JP4566232B2 - Superconducting magnet device - Google Patents

Description

  The present invention relates to a superconducting magnet device used in a magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus).

  In recent years, the use of superconducting magnet devices has become common as a static magnetic field generation source with high strength, high uniformity, and time stability. In particular, the MRI apparatus is widely used as a static magnetic field generation source. In the magnet used in the MRI apparatus, in order to take a precise and high-contrast human (patient) tomographic image at high speed and to acquire a high-functional image, within a spherical space of 30 to 45 cm in diameter at the magnet center as an imaging space, Magnetic field strength of 0.5 to 3 Tesla, magnetic field uniformity of 1 to 10 ppm, and time-stable static magnetic field characteristics of 0.05 ppm / h are required.

These characteristics can only be met by a superconducting magnet device that employs a superconducting coil capable of lossless and high current density and a permanent current mode operation unique to superconducting phenomena and adopts a coil arrangement based on strict magnetic field uniformity design. Absent.
At the same time, the MRI apparatus magnet is required to reduce the leakage magnetic field generated by the magnet itself in order to prevent the influence of the magnetic field on the cardiac pacemaker wearer and other devices.

  As described above, the magnet for the MRI apparatus has many requirements for the coil design, but a Helmholtz coil is generally used as a coil arrangement for realizing it. This has a structure in which two or more coils are arranged coaxially. Conventionally, each coil constituting the Helmholtz coil is formed such that its winding width and winding height are constant and the cross section is substantially rectangular (see, for example, Patent Document 1).

  On the other hand, an example in which a uniform magnetic field is obtained with a single coil without using a Helmholtz coil is also shown. In this example, the single coil does not have a substantially rectangular cross-sectional structure, but the superconductivity is such that the coil outer diameter (coil height) gradually increases from the axial center to the axial end. It is formed by winding a wire, and its coil cross-sectional shape is not a substantially rectangular shape but a non-rectangular shape in which the height is changed by partially winding (see, for example, Patent Document 2).

JP 08-168476 A Japanese Patent Application Laid-Open No. 61-082424

In the case of a Helmholtz coil, the superconducting coil used in the conventional MRI apparatus, which is a superconducting magnet device, has a substantially rectangular shape in cross section of the plurality of superconducting coils. Even if there was an ideal coil shape and coil arrangement, it could not be adopted. Therefore, an expensive superconducting wire is used more than necessary to form a coil. Furthermore, as the magnetomotive force increases, the electromagnetic force of the coil and the self-magnetic field created by the coil itself increase, and more robust electromagnetic force support and higher performance and more expensive superconducting wire are required. There were problems such as.
Moreover, since the cross-sectional shape of the coil is a substantially rectangular shape, the shape of the vacuum heat insulating container in which the coil group is accommodated is also greatly restricted. As a result, the outer shape of the superconducting magnet device was also affected.

  Furthermore, in an example in which the coil cross-sectional shape is not a substantially rectangular shape, the ideal coil shape or coil arrangement cannot be reflected because of the configuration of the electromagnetic coil by only a single coil, and winding is also performed on a portion where no winding is necessary. It becomes a coil to which a wire is applied, and it is difficult to obtain a coil having a small magnetomotive force or a small amount of required wire.

  The present invention has been made to solve the above-described problems, and can be used by making a coil having a smaller magnetomotive force or a smaller amount of necessary wire material and uniformizing the magnetic flux density in the superconducting coil. It aims at suppressing the performance of a superconducting wire and obtaining an inexpensive superconducting magnet device.

  The superconducting magnet device according to the present invention is arranged and accommodated so as to be coaxial in the first and second containers opposed to each other with a predetermined space therebetween, and the first and second containers. A uniform magnetic field is generated between the two containers. The first and second coil groups are formed of a plurality of superconducting coils wound in an annular shape and spaced apart from each other. Among the plurality of superconducting coils, The cross-sectional shape of the two superconducting coils arranged in the same container and adjacent to each other is a non-rectangular shape obtained by cutting off the corner portion that is the closest part of the two superconducting coils from a substantially rectangular shape. The corner portion is formed by a winding frame or a spacer.

