JP2001110627A - Refrigerator cooled superconducting magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a refrigeration cooled superconducting magnet using a Helmholtz-type coil, for uniformly cooling the coil in upper and lower stages, and to provide a uniform and stable magnetic field space. SOLUTION: The upper and lower coils of a superconducting magnet are interlocked to the upper and lower coil-cooling flanges, respectively, the cooling stages of a refrigerator are interlocked to a heat transfer bussbar for interlocking both the cooling flanges, and the low-temperature side electrode part of an oxide superconducting current lead for energizing the upper and lower coils is provided at the outer-side part of the gap of the upper and lower coils.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator-cooled superconducting magnet, and more particularly to a refrigerator-cooled superconducting magnet using Helmholtz type coils.

[0002]

2. Description of the Related Art A superconducting magnet using a Helmholtz type coil has a high spatial accuracy of a magnetic field, and is often used when a magnetic field having a uniform magnetic field space is required. FIG. 3 is an explanatory view of a conventionally known refrigerator-cooled superconducting magnet of a type in which a Helmholtz-type superconducting coil 2 is cooled only in a vacuum vessel 1 by solid-state heat conduction from a two-stage GM refrigerator 3.

A Helmholtz-type superconducting coil 2 installed in a vacuum vessel 1 has an upper coil winding 41, an upper coil 21 and a lower coil winding 4 integrally formed with a two-step upper and lower spacing. A lower coil 22 is wound around a coil winding frame 42, and the upper coil 21 and the lower coil 22 are connected in series as described below. That is, 51 is the lower coil 22
The winding start electrode 52, the winding end electrode of the lower coil 22; the winding start electrode 61 of the upper coil 21; the winding end electrode 62 of the upper coil 21; the winding end electrode 52 of the lower coil 22 and the winding end of the upper coil 21; The first electrode 61 is connected to a bus bar (upper and lower connection leads) 7.

In the above-described superconducting coil 2, a lower coil bobbin 42 is mounted and fixed on a second heat load flange 8 connected to a support (not shown). The GM refrigerator 3 is connected to a second cooling stage 32 of the GM refrigerator 3 by a heat transfer body 9. Therefore, the lower coil 22 is mounted on the lower coil form 4 placed on the second heat load flange 8.
The upper coil 21 is cooled by the heat transfer from
The cooling is performed by the heat transfer from the upper coil winding 41 that is integrally connected to the lower coil winding 42 via the second coil winding 42. The end-of-winding electrode 62 of the upper coil 21 and the start-of-winding electrode 51 of the lower coil 22 are connected to a power source via an oxide superconducting current lead 10, respectively.

[0005] Reference numeral 101 denotes a low-temperature side electrode of an oxide superconducting current lead, which is electrically insulated from the second heat load flange 8 but is connected so as to be able to conduct heat. 21 is connected to the end-of-winding electrode 62.
Reference numeral 102 denotes a high-temperature-side electrode, which is electrically insulated but electrically connected to the first heat load flange 11 via a copper mesh wire 12, a copper current lead 13, and an insulating plate 14. T
Is a heat transfer body between the first cooling stage 31 of the refrigerator 3 and the first heat load negative flange 11. Reference numeral 16 denotes a vacuum sealing current introduction terminal.

Although not shown, the winding start electrode 51 of the lower coil 22 is also connected to a power source via the oxide superconducting current lead 10 by means similar to the connection means. In the figure, 17 is a heat shield plate, 18 is a main flange of a vacuum vessel, 19 is a gantry, and 20 is a magnetic field space.

In the above-mentioned conventional Helmholtz type superconducting magnet, the lower coil 22 of the upper and lower two-stage coils is mounted on the second heat load flange 8, so that the height of the device is increased and the upper and lower coils are connected. There was a problem that cooling was not uniform.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, can reduce the size of the apparatus, and uniformly cools the upper and lower two-stage coils to form a uniform and stable magnetic field space. It is an object of the present invention to provide a refrigerator-cooled superconducting magnet using a Helmholtz type coil that can be formed.

[0009]

SUMMARY OF THE INVENTION In a refrigerator cooled superconducting magnet using a Helmholtz type coil,
An upper coil and a lower coil of the superconducting magnet are connected to an upper coil cooling flange and a lower coil cooling flange, respectively, and a cooling stage of a refrigerator is connected to a heat transfer busbar connecting the two cooling flanges.

The low-temperature side electrode portion of the oxide superconducting current lead for energizing the upper coil and the lower coil is arranged outside the gap between the upper coil and the lower coil.

[0011]

Embodiments of the present invention will be described below with reference to FIG. FIG. 1 is an explanatory view of a refrigerator-cooled superconducting magnet using a Helmholtz type coil according to the present invention. The same parts as those of the conventional device shown in FIG. 3 are denoted by the same reference numerals.

