JP4661189B2 - Superconducting magnet device and MRI apparatus and NMR analyzer equipped with the superconducting magnet device - Google Patents

Description

  The present invention relates to a superconducting magnet device, and a magnetic resonance imaging (MRI) device and a nuclear magnetic resonance (NMR) analyzer provided with the superconducting magnet device.

  A magnetic resonance imaging device uses the fact that the nuclear magnetic resonance (NMR) phenomenon of the hydrogen nuclei that make up most of the living body to vary from tissue to tissue, and images biological tissue. The speed of the change is shown as the contrast of the image. In order to take an image of a living tissue, a superconducting magnet is used because it requires a strong magnetic field strength of 0.3 T or more, a high static magnetic field uniformity of about 10 ppm, and a high magnetic field stability.

  In [Patent Document 1], a static magnetic field generation source of a superconducting magnet device is composed of two sets of superconducting coils arranged opposite to each other across a uniform magnetic field generation region, and each group of coils has a current in a certain direction. A superconducting magnet device is described that includes a main coil that flows current, a canceling coil that flows current in a direction opposite to the main coil, and a correction coil that corrects the magnetic field uniformity.

  [Patent Document 2] includes a cylindrical superconducting coil, a radiation shield composed of a cylindrical body disposed so as to surround the superconducting coil and provided with a plurality of slits in the axial direction at appropriate intervals, a superconducting coil, and There is described a superconducting magnet for an MRI apparatus that includes a vacuum vessel that coaxially houses a radiation shield and has a normal temperature bore in the center.

  [Patent Document 3] states that the center axis of a split type multi-layer cylindrical superconducting coil system is placed horizontally so that the ratio of the maximum empirical magnetic field to the central magnetic field is 1.3 or less and the central axis of the coil is horizontal. 1 room temperature space is formed through the cryostat, a room temperature shim coil system is arranged in the first greenhouse space to improve the magnetic field uniformity, and a second room temperature space passing through the center of the split gap in the vertical direction is formed. An NMR analyzer is described that is formed by penetrating a cryostat and inserting a sample to be measured and an NMR probe having a solenoid type probe coil in a second room temperature space.

Japanese Patent Laid-Open No. 9-153408 JP 7-22231 A JP 2003-329755 A

  In the MRI apparatus, a feeling of opening that does not give the subject a feeling of pressure and a structure that allows easy access to the subject are desired, and it is necessary to arrange the vacuum containers as wide as possible. On the other hand, in order to form a strong and uniform magnetic field in the imaging space, it is necessary to bring the superconducting coils arranged facing each other closer to each other. Therefore, the measurement space is secured to such an extent that the subject does not feel pressure, and the superconducting coil is designed to be arranged as close to the imaging space as possible.

  However, in the MRI apparatus described in [Patent Document 1], generally, as shown in FIG. 13, two superconducting coils 25 </ b> A and 26 </ b> A having the same current direction are coaxially arranged at positions facing each other. In this case, during excitation and demagnetization and during operation after excitation (hereinafter referred to as rated operation), current in the same direction flows through the superconducting coils 25A and 26A. Therefore, electromagnetic force is applied in the Z direction indicated by arrows 7 and 8. Work.

  On the other hand, when the superconducting coil 26A is quenched, an eddy current flows in the imaging space side of the radiation shield 3A having the highest electrical conductivity around the coil, and interaction with the magnetic field causes a rated operation as indicated by an arrow 9. Reverse electromagnetic force works. For this reason, it is necessary to provide the support member 11A also on the imaging space side of the superconducting coil 26A, and there is a problem that the superconducting coil cannot be disposed at a position close to the imaging space because of the support member 11A.

  Further, since the electromagnetic forces attracting each other in the directions indicated by the arrows 7 and 8 act on the superconducting coils 25A and 26A, the lead wire 10 provided between the superconducting coils 25A and 26A protrudes to the support member 11A side. Therefore, if the superconducting coil 26A moves in the direction of the arrow 9 due to the reverse electromagnetic force at the time of quenching, there also arises a problem that the lead wire 10 of the superconducting coil 26A is broken. Moreover, the problem that the radiation shield 3 is damaged or deform | transformed by the eddy current at the time of quenching also arises. In the case of the MRI apparatus, not only the heat insulation performance is deteriorated due to the breakage or deformation of the radiation shield, but also when an eddy current flows through the radiation shield 3 due to application of a gradient magnetic field, it is said that imaging that can withstand practical use cannot be performed due to slight vibration caused by electromagnetic force. A problem occurs.

