主成分をＲＥ－Ｂａ－Ｃｕ－Ｏで表せる酸化物超電導バルク体がある。ここで、ＲＥは、イットリウム（元素記号Ｙ）、サマリウム（Ｓｍ）、ランタン（Ｌａ）、ネオジム（Ｎｄ）、ユーロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）、エルビウム（Ｅｒ）、イッテルビウム（Ｙｂ）を表し、そのうち少なくとも１種または２種以上を合わせてなるものである。 As a material of the high-temperature superconducting bulk body 11 (11a, 11b) that works as a superconducting permanent magnet by cooling, for example, there is an oxide superconducting bulk body whose main component can be expressed by RE-Ba-Cu-O. Here, RE represents yttrium (element symbol Y), samarium (Sm), lanthanum (La), neodymium (Nd), europium (Eu), gadolinium (Gd), erbium (Er), ytterbium (Yb), Of these, at least one type or two or more types are combined.
　絶対温度で９０Ｋ以上の超電導遷移温度を持つイットリウム系、ネオジム系、サマリウム系などの酸化物超電導体を合成する際、原料をいったん融点よりも高く加熱して溶融させ、再び凝固させるいわゆる溶融法で合成すると、粗大な結晶が成長し形成される高温超電導バルク体（酸化物超電導バルク体）が得られる。超電導となる母相には、絶縁相が微細に分散した組織が得られ、この分散層の存在に起因するピン止め点が磁束を捕捉して、高温超電導バルク体（酸化物超電導バルク体）は擬似的な永久磁石として働く。 When synthesizing yttrium-based, neodymium-based, and samarium-based oxide superconductors having a superconducting transition temperature of 90 K or higher in absolute temperature, the raw material is heated to a temperature higher than the melting point and then melted and then solidified again. When synthesized, a high-temperature superconducting bulk body (oxide superconducting bulk body) in which coarse crystals are grown and formed is obtained. In the parent phase that becomes superconducting, a structure in which the insulating phase is finely dispersed is obtained. The pinning point due to the presence of this dispersed layer captures the magnetic flux, and the high-temperature superconducting bulk body (oxide superconducting bulk body) is Works as a pseudo permanent magnet.
　なお、高温超電導バルク体（酸化物超電導バルク体）の合成には５０％以下の銀（Ａｇ）が添加されることもある。銀（Ａｇ）は、超電導相の性能を大きく損なうことなく組織中に分散し、試料のき裂の伝播を抑制して機械的強度を向上したり、融点を降下して結晶成長を早くしたり、種結晶との温度差を与えてその融点を抑制して結晶方位に寄与させることができる。 In addition, 50% or less of silver (Ag) may be added to the synthesis of the high-temperature superconducting bulk body (oxide superconducting bulk body). Silver (Ag) is dispersed in the structure without significantly degrading the performance of the superconducting phase, suppressing the propagation of cracks in the sample to improve the mechanical strength, or lowering the melting point to accelerate crystal growth. By giving a temperature difference from the seed crystal, the melting point can be suppressed and the crystal orientation can be contributed.
　高温超電導バルク体（酸化物超電導バルク体）は、その結晶方位によって超電導特性に異方性があり、結晶軸のｃ軸に垂直な方向の臨界電流密度が他の結晶方位に比べて高い。このため、結晶軸のｃ軸を一方向に配向すると優秀な磁場の捕捉ができる。したがって、高温超電導バルク体（酸化物超電導バルク体）をその着磁する磁場方向にｃ軸を配向することで優れた捕捉磁場特性が得られる。 A high-temperature superconducting bulk body (oxide superconducting bulk body) has anisotropy in superconducting characteristics depending on the crystal orientation, and has a higher critical current density in the direction perpendicular to the c-axis of the crystal axis than other crystal orientations. For this reason, when the c-axis of the crystal axis is oriented in one direction, an excellent magnetic field can be captured. Therefore, excellent trapping magnetic field characteristics can be obtained by orienting the c-axis in the direction of the magnetic field in which the high-temperature superconducting bulk (oxide superconducting bulk) is magnetized.
　また、高温超電導バルク体１１（１１ａ，１１ｂ）のその他の材料として、例えば二ホウ化マグネシウム（ＭｇＢ2 ）がある。二ホウ化マグネシウムを用いた高温超電導バルク体は、絶対温度で約３９Ｋの超電導遷移温度を持つため、前述の酸化物超電導バルク体と比較して、超電導遷移温度が低く、高温超電導バルク体１１（１１ａ，１１ｂ）をより低温に冷却する必要がある、即ち、高い冷凍能力を有する冷凍機１３が必要になるというデメリットがある。一方で、二ホウ化マグネシウムを用いた高温超電導バルク体は、バルク体を製造する過程において、原料粉末を混合し、バルク体に成型した後に熱処理を行うだけでよいので、前述の酸化物超電導バルク体と比較して、大型のバルク体の製造が容易であること、複雑な結晶構造を持たないこと、金属でも軽い物質であること、というメリットが挙げられる。 Another material for the high-temperature superconducting bulk material 11 (11a, 11b) is, for example, magnesium diboride (MgB 2 ). Since the high-temperature superconducting bulk body using magnesium diboride has a superconducting transition temperature of about 39 K in absolute temperature, the superconducting transition temperature is lower than that of the oxide superconducting bulk body described above, and the high-temperature superconducting bulk body 11 ( 11a, 11b) must be cooled to a lower temperature, that is, there is a demerit that a refrigerator 13 having a high refrigerating capacity is required. On the other hand, the high-temperature superconducting bulk body using magnesium diboride has only to be heat-treated after mixing the raw material powder and forming the bulk body in the process of manufacturing the bulk body. Compared to the body, there are advantages that it is easy to produce a large bulk body, that it does not have a complicated crystal structure, and that a metal is a light substance.
