JPH0590917U - Permanent current switch - Google Patents

Abstract

(57) [Summary] [Purpose] To stabilize the training characteristics of the persistent current switch. [Structure] The permanent current switch 10 is a coil 12 in which a superconducting wire 12a having a rectangular cross section is wound around a winding frame 11 by non-induction.
And the rectangular heater wire 13 arranged in this coil
And the inside of the superconducting wire and the heater wire are impregnated with an epoxy resin and solidified, and an insulating layer and a fiber coating layer in which glass fibers are braided are provided on the outside of the superconducting wire and the heater wire. 931 Nb-in a Cu-Ni alloy matrix
Critical current value Ic = 1 in which Ti alloy filament is embedded
When a coil is formed using a superconducting wire of 200A (0.5T), 400A to 600A in the case of a circular cross section
(0.5T) Quench current value is improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to improvement of the structure of a persistent current switch used for operating a superconducting magnet.

[0002]

[Prior Art]

 A permanent current switch (hereinafter referred to as PCS) is used to operate a superconducting magnet in a permanent current mode in which a constant magnetic field is maintained for a long time without requiring current supply from an external power source. In this PCS 1, for example, as shown in FIG. 3, a large number of Nb-Ti alloy filaments are arranged in a high resistance matrix such as Cu-Ni alloy on a reel 2 made of FRP (fiber reinforced plastics). After winding a superconducting wire 3a having a multi-core structure and winding a heater wire 4 made of a constantan wire or the like into the coil 3, an FRP reinforcing outer cylinder 5 is arranged outside the coil 3 and an epoxy resin is provided inside. It has a structure in which the coil 3 and the heater wire 4 are solidified together with the winding frame 2 and the outer cylinder 5 by being impregnated with resin, and the superconducting wire is non-inductively wound to prevent generation of a magnetic field by itself when energized. There is.

The PCS 1 having the above structure is connected in parallel with the superconducting magnet, is held in liquid helium together with the superconducting magnet, and heats the heater wire 4 to operate from the on state to the off state.

[0004]

[Problems to be solved by the device]

 In the PCS1 with the above structure, the superconducting wire 3a is impregnated with epoxy resin and solidified integrally to stop the movement of the superconducting wire 3a. However, due to the movement of the superconducting wire during excitation, the criticality of the superconducting wire itself is caused. Quenching is often recognized at a current value significantly lower than the current value (Ic), for example, Ic / 3 or less.

That is, PCS1 is used by cooling it down to 4.2K, but when the epoxy resin cured at room temperature is cooled to an extremely low temperature, cracks are likely to occur in the epoxy resin, resulting in minute movement of the superconducting wire. Quenches due to, and cannot exhibit sufficient characteristics. In particular, since the superconducting wire uses a multifilamentary wire with a circular cross section, the space factor of the epoxy resin becomes large, and it is difficult to form a coil by perfect alignment winding, so cracks occur at the epoxy rich portion. There is a problem that the superconducting wire is easily moved.

In order to prevent the quenching of the PCS impregnated with the epoxy resin as described above, glass fibers are filled between the superconducting wires (Japanese Utility Model Laid-Open No. 63-89208), or between the superconducting wires and between the layers. A glass fiber sheet arranged (Japanese Utility Model Publication No. 2-56409) is known, but it is difficult to prevent minute movement of the superconducting wire even in these PCSs.

The present invention has been made to improve the above-mentioned points, and an object thereof is to provide a PCS having stable training characteristics by preventing a minute movement of a superconducting wire as much as possible to improve a quench current value. And

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention comprises a winding frame, a coil of superconducting wire wound around the winding frame inductively, and a heater wire arranged in the coil. A permanent current switch in which a winding frame, a coil, and a heater wire are integrally solidified by being impregnated with a curable resin, in which the cross section of the superconducting wire and the heater wire is rectangular, and a fiber coating layer is provided on the outside thereof. Is.

As the superconducting wire in the present invention, one having a large resistance value of several Ω to several hundred Ω in the normal conducting state is advantageous, and therefore, for example, a large number of Nb-Ti alloys are contained in a Cu-Ni alloy. A composite wire having a multi-core structure having a high-resistance matrix having a rectangular cross section in which Nb ₃ Sn filaments are arranged is used. On the other hand, as the heater wire, a wire having a rectangular cross-section made of high resistance wire such as constantan wire or tungsten wire is used.

The above superconducting wire and heater wire are preferably provided with an insulating layer made of a synthetic resin such as formal resin, ester imide resin, polyimide resin, polyester resin or the like on the outer periphery thereof, and a glass fiber or Kevlar fiber on the outside thereof. A fiber coating layer braiding (trade name of aromatic polyamide fiber manufactured by DuPont, USA) is sequentially provided. Alternatively, after the glass fiber or the like is wound around the outer periphery of the composite wire in a single or multiple layers, the glass wound layer may be impregnated with a synthetic resin such as formal resin.