  Therefore, as described in [Patent Document 2], since the rigidity strength is enhanced by inserting a slit in the radiation shield and fitting an electric insulator or the like into the slit, even if electromagnetic force due to eddy current is generated. Imaging that can withstand practical use is possible without deformation and vibration. However, there has been a problem that the heat transfer performance of the radiation shield is lowered and the temperature becomes high.

  On the other hand, a superconducting magnet for generating a uniform static magnetic field in the measurement space is used for the NMR analyzer as well as the MRI apparatus. An NMR analyzer is an apparatus that analyzes the physical and chemical properties of a sample using the nuclear magnetic resonance phenomenon of hydrogen nuclei that occurs when an electromagnetic wave is irradiated to the sample to be measured. Currently, there is an increasing need for sensitive analysis of organic compounds having complex molecular structures such as proteins.

  However, in order to improve the sensitivity, a high magnetic field of 10 T or more and a highly uniform magnetic field in a measurement space of 0.1 ppm or less are necessary, which causes a problem that the apparatus becomes large. Therefore, development of a compact high-resolution NMR analyzer excellent in installation property and operability as described in [Patent Document 3] has been underway.

  Also in the NMR apparatus, generally, as shown in FIG. 14, two superconducting coil systems 36a and 36b having the same current direction and different diameters are arranged concentrically. In this case, during rated operation, currents in the same direction flow through the superconducting coil systems 36a and 36b, so that electromagnetic force acts in the radial direction as indicated by arrows 44 and 45.

  When the superconducting coil system 36a is quenched, an eddy current flows outside the radial shield 33 having the highest electrical conductivity around the coil, and the rated operation is performed as indicated by an arrow 46 due to the interaction with the magnetic field. Electromagnetic force in the opposite direction to time works. For this reason, it is necessary to support the radially outer side of the superconducting coil system 36a, and there is a problem that the apparatus cannot be made compact.

  The first object of the present invention is to save wasteful support members by maintaining good heat transfer performance of the radiation shield and by making the direction of electromagnetic force when the superconducting coil is quenched to be the same direction as during rated operation. It is to provide a conventional MRI apparatus.

  A second object of the present invention is to provide an MRI apparatus that secures a sufficient measurement space, increases the magnetic field, and increases the measurement space.

  The third object of the present invention is to provide a compact NMR analyzer that eliminates useless support members by setting the direction of electromagnetic force when the superconducting coil is quenched to the same direction as during rated operation. is there.

  In order to achieve the above object, the present invention includes at least two superconducting coils having the same direction of current during rated operation and an electromagnetic force attracting each other, and for generating a uniform magnetic field in an imaging space. A plurality of superconducting coils and a pair of refrigerant containers that house a supporting member that supports the superconducting coils, and a pair of radiation shields that cover the refrigerant containers, the two superconducting coils at positions closer to the superconducting coils than the radiation shields A nonmagnetic good conductor is disposed between the coils.

  Since most of the eddy current generated during quenching of the superconducting coil flows through the non-magnetic good conductor, it is possible to prevent the heat insulation performance from being deteriorated due to damage or deformation of the radiation shield that occurs when the eddy current flows only through the radiation shield.

  As a result, the stability of the apparatus can be ensured, and the cost required to give the radiation shield strength and the cost required for the coil support member can be reduced.

  Further, even when the superconducting coil is quenched, the direction of the electromagnetic force acting on the superconducting coil is not changed from that during rated operation, so that a support member between the superconducting coil and the imaging space becomes unnecessary. As a result, it is possible to prevent the measurement space from becoming narrower in order to increase the magnetic field for improving the sensitivity and to increase the uniformity of the measurement space. Moreover, it can prevent that the lead wire of a coil cuts.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of an MRI apparatus, and FIG. 2 is a perspective view showing an appearance thereof. However, in FIG. 2, the main coils 21A and 21B are shown, and the other superconducting coils are omitted.