　なお、高温超電導バルク体１１（１１ａ，１１ｂ）を着磁する際、バルク体には内部に流れる電流と、外部磁場により内部にローレンツ力が働く。このローレンツ力によるバルク体の破壊を防ぐため、高温超電導バルク体１１（１１ａ，１１ｂ）に樹脂やエポキシ系接着剤を含浸させてもよく、ステンレスやアルミニウム等の金属製リングで高温超電導バルク体１１（１１ａ，１１ｂ）の周囲を固定する等してもよい。 In addition, when magnetizing the high-temperature superconducting bulk body 11 (11a, 11b), a Lorentz force acts on the bulk body due to the current flowing inside and the external magnetic field. In order to prevent destruction of the bulk body due to this Lorentz force, the high-temperature superconducting bulk body 11 (11a, 11b) may be impregnated with a resin or an epoxy adhesive, and the high-temperature superconducting bulk body 11 is made of a metal ring such as stainless steel or aluminum. The periphery of (11a, 11b) may be fixed.
＜着磁装置＞
　次に、磁場発生装置１の高温超電導バルク体１１（１１ａ，１１ｂ）を着磁する着磁装置３０および磁場調整装置２０について、図４および図５を用いて説明する。図４は、第１実施形態の磁場発生装置１に磁場調整装置２０を装着し着磁装置３０に挿入した状態を示す斜視図である。図５は、第１実施形態の磁場発生装置１、磁場調整装置２０および着磁装置３０のＢ－Ｂ線断面図である。 <Magnetic device>
Next, the magnetizing device 30 and the magnetic field adjusting device 20 that magnetize the high-temperature superconducting bulk material 11 (11a, 11b) of the magnetic field generating device 1 will be described with reference to FIGS. FIG. 4 is a perspective view showing a state where the magnetic field adjustment device 20 is mounted on the magnetic field generator 1 of the first embodiment and inserted into the magnetizing device 30. FIG. 5 is a cross-sectional view of the magnetic field generation device 1, the magnetic field adjustment device 20, and the magnetizing device 30 according to the first embodiment taken along line BB.
　着磁装置３０は、空間的、時間的に均一な磁場（静磁場）を発生させる装置であり、例えば、超電導線材で製作された着磁用コイル群３０１ａ，３０１ｂを備え、図５に示す矢印Ｂ0 の向きに均一な磁場を発生させている。なお、着磁用コイル群３０１ａ，３０１ｂは、冷却システム（図示せず）により超電導遷移温度以下に冷却され、超電導を維持する。この冷却システム（図示せず）としては、磁場発生装置１と同様に熱伝導部材によりコイルと冷凍機とを接続し熱伝導により冷却するものであってもよく、液体窒素や液体ヘリウムにより着磁用コイル群３０１ａ，３０１ｂを侵漬するものであってもよい。 The magnetizing device 30 is a device that generates a spatially and temporally uniform magnetic field (static magnetic field). For example, the magnetizing device 30 includes magnetizing coil groups 301a and 301b made of a superconducting wire, and an arrow shown in FIG. A uniform magnetic field is generated in the direction of B 0 . The magnetizing coil groups 301a and 301b are cooled to a superconducting transition temperature or lower by a cooling system (not shown) to maintain superconductivity. As this cooling system (not shown), a coil and a refrigerator may be connected by a heat conducting member and cooled by heat conduction similarly to the magnetic field generator 1, and magnetized by liquid nitrogen or liquid helium. The coil groups 301a and 301b may be immersed.
　また、着磁装置３０は、着磁用コイル群３０１ａ，３０１ｂに流れる電流を制御する外部電源装置（図示せず）を備え、所定の磁場強度の静磁場を発生させることができる。なお、発生させる磁場を空間的に均一にするために、超電導シムコイルにより磁場調整をするのが好ましい。磁場発生装置１の高温超電導バルク体１１（１１ａ，１１ｂ）には、この着磁装置３０での磁場以下の均一度で着磁されるため、着磁装置３０の磁場均一度は高い方がよく、例えば設定した磁場強度に対して磁場発生装置１を挿入する空間内の分布を数ｐｐｍ程度以下にすることが望ましい。 Further, the magnetizing device 30 includes an external power supply device (not shown) for controlling the current flowing in the magnetizing coil groups 301a and 301b, and can generate a static magnetic field having a predetermined magnetic field strength. In order to make the generated magnetic field spatially uniform, it is preferable to adjust the magnetic field with a superconducting shim coil. Since the high-temperature superconducting bulk material 11 (11a, 11b) of the magnetic field generator 1 is magnetized with a uniformity equal to or less than the magnetic field of the magnetizing device 30, the magnetic field uniformity of the magnetizing device 30 is better. For example, it is desirable that the distribution in the space in which the magnetic field generator 1 is inserted with respect to the set magnetic field intensity is about several ppm or less.
