JPH0536524A - Superconducting high-precision magnetic field magnet reel - Google Patents

Abstract

PURPOSE:To provide a spool for a superconducting magnet and the magnet to be used in applications where a desired magnetic field distribution is to be correctly obtained. CONSTITUTION:After an insulator 2 is fixed to a metallic spool 1 which has been roughly worked, the insulator 2 is worked to obtain a coil groove 3 of a desired size. Thus a magnetic field distribution approximately as designed can be obtained even if the spool has been cooled for use, whereby correction of the magnetic field distribution is completed in a short time. In addition, since a rigid superconducting magnet can be obtained, quenching is not likely to occur and the spool can be used with a load factor increased, so that an amount of superconducting lines used can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to applications in which the magnetic field distribution generated by a superconducting magnet is desired to be accurately defined, such as superconducting NMR (nuclear magnetic resonance) apparatus for scientific and scientific instruments and medical superconducting MRI (nuclear magnetic resonance imaging). The present invention relates to a reel for a superconducting magnet used in devices and the like, and a superconducting magnet using the reel.

[0002]

2. Description of the Related Art For example, a superconducting magnet for generating a magnetic field of high homogeneity over a wide range, such as an MRI apparatus, often has a combination of a plurality of superconducting windings. The size and number of turns of each winding and the arrangement size of each winding are required to be extremely accurate, and the manufacturing dimensions of the winding frame must be taken into consideration in consideration of thermal expansion (thermal contraction) due to the temperature difference between the time of production and use. It has been decided.

On the other hand, a winding frame used for manufacturing a superconducting magnet is often made of metal from the viewpoint of mechanical strength. For this reason, an insulator is installed on the winding frame so as to electrically insulate the wound superconducting wire from the winding frame. There are many possible methods for achieving this electrical insulation.
For example, there are Japanese Utility Model Laid-Open No. 54-133780 and Japanese Patent Laid-Open No. 63-87710. In the former, a glass reel reinforced resin is wrapped around and attached to a metal reel to provide electrical insulation. In the latter case, a metal support frame is integrated with a metal and an insulator with a small difference in thermal expansion coefficient to form a reel, which prevents damage to the reel and prevents slippage between the superconducting winding and the reel. I'm out.

[0004]

The above-mentioned prior art does not give special consideration to the dimensional accuracy due to processing, and has a problem in applying it to a superconducting magnet for which the magnetic field distribution is desired to be accurately defined.

An object of the present invention is to solve this problem and to provide a winding frame for a superconducting magnet at low cost.

[0006]

In order to achieve the above object, the present invention fixes an insulator to a metal reel which has not been machined to a very high degree of precision with respect to the required dimensional precision, and the insulator is fixed. Was processed with high accuracy to obtain a winding frame with desired dimensional accuracy.

[0007]

[Operation] Stainless steel is often used as the metal of the bobbin used in the superconducting magnet, but this is a metal that is difficult to machine, and it takes a lot of time to process it to high-precision dimensions. Need. For this reason, the metal part is processed with rough accuracy, the insulator is fixed to the metal part, and then the insulator is processed with high accuracy, so that the winding frame used for the superconducting magnet for high-precision magnetic field generation can be easily performed. Can be obtained.

If a glass fiber reinforced epoxy resin is used as an insulator fixed to a metal, the coefficient of thermal expansion differs between the fiber direction and the direction perpendicular thereto, which may affect the dimensional accuracy. On the other hand, when an epoxy resin containing a filler is used as an insulator, the dimensional accuracy is improved because there is no anisotropy of the coefficient of thermal expansion. Furthermore, the coefficient of thermal expansion can be made closer to that of metal by selecting the type of filler, and the thermal conductivity can be increased.