  As shown in FIGS. 1 and 2, the Z axis is taken in the direction of the magnetic field central axis 12, and the X axis and the Y axis are taken in the horizontal direction perpendicular to the Z axis. The test subject lies on the bed so that his / her examination area fits in the imaging area 1. The generation source of the uniform magnetic field formed in the Z direction indicated by the arrow 6 is composed of three sets of superconducting coils arranged at opposing positions with the imaging region 1 in between. Three sets of superconducting coils are composed of main coils 21A and 21B for flowing a current in a certain direction, cancellation coils 22A and 22B for flowing a current in the opposite direction to the main coils 21A and 21B, and correction coils 23A and 23B for correcting the magnetic field uniformity. is there. The three sets of superconducting coils are formed by winding a superconducting wire around the Z-axis.

  The main coil 21A, the cancellation coil 22A, and the correction coil 23A are housed in a refrigerant container 2A together with a cooling refrigerant. A radiation shield 3A is provided around the refrigerant container 2A, and the radiation shield 3A is housed in a vacuum container 4A. . In many cases, it is known that a material having a high thermal conductivity at a low temperature has a high electric conductivity. For the radiation shields 3A and 3B, a material having a good thermal conductivity, for example, aluminum is used. Similarly, the main coil 21B, the cancellation coil 22B, and the correction coil 23B are housed in the refrigerant container 2B together with the cooling refrigerant. A radiation shield 3B is provided around the refrigerant container 2B, and the radiation shield 3B is housed in the vacuum container 4B. ing. The vacuum vessel 4 </ b> A and the vacuum vessel 4 </ b> B are connected by the support column 5 in a state of facing each other.

  On the imaging region 1 side of the vacuum vessels 4A and 4B, gradient magnetic field coils 24A and 24B for spatially changing the magnetic field in a form superimposed on a uniform magnetic field are arranged in order to obtain position information. The gradient magnetic field coils 24A and 24B are provided with a coil formed by winding a superconducting wire around the Z axis and a coil that generates a gradient magnetic field in the X and Y directions (not shown).

  FIG. 3 is a longitudinal sectional view of the vacuum vessel 4A and shows a part of the region of X> 0, Z> 0 in FIG. A radiation shield 3A is installed inside the vacuum container 4A via a support member 17, and a refrigerant container 2A is installed inside the radiation shield 3A via a support member 17. These support members 17 are made of a low thermal conductivity material such as FRP (fiber reinforced plastic) so that heat does not enter from the outside, and the contact area with each container is reduced within a range where sufficient strength can be secured. It is set.

A plurality of superconducting coils are installed inside the refrigerant container 2A. In FIG. 3, among the plurality of superconducting coils, the superconducting coils 25A, which have the same current direction during rated operation and have electromagnetic forces attracting each other, 26A is illustrated. Superconducting coils 25 </ b> A and 26 </ b> A are coaxially arranged in support member 11 so as to face each other.

  As shown in FIG. 3, between the superconducting coil 25A and the superconducting coil 26A, between the superconducting coil 25A or the superconducting coil 26A and the support member 11, for example, aluminum, aluminum alloy, copper, or aluminum at a low temperature is equivalent. An annular nonmagnetic good conductor 13 made of a material having the electrical conductivity of is arranged. The distance between the superconducting coil 26A and the nonmagnetic good conductor 13 is set to be shorter than the distance between the superconducting coil 26A and the radiation shield 3A. That is, the distance between the superconducting coil 25A or 26A and the nonmagnetic good conductor 13 is set to be shorter than the distance between the superconducting coil 25A or 26A and the radiation shield 3A.

The nonmagnetic good conductor 13 has an annular shape. As shown in FIG. 4, the nonmagnetic good conductor 13 is stacked on the support member 11 and the outer peripheral portion is fixed with a plurality of bolts 16. The screw hole 15 has a diameter larger than the diameter of the bolt 16 in consideration of the thermal expansion of the nonmagnetic good conductor 13 due to heat generation at the time of quenching, the surface where the coil and the nonmagnetic good conductor 13 are in contact, the support member 11 and the nonmagnetic The surface that is in contact with the good conductor 13 is subjected to peeling treatment and insulation treatment.