　磁場発生装置１を着磁装置３０に挿入した際、着磁装置３０から発生する磁場Ｂ0 により高温超電導バルク体１１（１１ａ，１１ｂ）自身が磁化するため、その影響で磁場の空間均一性が乱れる。磁場調整装置２０は、この乱れた磁場を調整（補正）する装置であり、真空断熱容器１４ａに取り付け可能な磁場調整装置２０ａと、真空断熱容器１４ｂに取り付け可能な磁場調整装置２０ｂと、磁場補正用システム制御部（図示せず）と、を備えている。 When the magnetic field generator 1 is inserted into the magnetizing device 30, the high-temperature superconducting bulk material 11 (11a, 11b) itself is magnetized by the magnetic field B 0 generated from the magnetizing device 30, so that the spatial uniformity of the magnetic field is affected by the influence. Disturbed. The magnetic field adjustment device 20 is a device that adjusts (corrects) this turbulent magnetic field, and includes a magnetic field adjustment device 20a that can be attached to the vacuum heat insulation container 14a, a magnetic field adjustment device 20b that can be attached to the vacuum heat insulation container 14b, and a magnetic field correction. System controller (not shown).
　磁場調整装置２０ａ，２０ｂは、磁場調整コイル群２０１ａ，２０１ｂがそれぞれ内蔵されている。この磁場調整コイル群２０１ａ，２０１ｂの材料としては、通常の電磁石で用いられる銅であってもよく、着磁装置３０と同様に、冷却システム（図示せず）により超電導遷移温度以下に冷却された超電導線材であってもよい。 The magnetic field adjustment devices 20a and 20b each include magnetic field adjustment coil groups 201a and 201b. The material of the magnetic field adjustment coil groups 201a and 201b may be copper used in a normal electromagnet, and is cooled to a superconducting transition temperature or lower by a cooling system (not shown), similarly to the magnetizing device 30. A superconducting wire may be used.
　磁場補正用システム制御部（図示せず）は、磁場調整コイル群２０１ａ，２０１ｂに流れる電流を制御することにより、磁場調整コイル群２０１ａ，２０１ｂで発生する磁場（調整磁場）を制御することができる。 The magnetic field correction system control unit (not shown) can control the magnetic field (adjusted magnetic field) generated in the magnetic field adjustment coil groups 201a and 201b by controlling the current flowing in the magnetic field adjustment coil groups 201a and 201b. .
＜磁場発生装置（高温超電導バルク体）の着磁方法＞
　次に、磁場発生装置１の着磁について、図６を用いて説明する。図６は、磁場発生装置１の着磁作業を示すフローチャートである。 <Magnetic method of magnetic field generator (high-temperature superconducting bulk body)>
Next, magnetization of the magnetic field generator 1 will be described with reference to FIG. FIG. 6 is a flowchart showing the magnetizing operation of the magnetic field generator 1.
　ステップＳ１０１において、着磁作業者は、着磁する磁場強度を設定し、着磁装置３０に入力する。着磁装置３０は、設定された磁場強度となるまで励磁する。 In step S101, the magnetizing operator sets the magnetic field strength to be magnetized and inputs it to the magnetizing device 30. The magnetizing device 30 excites until the set magnetic field strength is reached.
　ステップＳ１０２において、着磁作業者は、磁場発生装置１に磁場調整装置２０（２０ａ，２０ｂ）を装着する。また、後述するステップＳ１０３の準備として、磁場発生装置１の被測定空間６にコイル群２とダミーサンプル（図示せず）を配置する。そして、磁場調整装置２０を装着した磁場発生装置１を着磁装置３０の磁場領域に挿入する（図４，図５参照）。ここで、図５に示すように、磁場調整装置２０ａ，２０ｂを磁場発生装置１の真空断熱容器１４ａ，１４ｂ（図２参照）に装着することにより、高温超電導バルク体１１ａ，１１ｂの近傍に磁場調整コイル群２０１ａ，２０１ｂが配置される。 In step S102, the magnetizing operator attaches the magnetic field adjustment device 20 (20a, 20b) to the magnetic field generator 1. Further, as a preparation for step S103 to be described later, the coil group 2 and a dummy sample (not shown) are arranged in the measured space 6 of the magnetic field generator 1. Then, the magnetic field generator 1 equipped with the magnetic field adjusting device 20 is inserted into the magnetic field region of the magnetizing device 30 (see FIGS. 4 and 5). Here, as shown in FIG. 5, by attaching the magnetic field adjusting devices 20a and 20b to the vacuum heat insulating containers 14a and 14b (see FIG. 2) of the magnetic field generator 1, a magnetic field is formed in the vicinity of the high-temperature superconducting bulk bodies 11a and 11b. Adjustment coil groups 201a and 201b are arranged.
　なお、磁場発生装置１を着磁装置３０の磁場領域に挿入する際、着磁装置３０の磁場中心に、磁場発生装置１の高温超電導バルク体１１ａと高温超電導バルク体１１ｂの間の中心がくるように、磁場発生装置１を挿入（配置）する。また、必要に応じて磁場発生装置１を着磁装置３０に非磁性（例えばアルミニウムやＦＲＰ）の支持治具（図示せず）により固定する。これにより、高温超電導バルク体１１（１１ａ，１１ｂ）の冷却が完了し、磁束がバルク体にトラップされた後、着磁装置３０の磁場を消磁する際（後述するステップＳ１０６）、磁気力によって着磁装置３０の中心に向かって磁場発生装置１が移動することを防ぐことができる。 When the magnetic field generator 1 is inserted into the magnetic field region of the magnetizing device 30, the center between the high temperature superconducting bulk body 11a and the high temperature superconducting bulk body 11b of the magnetic field generating device 1 comes to the magnetic field center of the magnetizing device 30. Thus, the magnetic field generator 1 is inserted (arranged). Moreover, the magnetic field generator 1 is fixed to the magnetizing device 30 with a non-magnetic (for example, aluminum or FRP) support jig (not shown) as required. As a result, after the cooling of the high-temperature superconducting bulk body 11 (11a, 11b) is completed and the magnetic flux is trapped in the bulk body, the magnetic field of the magnetizing device 30 is demagnetized (step S106 described later). It is possible to prevent the magnetic field generator 1 from moving toward the center of the magnetic device 30.