  The superconducting magnet apparatus according to the present invention is a container provided with a cylindrical opening, and is arranged and accommodated in the container so as to be coaxial, and generates a uniform magnetic field in the opening of the container. A plurality of superconducting coils arranged at a distance from each other, and the cross-sectional shape of the two adjacent superconducting coils in the coil group varies from a substantially rectangular shape to the closest of the two superconducting coils. It is formed by winding so as to have a non-rectangular shape such as a corner portion that is cut off, and the corner portion is constituted by a winding frame or a spacer.

  The superconducting magnet device according to the present invention is arranged and accommodated so as to be coaxial in the first and second containers arranged opposite to each other with a predetermined space therebetween, and the first and second containers. A uniform magnetic field is generated between the two containers. The first and second coil groups are formed of a plurality of superconducting coils wound in an annular shape and spaced apart from each other. Among the plurality of superconducting coils, The cross-sectional shape of the two superconducting coils arranged in the same container and adjacent to each other is a non-rectangular shape obtained by cutting off the corner portion that is the closest part of the two superconducting coils from a substantially rectangular shape. Since the corners are formed by winding frames or spacers, the magnetic flux density in the superconducting coil can be made uniform, the performance of the superconducting wire used can be suppressed, and an inexpensive electromagnet device can be manufactured. It becomes.

  Further, according to the superconducting magnet device of the present invention, a container provided with a cylindrical opening, and arranged and accommodated in the container so as to be coaxial, and generates a uniform magnetic field in the opening of the container. A coil group comprising a plurality of superconducting coils that are rotated and spaced apart from each other, and the cross-sectional shape of two adjacent superconducting coils in the coil group varies from a substantially rectangular shape to the most recent of the two superconducting coils. It is formed so as to have a non-rectangular shape in which the corner portion that is a contact portion is cut, and the corner portion is constituted by a winding frame or a spacer, so that the magnetic flux density in the superconducting coil can be made uniform. It becomes possible to suppress the performance of the superconducting wire to be used and to manufacture an inexpensive electromagnet device.

Reference Example 1
FIG. 1 is a cross-sectional view showing a superconducting magnet apparatus for an MRI apparatus, which is Reference Example 1 of the present invention. As shown in FIG. 1, an upper vacuum heat insulating container (corresponding to a first container) 1a and a lower vacuum heat insulating container (corresponding to a second container) 1b having a predetermined space and having a substantially cylindrical shape are formed. A plurality of superconducting coils arranged in an annular shape so as to be coaxial with the axis along the Z direction in the figure are arranged and housed in each container. Two containers (1a, 1b) are connected by a communication pipe 3, and the upper vacuum heat insulating container 1a has a structure supported by the communication pipe 3. Such a superconducting magnet device is called an open type or an open type. FIG. 2 shows a perspective view of this open type superconducting magnet device. In FIG. 2, an arrow 4a pointing between the two containers (1a, 1b) indicates the direction in which the subject (human body) is inserted into the superconducting magnet device when imaging is performed by the MRI apparatus. Yes.

The plurality of superconducting coils are housed in the cryogenic containers 2a and 2b in the upper and lower vacuum heat insulating containers 1a and 1b, respectively. Further, liquid helium for cooling the superconducting coil is placed in the cryogenic containers 2a and 2b.
In this example, superconducting coils 10a, 11a, 12a, 13a (corresponding to the first coil group) are arranged and housed in the upper vacuum heat insulating container 1a so as to be coaxial, and similarly, the superconducting coils 10b, 11b, 12b and 13b (corresponding to the second coil group) are arranged and accommodated in the lower vacuum heat insulating container 1b so as to be coaxial.

The upper and lower vacuum heat insulating containers 1a and 1b accommodate the cryogenic containers 2a and 2b, respectively, and reduce evaporation of liquid helium from the cryogenic containers 2a and 2b. Although not shown, a plurality of heat shield tanks are usually installed between the cryogenic containers 2a and 2b and the upper and lower vacuum heat insulating containers 1a and 1b in order to reduce evaporation of liquid helium.
Moreover, the superconducting coil arrange | positioned in cryogenic container 2a, 2b winds a superconducting wire around the winding frame which is coaxially arrange | positioned and which is not shown in figure. A superconducting magnet device having a cross-sectional structure as shown in FIG. 1 is obtained by first combining superconducting coils individually wound through a further support structure.
In the superconducting magnet apparatus configured as shown in FIG. 1, a uniform magnetic field space 4 located between the containers (1a, 1b) is formed by a plurality of superconducting coils housed in the upper and lower vacuum heat insulating containers 1a, 1b. Generate an upward uniform magnetic field.