  Thus, since the distance between the nonmagnetic good conductor 13 and the superconducting coil 26A is shorter than the distance between the radiation shield 3A and the superconducting coil 26A, the eddy current generated when the superconducting coil is quenched flows through the nonmagnetic good conductor 13. For this reason, the electromagnetic force acting on the superconducting coil 26A is upward in the Z direction in the same direction as during rated operation, and there is no need to provide the support member 11A on the lower portion of the superconducting coil 26A. As a result, since the distance between the superconducting coil 26A and the superconducting coil disposed below the imaging region 1 can be reduced, a magnetic field with high magnetic field uniformity and strong magnetic field strength can be formed in the imaging region 1, and high openness can be achieved. Can be secured. Moreover, the problem that the lead wire of the coil is cut can be solved. Further, since the nonmagnetic good conductor 13 is disposed around the superconducting coil via the insulating layer, a quench back effect can be expected when the superconducting coil is quenched.

  Next, as shown in FIG. 5, when the superconducting coils 25A and 26A are coaxially arranged opposite to each other at a position away from the imaging region 1, similarly, for example, aluminum, aluminum alloy, copper, low temperature By arranging the non-magnetic good conductor 13 which is a material having electrical conductivity equivalent to aluminum, the direction of the electromagnetic force acting on the superconducting coil 25A becomes downward in the same Z direction as in rated operation, so a support member becomes unnecessary. The problem that the coil lead wire is broken can also be solved. Moreover, since the nonmagnetic good conductor 13 is disposed around the superconducting coil via the insulating layer, a quench back effect can be expected when the superconducting coil is quenched.

  Further, as shown in FIG. 6, when superconducting coils 25A and 26A having different diameters are arranged concentrically, the nonmagnetic good conductor 13 is arranged between the supporting member 11 and either the superconducting coil 25A or the superconducting coil 26A. Since the direction of the electromagnetic force acting on the superconducting coil 25A is the same as that during rated operation, the problem that the lead wire of the coil is cut off can be solved, and the nonmagnetic good conductor 13 is superconducted through the insulating layer. Since it is arranged around the coil, a quench back effect can be expected when the superconducting coil is quenched.

  A second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a longitudinal sectional view of the vacuum vessel 4A and shows a part of the region of X> 0, Z> 0 in FIG. As in FIG. 3, a plurality of superconducting coils are installed inside the refrigerant container 2 </ b> A. In FIG. 7, among the plurality of superconducting coils, the current direction during rated operation is the same, and electromagnetic forces attracting each other work. The superconducting coils 25A and 26A are shown. Superconducting coils 25 </ b> A and 26 </ b> A are coaxially arranged in support member 11 so as to face each other.

As shown in FIG. 7, the annular nonmagnetic good conductor 13 of this embodiment includes a superconducting coil 25 </ b> A,
It arrange | positions in the support member 11 of the part pinched | interposed by 26A. The distance between the superconducting coil 26A and the nonmagnetic good conductor 13 is arranged to be shorter than the distance between the superconducting coil 26A and the radiation shield 3A.

  FIG. 8 is a modification of the example shown in FIG. The example shown in FIG. 8 is configured in the same manner as the example shown in FIG. 7, but in this example, the nonmagnetic good conductor 13 is arranged on the outer peripheral side of the support member 11 in the portion sandwiched between the superconducting coils 25A and 26A. And it is being fixed with the some volt | bolt 16 from the outer peripheral side. If there is a space on the inner peripheral side, it may be fixed on the inner peripheral side of the support member 11. The distance between the superconducting coil 26A and the nonmagnetic good conductor 13 is arranged to be shorter than the distance between the superconducting coil 26A and the radiation shield 3A.

  Similar to the example shown in FIG. 3, the nonmagnetic good conductor 13 has an annular shape. As shown in FIG. 4, the nonmagnetic good conductor 13 is stacked on the support member 11, and the outer peripheral portion is fixed with a plurality of bolts 16. The screw hole 15 has a diameter larger than the diameter of the bolt 16 in consideration of the thermal expansion of the nonmagnetic good conductor 13 due to heat generation at the time of quenching, and the surface where the support member 11 and the nonmagnetic good conductor 13 are in contact with each other is peeled off. Insulation treatment is applied. Other portions are configured in the same manner as the example shown in FIG.

