JP6208077B2 - Superconducting electromagnet - Google Patents

Description

  The present invention relates to a superconducting electromagnet.

  Conventionally, as a technology in such a field, a superconducting electromagnet described in Patent Document 1 below is known. In this superconducting electromagnet, a coil is housed in a cryostat, and a bus bar for introducing a current into the coil is routed inside the cryostat.

JP 2001-110627 A

  When it is desired to reduce the size of the cryostat in this type of superconducting electromagnet, the bus bar structure described above is difficult to cope with the size reduction. That is, if the bus bar is shortened, the inflow of heat from the outside through the bus bar is increased, and the cooling efficiency is lowered. Further, when the coil is thermally contracted, it is difficult to sufficiently absorb the distortion due to the heat shrinkage with a short bus bar. In view of such a problem, an object of the present invention is to provide a superconducting electromagnet having a structure that facilitates miniaturization of a cryostat.

  The superconducting electromagnet of the present invention includes a coil, a cryostat that houses and cools the coil, and a power supply unit that has a conductive unit that sends current supplied from the outside of the cryostat to the coil and supplies power to the coil. The conductive portion includes a first portion located on the current path connecting from the outside to the coil and located in the cryostat and a second portion located closer to the coil than the first portion, and the first portion. A detour conductive that connects with a path longer than the linear distance to the second part and permits the relative displacement by elastic deformation when a relative displacement between the first part and the second part occurs. It has the part.

  In this superconducting electromagnet, the first part and the second part of the conductive part are connected by a path longer than the linear distance via the roundabout conductive part. Therefore, the whole conductive part can be reduced in size while ensuring a long heat transfer distance of heat entering from the outside through the conductive part. Further, since the relative displacement between the first part and the second part is allowed by the elastic deformation of the roundabout conductive portion, it is possible to cope with the thermal contraction of the coil.

  Specifically, the roundabout conductive portion reciprocates at a plurality of U-shaped bent portions when viewed from a direction orthogonal to the thickness direction and orthogonal to a straight line connecting the first portion and the second portion. It is good also as making the bent board shape to meander.

  The conductive part is located on the coil side of the bypass conductive part, cooled to be cooled by heat conduction from the cryostat's low heat source, and located on the coil side of the cooled part, and is located on the current path. When the relative displacement between the third part and the fourth part occurs in the direction of thermal contraction of the coil, the third part and the fourth part located on the coil side of the third part are connected by deformation. It is good also as having a flexible conductive part which permits relative displacement.

  According to this configuration, when the cooled part is cooled, the heat entering the coil side from the outside via the bypass conductive part can be removed by the cooled part, and the cooling efficiency can be further improved. . Further, since the relative displacement between the third part and the fourth part due to the thermal contraction of the coil is allowed by the deformation of the flexible conductive portion, it is possible to cope with the thermal contraction of the coil. Specifically, the low heat source may be a heat shield that surrounds the coil, and the portion to be cooled may be in contact with the heat shield via an electrical insulating material.

  According to the present invention, it is possible to provide a superconducting electromagnet having a structure that facilitates miniaturization of a cryostat.

It is a perspective view which shows the magnet apparatus which employ | adopted the superconducting electromagnet which concerns on embodiment of this invention. It is a perspective view which shows the cryostat of a superconducting electromagnet. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is a perspective view which shows the electric current introduction part of a superconducting electromagnet. It is sectional drawing which shows the electric current introduction part of a superconducting electromagnet.

  Hereinafter, an embodiment of a superconducting electromagnet according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In the following description, the terms “upper” and “lower” are used with reference to the attitude of the superconducting electromagnet 1 in the state shown in each figure. However, the posture of the superconducting electromagnet 1 is not limited to that shown in the figure, and may be changed as appropriate. FIG. 1 is a perspective view showing a magnet device 100 employing a superconducting electromagnet 1 according to this embodiment. FIG. 2 is a perspective view showing the cryostat 3 of the superconducting electromagnet 1. 3 is a cross-sectional view taken along the line III-III in FIG. FIG. 4 is a perspective view showing the coil 10 of the superconducting electromagnet 1 and its support structure, and shows a state where the vacuum vessel 3 a and the heat shield 13 are removed from the cryostat 3.