Superconducting magnet devices for MRI devices are required to have high magnetic field uniformity and low leakage magnetic field. However, it is strictly necessary to generate the required magnetic field as efficiently as possible, that is, under the condition of minimum magnetomotive force or minimum amount of required wire. When the optimum design is performed, the coil shape becomes a non-rectangular shape (in other words, a shape in which the coil winding width and the winding height are not constant) as shown in FIG.
In addition, the coil constituting the superconducting magnet device has the property of moving in the Z direction as much as possible, that is, in the Z = 0 (plane) direction, and from the Z axis on the R direction of the coil (Z = 0 plane). The direction of going away.) The maximum outer diameter dimension, that is, the outermost peripheral part of the superconducting coils 10a, 10b has a property of going to the outside as much as possible (direction going away from the Z axis).

  In each container (1a, 1b), the winding diameter of the superconducting coils 10a, 10b is the largest. For example, the superconducting coil 10a has a substantially fan-shaped cross section as shown in FIG. It is formed so as to become. This shape will be described with reference to FIG. 3 showing an enlarged sectional view of the superconducting coil 10a. The coil winding height in the direction along the opposing surfaces of the two containers (1a, 1b.) Decreases as the distance from the opposing surface decreases, and the coil winding width along the Z direction is the outermost circumference of the coil ( It is formed so as to be the maximum at the maximum outer circumference. The winding height corresponds to a dimension obtained by subtracting the minimum winding diameter from the maximum winding diameter at an arbitrary position on the Z axis.

  In addition, among the superconducting coils, the superconducting coils 11a, 12a, 13a and 11b, 12b, 13b having the second largest winding diameter are wound so that the cross-sectional shape is substantially bowl-shaped. This shape will be described with reference to FIG. 4 showing an enlarged sectional view of the superconducting coil 11a. The position where the coil winding height in the direction along the opposing surface of the two containers (1a, 1b.) Decreases with increasing distance from the opposing surface, and the position where the winding width is maximum is the most of each coil. It is formed so as to correspond to the intermediate position of the winding height on the side close to the facing surface.

  1 and 4 show examples in which the cross-sectional shapes of the superconducting coils 11a, 12a, 13a and 11b, 12b, and 13b are substantially bowl-shaped, but structures other than the coils constituting the superconducting magnet device are shown. In some cases, the structure may be formed so as to avoid the structure due to the arrangement. In such a case, the substantially bowl-shaped superconducting coil 11a as shown in FIG. 4 is arranged with the base position being the same, by sliding the apex position, and connecting the two so that a part of them overlaps. For example, the coil can be wound and formed so as to be a double-cove type. In any case, in the case of an open-type superconducting magnet device, the cross-sectional shape of the superconducting coil constituting the coil coil is such that the coil winding height in the direction along the opposing surfaces of the two containers decreases as the distance from the opposing surfaces increases. Formed to be.

In FIG. 1, for example, there is a slight gap between the cryogenic container 2a (2b) and the superconducting coil 10a (10b), but this gap is used to arrange the winding frame of the superconducting coil 10a (10b) and other necessary members. It is a space and cannot be used for the coil.
Next, FIG. 5 shows an enlarged cross-sectional view of a region A surrounding the superconducting coil 10a of FIG. 1, and the state of the winding will be described. In FIG. 1, a schematic diagram in which the reel and the like are omitted is shown. However, as shown in FIG. 5, the overall shape is annular, and the side corresponding to the maximum outer periphery is open, and the cross-sectional shape is a U shape. A superconducting coil 10 a is formed by winding a superconducting wire 21 around a certain winding frame 20.

  In order to obtain the superconducting coil 10a having a substantially fan-shaped cross section, first, the insulating layer 25 is wound around a surface (the innermost peripheral surface in the winding frame 20) which becomes the bottom in the winding frame 20. The insulating layer 25 can be formed, for example, by winding the same insulating material as an interlayer insulating material 23 described later around the winding frame 20 several times. Next, the interlayer insulating material 23 is disposed on the insulating layer 25 (may be omitted if the insulating layer 25 is made of the same material as the interlayer insulating material 23). Next, spacers 22 and 22a prepared in advance are arranged in other regions (located on both sides in the winding frame 20) so as to open a region for a wire winding space for the first layer in the winding frame 20. To do. As shown in FIG. 5, a spacer 22 having a minimum size (width) is provided on each side surface of the winding frame 20 so that the winding frame 20 and the superconducting wire 21 are not in direct contact with each layer. A spacer 22a having an arbitrarily adjusted size is disposed on the inner side surface of the other winding frame 20 so as to cover the other region while leaving a necessary winding width. The spacers 22 and 22a are made of, for example, a glass epoxy material. Next, the superconducting wire 21 is wound, and when the first layer is finished, the interlayer insulating material 23 is attached.