　ここで、磁場発生装置１を着磁装置３０の磁場領域に挿入すると、高温超電導バルク体１１の成分に依存して、着磁装置３０の磁場により高温超電導バルク体１１が磁化する。このため、磁化した高温超電導バルク体１１により、着磁装置３０の磁場の空間均一性が乱される。なお、このときの磁化の度合いは、高温超電導バルク体１１のＲＥ元素成分により、Ｙ、Ｓｍ、Ｅｕ、Ｇｄの順に大きくなる。よって、例えば高温超電導バルク体１１としてＹ系のものを使用することにより磁化の影響を小さくできる。しかしながらＹ系の高温超電導バルク体は、捕捉磁場特性が他の酸化物超電導バルク体に比べて悪いことや、大型材の製造が難しいというデメリットがある。 Here, when the magnetic field generator 1 is inserted into the magnetic field region of the magnetizing device 30, the high-temperature superconducting bulk body 11 is magnetized by the magnetic field of the magnetizing device 30 depending on the components of the high-temperature superconducting bulk body 11. For this reason, the magnetic high-temperature superconducting bulk body 11 disturbs the spatial uniformity of the magnetic field of the magnetizing device 30. The degree of magnetization at this time increases in the order of Y, Sm, Eu, and Gd depending on the RE element component of the high-temperature superconducting bulk body 11. Therefore, for example, by using a Y-type high-temperature superconducting bulk body 11, the influence of magnetization can be reduced. However, Y-based high-temperature superconducting bulk bodies have demerits that the trapping magnetic field characteristics are poor compared to other oxide superconducting bulk bodies, and that it is difficult to manufacture large materials.
　ステップＳ１０３において、システム制御部３は、磁場発生装置１の被測定空間６に配置されたコイル群２を用いて、被測定空間６に配置されたダミーサンプル（図示せず）について、設定した磁場強度（Ｓ１０１参照）でのＮＭＲ信号を取得する。このとき、磁化した高温超電導バルク体１１による磁場の乱れのため、所得した画像に濃淡が生じる。 In step S103, the system control unit 3 uses the coil group 2 arranged in the measured space 6 of the magnetic field generator 1 to set the magnetic field set for the dummy sample (not shown) arranged in the measured space 6. An NMR signal at the intensity (see S101) is acquired. At this time, due to the disturbance of the magnetic field due to the magnetized high-temperature superconducting bulk body 11, light and shade is generated in the obtained image.
　そして、磁場調整装置２０の磁場補正用システム制御部（図示せず）は、所得した画像の濃淡に基づいて、画像に濃淡が解消するように、即ち、磁場の乱れが解消するように、磁場調整装置２０ａ，２０ｂの磁場調整コイル群２０１ａ，２０１ｂに流れる電流を制御して磁場を調整し、均一化させる。なお、必要に応じて、再度ＮＭＲ信号を取得して磁場均一性の確認を行ってもよい。 Then, the magnetic field correction system control unit (not shown) of the magnetic field adjustment device 20 makes the magnetic field so as to eliminate the shading in the image based on the shading of the acquired image, that is, so as to eliminate the disturbance of the magnetic field. The current flowing through the magnetic field adjustment coil groups 201a and 201b of the adjustment devices 20a and 20b is controlled to adjust and equalize the magnetic field. If necessary, the NMR signal may be acquired again to check the magnetic field uniformity.
　ステップＳ１０４において、冷凍機１３により高温超電導バルク体１１を冷却する。冷却することにより、高温超電導バルク体１１が超電導化し、ピン止め力が働き内部に侵入している磁束をトラップさせる。 In step S104, the high-temperature superconducting bulk body 11 is cooled by the refrigerator 13. By cooling, the high-temperature superconducting bulk body 11 becomes superconducting, and the pinning force works to trap the magnetic flux entering the inside.
　ステップＳ１０５において、高温超電導バルク体１１を所定温度まで冷却が完了したか判定する。所定温度まで冷却が完了した場合（Ｓ１０５・Ｙｅｓ）。ステップＳ１０６に進む。所定温度まで冷却が完了していない場合（Ｓ１０５・Ｎｏ）。ステップＳ１０３に戻り、ステップＳ１０３およびステップＳ１０４を繰り返す。 In step S105, it is determined whether the high-temperature superconducting bulk body 11 has been cooled to a predetermined temperature. When cooling to a predetermined temperature is completed (S105 / Yes). Proceed to step S106. When cooling to the predetermined temperature is not completed (No at S105). Returning to step S103, steps S103 and S104 are repeated.
　これは、高温超電導バルク体１１の磁化の影響が、温度により変化するためである。このため、高温超電導バルク体１１を冷却しつつ（Ｓ１０４）、定期的にＮＭＲ信号を取得して磁場の均一度の確認と、磁場調整装置２０の磁場調整コイル群２０１ａ，２０１ｂに流れる電流を制御して磁場の調整を行う（Ｓ１０３）。 This is because the influence of the magnetization of the high-temperature superconducting bulk body 11 changes depending on the temperature. For this reason, while cooling the high-temperature superconducting bulk body 11 (S104), NMR signals are periodically acquired to check the uniformity of the magnetic field, and the current flowing through the magnetic field adjustment coil groups 201a and 201b of the magnetic field adjustment device 20 is controlled. Then, the magnetic field is adjusted (S103).