  As shown in FIGS. 1 to 4, the magnet device 100 is configured by arranging a pair of upper and lower superconducting electromagnets 1 so as to face each other and supporting the superconducting electromagnet 1 with a support base 101. The superconducting electromagnet 1 includes a cryostat 3 having a vacuum vessel 3 a that houses a coil 10 therein, and a yoke 4 provided outside the cryostat 3. The cryostat 3 of the upper superconducting electromagnet 1 and the cryostat 3 of the lower superconducting electromagnet 1 are opposed to each other while being reversed upside down, and are connected to each other via the support column 6 so as to be separated from each other. The magnet device 100 functions as a deflection magnet that switches the trajectory of the charged particle beam B passing between the pair of cryostats 3. For example, the magnet device 100 can switch the trajectory of the charged particle beam B emitted from the accelerator between the trajectory T1 and the trajectory T2. Examples of the accelerator that emits the charged particle beam B include a circular accelerator such as a ring cyclotron, an AVF cyclotron, a synchrotron, and a betatron, and a linear accelerator such as a linac.

  The superconducting electromagnet 1 has an annular shape around the vertical central axis A, generates a magnetic flux, a load support portion 7 that supports the load of the coil 10, a refrigerator 8 that cools the coil 10, and a current flowing through the coil 10. And an electric current introduction section 9 for introducing the electric current. The coil 10 has a coil body having a configuration in which a superconducting wire is wound, and a high-temperature superconducting wire may be used as the superconducting wire. For example, Bi2223, Bi2212, Y123, MgB2, an oxide superconductor, or the like may be used as the high-temperature superconducting wire. A low temperature superconducting wire may be used as the superconducting wire. In order to efficiently cool the coil 10 using such a superconducting wire to about 20K, the superconducting electromagnet 1 includes a heat shield 13 surrounding the coil 10 inside the vacuum vessel 3a of the cryostat 3. The heat shield 13 is in contact with the low-temperature head of the refrigerator (low heat source) 8, and the heat shield 13 is cooled to about 50K.

  Next, the current introduction unit (power supply unit) 9 will be described in more detail with reference to FIGS. 4 and 5. Here, as shown in FIGS. 4 and 5, an XYZ orthogonal coordinate system having the Z axis in the vertical direction may be set and used to explain the positional relationship of each part. The current introduction part 9 includes a container cylindrical part 3 b that forms part of the vacuum container 3 a and a shield cylindrical part 13 b that forms part of the heat shield 13. The container cylindrical portion 3 b is erected vertically on the upper surface side of the cryostat 3. On the upper surface of the container cylindrical portion 3b, two input terminals 31, 31 for introducing a current are provided so as to be exposed to the outside of the vacuum container 3a. For example, a thin-walled cylinder made of GFRP may be provided immediately inside the container cylindrical portion 3b in order to achieve electrical insulation. The shield cylindrical portion 13b is erected vertically on the upper surface side of the heat shield 13, and extends to a position in the middle of the container cylindrical portion 3b inside the container cylindrical portion 3b. An elongated opening 14 extending in the Y direction is formed on the upper surface of the shield cylindrical portion 13b. An ultra-cold-resistant insulating tape or the like may be applied to the inside of the shield cylindrical portion 13b in order to achieve electrical insulation.

  The current introduction unit 9 includes a pair of a positive electrode side conductive unit 20A and a negative electrode side conductive unit 20B for sending current supplied from the outside of the machine body to the coil 10. The positive electrode side conductive portion 20A and the negative electrode side conductive portion 20B are arranged adjacent to each other in the container cylindrical portion 3b, and are electrically insulated from each other by sandwiching an insulating member (not shown) therebetween. . As shown in the figure, the configuration of the positive electrode side conductive portion 20A and the negative electrode side conductive portion 20B is symmetrical with respect to the vertical plane. Therefore, the configuration of the positive electrode side conductive portion 20A will be described below. A description of the overlapping negative electrode side conductive portion 20B is omitted.

  The positive electrode side conductive portion 20A extends inside the container cylindrical portion 3b so as to connect between the input terminal 31 and the coil electrode 32 that is an inlet of current to the coil 10, and the shield cylindrical portion 13b in the middle thereof. Passes through the opening 14. The positive electrode side conductive portion 20 </ b> A is not in contact with the edge of the opening 14 by adjusting the dimension of the opening 14. The positive electrode side conductive portion 20 </ b> A is configured by a plurality of conductive members constituting a current path from the input terminal 31 to the coil electrode 32. The conductive members constituting the current path include a bus bar 21, a bent portion 22, an upper conductor block 23, a wire current lead 24, a lower conductor block 26, and a copper braided wire 27 that are sequentially connected from the input terminal 31 side. ing. These conductive members are made of copper, for example, and have high conductivity and high heat conductivity. However, as will be described later, the wire current lead 24 may be made of a superconductive material.