  Also in this embodiment, since the distance between the nonmagnetic good conductor 13 and the superconducting coil 26A is shorter than the distance between the radiation shield 3A and the superconducting coil 26A, the eddy current generated when the superconducting coil is quenched flows through the nonmagnetic good conductor 13. Therefore, since the electromagnetic force acting on the superconducting coil 26A is upward in the same Z direction as that during rated operation, a support member for the lower portion of the superconducting coil 26A is not necessary.

  As a result, since the distance between the superconducting coil 26A and the superconducting coil disposed below the imaging region 1 can be reduced, a magnetic field with high magnetic field uniformity and strong magnetic field strength can be formed in the imaging region 1, and high openness can be achieved. Can be secured. Moreover, the problem that the lead wire of the coil is cut can be solved.

  Also in this embodiment, when the superconducting coils 25A and 26A are arranged coaxially and oppositely at positions away from the imaging region 1 as shown in FIG. 5, the operations and effects described in FIG. Further, as shown in FIG. 6, even when superconducting coils 25A and 26A having different diameters are arranged concentrically, the operation and effect described in FIG.

  A third embodiment of the present invention will be described with reference to FIG. 9 is configured in the same manner as the example shown in FIG. 3, but in the example shown in FIG. 9, a part of the support member 11, that is, a region between the superconducting coils 25A and 26A is formed in an annular shape. The nonmagnetic good conductor 13 is different from the nonmagnetic good conductor 13 in that the nonmagnetic good conductor 13 is fixed to the support member 11 with a plurality of bolts 16 from the inner peripheral side in the circumferential direction.

  Also in this embodiment, since the distance between the nonmagnetic good conductor 13 and the superconducting coil 26A is shorter than the distance between the radiation shield 3A and the superconducting coil 26A, the eddy current generated during quenching of the superconducting coil flows through the nonmagnetic good conductor 13 and superconducting. Since the electromagnetic force acting on the coil 26A is upward in the same Z direction as in rated operation, a support member for the lower portion of the superconducting coil 26A is not necessary.

  As a result, since the distance between the superconducting coil 26A and the superconducting coil disposed below the imaging region 1 can be reduced, a magnetic field with high magnetic field uniformity and strong magnetic field strength can be formed in the imaging region 1, and high openness can be achieved. Can be secured. Moreover, the problem that the lead wire of the coil is cut can be solved. Moreover, since the nonmagnetic good conductor 13 is disposed around the superconducting coil via the insulating layer, a quench back effect can be expected when the superconducting coil is quenched.

  Also in this embodiment, when the superconducting coils 25A and 26A are arranged coaxially and oppositely at positions away from the imaging region 1 as shown in FIG. 5, the operations and effects described in FIG. Further, as shown in FIG. 6, even when superconducting coils 25A and 26A having different diameters are arranged concentrically, the operation and effect described in FIG.

  A fourth embodiment of the present invention will be described with reference to FIG. FIG. 15 is a view showing the surface on the imaging region side of the upper radiation shield provided with the slits. In addition to the arrangement structure of the nonmagnetic good conductor 13 shown in the first, second, and third embodiments, a plurality of slits 47 are provided at appropriate intervals in the circumferential direction on the surface of the radiation shield 3A on the imaging region side. . Thereby, the effect of further reducing the eddy current generated in the radiation shield 3A can be expected.

  Also in this embodiment, when the superconducting coils 25A and 26A are arranged coaxially and oppositely at positions away from the imaging region 1 as shown in FIG. 5, the operations and effects described in FIG. Further, as shown in FIG. 6, even when superconducting coils 25A and 26A having different diameters are arranged concentrically, the operation and effect described in FIG.

  Next, an example applied to the NMR analyzer will be described with reference to FIGS. FIG. 10 is a longitudinal sectional view showing an example of the NMR analyzer, and FIG. 11 is a perspective view showing the appearance thereof. However, in FIG. 11, one superconducting coil system 36 is shown on the left and right, and the others are omitted.