  Next, spacers 22 and 22a for the second layer (spacer 22a has a width one step smaller than that for the first layer) are arranged so that superconducting wire 21 is wider than the first layer. Wind around. Note that the winding width is not necessarily different depending on each layer, but it goes without saying that the same winding width may be obtained in a plurality of successive layers depending on the thickness of the wire and the dimension of the coil to be obtained. Yes. Thus, by changing the width of the spacer 22a arranged in each layer, the wire winding space can be adjusted, and the winding width (layer width) of the coil can be changed step by step. Note that fine adjustment of the winding width may be performed by adjusting the winding pitch. The third and subsequent layers are also wound in the same manner. When the winding is completed, the surface (upper part) of the superconducting coil 10a is pressed and fixed by the upper presser 24 that also serves as an insulating material.

At this time, for example, a thermosetting filler (adhesive) is sufficiently applied to the gaps between the superconducting wires 21, and after the coil is formed, the superconducting wires are cured by exposure to a high temperature in a drying furnace or the like. Group 21 is a rigid body having high rigidity.
In the case of forming a superconducting coil (for example, superconducting coil 11a) having a substantially saddle-shaped cross-sectional shape, first, as in the case of the above-described substantially fan shape, winding is performed by changing the width of the spacer 22a by each layer. Adjust the turning width (layer width), wind the winding so that the maximum winding width is achieved in the layer corresponding to the middle position of the winding height (dimension proportional to the number of layers), and go to the upper layer As the coil winding width becomes narrow, it can be manufactured by arranging a wide spacer stepwise and performing the winding work.

As described above, when the superconducting wire 21 is wound around the winding frame 20 to form the superconducting coil 10a, other regions are provided in the winding frame 20 so as to secure a wire winding space in an arbitrary region for each layer. If a coil manufacturing method in which the spacers 22 and 22a are arranged in the space and the superconducting wire 21 is wound in the space secured by the spacers 22 and 22a is applied, the coil cross section has no side at all, for example, a substantially circular cross section. Shaped coils can also be produced.
In addition, the cross-sectional shape of the winding frame 20 does not necessarily need to be a linear U-shape, and may have a curve. In that case, the cross-sectional shape of the spacers 22 and 22a to be used can be efficiently performed by processing the portion along the curve of the winding frame 20 into a shape reflecting the same curve.

  Previously, optimization was only performed for coils with a rectangular cross section from the beginning, or the optimal non-rectangular coil shape was approximately rectangularized for some reason, such as facilitating manufacturing. In addition, all the coils constituting the superconducting magnet device have been manufactured so that the cross section thereof has a rectangular shape. Therefore, although there is an ideal coil shape and coil arrangement with a smaller magnetomotive force or a small amount of required wire, it has not been adopted. However, in the present invention, the superconducting coil 10a and other coils are also wound and formed so as to reflect the optimized ideal shape so that the cross section thereof is a non-rectangular shape. An optimum superconducting coil can be realized, and an optimum superconducting magnet device for an MRI apparatus can be obtained.

  If these superconducting coils having a non-rectangular cross section are approximately rectangularized, the optimally calculated magnetic field uniformity and leakage magnetic field are deteriorated. In addition, when the coil is optimized from the beginning with a rectangular coil, a coil arrangement with a small magnetomotive force or a minimum amount of required wire cannot be obtained.

  As described above, the coil cross-sectional shape is described as being formed into a substantially rectangular shape or a substantially saddle shape that is a non-rectangular shape. However, only the necessary coil is required in addition to reflecting the shape in all the coils constituting the superconducting magnet device. Non-rectangular shapes can also be reflected. For example, regarding the superconducting coils whose cross-sectional shape is not rectangular or non-rectangular, there are some coils due to space problems and ease of manufacture. Can be formed to have a constant winding width and a constant winding height so that the cross section has a substantially rectangular shape.

