JP2590346Y2 - Permanent current switch - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a permanent current switch used for operating a superconducting magnet.

[0002]

2. Description of the Related Art To operate a superconducting magnet in a permanent current mode in which a constant magnetic field is maintained for a long time without requiring a current supply from an external power supply, a permanent current switch (hereinafter referred to as a PC) is used.
S) is used. This PCS1 is, for example, shown in FIG.
As shown in FIG. 1, a superconducting wire provided with an enamel coating layer on the outer periphery of a high-resistance matrix such as a Cu—Ni alloy is wound on a winding frame 2 made of FRP (fiber reinforced plastics). After winding the heater wire 4 composed of a wire or the like, a reinforcing outer cylinder 5 made of FRP is disposed outside the coil 3 to seal a necessary portion, and then the inside is impregnated with epoxy resin so that the coil 3 and the heater wire are impregnated. 4 is solidified integrally with the winding frame 2 and the outer cylinder 5, and the superconducting wire is non-inductively wound to prevent the generation of a magnetic field by itself when energized.

The PCS 1 is connected in parallel with a superconducting magnet, and is held in liquid helium together with the superconducting magnet. The PCS 1 having the above structure heats the heater wire 4 during the off operation of the on-off operation to bring the coil 3 into the normal conducting state. However, the heat generated at that time evaporates the liquid helium, so that the off operation is performed. It is desirable that the amount of heat released from the PCS sometimes be as small as possible. In the case of the PCS 1 shown in FIG. 2, since the FRP winding frame 2 and the outer cylinder 5 function as a heat insulating material, they contribute to reducing the amount of heat released during the off operation, but have a sufficient effect. can not, especially when the coil 3 is made of a superconducting wire of compound system such as Nb ₃ Sn, since the greater its release heat, has a disadvantage that it is quite sufficient.

[0004] On the other hand, even if the PCS 1 is sufficiently insulated, it takes time to stop the heating of the heater wire 4 and cool it down, so that the switching time from the off state to the on operation becomes longer. There is. In order to satisfy such conflicting demands, a cylindrical member is disposed outside the coil and is spaced apart from the coil, and one side of a cylindrical gap formed between the coil and the cylindrical member is released. A PCS having a structure in which the other side is closed and a plurality of through holes are provided in the closed portion is known (JP-A-63-81874).

[0005]

In the PCS having the above-mentioned structure, the helium gas is filled in the cylindrical void portion at the time of the off operation to serve as a heat insulating portion, while at the time of the on operation, liquid helium enters and acts as a cooling portion. By that, of
It has the advantage that the amount of evaporation of liquid helium during the f-operation can be reduced, and the switching from the off state to the on-operation can be performed in about the same time as in the past, but it is desired to further reduce the switching time. ing.

The present invention has been made in order to improve the above point, and has a sufficient heat insulating effect at the time of off operation of the PCS, shortens the switching time to the on operation, and reduces the cooling efficiency in the on state. It is an object of the present invention to provide a PCS having a structure with enhanced stability.

[0007]

In order to achieve the above object, the present invention provides a coil comprising a winding frame, a superconducting wire and a heater wire wound on the winding frame, and a coil formed outside the coil. A part or whole of the outer cylinder is made of a material with good thermal conductivity in a permanent current switch that has a placed outer cylinder and a coil that is impregnated with a curable resin and solidified integrally with the winding frame and the outer cylinder. A cylindrical member is disposed outside the coil and is spaced apart from the coil. One side of a cylindrical gap formed between the coil and the cylindrical member is opened, and the other side is closed. Are provided with a plurality of through holes.

As the superconducting wire in the present invention, a wire having a large resistance value of several ohms to several hundred ohms in a normal conducting state is advantageous, for example, Cu- (10 to 30) wt% Ni
Insulated conductors synthetic resin covering, such as formal resin on the outer periphery of the composite wire of the multi-core structure is employed with a high-resistance matrix arranged a large number of Nb-Ti alloy and Nb ₃ Sn filaments in the alloy.

On the other hand, a high resistance wire such as a constantan wire or a tungsten wire is used as the heater wire. Also,
The outer cylinder is formed of Cu or Al, or is formed of Cu or Al and FRP in a cylindrical shape, and is spaced apart outside the coil.