  As shown in FIG. 10, the Z axis is taken in the direction of the magnetic field center axis, and the X axis and Y axis are taken in the direction perpendicular to the Z axis. The source of the uniform magnetic field formed in the Z direction indicated by the arrow 35 is the superconducting coil system 36. As shown in FIG. 12, each superconducting coil system 36 is formed by winding a superconducting wire around the Z axis. The NMR analyzer includes a refrigerant container 32 that houses a superconducting coil system 36 together with a refrigerant (not shown), a radiation shield 33 that covers the refrigerant container 32, and a cryostat 34 that covers the radiation shield 33. The cryostat 34 includes a first room temperature space 37 penetrating the cryostat 34 along the Z axis, a second room temperature space 38 penetrating the cryostat 34 along the X axis, and a cryostat 34 penetrating along the Y axis (not shown). A third room temperature space is formed. A sample to be measured 31 is placed at the intersection of the first, second, and third greenhouse spaces. The radiation shield 33 is mainly made of a material having good thermal conductivity, such as aluminum. In many cases, it is known that a material having a high thermal conductivity at a low temperature has a high electric conductivity. In the NMR analyzer, although not shown, an NMR probe, a superconducting shim coil system, an electromagnetic wave irradiation system, an electromagnetic wave detection system, and the like are provided.

  FIG. 12 is a longitudinal sectional view of the radiation shield 33 and shows a part of the region of X> 0, Z> 0 in FIG. A refrigerant container 32 is installed inside the radiation shield 33 via a support member 43. These support members 17 are made of a low thermal conductivity material such as FRP (fiber reinforced plastic) so that heat does not enter from the outside, and the contact area with each container is reduced within a range where sufficient strength can be secured. It is set.

  A plurality of superconducting coils are installed inside the refrigerant container 32. In FIG. 12, among the plurality of superconducting coils, the direction of current during rated operation is the same, and a superconducting coil system 36a in which electromagnetic forces attracting each other work. , 36b, a superconducting coil system 36 is shown. The superconducting coil systems 36 a and 36 b having different diameters are disposed concentrically within the support member 39.

  As shown in FIG. 12, between the superconducting coil system 36a and the superconducting coil system 36b, between either the superconducting coil system 36a or the superconducting coil system 36b and the support member 39, for example, aluminum, aluminum alloy, copper, An annular nonmagnetic good conductor 40 made of a material having an electrical conductivity equivalent to aluminum at a low temperature is disposed. Further, the distance between the superconducting coil system 36 a and the nonmagnetic good conductor 40 is set to be shorter than the distance between the superconducting coil system 36 a and the radiation shield 33.

  The nonmagnetic good conductor 40 has an annular shape. As shown in FIG. 12, the outer periphery of the nonmagnetic good conductor 40 is fixed to a support member 39 with a plurality of bolts 41. The screw hole 42 has a diameter larger than the diameter of the bolt 41 in consideration of the thermal expansion of the nonmagnetic good conductor 40 due to heat generation at the time of quenching, the surface where the coil and the nonmagnetic good conductor 40 are in contact, the support member 39 and the nonmagnetic The surface that is in contact with the good conductor 40 is subjected to peeling treatment and insulation treatment.

The support member 43 between the refrigerant container 32 and the radiation shield 33 uses a low thermal conductivity material, for example, FRP (fiber reinforced plastic) so that heat does not enter from the outside. The contact area with the container is reduced. Since the distance between the nonmagnetic good conductor 40 and the superconducting coil system 36a is shorter than the distance between the radiation shield 33 and the superconducting coil system 36a, the eddy current generated at the time of quenching flows through the nonmagnetic good conductor 40 and acts on the superconducting coil system 36a. The force is downward in the Z direction, the same as during rated operation. As a result, it is not necessary to provide a support member in the upper region of the superconducting coil system 36a. Further, since the nonmagnetic good conductor 40 is disposed around the superconducting coil via the insulating layer, a quench back effect can be expected when the superconducting coil is quenched.

  In addition, although the superconducting coil and the nonmagnetic good conductor have been described as being coaxial and annular, they may not be strictly coaxial but may be noncircular. The second embodiment, the third embodiment, and the fourth embodiment can also be applied to an NMR apparatus.

  As described above, according to each embodiment, since the eddy current generated at the time of quenching the superconducting coil flows to the non-magnetic good conductor, the heat insulation performance due to the breakage or deformation of the radiation shield that occurs when the eddy current flows to the radiation shield. Can be prevented.