　なお、冷却温度が十分低く、高温超電導バルク体１１の反磁性により磁場調整装置２０による磁場調整が困難になった場合、高温超電導バルク体１１の冷却を中止し、必要な温度まで昇温して超電導状態を壊した後、磁場調整装置２０により再度磁場調整したのち、冷却を再開する。 If the cooling temperature is sufficiently low and the magnetic field adjustment by the magnetic field adjusting device 20 becomes difficult due to the diamagnetism of the high-temperature superconducting bulk body 11, the cooling of the high-temperature superconducting bulk body 11 is stopped and the temperature is raised to a necessary temperature. After breaking the superconducting state, the magnetic field adjustment device 20 adjusts the magnetic field again, and then cooling is resumed.
　高温超電導バルク体１１を所定温度まで冷却完了した後、ステップＳ１０６において、着磁装置３０を消磁する。このときの温度（ステップＳ１０５の所定温度）は、高温超電導バルク体１１の最低到達温度に対して数Ｋ～１０Ｋ程度高いことが望ましい。これは、着磁が完了した高温超電導バルク体１１を所定温度から最低到達温度まで過冷却させることにより、高温超電導バルク体１１の磁場の時間変動を抑えることができる。 After completing the cooling of the high-temperature superconducting bulk body 11 to a predetermined temperature, the magnetizing device 30 is demagnetized in step S106. The temperature at this time (predetermined temperature in step S105) is preferably about several K to 10K higher than the lowest temperature reached by the high-temperature superconducting bulk body 11. This can suppress time fluctuation of the magnetic field of the high-temperature superconducting bulk body 11 by supercooling the high-temperature superconducting bulk body 11 that has been magnetized from a predetermined temperature to the lowest temperature.
　着磁装置３０の磁場を消磁していくと、高温超電導バルク体１１の内部では、電磁誘導によりトラップした磁束（Ｓ１０４参照）を維持するように誘導電流が生じ、この誘導電流が超電導電流として高温超電導バルク体１１の内部流れ続け、高温超電導バルク体１１が超電導永久磁石として働く。 When the magnetic field of the magnetizing device 30 is demagnetized, an induced current is generated in the high-temperature superconducting bulk body 11 so as to maintain the magnetic flux trapped by electromagnetic induction (see S104), and this induced current becomes a superconducting current at a high temperature. The superconducting bulk body 11 continues to flow, and the high-temperature superconducting bulk body 11 functions as a superconducting permanent magnet.
　着磁装置３０の消磁が終わった後、ステップＳ１０７において、着磁作業者は磁場発生装置１を着磁装置３０および磁場調整装置２０から取外し、磁場発生装置１の着磁を完了する。 After demagnetization of the magnetizing device 30, the magnetizing operator removes the magnetic field generating device 1 from the magnetizing device 30 and the magnetic field adjusting device 20 in step S107, and completes the magnetization of the magnetic field generating device 1.
　このように、高温超電導バルク体１１は、内部に流れる電流が臨界電流値以下であれば、もとの磁場をコピーしたように、磁束をトラップできる。このため、第１実施形態に係る磁場発生装置１には、着磁装置３０と磁場調整装置２０による補正された均一な磁場を着磁することができる。特に、磁場調整装置２０を磁場発生装置１と着脱可能に構成することにより、磁場調整コイル群２０１ａ，２０１ｂを高温超電導バルク体１１ａ，１１ｂの近傍に配置して、高温超電導バルク体１１ａ，１１ｂの近傍の磁場を好適に調整することができる。
　また、ＭＲＩ装置Ｓのような空間的、時間的に均一な高磁場を要求される磁場発生装置として、高温超電導バルク体１１を有する磁場発生装置１を用いることができる。 As described above, the high-temperature superconducting bulk body 11 can trap the magnetic flux as if the original magnetic field was copied if the current flowing through the high-temperature superconducting body 11 was less than the critical current value. For this reason, the magnetic field generator 1 according to the first embodiment can be magnetized with a uniform magnetic field corrected by the magnetizing device 30 and the magnetic field adjusting device 20. In particular, the magnetic field adjusting device 20 is configured to be detachable from the magnetic field generating device 1, so that the magnetic field adjusting coil groups 201a and 201b are arranged in the vicinity of the high temperature superconducting bulk bodies 11a and 11b, and the high temperature superconducting bulk bodies 11a and 11b are arranged. The nearby magnetic field can be suitably adjusted.
Further, as a magnetic field generator that requires a spatially and temporally uniform high magnetic field like the MRI apparatus S, the magnetic field generator 1 having the high-temperature superconducting bulk body 11 can be used.