[0009]

EXAMPLE An example of applying the present invention to a superconducting magnet of an MRI apparatus will be described below. This magnet is composed of six superconducting coils with an inner diameter of about 1 m. From the viewpoint of the homogeneity of the generated magnetic field, the dimensions such as the inner diameter, outer diameter and length of each coil, the number of turns and the arrangement dimension of each coil are It is required to be extremely accurate. The six coils are wound on one reel. FIG. 1 shows the processed state of the winding frame used for this magnet. (A) shows that a metal winding frame 1 made of stainless steel processed with rough accuracy is fixed with an insulator 2 of epoxy resin containing a filler. 2B shows a part of the cross section of the winding frame in the opened state, and FIG. 2B shows a part of the cross section of the winding groove 3 finished to a desired dimensional accuracy by machining the insulator 2 part. There is. Comparing the cost of the reel according to the present invention manufactured in this way with the cost when the glass epoxy resin plate is processed and fitted into the metal reel by the conventional manufacturing method, the cost according to the present invention is lower. . FIG. 2 shows a cross section of a part of the magnet completed by using the winding frame finished as shown in FIG. Superconducting wire 4 and winding groove 3 on the bobbin
However, it was wound while applying the same filler-containing epoxy resin as the insulator 2 used for the winding frame.
After winding the superconducting wire 4, a glass cloth 5 coated with the same epoxy resin was wound thereon to strengthen the insulation. And
Further, a stainless steel bind wire 6 was wound thereon as a reinforcement against electromagnetic force in the radial direction, and the same epoxy resin 7 was also applied and wound around this. afterwards,
The epoxy resin was heat-cured to complete an impregnated coil. As shown in FIG. 1B, since the metal reel 1 is roughly processed, the insulator 2 is more firmly fixed. When the completed superconducting magnet was stored in a cryostat and an excitation test was conducted, a rated current could be passed without quenching, and the distribution of the generated magnetic field was close to the design value, and the shimming work was completed in a short time.

Next, a second embodiment of the present invention is shown in FIG. This includes a main coil 8 and two correction coils 9a,
This is a magnet for NMR by combining a total of three superconducting coils 9b. Each coil is wound around another winding frame 10a to 10c, and is fixed at a predetermined position after completion. Similar to the first embodiment, the reels 10a to 10c of each coil have a predetermined dimensional accuracy obtained by fixing a filler-containing epoxy resin as an insulator to a metal reel and machining the insulator. It is finished. In the case of the present embodiment, the winding portion is not impregnated, but the binding made of stainless steel is hung.

[0011]

According to the present invention, since the magnetic field generated when the magnet is cooled for use is almost as designed, the time for shimming work for correcting the generated magnetic field can be greatly shortened. it can. Further, when impregnated, the winding portion is integrated with the winding frame to form an extremely strong superconducting coil, and quenching does not occur, so that the load factor can be increased and used. That is, it is possible to reduce the amount of the superconducting wire used to generate the same magnetic field strength, which improves the economical efficiency. Further, since the metal portion that is difficult to process can be rough-processed, the manufacturing cost of the entire reel can be reduced.

[Brief description of drawings]

FIG. 1 is a cross section of a reel according to an embodiment of the present invention.

FIG. 2 is a sectional view of a superconducting magnet embodying the present invention.

FIG. 3 is a sectional view of a superconducting magnet according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... Metal reel, 2 ... Insulator, 3 ... Winding groove.

Claims (7)

[Claims] 1. A reel for a superconducting magnet, characterized in that an insulator is fixed to a metal reel, and the insulator is processed to obtain a desired precision. 2. The bobbin for a superconducting magnet according to claim 1, wherein the insulator is an epoxy resin containing a filler. 3. A plurality of winding portions for a superconducting wire are provided.
Reel for superconducting magnet. 4. A superconducting magnet using the winding frame according to claim 1, 2, or 3. 5. A superconducting magnet in which a plurality of superconducting magnets using the winding frame according to claim 1, 2 or 3 are combined. 6. The superconducting magnet according to claim 4, which is impregnated with an impregnating agent. 7. A superconducting magnet, wherein the impregnating agent according to claim 6 is the insulator.