JPS60147656A - Superconductor capable of detecting superconduction breakdown - Google Patents

Abstract

PURPOSE:To detect surely superconduction breakdown even in case of a large- sized superconductive coil by inserting one superconduction breakdown detecting superconductive stand, which is not subjected to stabilizing treatment, at least to one primary stranded wire. CONSTITUTION:A superconduction breakdown detecting superconductive strand 9 which is not subjected to stabilizing treatment is inserted into the stranded wire where 3 superconductive strands 8 subjected to stabilizing treatment with a metal such as copper or the like are stranded, and this stranded wire is convered together with bundled conductors 11, where primary stranded wires 10 are stranded, with a casing 12 for airtightness or reinforcing, and a very low- temperature cooling medium for cooling is filled up in gaps of bundled conductors 11, thus constituting a superconductor 2. A current approximating the transition current value is flowed to the superconductive strand 9. If superconduction breakdown is caused in a part of the primary stranded wires 10, the cooling medium around the superconductive strand 9 is gasified, and the superconductive strand 9 causes superconduction breakdown to generate a large voltage, and it is detected by a superconduction breakdown detector 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to four novel superconductors that can detect superconductor breakdown with high sensitivity.

[Prior art]

Conventionally, there has been a device shown in FIG. 1 as a device for detecting superconducting breakdown in superconducting coils. In the figure, l is a superconducting coil, which is made by winding a superconducting conductor into a coil shape. 3 is a superconducting breakdown detector, and its terminals 3a and 3
b is a circuit breaker attached to the current input/output part of the superconducting coil l, and g is a circuit breaker operated by the superconducting breakdown detector 3;
S is a protective resistor connected between both ends of the superconducting coil l, and B is a power source.

Next, the operation will be explained. As long as the superconducting conductor maintains its superconducting state, there is a voltage between the terminals 3a and 3b attached to the current input/output part of the superconducting coil in a steady state! Not detected. However, when a part of the superconducting conductor undergoes superconductivity breakdown and transitions to a normal conducting state, resistance is generated in the normal conducting part, so that a voltage is generated between the terminals 3a and Jb. This voltage is detected by the superconducting breakdown detector 3, and the circuit breaker is opened to interrupt the circuit between the power source 6 and the superconducting coil. Therefore, the current flowing through the superconducting coil is attenuated by flowing through the protective resistor 6.

In order to distinguish between superconducting breakdown voltage and noise, the superconducting breakdown detector 3 is set to determine that superconducting breakdown has occurred, for example, when a signal of /mV continues for 10 milliseconds or more.

Since the conventional superconducting breakdown detection device is configured as described above, it has the disadvantage of malfunctioning as described below when using a large superconducting coil.

(1) Inductance L of superconducting coil = 70 Henry, power supply ripple rate (ΔI/sec) −=, O
-e ampet seconds, an inter-terminal voltage Δt O,Oi is generated for 10 milliseconds, resulting in malfunction.

(2) If the magnetic field of the superconducting coil is S tesla and the superconductor is moved by 1 μm over a length of /m in io milliseconds due to electromagnetic force, then there is also /m between the terminals. mV
voltage is generated, and as in (1), malfunction occurs.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and because a small number (7 in total) of superconducting strands for detecting superconducting breakdown were inserted into the primary stranded wire, large-sized superconducting The purpose of this invention is to provide four superconducting bodies that can reliably detect superconducting breakdown even in coils.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In Figure 1, C indicates four superconducting bodies, g indicates a superconducting strand stabilized with a metal such as copper, W indicates a superconducting strand for detecting superconducting breakdown that has not been stabilized, and 10 indicates a stable superconducting strand. 3 strands of ultra-transparent mg treated with oxidation treatment were placed on a twisting table/this twisted gland, l
/ is a bundled conductor made by twisting several 7th order stranded wires into a bundle,
/, 2 is a casing surrounding the bundled conductor /l for airtightness or reinforcement. 13 is a gap between the bundled conductors //, and is filled with a cryogenic refrigerant for cooling.

Figure 3 shows the four superconducting elements i for superconducting breakdown detection in Figure 2.
? Only the primary stranded wire 10 containing .

In the present invention configured as described above, a current close to a critical current value is caused to flow through the superconducting element wire for superconductivity detection. Here, if a superconducting breakdown occurs in a very small part of the primary stranded wire 10 (for example, the oblique part in FIG. Since the refrigerant surrounding the refrigerant gasifies and the superconducting strands for detecting superconducting breakdown are not stabilized, the superconducting strands for detecting superconducting breakdown immediately cause superconducting breakdown and a large voltage is generated. Therefore, by detecting this voltage with the superconducting breakdown detector 3 shown in Fig. 1, superconducting breakdown can be reliably detected from its initial state. The case where the superconducting wire for destruction detection is inserted into the primary stranded wire /θ has been shown, but the qth
If each of the superconducting strands 9a and 9b for detecting superconducting breakdown is inserted in a folded manner as shown in the figure, no stray electromotive force will be generated even during excitation and demagnetization. Also, as shown in Figure 3, there are many lead wires /4'a, /! in the middle. b and /'
By wearing an Ic, it is also possible to detect the location of superconducting breakdown. In the above-mentioned figures No. 1 and S, for simplicity, the primary stranded wire 10 consisting of three superconducting strands is represented by two parallel lines.

The embodiment shown in FIG. 3 is based on the assumption that a refrigerant is sealed inside and outside the casing. However, when the communication port /3 is provided as shown in Fig. 6, the casing /J has only a reinforcing function, and the inside and outside of the casing are filled with the same refrigerant and are in communication with each other. [Effects] As described above, in this invention, superconducting strands for detecting superconducting destruction are inserted into the primary stranded wires. Destruction can now be detected.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional superconducting breakdown detection device, and FIG. 1 is a perspective view showing another embodiment. l is a superconducting coil, C is 4 superconductors, 3 is a superconducting breakdown detector, 3a and 3b are terminals, ri is a circuit breaker, left is a protective resistor,
O is a wire, g is a superconducting wire subjected to stabilization treatment, ri is a superconducting wire for superconducting breakdown detection, lθ is a primary stranded wire, // is a bundled conductor, 12 is a casing, /3 is a refrigerant filling Gap, /
4' is a lead wire, and /S is a continuous trace port. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent: Masu Oiwa Yuzu 1 figure Suuen Itu Gong 4 figure Kong 5 figure

Claims (1)

[Claims] (1) A bundle made by twisting three stabilized superconducting strands together to make a primary strand, and twisting several of these primary strands together into a bundle. A superconducting breakdown characterized in that in four superconducting bodies in which conductors are housed in a casing, at least one superconducting strand for detecting superconducting breakdown that has not been subjected to stabilization treatment is inserted into one primary stranded wire. Four detectable superconductors. (, 2) The superconductor 4 body according to claim 1, wherein i superconducting strands for superconducting breakdown detection are inserted from end to end of the seventh strand. (3) The four superconducting bodies according to claim 1, wherein each of the two superconducting strands for detecting superconducting breakdown is folded back and inserted from each end of the primary strand. (li) The superconductor 4 body according to claim 2, in which a large number of lead wires are attached to the middle of one superconducting element wire for detecting superconducting breakdown.