　また、磁場発生装置１は、高温超電導バルク体１１を冷凍機１３により冷却し続ければ、着磁後に磁場調整装置２０を取外しても、高温超電導バルク体１１が超電導永久磁石として働く。このため、磁場発生装置１の磁場発生源を高温超電導バルク体１１のみで構成でき、図１から図３に示すように、磁場発生装置１を小型化できる。このため、磁場調整装置２０および着磁装置３０が設けられた場所と、ＭＲＩ装置Ｓを設置する場所とが、離れた場所であっても、着磁装置３０および磁場調整装置２０を用いて磁場発生装置１を着磁した後、冷凍機１３に電力を供給する搬送用冷凍機電源ユニット（図示せず）とともに、磁場発生装置１をＭＲＩ装置Ｓの設置場所まで搬送させることができる。 In addition, if the magnetic field generator 1 continues to cool the high-temperature superconducting bulk body 11 with the refrigerator 13, the high-temperature superconducting bulk body 11 works as a superconducting permanent magnet even if the magnetic field adjusting device 20 is removed after magnetization. For this reason, the magnetic field generation source of the magnetic field generator 1 can be comprised only by the high-temperature superconducting bulk body 11, and as shown in FIGS. 1-3, the magnetic field generator 1 can be reduced in size. For this reason, even if the place where the magnetic field adjusting device 20 and the magnetizing device 30 are provided and the place where the MRI apparatus S is installed are separated from each other, the magnetic field can be obtained using the magnetizing device 30 and the magnetic field adjusting device 20. After magnetizing the generator 1, the magnetic field generator 1 can be transported to the installation location of the MRI apparatus S together with a transport refrigerator power supply unit (not shown) for supplying power to the refrigerator 13.
≪第２実施形態≫
＜磁場発生装置＞
　第２実施形態に係る磁場発生装置１Ｃについて、図７および図８を用いて説明する。図７は、第２実施形態の磁場発生装置１Ｃの斜視図である。図８は、第２実施形態の磁場発生装置１ＣのＣ－Ｃ線断面図である。 << Second Embodiment >>
<Magnetic field generator>
A magnetic field generator 1 </ b> C according to the second embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is a perspective view of the magnetic field generator 1C of the second embodiment. FIG. 8 is a cross-sectional view taken along the line CC of the magnetic field generator 1C of the second embodiment.
　第１実施形態に係る磁場発生装置１は、図２に示すように、円柱形状に加工された一対の高温超電導バルク体１１ａ，１１ｂを備えているのに対し、第２実施形態に係る磁場発生装置１Ｃは、図８に示すように、高温超電導バルク体１１ｃをリング状に加工し、リング中心の空洞部分（被測定空間６）に磁場を発生させるようにした点で異なっている。 As shown in FIG. 2, the magnetic field generator 1 according to the first embodiment includes a pair of high-temperature superconducting bulk bodies 11a and 11b processed into a cylindrical shape, whereas the magnetic field generation according to the second embodiment. As shown in FIG. 8, the apparatus 1 </ b> C is different in that the high-temperature superconducting bulk body 11 c is processed into a ring shape and a magnetic field is generated in a hollow portion (measurement space 6) at the center of the ring.
　リング状の高温超電導バルク体１１ｃは、例えば磁場を発生させる空洞部分の軸方向長さを延長させる目的で、複数のリングを積層させる構造にすることもできる。また、高温超電導バルク体１１ｃは、厚み方向に複数の高温超電導バルク体を積層して用いる等、複数個の高温超電導バルク体から構成されてもよい。第２実施形態に係る磁場発生装置１Ｃでは、第１実施形態に係る磁場発生装置１と比較して、被測定空間６の周方向をリング状の高温超電導バルク体１１ｃで覆うことができ、より均一な磁場を着磁させやすい構造になっている。 The ring-shaped high-temperature superconducting bulk body 11c can also have a structure in which a plurality of rings are stacked, for example, for the purpose of extending the axial length of the cavity that generates the magnetic field. Moreover, the high-temperature superconducting bulk body 11c may be composed of a plurality of high-temperature superconducting bulk bodies, such as using a plurality of high-temperature superconducting bulk bodies stacked in the thickness direction. In the magnetic field generation device 1C according to the second embodiment, compared to the magnetic field generation device 1 according to the first embodiment, the circumferential direction of the space to be measured 6 can be covered with the ring-shaped high-temperature superconducting bulk body 11c. The structure is easy to magnetize a uniform magnetic field.
　また、高温超電導バルク体１１ｃをリング状の構造とすることにより、図７に示すように、真空断熱容器１４は、先端中央に高温超電導バルク体１１ｃからの静磁場が発生する被測定空間６となる室温ボアを有する円筒形状にすればよく、第１実施形態の真空断熱容器１４と比べて簡易な構造にすることができる。 Further, by forming the high-temperature superconducting bulk body 11c into a ring-shaped structure, as shown in FIG. 7, the vacuum heat insulating container 14 has a space to be measured 6 in which a static magnetic field from the high-temperature superconducting bulk body 11c is generated at the center of the tip. What is necessary is just to make it the cylindrical shape which has the room temperature bore which becomes, and can be made into a simple structure compared with the vacuum heat insulation container 14 of 1st Embodiment.
　図８に示すように、熱伝導部材１２は、熱伝導率の大きい材料、例えば無酸素銅等により構成され、主に棒状に加工し用いられるが、真空断熱容器１４と同様、第１実施形態と比較して、リング状の高温超電導バルク体１１ｃと冷凍機コールドヘッド１３１とを同軸上に連結するよう構成すればよいので、より簡易な構造とすることができる。 As shown in FIG. 8, the heat conducting member 12 is made of a material having a high heat conductivity, such as oxygen-free copper, and is mainly processed and used in a rod shape. However, like the vacuum heat insulating container 14, the first embodiment is used. Compared to the above, since the ring-shaped high-temperature superconducting bulk body 11c and the refrigerator cold head 131 may be configured to be connected coaxially, a simpler structure can be achieved.
