JPH03250705A - superconducting magnet - Google Patents

Abstract

PURPOSE:To prevent disturbance in the uniformity of a magnetic field without lowering the mechanical and thermal strengths of a bobbin by forming at least the bobbin of the coil, nearest to a magnetic field generating area, of a material composed mainly of titanium. CONSTITUTION:At least the bobbin 20 of the coil nearest to a magnetic field generating area is formed of a material composed mainly of titanium. As a result, it does not occur even in a strong magnetic field that the bobbin itself is magnetized and affects the state of the magnetic filed within the area of the magnetic field. Moreover, when a high-temperature process is performed by W&R method for producing a compound phase in a superconducting wire, it hardly occurs that bobbins 20-28 are annealed and deformed or deteriorated. Therefore, disturbance in the uniformity of the magnetic field can be prevented while the strength is maintained at a high level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a superconducting magnet, and particularly to a superconducting magnet used in a nuclear magnetic resonance apparatus (hereinafter abbreviated as rNMR).

[Conventional technology]

Superconducting magnets generate a strong magnetic field in the central bore of the coil by passing a current through a coil formed by winding superconducting wire around a winding frame, and they consume less power and are more compact than normal-conducting magnets. However, it has the advantage of producing a strong magnetic field. For this reason, it is now used in various fields such as NMR.

Conventionally, in such superconducting magnets, stainless steel has been mainly used as the winding frame.

By the way, in superconducting magnets for NMR, compound superconducting wires are often used as conducting wires, and in this case,
W&R (Wind & React) generates a compound phase such as Nb3Sn after winding a superconducting wire around a winding frame in advance to prevent deterioration in current carrying performance due to distortion during winding of the conductor.
law has been adopted.

[Problem to be solved by the invention] However, since the winding frame of conventional superconducting magnets is made of stainless steel, the winding frame itself becomes magnetized when used in a device that generates a high magnetic field such as an NMR magnet. , which was likely to cause disturbances in the magnetic field homogeneity within the bore. This situation is a fatal problem, especially in superconducting magnets for NMR, which require a high degree of magnetic field uniformity on the order of 10-97 cm.

In order to solve this problem, it may be possible to form the winding frame from non-magnetized copper, but in this case, the W
When using a compound superconducting wire produced by the &R method, there is a problem in terms of strength. In other words, under the W&R Act, 8
Since the treatment is carried out at a high temperature of about 0.000C for 100 to 200 hours, copper and the like are annealed by heat, resulting in deformation (2) and alteration, which may prevent the superconducting magnet from operating normally.

Therefore, an object of the present invention is to provide a superconducting magnet that can prevent disturbances in magnetic field uniformity without reducing the mechanical and thermal strength of the winding frame in order to always operate the magnet normally. .

[Means for Solving the Problems] The present invention provides at least the winding of the coil closest to the magnetic field ordering area in order to maintain the mechanical and thermal strength of the winding frame at a high value and to prevent disturbance of the magnetic field uniformity. The frame is made of a material whose main component is titanium.

[Effect]

In the superconducting magnet according to the present invention, at least the winding frame of the coil closest to the magnetic field generation region is molded from a material mainly composed of titanium, so even in a strong magnetic field, the winding frame is magnetized and the magnetic field is There are no obstacles that would affect the state of the magnetic field within the region.

Also, when high-temperature treatment is performed to generate a compound phase in superconducting wire using the W&R method, the winding frame becomes dull and deformed.
There is little chance of deterioration.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The figure shows the internal structure of a superconducting magnet according to an example. This superconducting magnet is capable of high-resolution NMR
It is for analysis, and superconducting main body coils 10, 12, 1
4, 16.18, a winding frame 2022.24, 26.28 around which these coils IO to 18 are wound, respectively, a shim coil frame 30 around which a superconducting shim coil (not shown) is wound, and a shim coil frame 30 that supports the entire magnet. It is composed of support legs 32.

Among superconducting coils 10 to 18, coil]012 is Nb
The coil 14 is formed by a 3Sn compound superconducting wire.
, 16 and 18 are formed of NbTi wire, and these coils 10 to 18 enter the outer periphery of the main body coil winding frame 20 to 28 from one side of the bore 34 perpendicularly to the plane of the paper, and are symmetrically connected to the opposite side of the bore 34. It is wound so that it comes out perpendicular to the paper from its position.

Note that the compound phase of the coils 10 and 12 is generated by the W&R method described above. That is, the coils 10 and 12 wound around the body coil winding frames 20 and 22 are transferred to the winding frame 2.
100 to 200 at approximately 800°C while wound to 0.22
After heat treatment for a period of time, N
b: Generate +Sn. At this time, since the winding frame 2022 made of titanium has high mechanical strength, it is less likely to be deformed or deteriorated.

The main body coil winding frames 20 to 28 are formed into thin-walled cylindrical shapes having flanges on the top and bottom, and are sequentially fitted so that the inner surface of the outer winding frame is in contact with the outer periphery of the flange of the inner winding frame. There is. Note that the winding frame 2628 is also the inner winding frame 20, 22 of the main body coil winding frames 20 to 28.
．． 24 is made of titanium, and the outermost winding frame 26.
28 is molded from stainless steel. This is done in consideration of ensuring magnetic field uniformity in the bore 34 and mechanical strength. That is, the closer the magnet is to the bore 34, the greater the influence it has on the magnetic field in the bore 34;
Because the coils 10 and 12 become high temperature during compound phase formation,
The inner winding frames 20 to 24 are made of titanium, which does not become magnetized even in a strong magnetic field and has strong heat resistance, while the outer winding frames 26 and 28, which are less affected by the magnetic field in the bore 34, are made of stainless steel as before. be.

The shim coil winding frame 30 is for winding a shim coil for adjusting the outer diameter of the coil, and is made of stainless steel like the main body coil winding frames 26 and 28.

When using the superconducting magnet configured as described above, current is passed through the superconducting coils IO to 18 while cooling the magnet in liquid helium. Then, the magnet 7 is excited and a strong magnetic field is generated within the bore 34. At this time, in this embodiment, the winding frames 20, 22 .
Since titanium is used for the winding frame 24, the winding frame itself is not magnetized, and the uniformity of the magnetic field in the bore 34 is not disturbed. Furthermore, even if several tons of pressure is applied to the magnet due to excitation, it will not be deformed or altered in quality. In the above embodiment, pure titanium is used for the winding frames 20, 22 and 24, but substantially the same effect can be obtained by using a titanium alloy.

Also, titanium and titanium alloys do not necessarily have a winding frame of 20°22.
Although it does not have to be applied to all 24,
It is necessary to apply this to at least the innermost winding frame 20.

〔Effect of the invention〕

As explained above, since the superconducting magnet according to the present invention has a winding frame mainly composed of titanium, it is possible to maintain high strength and prevent disturbance of magnetic field uniformity.

Further, as a derivative effect, corrosion resistance and light weight can be achieved.

[Brief explanation of drawings]

The figure is a sectional view of a superconducting magnet according to an embodiment of the present invention. 10.12, 14, 16.18 22゜26゜8 Superconducting coil winding frame

Claims (1)

[Scope of Claims] A superconducting magnet comprising at least one coil unit in which a coil made of superconducting wire is wound around a winding frame around a magnetic field generation region, wherein the winding frame of at least the innermost layer of the coil units is made of titanium. A superconducting magnet characterized by being molded from a material whose main component is