Reference Example 2
In the reference example 1 described above, the open type superconducting magnet device has been described. Here, a superconducting magnet device called a solenoid type or a horizontal type will be described. FIG. 6 is a perspective view showing the outer shape of the solenoid-type superconducting magnet device. In the figure, an arrow 4b indicates that a cylindrical opening of a cylindrical vacuum shut-off container 5 (corresponding to a container) is examined during imaging. The direction in which a person is inserted is shown. FIG. 7 is a cross-sectional view of a solenoid type superconducting magnet device. A cryogenic vessel 6 is disposed in a substantially cylindrical vacuum breaker vessel 5, and an annular superconducting coil 51-1 is placed in the cryogenic vessel 6. 59 (corresponding to the coil group) are arranged and accommodated so as to be coaxial (along the Z axis). In this example, the superconducting coils 51 and 52 disposed at both ends of the cylinder (coaxially located at both ends of the coil group) are substantially fan-shaped in cross section, and are coaxially arranged in the coil group. The superconducting coils 53 to 59 arranged at positions other than both ends in FIG.

Also in this case, in the optimization of the coil shape, as the conditions of the magnetic field uniformity and the leakage magnetic field become stricter, in other words, the coil becomes R as much as possible as it tries to satisfy the necessary condition with as little magnetomotive force or necessary wire amount as possible. Direction (when the axis of the cylinder is the Z-axis, the R direction corresponds to the direction on the Z = 0 (plane) and away from the Z-axis). The maximum dimension of the coil in the Z-axis direction, that is, the portion of the superconducting coils 51 and 52 located at both ends of the coil group, located on the coil outer side and the opening end side, wants to go as far as possible.
Therefore, the optimized superconducting coil is formed such that its winding width decreases as the distance from the inner surface of the cylindrical opening of the vacuum heat insulating container 5 increases.

  As shown in the enlarged sectional view of the superconducting coil 52 in FIG. 8, among all the superconducting coils 51 to 59 (corresponding to the coil group) constituting the superconducting magnet device, they are coaxially positioned at both ends of the coil group. The superconducting coils 51 and 52 have the feature that the winding width decreases as they move away from the inner surface of the cylindrical opening as described above, and the winding height is at the opening end of the cylindrical opening. It is formed so as to increase as it approaches, and its cross-sectional shape is substantially a fan shape.

  Further, in the coil group, the superconducting coils 53 to 59 arranged at positions other than both ends on the same axis have the maximum winding height as shown in the enlarged sectional view of the superconducting coil 53 in FIG. This position corresponds to an intermediate position of the winding width on the side closest to the inner surface of the cylindrical opening of each coil, and the coil is formed so that the cross-sectional shape of the coil is substantially bowl-shaped.

  Next, FIG. 10 shows an enlarged cross-sectional view of a region B surrounding the superconducting coil 52 of FIG. 7, and the winding state will be described. As in Reference Example 1, a superconducting wire 21 is wound around a U-shaped winding frame 20 to form a coil. Here, the width of the spacer 22b arranged on one side of the winding frame 20 is a layer. Winding work so that the winding width of the superconducting wire 21 becomes smaller as the number of layers increases than the winding width of the first layer so that the winding width gradually increases as the number of layers increases. Finally, a superconducting coil 52 having a substantially fan-shaped cross section is obtained.

Further, in order to obtain superconducting coils 53 to 59 having a substantially bowl shape in cross section, the widths of the two spacers arranged on both sides in the winding frame 20 are made the same, and gradually as the number of layers increases. The spacer is adjusted so that the spacer width is increased, and the winding operation is performed so that the winding width of the superconducting wire 21 is reduced every time the number of layers is increased. Coils 53 to 59 are obtained.
Thus, by winding and forming so that the cross-sectional shape of the superconducting coils 51 to 59 constituting the superconducting magnet device is a non-rectangular shape such as an optimized substantially fan shape or substantially saddle shape, An optimum superconducting coil can be realized, and an optimum superconducting magnet device can be obtained.

Reference Example 3.
In the reference example 1 described above, the outer shape of the container (1a, 1b) for housing the superconducting coil of the open type electromagnet device is cylindrical, and the cross-sectional shape along the Z-axis is rectangular as shown in FIG. Although an example has been described, in this reference example 3, in order to make the opening end into which the subject is inserted into the open superconducting magnet device more open, the outer peripheral corner on the opposite surface side of the container is scraped off. An example of a tapered shape will be described.