　ちなみに、後述するように、磁場発生装置１Ｃを挿入する着磁装置３０ｃ（図１０参照）は、高温超電導バルク体１１ｃの軸方向（図１０の矢印Ｂ0 の向き）に磁場を発生させるため、着磁装置３０ｃからの漏洩磁場が第１実施形態に比べて大きくなる。このため、第１実施形態の場合よりも、磁場発生装置１Ｃの熱伝導部材１２および真空断熱容器１４の長さを長くして、冷凍機１３が動作可能な磁場強度まで着磁装置３０ｃの磁場発生部分から冷凍機１３の距離を離す必要がある。 Incidentally, as described later, (see Fig. 10) magnetizing apparatus 30c for inserting the magnetic field generator. 1C, for generating a magnetic field in the axial direction of the high-temperature superconducting bulk body 11c (the direction of arrow B 0 in FIG. 10), The leakage magnetic field from the magnetizing device 30c is larger than that in the first embodiment. For this reason, compared with the case of 1st Embodiment, the length of the heat conductive member 12 and the vacuum heat insulation container 14 of the magnetic field generator 1C is lengthened, and the magnetic field of the magnetizing device 30c to the magnetic field intensity which can operate the refrigerator 13 is obtained. It is necessary to separate the refrigerator 13 from the generation part.
　その他、第１実施形態と同様、真空断熱容器１４と高温超電導バルク体１１ｃ、熱伝導部材１２、および冷凍機コールドヘッド１３１が直接接触しないよう、真空断熱容器１４と熱伝導部材１２とを、ＦＲＰ等の熱伝導率の小さい材料で作られた荷重支持体（図示せず）により間接的に支持固定してもよい。 In addition, as in the first embodiment, the vacuum heat insulation container 14 and the heat conduction member 12 are connected to the FRP so that the vacuum heat insulation container 14 and the high-temperature superconducting bulk body 11c, the heat conduction member 12, and the refrigerator cold head 131 are not in direct contact with each other. Alternatively, the support may be indirectly supported and fixed by a load support (not shown) made of a material having a low thermal conductivity such as the like.
＜着磁装置＞
　次に、磁場発生装置１Ｃの高温超電導バルク体１１ｃを着磁する着磁装置３０ｃおよび磁場調整装置２０ｃについて、図９および図１０を用いて説明する。図９は、第２実施形態の磁場発生装置１Ｃに磁場調整装置２０ｃを装着し着磁装置３０ｃに挿入した状態を示す斜視図である。図１０は、第２実施形態の磁場発生装置１Ｃ、磁場調整装置２０ｃおよび着磁装置３０ｃのＤ－Ｄ線断面図である。 <Magnetic device>
Next, a magnetizing device 30c and a magnetic field adjusting device 20c for magnetizing the high-temperature superconducting bulk body 11c of the magnetic field generating device 1C will be described with reference to FIGS. FIG. 9 is a perspective view showing a state where the magnetic field adjustment device 20c is mounted on the magnetic field generation device 1C of the second embodiment and is inserted into the magnetization device 30c. FIG. 10 is a cross-sectional view taken along the line DD of the magnetic field generator 1C, the magnetic field adjusting device 20c, and the magnetizing device 30c of the second embodiment.
　第１実施形態の場合と同様に、磁場発生装置１の高温超電導バルク体１１ｃの近傍に磁場調整装置２０ｃの磁場調整コイル群２０１ｃを配置する必要がある。ここで、図１０に示すように、高温超電導バルク体１１ｃはリング状であり、真空断熱容器１４も円筒形状で構成されるため、磁場調整装置２０ｃ一つを磁場発生装置１に取り付けるだけでよい。 As in the case of the first embodiment, it is necessary to arrange the magnetic field adjustment coil group 201c of the magnetic field adjustment device 20c in the vicinity of the high-temperature superconducting bulk body 11c of the magnetic field generation device 1. Here, as shown in FIG. 10, the high-temperature superconducting bulk body 11 c has a ring shape, and the vacuum heat insulating container 14 also has a cylindrical shape. Therefore, only one magnetic field adjustment device 20 c needs to be attached to the magnetic field generation device 1. .
　また、図１０に示すように、着磁装置３０ｃの着磁用コイル群３０１ｃは、リング状の高温超電導バルク体１１ｃの軸方向（矢印Ｂ0 の向き）に均一な磁場を発生させている。このように、リング状の高温超電導バルク体１１ｃの軸方向に着磁することで、より均一な磁場分布を得られる。なお、着磁の手順は、第１実施形態（図６参照）と同様であり、説明を省略する。 Further, as shown in FIG. 10, the magnetizing coils 301c of magnetizing apparatus 30c is to generate a uniform magnetic field in the axial direction of the ring-shaped high-temperature superconducting bulk body 11c (the direction of arrow B 0). Thus, by magnetizing in the axial direction of the ring-shaped high-temperature superconducting bulk body 11c, a more uniform magnetic field distribution can be obtained. The magnetization procedure is the same as that in the first embodiment (see FIG. 6), and a description thereof will be omitted.
　このように、第２実施形態に係る磁場発生装置１Ｃは、被測定空間６の周方向周囲を高温超電導バルク体１１ｃで囲むことができ、より均一な磁場分布を得られる。また、熱伝導部材１２および真空断熱容器１４を簡易な構成とすることができる。 Thus, the magnetic field generator 1C according to the second embodiment can surround the circumference of the space 6 to be measured with the high-temperature superconducting bulk body 11c and obtain a more uniform magnetic field distribution. Moreover, the heat conductive member 12 and the vacuum heat insulation container 14 can be made into a simple structure.
