JPH01278003A - Method of preventing breakdown of superconducting magnet - Google Patents

Abstract

PURPOSE:To obviate the need of providing a protection resistance and to realize a small-sized magnet by utilizing a voltage generated across a quenched coil for heating the other coil, and quenching this coil for preventing breakdown of the magnet. CONSTITUTION:A circuit of a superconducing magnet 7 consists of superconducting coils 8, 9 arranged on the inside and outside, heater lines 10, 11 connected between the terminals of the coils 8, 9 respectively and a power supply 12. The coils 8, 9 are arranged within a cryostat L and the heater lines 10 and 11 are wound between the superconducting lines of the coils 9 and 8, respectively. In a magnet 7 thus constructed, if the inside coil 8 is quenched, a voltage is generated across the coil 8 to heat the heater lines 10 and the coil 9 is also quenched thereby. Thus, the magnet can be prevented from breaking down. In this manner, the need of providing a protection resistance can be obviated and the size of the magnet can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing destruction of a superconducting magnet, and particularly relates to an improvement in a method for preventing destruction of a superconducting magnet constituted by a plurality of superconducting coils due to quenching.

[Prior art] In a superconducting magnet composed of multiple superconducting coils, when one coil quenches, that is, when the coil in the superconducting state suddenly returns to the normal conducting state, the energy of the other coils is released. Burnout may occur concentrated in the quenched coil.

Conventionally, as a method to prevent small magnets from being destroyed by wenching as described above, a protective resistor is connected in parallel to each coil, so that when one coil quenches, the energy of other coils that are not quenched is absorbed. A protective resistor is used to prevent the quenched coil from burning out.

FIG. 3 shows an example of such a circuit, in which a protective resistor 4.5 is connected between each terminal of two superconducting coils 2 and 3 arranged in the cryostat 1, and this is connected to the coil 2.3.
These are placed on the outside of each. In addition, coil 2.
3 is excited by a single power supply 6.

[Problems to be Solved by the Invention] However, in the case of protecting the coil as described above, since the energy of the coil that is not quenched is consumed by the protective resistor, the space occupied by the protective resistor increases, and the entire magnet has to be made smaller. There were some drawbacks that made it difficult to adapt.

The present invention has been made to solve the above-mentioned difficulties.
The purpose is to provide a method for preventing destruction of small magnets by quenching.

[Means for Solving Eight Problems] In order to achieve the above object, the present invention provides a method for preventing destruction of a superconducting magnet composed of a plurality of superconducting coils excited by a single power source. The feature is that the voltage generated between the terminals of the quenched coil is used to heat the other coils to quench them, thereby preventing the magnet from being destroyed.

As an example of a configuration for carrying out the present invention, heater wires are connected between the terminals of each coil, and these heater wires are brought into contact with superconducting wires forming other coils, or windings are made between the superconducting wires. It is possible that the On the other hand, when a single heater wire is provided, it is connected between the innermost coils, and this heater wire is brought into contact with the superconducting wire forming the coil with the maximum stored energy, or it is wound between the superconducting wires. It is preferable to take The reason for this is that the innermost coil is placed in the maximum magnetic field and is therefore the easiest to quench, and furthermore, it is often possible to prevent the magnet from being destroyed by quenching the coil with the maximum stored energy.

The above heater wire may be brought into contact with the superconducting wire forming the coil, or may be wound between the superconducting wires, but in these cases, it may be placed through another layer; It is only necessary that the heat of the heater wire heated by the voltage generated across the quenched coil is sufficiently transferred to quench the other coils.

[Function] In the method for preventing destruction of a superconducting magnet configured as described above, when one coil quenches, the voltage generated between the terminals of this coil heats, for example, a heater wire, and this heat causes other By quenching the coils in a chain, energy is prevented from concentrating on the coil that was quenched first, and the magnet can be protected.

[Example] Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1(a) shows an example of the circuit configuration of a superconducting magnet 7 for carrying out the method of the present invention, in which 8.9 are superconducting coils arranged on the inside and outside, respectively, 10.
11 is a heater wire connected between both terminals of the coils 8 and 9, and 12 is a power source. The above coils 8.9 are arranged in the cryostat L, and the heater wires 10. and 11 are wound between the superconducting wires of coils 9 and 8, respectively.

In such a magnet 7, when the inner coil 8 is quenched, a voltage is generated at both ends of the coil 8 and the heater 10 is generated.
heat up. As a result, the coil 9 is also quenched, thereby preventing the magnet from being destroyed.

FIG. 1(b) shows an example of another circuit configuration, in which coils 13, 14, .
15 are arranged in order, and the outermost coil 15 having the maximum stored energy is heated by the heater wire 16 connected to both ends of the innermost coil 13 which is most easily quenched.

Note that the same parts as in FIG. 1(a) are indicated by the same reference numerals in FIG. 1(b).

FIG. 2 shows a schematic diagram of a superconducting magnet 17 for carrying out the method of the invention, in which case the magnet consists of two coils 18, 19 connected to both ends of the inner coil 18. The heater wire 20 is wound inside the outer coil 19.

[Effects of the Invention] As described above, according to the present invention, the voltage generated between the quenched coils can heat another coil, thereby quenching this coil.
It becomes unnecessary to provide a protective resistor that requires a large space, and the magnet can be made smaller. In addition, the destruction of the magnet is completely prevented, and its configuration is simple.

[Brief explanation of the drawing]

FIG. 1(,) is a diagram showing the circuit configuration of one embodiment of a superconducting magnet for carrying out the method of the present invention, FIG. 1(b) is a circuit diagram of another embodiment, and FIG. A schematic diagram showing an example of a superconducting magnet for carrying out the method of
FIG. 3 is a circuit diagram of a conventional small superconducting magnet. 4.5・・・・・・・・・・・・Protective resistance 6.1
2・・・・・・・・・・・・・Power supply 7.7', 17
・・・・・・・・・Superconducting magnet 10.11.1
6.20... Heater wire Figure 1. Figure 2 1f Figure 3 L-J

Claims (2)

[Claims] 1. A method for preventing destruction of a superconducting magnet composed of a plurality of superconducting coils excited by a single power source, in which the voltage generated between the terminals of the quenched coil in the coil is used to heat the other coils. , a method for preventing destruction of a superconducting magnet, characterized in that destruction of the magnet is prevented by quenching this. 2. 2. The method for preventing destruction of a superconducting magnet according to claim 1, wherein the other coil is a coil having at least the maximum stored energy among the coils constituting the superconducting magnet.