In the former case, the surface of the fiber winding layer impregnated with the curable resin in the outer fiber coating layer and in the latter case with the synthetic resin is not smooth, that is, in the spiral direction of the surface. Since a large number of fine grooves are formed, the curable resin can be easily and sufficiently impregnated between the superconducting wire and the heater wire.

[0012]

[Action]

 With the above configuration, in the persistent current switch of the present invention, since the superconducting wire and the heater wire have a rectangular cross section, the fiber coating layer is aligned in the winding frame with a high tension without breaking the fiber coating layer as compared with a circular cross section. It can be wound, and since the epoxy-rich portion is not created by impregnating the curable resin in the fiber coating layer on the outside or between the wires on the outside, minute movements of the superconducting wire due to cracks can be prevented. It can be significantly reduced.

[0013]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of a persistent current switch of the present invention. A PCS 10 is a heater made up of a coil 12 in which a superconducting wire is wound on an FRP winding frame 11, and a constantan wire or the like arranged in this coil. The wire 13 and the outer cylinder 14 arranged outside the coil are provided, and the insides of the winding frame 11 and the outer cylinder 14 are impregnated with epoxy resin to be solidified integrally. It is non-inductively wound to prevent the generation of magnetic field.

As shown in FIG. 2A, the superconducting wire 12a is composed of a composite wire having a rectangular cross section in which a large number of Nb-Ti alloy filaments 12c are arranged in a Cu- (10-30) wt% Ni alloy matrix 12b. An insulating layer 15 of formal resin is provided on the outer periphery thereof, and a fiber coating layer 16 in which glass fibers are braided is further provided on the outer side thereof. On the other hand, in the heater wire 13, as shown in FIG. 2b, an insulating layer 15 and a fiber coating layer 16 in which glass fibers are braided are provided on the outer side of a rectangular wire made of a constantan wire 13a, like the superconducting wire. ing.

As a specific example, a copper ratio obtained by embedding 931 Nb—Ti alloy filaments in a Cu—Ni alloy matrix having a cut surface of 0.6 mm × 1.1 mm (corner angle 0.2 mmR). 1.1, the critical current value Ic = 1200A (0.5T) superconducting wire with the outer periphery of the formal resin insulating layer and the glass fiber braided fiber coating layer, using a wire rod, with a tension of 18kgf / mm ² . When the coil was formed, it could be stably used up to 600 A (0.5 T). On the other hand, a formal resin insulation layer and a fiber coating layer in which glass fiber is braided are provided on the outer periphery of a superconducting wire having a circular cross section with an outer diameter of φ0.9 mm, which has almost the same cross-sectional area and the same structure and characteristics. When a PCS was manufactured with a tension of 10 kgf / mm ² using the wire provided, the current value that could be stably used was 400 A (0.5 T).

[0016]

[Effect of the device]

 As described above, according to the persistent current switch of the present invention, since the superconducting wire and the heater wire have a rectangular cross section and have a fiber coating layer on the outer side, it is possible to perform the winding in an aligned manner and also to apply the coil with a high tension. In addition to the formation of the epoxies, the epoxide-rich portion is significantly reduced, so that the training characteristics are stable and the quench at the low current value can be prevented. You can

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing one embodiment of a superconducting wire (a) and a heater wire (b) used in the persistent current switch of the present invention.

FIG. 3 is a sectional view showing a conventional persistent current switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Permanent current switch 12 ... Coil 12a ... Superconducting wire 13 ... Heater wire 13a ... Constantan wire 15 ... Formal resin insulating layer 16 ... Fiber coating layer made of glass braid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi City Miyake, 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture, Showa Electric Wire & Cable Co., Ltd. 2-1-1 No. 1 Showa Cable Denki Co., Ltd. (72) Inventor Yuichiro Oda 2-1-1 1-1 Showa Densen Denki Co., Ltd. (72) Inventor Tomoyuki Kumano Kawasaki City, Kanagawa Prefecture 2-1-1 Oda Sakae, Kawasaki-ku Showa Electric Wire & Cable Co., Ltd. (72) Nobuo Aoki 2-1-1, Odae Sakae, Kawasaki-ku, Kawasaki, Kanagawa

Claims (3)

[Scope of utility model registration request] 1. A winding frame, a coil composed of a superconducting wire which is non-inductively wound on the winding frame, and a heater wire arranged in the coil, wherein a curable resin is impregnated in the winding frame. In the permanent current switch in which the winding frame, the coil, and the heater wire are integrally solidified, the superconducting wire and the heater wire have a rectangular cross section, and a fiber coating layer is provided on the outside thereof. Permanent current switch to. 2. The persistent current switch according to claim 1, wherein the superconducting wire and the heater wire have an insulating layer on their outer circumferences, and a fiber coating layer braided with glass fibers is provided on the outer side thereof. 3. The permanent current switch according to claim 1, wherein the fiber coating layer is a wound layer of glass fiber impregnated with a synthetic resin.