Ｓ　　　　　　　　　　　　　　磁気共鳴イメージング装置（ＭＲＩ装置）
１、１Ｃ　　　　　　　　　　　磁場発生装置
２　　　　　　　　　　　　　　コイル群
３　　　　　　　　　　　　　　システム制御部
４　　　　　　　　　　　　　　出力装置
５　　　　　　　　　　　　　　冷凍機電源ユニット
６　　　　　　　　　　　　　　被測定空間
１１，１１ａ，１１ｂ，１１ｃ　高温超電導バルク体
１２　　　　　　　　　　　　　熱伝導部材
１３　　　　　　　　　　　　　冷凍機
１３１　　　　　　　　　　　　コールドヘッド
１４　　　　　　　　　　　　　真空断熱容器
２０，２０ａ，２０ｂ，２０ｃ　磁場調整装置
２０１ａ，２０１ｂ，２０１ｃ　磁場調整コイル群
３０，３０ｃ　　　　　　　　　着磁装置（静磁場発生装置）
３０１ａ，３０１ｂ，３０１ｃ　着磁用コイル群 S Magnetic resonance imaging system (MRI system)
DESCRIPTION OF SYMBOLS 1, 1C Magnetic field generator 2 Coil group 3 System control part 4 Output device 5 Refrigerator power supply unit 6 Measurement space 11, 11a, 11b, 11c High-temperature superconducting bulk body 12 Thermal conduction member 13 Refrigerator 131 Cold head 14 Vacuum insulation container 20, 20a, 20b, 20c Magnetic field adjusting devices 201a, 201b, 201c Magnetic field adjusting coil groups 30, 30c Magnetizing device (static magnetic field generating device)
301a, 301b, 301c Magnetizing coil group

Claims (5)

  1. 　真空断熱容器と、
    　前記真空断熱容器の内部に配置され、冷却され磁場を印加されることにより超電導電流が内部を流れて前記磁場を捕捉し、補足した前記磁場を供給する高温超電導バルク体と、
    　前記高温超電導バルク体を極低温に冷却する冷凍機と、を備え、
    　前記高温超電導バルク体は、
    　該高温超電導バルク体に磁場を印加する着磁装置と、
    　　該高温超電導バルク体の近傍の磁場を調整する着脱可能な磁場調整装置と、を用いて着磁される
    ことを特徴とする磁場発生装置。     A vacuum insulation container;
    A high-temperature superconducting bulk body that is disposed inside the vacuum insulation container, is cooled and applied with a magnetic field so that a superconducting current flows inside to capture the magnetic field and supplies the supplemented magnetic field;
    A refrigerator that cools the high-temperature superconducting bulk body to a cryogenic temperature, and
    The high temperature superconducting bulk body is:
    A magnetizing device for applying a magnetic field to the high-temperature superconducting bulk body;
    A magnetic field generator characterized by being magnetized using a detachable magnetic field adjusting device for adjusting a magnetic field in the vicinity of the high-temperature superconducting bulk body.
  2. 　前記高温超電導バルク体は、
    　一対の高温超電導バルク体を有し、該一対の高温超電導バルク体の対向面に捕捉した前記磁場を供給する
    ことを特徴とする請求項１に記載の磁場発生装置。     The high temperature superconducting bulk body is:
    The magnetic field generator according to claim 1, further comprising a pair of high-temperature superconducting bulk bodies and supplying the captured magnetic field to opposing surfaces of the pair of high-temperature superconducting bulk bodies.
  3. 　前記高温超電導バルク体は、
    　リング状の高温超電導バルク体を有し、該リング状の高温超電導バルク体の中央部に捕捉した前記磁場を供給する
    ことを特徴とする請求項１に記載の磁場発生装置。     The high temperature superconducting bulk body is:
    The magnetic field generator according to claim 1, wherein the magnetic field generator has a ring-shaped high-temperature superconducting bulk body and supplies the captured magnetic field to a central portion of the ring-shaped high-temperature superconducting bulk body.
  4. 　請求項１乃至請求項３のいずれか１項に記載の磁場調整装置により被検体を設置する被測定空間に静磁場を発生させ、前記被検体からの磁気共鳴信号を取得することにより、前記被検体の画像を得ることを特徴とする磁気共鳴イメージング装置。 The magnetic field adjustment device according to claim 1 generates a static magnetic field in a measurement space in which the subject is set, and acquires a magnetic resonance signal from the subject, thereby obtaining the subject. A magnetic resonance imaging apparatus characterized by obtaining an image of a specimen.
  5. 　静磁場を発生させ、高温超電導バルク体に静磁場を印加する静磁場発生装置と、
    　前記高温超電導バルク体を有する磁場発生装置と着脱可能に構成され、印加された前記静磁場により前記高温超電導バルク体が磁化し、磁化した該高温超電導バルク体による磁場の乱れを調整する磁場調整装置と、を備える
    ことを特徴とする高温超電導バルク体の着磁装置。     A static magnetic field generator for generating a static magnetic field and applying the static magnetic field to the high-temperature superconducting bulk body;
    Magnetic field adjustment device configured to be detachable from the magnetic field generator having the high-temperature superconducting bulk body, and magnetizing the high-temperature superconducting bulk body by the applied static magnetic field, and adjusting magnetic field disturbance due to the magnetized high-temperature superconducting bulk body And a magnetizing device for a high-temperature superconducting bulk body.
PCT/JP2014/064569 2013-07-31 2014-06-02 Magnetic field-generating device, magnetic resonance imaging apparatus using same, and magnetization unit for high temperature superconducting bulks WO2015015892A1 (en)

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