FIG. 11 is a cross-sectional view of an open-type superconducting magnet device, in which the outer peripheral portions of the opposing surfaces of the upper and lower vacuum heat insulating containers 31a and 31b are respectively formed to be tapered (tapered portion). Is shown by reference numeral 30). Along with this, the superconducting coils 10c and 10d located on the outer peripheral portion of the opposing surface are wound so that the height increases as the distance from the opposing surfaces of the two containers increases along the shape of the tapered portion 30, and It is formed so that the winding width increases as it goes from the outer periphery of the container toward the axis (corresponding to the axis of the cylindrical container).
Needless to say, the shape of the cryogenic containers 32a and 32b also reflects the taper in accordance with the shape of the tapered portion 30 of the upper and lower vacuum heat insulating containers 31a and 31b.

FIG. 12 shows an enlarged cross-sectional view of the region C including the superconducting coil 10d in FIG. 11, and the state of the winding will be described. In this case, since the taper shape is reflected in the outer shape of the superconducting coils 10c and 10d, it is inappropriate to use a U-shaped winding frame with a cross-sectional shape of L as shown in FIG. A character-shaped reel 20a is used.
The winding work is performed as follows. First, the insulating layer 25 and, if necessary, the interlayer insulating material 23 are wound around the bottom surface of the winding frame 20a (the innermost peripheral surface of the winding frame 20a), and then the two spacers 22 and 22c are respectively disposed on both sides. To place. The spacer 22 is disposed along the inner surface of the winding frame 20a (inner surface extending in the height direction of the coil), and a space for winding the superconducting wire 21 of the first layer is provided from there, and the spacer 22c is disposed. . The spacer 22c arranged on the side not along the winding frame 20a has a curved surface reflecting the taper shape 30, and the surface is curved so as to follow the taper shape when the coil has been wound. It will be in the state processed into.

  Next, the superconducting wire 21 is wound between the two spacers 22 and 22c in the first layer, and similarly, the winding work is performed while gradually winding the second layer and the third layer to reduce the width. The coil surface is covered and fixed with an upper presser 24a that is curvedly processed so as to reflect the tapered shape. At this stage, the superconducting coil 10d is surrounded by the winding frame 20a and the upper presser 24a. The processing using the thermosetting adhesive filled in the coil is the same as in Reference Example 1 regardless of the shape of the winding frame 20a, and thus the description thereof is omitted.

In this way, the superconducting coil 10d having an outer shape reflecting the tapered shape is formed and disposed inside the low temperature container 32b located in the tapered portion 30 of the lower vacuum heat insulating container 31b, so that the magnetomotive force is minimized or the necessary wire amount is minimized. While satisfying the above conditions, the outer shape of the open superconducting magnet device can be made into a shape having a wide frontage and excellent openness. By obtaining an MRI apparatus equipped with a superconducting magnet device with excellent openness, the subject's discomfort and fear can be eased.
In addition, it cannot be overemphasized that it can be set as a more open structure compared with the case where it does not make a taper shape only by making one of the opposing surface side outer peripheral parts into a taper shape among two containers (31a, 31b.). Yes.

  Further, by forming the cross-sectional shape of the coil disposed in the tapered portion 30 of the container (31a, 31b.) Into a substantially fan shape instead of a rectangular shape, the magnetomotive force is markedly greater than when a rectangular coil is disposed. Coil can be realized with a small amount of wire or a small amount of required wire. Secondaryally, electromagnetic force applied to the coil, magnetic flux density in the coil can be reduced, simplification of the support structure, cost reduction, and low use of superconducting wire. Cost reduction can be realized.

Reference Example 4.
Next, a case where the cylindrical open portion opening end of the solenoid type superconducting magnet device is formed in a tapered shape will be described. FIG. 13 is a cross-sectional view of a solenoid type superconducting magnet device. The vacuum insulating container (corresponding to a container) 41 has an opening diameter of the cylindrical opening as it goes from the inside of the opening to the opening end at both ends thereof. The taper is formed so as to be large (tapered portion 40), and the superconducting coils 51a and 52a located at both ends thereof are formed in the cylindrical opening of the vacuum heat insulating container 41 so as to follow the shape of the tapered portion 40. It forms so that the winding width | variety becomes large as it distances from an inner surface, and the winding height becomes large as it goes to an opening part inner side from the extreme end part of the vacuum heat insulation container 41. As shown in FIG.