[0010]

With the above construction, in the permanent current switch of the present invention, a cylindrical gap is formed between the coil and the cylindrical member, and part or all of the outer cylinder is formed of a material having good heat conductivity. As a result, when the PCS is turned off, the cylindrical space is filled with helium gas due to the heat released from the coil and acts as a heat insulating portion. When the PCS is turned on, the liquid helium immediately enters the cylindrical space and heat of the outer tube is reduced. Since the coil is cooled through the material having good conductivity, the amount of evaporation of liquid helium at the time of the off operation is reduced, and the switching time from the off state to the on operation is shortened.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of a permanent current switch of the present invention. A PCS 10 forms a coil 12 by winding a superconducting wire on an FRP winding frame 11, and a heater wire made of a constantan wire or the like in the coil. After winding 13, an outer cylinder 14 is arranged outside the coil, and the inside is impregnated with epoxy resin and solidified integrally, and the superconducting wire is non-inductively wound to prevent the generation of a magnetic field by itself when energized. I have.

The outer cylinder 14 is formed of Cu. A cylindrical member 15 made of FRP is disposed outside the outer cylinder 14, and the inner diameter of the cylindrical member 15 is larger than the outer diameter of the outer cylinder 14. It is large, and a cylindrical gap 16 is formed between them.
One end side 16a of the cylindrical gap portion 16 is open,
The other end has an inner flange 15a.
a is fixed to the flange plate 11a of the winding frame 11 by a bolt 17. In the inner flange 15a, a plurality of through holes 16b communicating with the cylindrical gap 16 are provided on the same radius around the axis of the PCS 10.

In use, the PCS 10 is immersed in liquid helium so that its axis coincides with the vertical direction, and the open end 16a is positioned on the lower side. In this state, the cylindrical gap 16 functions as a heat insulating part when the PCS 10 is turned off (when the heater wire 13 is heated), and functions as a cooling part when it is turned on (when the heating of the heater wire 13 is stopped).

That is, the heater wire 13 is energized and the PCS 10
Is turned off, the liquid helium in the cylindrical gap portion 16 evaporates and is filled with helium gas.
f Maintained during operation. Since this gas has a lower thermal conductivity than liquid helium, the cylindrical void portion 16 functions as a heat insulating portion. On the other hand, when the energization of the heater wire 13 is stopped, the helium gas in the cylindrical gap 16 escapes upward from the through-hole 16b, and the inside of the cylindrical gap 16 is immediately filled with liquid helium, and By cooling the coil 12, it immediately returns to the on state.

[0015]

As described above, according to the permanent current switch of the present invention, the amount of evaporation of liquid helium at the time of the off operation can be reduced, and the switching time from the off state to the on operation can be shortened. Has the advantage that its structure is also simple.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a PCS according to the present invention.

FIG. 2 is a cross-sectional view of a conventional PCS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... PCS (Permanent current switch) 11 ... Winding frame 12 ... Coil 13 ... Heater wire 14 ... Outer cylinder 15 ... Cylindrical member 16 ... Cylindrical cavity part 16b ... Through-hole

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiichiro Maeda 2-1-1, Sakae Oda, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. Chome 1-1 Showa Electric Wire & Cable Co., Ltd. (56) References JP-A-63-239876 (JP, A) JP-A-63-81874 (JP, A) JP-A-61-289680 (JP, A) ( 58) Fields surveyed (Int.Cl. ⁶ , DB name) H01L 39/20 H01L 39/14-39/16

Claims (2)

(57) [Scope of request for utility model registration] 1. A coil comprising a coil, a superconducting wire and a heater wire wound on the coil, and an outer cylinder disposed outside the coil, wherein a curable resin is applied to the coil. In the permanent current switch which is impregnated and solidified integrally with the winding frame and the outer cylinder, a part or the whole of the outer cylinder is formed of a material having good heat conductivity, and the cylinder is spaced apart from the outside of the coil. A cylindrical member formed between the coil and the cylindrical member, one side of which is opened, and the other side is closed, and a plurality of through holes are provided in the closed portion. A permanent current switch. 2. The permanent current switch according to claim 1, wherein the superconducting wire comprises a compound superconducting wire.