The present invention focuses on the fact that the side of the gap between the upper coil and the lower coil of the Helmholtz type superconducting coil has a lower leakage magnetic field from the superconducting coil than the outer end surfaces of the upper and lower coils. For example, when a magnetic field of 20,000 gauss is generated at the center of the magnet, 10,000 is generated just above the upper coil and 10,000 directly below the lower coil.
Although a magnetic field of more than Gauss is generated, there is a portion on the side of the gap between the upper and lower coils at about 5,000 Gauss. )

The upper coil cooling flange 81 is brought into close contact with the upper end surface (lower end surface) of the upper coil 21 via the upper coil former 41, and the lower coil former 42 is attached to the lower end surface (upper end surface) of the lower coil 22.
The lower coil cooling flange 82 is brought into close contact with the
These cooling flanges 81 and 82 are connected by a heat transfer bus bar 83, and the heat transfer bus bar 83 is connected to a second cooling stage 32 of the refrigerator 3 by bolts or the like.
It is connected to. Therefore, the upper coil 21 is cooled by the cooling flange 81 via the upper coil winding frame 41, and the lower coil 22 is cooled by the lower coil cooling flange 82 via the lower coil winding frame 42, respectively.

Numeral 51 is a winding start electrode of the lower coil 22 and 52 is a winding end electrode of the lower coil 22. These electrodes protrude from the gap side with the upper coil 21. These electrodes are naturally electrically insulated from the lower coil frame 42. 61 is a winding start electrode of the upper coil 21 and 62 is a winding end electrode of the upper coil 21. These electrodes protrude from the gap side with the lower coil 22. These electrodes are naturally electrically insulated from the upper coil frame 41.

The low-temperature side electrode 101 of the oxide superconducting current lead 10 is disposed on the side of the gap between the upper coil 21 and the lower coil 22 and is connected to the winding end electrode 62 of the upper coil 21. The high-temperature side electrode 102 of the oxide superconducting current lead 10 is connected to a power supply via a copper wire 12 and a copper current lead 13. Reference numeral 15 denotes a current lead thermal anchor, one end of which is fixed to the first stage cooling flange 11 via an electrical insulating plate 14, and the other end of which fixes the copper mesh wire 12. Although not shown, the winding start electrode 51 of the lower coil 22 is also connected to a power source via the oxide superconducting current lead 10 by means similar to the above-mentioned connecting means.

The low-temperature side electrode 101 of the oxide superconducting current lead is wound around a coil winding frame with an insulator such as a glass fiber reinforced resin sheet or aluminum nitride in order to cool it to the same temperature level as the oxide superconducting coil. Is connected to a copper busbar 101 'attached to the busbar. Reference numeral 21 denotes a spacer made of a nonmagnetic rigid material such as stainless steel.
Upper and lower coils 2 installed between upper and lower coils 21 and 22
Holds 1, 22.

The upper and lower superconducting coils of the embodiment shown in FIG. 1 are examples using ordinary coils of NbTi alone, but the embodiment shown in FIG.
The hybrid superconducting coils 21a, 21b, 22a, 22b of Nb3Sn and NbTi are used for 1, 22 respectively.
Other configurations are the same as those of the embodiment of FIG.

[0018]

According to the present invention, the upper and lower two-stage Helmholtz type coils are connected to the upper coil cooling flange and the lower coil cooling flange, respectively. Since the apparatus is connected to the cooling stage of the machine, it is possible to reduce the size of the apparatus, and to uniformly cool the upper and lower two-stage coils to provide a uniform and stable magnetic field space. Furthermore, the low-temperature side electrode part of the oxide superconducting current lead is installed at a place where the leakage magnetic field is low outside the gap between the upper and lower two-stage coils, so that the oxide superconducting current lead is prevented from a strong leakage magnetic field from the superconducting coil. It also has the effect of being able to do it.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a refrigerator-cooled superconducting magnet according to the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of a refrigerator cooled superconducting magnet according to the present invention.

FIG. 3 is a longitudinal sectional view of a conventionally known refrigerator cooled superconducting magnet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Superconducting coil 21 Upper coil 22 Lower coil 21a, 21b Hybrid upper coil 22a, 22b Hybrid lower coil 3 GM refrigerator 31 First cooling stage 32 Second cooling stage 4 Coil frame 41 Upper coil winding Frame 42 Lower coil winding frame 51 Lower coil winding start electrode 52 Lower coil end winding electrode 61 Upper coil winding start electrode 62 Upper coil end winding electrode 7 Busbar 8 Second heat load flange 81 Upper coil cooling flange 82 Lower coil Cooling flange 83 Heat transfer bus bar 9 Heat conductor 10 Oxide superconducting current lead 101 Low temperature electrode of oxide superconducting current lead 10 'Copper bus bar 102 High temperature electrode of oxide superconducting current lead 11 First heat load flange 12 Copper mesh wire 13 Current Lead Made of Copper 14 Insulating Plate 15 Heat Anchor for Current Lead 16 Vacuum Seal Current Introduction Terminal 17 Heat shield plate 18 Main flange of vacuum vessel 19 Mount 20 Magnetic field space T Heat transfer body

Claims (2)

[Claims] 1. A refrigerator-cooled superconducting magnet using a Helmholtz type coil, wherein an upper coil and a lower coil of the superconducting magnet are connected to an upper coil cooling flange and a lower coil cooling flange, respectively, and these two cooling flanges are connected. A refrigerator-cooled superconducting magnet characterized in that a cooling stage of a refrigerator is connected to a heat transfer busbar. 2. The refrigerator cooling device according to claim 1, wherein the low-temperature side electrode portion of the oxide superconducting current lead for energizing the upper coil and the lower coil is disposed outside the gap between the upper coil and the lower coil. Type superconducting magnet.