  As a result, the stability of the apparatus can be ensured, and the cost required to give the radiation shield strength and the cost required for the coil support member can be reduced.

  In addition, even when the superconducting coil is quenched, the direction of the electromagnetic force acting on the superconducting coil is not different from that during rated operation, so a support member for supporting the superconducting coil on the imaging space side is unnecessary, and the superconducting coil and the imaging space below Since the distance from the superconducting coil arranged in the can be reduced, a magnetic field with high magnetic field uniformity and strong magnetic field strength can be formed in the imaging space, and a high degree of openness can be ensured. As a result, the subject's feeling of opening and accessibility to the subject can be improved.

  Moreover, the problem that the lead wire of the coil is cut can be solved. In addition, when the nonmagnetic good conductor is in contact with the superconducting coil through the insulating layer, a quench back effect can be expected when the superconducting coil is quenched.

  In this way, a high-quality image can be obtained, and an MRI apparatus having high accessibility to the subject and high measurement space can be manufactured at low cost. Also, the NMR apparatus has the same effect as described above, and even when the superconducting coil is quenched, the direction of the electromagnetic force acting on the superconducting coil is the same as that during rated operation, so the amount of the support member is reduced. The This can suppress an increase in the size of the apparatus in order to achieve a high magnetic field for improving sensitivity and a highly uniform magnetic field in the measurement space. Thus, a highly sensitive and compact NMR analyzer can be made at low cost.

1 is a longitudinal sectional view of an MRI apparatus according to a first embodiment of the present invention. It is a perspective view which shows the structure of a part of MRI apparatus. It is a longitudinal cross-sectional view which shows a part of MRI apparatus shown in FIG. It is a perspective view which shows an example of the screwing of a nonmagnetic good conductor. It is a longitudinal cross-sectional view which shows the example by which the superconducting coil is coaxially arrange | positioned in the position away from the imaging region and mutually opposing. It is a longitudinal cross-sectional view which shows the example which has arrange | positioned the superconducting coil from which a diameter differs concentrically. It is a longitudinal cross-sectional view which shows the 2nd Example of this invention. It is a longitudinal cross-sectional view which shows the modification of FIG. It is a longitudinal cross-sectional view which shows the 3rd Example of this invention. It is a longitudinal cross-sectional view of an NMR analyzer. It is a perspective view which shows the external appearance of a NMR analyzer. It is a longitudinal cross-sectional view which shows a part of structure of FIG. It is the figure which showed the direction of the electromagnetic force which acts on the superconducting coil at the time of rated operation and quenching of the conventional MRI apparatus. It is the figure which showed the direction of the electromagnetic force which acts on the superconducting coil at the time of the rated operation and quenching of the conventional NMR analyzer. It is the figure which showed the surface by the side of the imaging region of a radiation shield.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Imaging region, 2A, 2B, 32 ... Refrigerant container, 3, 3A, 3B, 33 ... Radiation shield, 4A, 4B ... Vacuum container, 5 ... Post, 10 ... Lead wire, 11, 17, 39, 43 ... Support Member, 13, 40 ... non-magnetic good conductor, 14 ... measurement space, 15, 42 ... screw hole, 16, 41 ... bolt, 21A, 21B ... main coil, 22A, 22B ... cancellation coil, 23A, 23B ... correction coil, 24A , 24B ... gradient magnetic field coil, 25A, 26A ... superconducting coil, 31 ... sample to be measured, 34 ... cryostat, 36, 36a, 36b ... superconducting coil system, 37 ... first room temperature space, 38 ... second room temperature space, 44, 45, 46 ... electromagnetic force, 47 ... slit.