  Here, the superconducting coils 51a and 52a located at both ends of the cylindrical vacuum heat insulating container 41 are formed so that the cross section thereof is not a substantially rectangular shape but a substantially fan shape reflecting a tapered shape. FIG. 14 shows an enlarged cross-sectional view of a region D surrounding the superconducting coil 52a of FIG. In the open type superconducting magnet device of Reference Example 3, when forming the superconducting coil 10d reflecting the taper shape, it was shown that the cross section as shown in FIG. 12 uses the L-shaped winding frame 20b. In the superconducting coils 51a and 52a constituting the solenoid type superconducting magnet device, the winding frame 20b is formed in a rectangular shape whose cross-sectional shape has a curve reflecting the taper shape due to the taper surface and the winding direction. Use what was done. The reel 20b is formed of aluminum, stainless steel, or the like, and a portion having a curved cross-sectional shape is processed in advance so as to reflect the shape of the tapered portion 40 by press working, and is joined to a straight portion by welding. can get.

In the winding work, first, the insulating layer 25b is wound around the winding frame 20b (in some cases, it is wound around the entire inside of the curved portion of the winding frame 20b), and the interlayer insulating material 23 is further disposed as necessary. The superconducting wire 21 is sequentially wound on the first layer, the second layer, and the superconducting coil 52a having a substantially fan-shaped cross section. Also in this case, similarly to the reference example 3, the spacers 22 and 22d are arranged in each layer, and the width between the spacers 22 and 22d is adjusted to be the coil winding width (winding width). As the spacer 22d, a spacer whose surface is curved in advance so as to be along the inner surface of the winding frame 20b reflecting the shape of the tapered portion 40 is used.
Thus, by forming the superconducting coil 51a reflecting the tapered shape 40 and disposing the superconducting coil 51a inside the low temperature container 42 located in the tapered portion 40 of the vacuum heat insulating container 41, the same effect as in Reference Example 3 can be obtained. it can.

Embodiment 1 FIG.
Next, Embodiment 1 of the present invention will be described with reference to FIG.
In general, a superconducting coil has a higher risk of quenching (normal conduction transition) as the maximum magnetic flux density in the coil increases, so the maximum magnetic flux density in the coil should be designed to be as small as possible, or as high as possible. Use superconducting wire that can withstand the magnetic flux density. In other words, if there is no superconducting wire that can withstand the maximum magnetic flux density in the coil, it does not have a function as an MRI apparatus.
For example, NbTi (niobium titanium), which is relatively inexpensive as a superconducting wire, has a limit of about 6T (Tesla). When the magnetic flux density exceeds that, superconducting wire such as Nb3Sn (niobium 3 tin) must be used. I don't get it. However, Nb3Sn is now 3-5 times more expensive than NbTi and is not economical.

On the other hand, in addition to further increasing the magnetic field, the MRI apparatus is required to be further compact and improve the openness, and the maximum magnetic flux density in the coil is also increasing accordingly.
At this time, looking at the magnetic flux density distribution in each coil, there is a property that the magnetic flux density increases as it approaches the coil surface by the self-magnetic field, and as shown in a sectional view of FIG. In the case where the coil 70 is present, the magnetic flux density in the closest part of the two adjacent coils 70 tends to increase because the coils 70 influence each other. In the coil 70 having a substantially rectangular cross-sectional shape, the portion having a high magnetic flux density often corresponds to the corner portion 70a that is the closest portion.

  Since it is better to wind one coil with one (one type) of superconducting wire as much as possible, the superconducting wire to be used must be selected to withstand the value of the maximum magnetic flux density. However, the corner portion 70a which becomes the maximum magnetic flux density occupies only a part of the region in one coil, and the other regions have a lower magnetic flux density. Therefore, a superconducting wire that can withstand the maximum magnetic flux density is used. The use can be said to be over-performing for low flux density parts.

  Therefore, as shown in a cross-sectional view of the coil in FIG. 15 (b), a cross-sectional shape with a corner 70a (corresponding to a corner) dropped so as to cut the closest part of two adjacent coils 70. By adopting the non-rectangular coil 70b formed by winding, the area where the magnetic flux density generated in the corner portion 70a is large when the coil 70 having a substantially rectangular cross section is formed, is eliminated. The magnetic flux density in the coil can be made uniform at a lower value. Therefore, the performance of the superconducting wire to be used can be suppressed, and the coil can be manufactured at low cost.