  The bus bar 21 has a bent and elongated plate shape, and the upper end of the bus bar 21 is connected to the input terminal 31. The lower end of the bus bar 21 is physically connected to the upper surface of the shield cylindrical portion 13b via an electrical insulating material 33 and an L-shaped copper bracket 34. If the connection part between the bus bar 21 and the input terminal 31 is the first part P1 on the current path and the connection part between the bus bar 21 and the shield cylindrical part 13b is the second part P2 on the current path, the bus bar 21 is There is a detour conductive portion 21a that connects the first part P1 and the second part P2 through a current path longer than the linear distance between the part P1 and the second part P2. Specifically, the roundabout conductive portion 21a has a plurality of U's as viewed from a direction orthogonal to the plate thickness direction and orthogonal to a straight line connecting the first site P1 and the second site P2 (viewed from the Y direction). It has a bent plate shape that winds so as to reciprocate left and right alternately at the letter-shaped bent portion.

  Due to the bent shape of the roundabout conductive portion 21a, the heat transfer distance of heat entering from outside the room temperature through the input terminal 31 and the bus bar 21 becomes long, and the heat intrusion from the input terminal 31 side can be suppressed. In addition, when the relative displacement between the first portion P1 and the second portion P2 occurs due to the bent shape, the bus bar 21 is elastically deformed to allow the relative displacement, and the positive electrode side conductive portion 20A The generated distortion is suppressed. Further, the above-described bent shape allows the bus bar 21 to be accommodated in a small vertical width, and such a bus bar 21 contributes to downsizing of the vertical dimension of the current introduction portion 9.

  As described above, at the second portion P2, the lower end of the bus bar 21 is connected to the upper surface of the shield cylindrical portion 13b via the electrical insulating material 33 and the bracket 34. As described above, since the heat shield 13 is cooled to about 50 K by the refrigerator (low heat source) 8, the shield cylindrical portion 13 b and the lower end (cooled portion) of the bus bar 21 are also heated by the heat conduction from the refrigerator 8. Cooled to the same temperature. On the other hand, electrical insulation between the bus bar 21 and the heat shield 13 is ensured by the interposition of the electrical insulating material 33. As the electrical insulating material 33, for example, a GFRP (glass fiber reinforced plastic) sheet or the like can be used. In the positive electrode side conductive part 20 </ b> A, the region from the first part P <b> 1 to the second part P <b> 2 that is the outer region of the heat shield 13 is a temperature from room temperature to about 50 K, and To the coil 10 has a temperature of about 50K to about 20K.

  The bent portion 22 extending further downward from the second portion P2 is bent in a U shape when viewed from the Y direction, and the lower end of the bent portion 22 is connected to the upper conductor block 23. The upper conductor block 23 and the lower conductor block 26 are connected by a vertical pillar 29 made of stainless steel. A wire rod current lead 24 extends in parallel with the vertical column 29, and the upper conductor block 23 and the lower conductor block 26 are electrically connected by the wire rod current lead 24. The wire current lead 24 has a plate shape with a thickness in the Y direction, and is made of, for example, a bismuth-based superconducting material. By adopting the superconductive material, heat generation due to energization is suppressed, and as a result, heat penetration from the outside through the positive electrode side conductive portion 20A and the negative electrode side conductive portion 20B is suppressed. Further, when the Lorentz force at the time of magnetic field generation is generated, and even when quenching due to thermal contraction of the coil 10 is generated, the current value is not reduced. Further, by adopting the plate-like wire current lead 24, energy saving, performance improvement, cost reduction, and shortening of the manufacturing period can be achieved.

  The lower conductor block (third portion) 26 and the coil electrode (fourth portion) 32 are physically connected by a flexible copper braided wire (flexible conductive portion) 27 to electrically It is connected. Therefore, even when a relative displacement in the thermal contraction direction of the coil 10 occurs between the lower conductor block 26 and the coil electrode 32 due to the thermal contraction of the coil 10, the relative displacement is allowed by the deformation of the copper braid 27. Moreover, the distortion which generate | occur | produces in 20 A of positive electrode side electroconductive parts is suppressed. The coil electrode 32 protrudes in the X direction from the outer surface of the main body of the coil 10 and is electrically connected to the superconducting wire of the coil 10.