Claims (9)

A radiation shield arranged so as to face each other across an imaging space which is an examination area of the subject,
A refrigerant container installed in the radiation shield;
A first superconducting coil and a second superconducting coil which are housed in the refrigerant container and arranged so that electromagnetic forces attracting each other act in the same direction of current during rated operation;
A support member that contacts and supports the first superconducting coil and the second superconducting coil;
A nonmagnetic good conductor provided between the first superconducting coil and the second superconducting coil;
Either one of the first superconducting coil and the second superconducting coil is further supported in contact with the refrigerant container,
An MRI apparatus, wherein a distance between the first or second superconducting coil and the nonmagnetic good conductor is shorter than a distance between the radiation shield and the first or second superconducting coil. A first superconducting coil and a second superconducting coil having different diameters, which are arranged coaxially in the support member, in which the electromagnetic force attracting each other acts in the same direction of current during rated operation;
A refrigerant container containing the first superconducting coil and the second superconducting coil;
A radiation shield covering the refrigerant container;
A cryostat covering the radiation shield;
A nonmagnetic good conductor provided between the first superconducting coil and the second superconducting coil,
The support member is in contact with and supports the first superconducting coil and the second superconducting coil;
Either one of the first superconducting coil and the second superconducting coil is further supported in contact with the refrigerant container,
An NMR analyzer characterized in that a distance between the first or second superconducting coil and the nonmagnetic good conductor is shorter than a distance between the radiation shield and the first or second superconducting coil. Among a plurality of superconducting coils housed in a refrigerant container installed in a radiation shield arranged so as to face each other with an imaging space interposed therebetween, electromagnetic waves attracting each other with the same current direction during rated operation in a support member A first superconducting coil and a second superconducting coil arranged so that a force acts;
A nonmagnetic good conductor provided between the first superconducting coil and the second superconducting coil,
The support member is in contact with and supports the first superconducting coil and the second superconducting coil;
Either one of the first superconducting coil and the second superconducting coil is further supported in contact with the refrigerant container,
A superconducting magnet apparatus, wherein a distance between the first or second superconducting coil and the nonmagnetic good conductor is shorter than a distance between the radiation shield and the first or second superconducting coil. Among a plurality of superconducting coils housed in a refrigerant container installed in a radiation shield arranged so as to face each other with an imaging space interposed therebetween, electromagnetic waves attracting each other with the same current direction during rated operation in a support member A first superconducting coil and a second superconducting coil arranged so that a force acts;
A nonmagnetic good conductor provided between the first superconducting coil and the second superconducting coil;
The support member is in contact with and supports the first superconducting coil and the second superconducting coil;
Either one of the first superconducting coil and the second superconducting coil is further supported in contact with the refrigerant container,
A superconducting magnet apparatus , wherein a distance between the first or second superconducting coil and the nonmagnetic good conductor is shorter than a distance between the radiation shield and the first or second superconducting coil . A plurality of superconducting coils including at least two superconducting coils in which the electromagnetic directions attracting each other with the same current direction during rated operation;
A pair of refrigerant containers for accommodating a support member that contacts and supports each of the plurality of superconducting coils;
A pair of radiation shields covering each of the refrigerant containers;
A non-magnetic good conductor disposed between two superconducting coils of the plurality of superconducting coils ;
Either one of the two superconducting coils is further supported in contact with the refrigerant container,
A superconducting magnet apparatus , wherein a distance between the two superconducting coils and the nonmagnetic good conductor is shorter than a distance between the radiation shield and the two superconducting coils . The nonmagnetic good conductor is
Between one of the first and second superconducting coils and the support member, among the support members provided between the first and second superconducting coils, between the first and second superconducting coils. It is installed in the position of either the inner peripheral side or the outer peripheral side of the support member provided in, or is installed via the insulating layer between the first and second superconducting coils. The MRI apparatus according to claim 1. The nonmagnetic good conductor is
Between one of the first and second superconducting coils and the support member, among the support members provided between the first and second superconducting coils, between the first and second superconducting coils. It is installed in the position of either the inner peripheral side or the outer peripheral side of the support member provided in, or is installed via the insulating layer between the first and second superconducting coils. The NMR analyzer according to claim 2. A superconducting magnet apparatus according to any one of claims 3 to 5,
A main coil for supplying a constant current direction, the the main coil cancel flowing reverse current and the coil, and a correction coil for correcting the magnetic homogeneity of the imaging space, space a magnetic field to obtain a location information of the imaging space MRI apparatus having the greater conductivity magnet apparatus having a magnetic field gradient coil for to change. A superconducting magnet apparatus according to any one of claims 3 to 5,
A cryostat for covering the radiation shield, NMR analyzer having the greater conductivity magnet device having a plurality of greenhouse space penetrating the cryostat.

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