  The coil 70b having a non-rectangular cross section as shown in FIG. 15B has the same procedure as that for forming a superconducting coil having a substantially fan-shaped cross section as shown in the above-described Reference Examples 1 to 4. Thus, it can be formed while adjusting its winding width and winding height.

  The effect is not only economically superior, but also increases the function of the margin produced by it (such as making the superconducting magnet device more compact and making the outer shape more open). Therefore, an economical and functional superconducting coil can be realized at the same time, and this superconducting coil can be used for a superconducting magnet device and other technologies.

It is sectional drawing which shows the open type superconducting magnet apparatus by the reference example 1 of this invention. It is a perspective view which shows the open type superconducting magnet apparatus by the reference example 1 of this invention. It is a cross-sectional enlarged view of a superconducting coil having a substantially fan-shaped cross section according to Reference Example 1 of the present invention. It is a cross-sectional shape enlarged view of the superconducting coil whose cross section is substantially bowl shape by the reference example 1 of this invention. It is sectional drawing which shows the mode of the coil | winding of the superconducting coil whose cross section is substantially fan shape by the reference example 1 of this invention. It is a perspective view which shows the solenoid type superconducting magnet apparatus by the reference example 2 of this invention. It is sectional drawing which shows the solenoid type superconducting magnet apparatus by the reference example 2 of this invention. It is a cross-sectional enlarged view of the superconducting coil whose cross section is substantially fan-shaped by Reference Example 2 of this invention.

It is a cross-sectional shape enlarged view of the superconducting coil whose cross section is substantially bowl shape by the reference example 2 of this invention. It is sectional drawing which shows the mode of the coil | winding of the superconducting coil whose cross section is substantially fan shape by the reference example 2 of this invention. It is sectional drawing which shows the open type superconducting magnet apparatus by the reference example 3 of this invention. It is sectional drawing which shows the mode of the coil | winding of the superconducting coil whose cross section is substantially fan shape by the reference example 3 of this invention. It is sectional drawing which shows the solenoid type superconducting magnet apparatus by the reference example 4 of this invention. It is sectional drawing which shows the mode of the coil | winding of the superconducting coil whose cross section is substantially fan shape by the reference example 4 of this invention. It is sectional drawing which shows the superconducting coil by Embodiment 1 of this invention.

Explanation of symbols

1a, 31a Upper vacuum insulation container 1b, 31b Lower vacuum insulation container 2a, 2b, 6, 32a, 32b, 42 Low temperature container 3 Communication pipe 4 Magnetic field uniform space 4a, 4b Arrow (subject insertion direction)
5, 41 Vacuum insulation container 10a, 10b, 10c, 10d, 11a, 11b, 12a, 12b, 13a, 13b, 51-59 Superconducting coil 20, 20a, 20b Reel 21 Superconducting wire 22, 22a, 22b, 22c, 22d Spacer 23 Interlayer insulating material 24, 24a, 24b Upper presser 25, 25b Insulating layer 30, 40 Tapered portion 70 Coil (section is substantially rectangular)
70a Corner portion 70b Coil (non-rectangular cross section).

Claims (2)

  Arranged and stored in the first and second containers opposed to each other with a predetermined space in between, the first and second containers are arranged coaxially, and a uniform magnetic field is applied between the first and second containers. The first and second coil groups are formed of a plurality of superconducting coils that are wound in an annular shape and are spaced apart from each other, and are arranged in the same container among the plurality of superconducting coils, The cross-sectional shape of the two adjacent superconducting coils is formed by winding so as to be a non-rectangular shape obtained by cutting away the corner portion that is the closest portion of the two superconducting coils from a substantially rectangular shape, Is a superconducting magnet device comprising a reel or a spacer.   A container provided with a cylindrical opening, and arranged and accommodated in the container so as to be coaxial, and generates a uniform magnetic field in the opening of the container. A coil group comprising superconducting coils is provided, and the cross-sectional shape of the two adjacent superconducting coils in the coil group is a non-rectangular shape obtained by cutting a corner portion that is the closest part of the two superconducting coils from a substantially rectangular shape. A superconducting magnet device, wherein the superconducting magnet device is formed so as to have a rectangular shape, and the corner portion is constituted by a winding frame or a spacer.

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