  In the current introduction unit 9 as described above, an external power source is connected to the input terminals 31 and 31, whereby a current is supplied to the coil 10 through the positive electrode side conductive unit 20 </ b> A and the negative electrode side conductive unit 20 </ b> B. Is generated.

  Then, the effect by the superconducting electromagnet 1 demonstrated above is demonstrated.

  In the superconducting electromagnet 1, the first part P <b> 1 and the second part P <b> 2 are connected via the bus bar 21 through a path longer than the linear distance in the positive electrode side conductive part 20 </ b> A and the negative electrode side conductive part 20 </ b> B. Therefore, while ensuring a long heat transfer distance of heat entering from the outside (from the input terminal 31 side) via the positive electrode side conductive portion 20A and the negative electrode side conductive portion 20B, the vertical width of the bus bar 21 can be suppressed, The current introduction part 9 can be reduced in size. Further, even when a relative displacement between the first part P1 and the second part P2 occurs due to the thermal contraction of the coil 10, the relative displacement is allowed by the deformation of the bus bar 21, so that the thermal contraction of the coil 10 is performed. Can also respond. Therefore, according to the superconducting electromagnet 1, the current introduction portion 9 can be easily downsized (particularly, the size in the Z direction), and as a result, the cryostat 3 can be easily downsized.

  Further, the positive electrode side conductive portion 20A and the negative electrode side conductive portion 20B are connected to the shield cylindrical portion 13b and cooled in the second portion P2. With this configuration, the heat that enters the coil 10 from the outside via the bus bar 21 can be removed at the second portion P2, and the cooling efficiency can be further improved. On the other hand, electrical insulation between the bus bar 21 and the heat shield 13 is ensured by the interposition of the electrical insulating material 33.

  Further, by employing the copper braided wire 27 for the positive electrode side conductive portion 20A and the negative electrode side conductive portion 20B, the relative displacement between the lower conductor block 26 and the coil electrode 32 due to the thermal contraction of the coil 10 is reduced. 27, the distortion generated in the lower part of the positive electrode side conductive part 20A and the negative electrode side conductive part 20B can be reduced, and the thermal contraction of the coil 10 can be dealt with.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and may be modified without changing the gist described in each claim.

  DESCRIPTION OF SYMBOLS 1 ... Superconductive electromagnet, 3 ... Cryostat, 9 ... Current introduction part (power supply part), 10 ... Coil, 13 ... Heat shield, 20A ... Positive electrode side conductive part, 20B ... Negative electrode side conductive part, 21a ... Detour conductive part, 26 ... Lower conductor block (third part), 32 ... Coil electrode (fourth part), 33 ... Electrical insulating material, P1 ... First part, P2 ... Second part (cooled part).

Claims (3)

Coils,
A heat shield surrounding the coil;
A cryostat having a vacuum vessel for housing the coil and the heat shield and cooling the coil by a refrigerator ;
A power supply unit that has a conductive unit that sends current supplied from outside the vacuum vessel of the cryostat to the coil through the opening of the heat shield, and supplies power to the coil, and
The conductive part is
On the current path from the outside to the coil , a first part that is a connection part between the conductive part and the vacuum vessel, and a second part that is a connection part between the conductive part and the heat shield , When connecting with a path longer than the linear distance between the first part and the second part, and when relative displacement between the first part and the second part occurs, elastic deformation causes A roundabout conductive part allowing the relative displacement ;
A part to be cooled that is cooled by heat conduction from the refrigerator through the heat shield connected at the second part;
The coil is located closer to the coil than the part to be cooled, the third part on the current path is connected to the fourth part located closer to the coil than the third part, and the heat shrinkage of the coil A flexible conductive part that allows the relative displacement by deformation when a relative displacement of the third part and the fourth part occurs in a direction;
A superconducting electromagnet characterized by comprising: The roundabout conductive part is:
A bent plate shape that winds so as to reciprocate at a plurality of U-shaped bent portions when viewed from a direction orthogonal to the plate thickness direction and orthogonal to a straight line connecting the first portion and the second portion. The superconducting electromagnet according to claim 1.   The superconducting electromagnet according to claim 2, wherein the cooled portion is in contact with the heat shield via an electrical insulating material.

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