Permanent current switch

Abstract

There is disclosed a permanent current switch which has a high temperature margin and which is thermally stable and which securely performs a switching operation between a superconducting state and a normal conducting state. The permanent current switch of the present invention has a coiled superconducting wire and a heater wire which switches the superconducting wire between the superconducting state and the normal conducting state, the superconducting wire is a magnesium diboride superconducting wire having a high-resistance metal on an outer side and a magnesium diboride superconducting portion on an inner side and prepared by forming a superconducting metal on a layer between the high-resistance metal and the magnesium diboride superconducting portion, and the permanent current switch further comprises a superconductive connecting section superconductively connected to a lead wire guided from the superconducting wire and a superconducting wire for a wiring line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a closed circuit for a general permanent current operation;

FIG. 2 is a diagram showing a sectional constitution of an MgB₂ wire prepared in an embodiment of the present invention;

FIG. 3 is a diagram showing a sectional constitution of a superconductive connecting section prepared in the embodiment of the present invention;

FIG. 4 is a diagram showing a permanent current switch prepared in the embodiment of the present invention;

FIG. 5 is a diagram showing a closed circuit for a permanent current operation, prepared in the embodiment of the present invention;

FIG. 6 is a diagram showing a result of a test performed in the embodiment of the present invention;

FIG. 7 is a diagram showing a result of a test performed in the embodiment of the present invention;

FIG. 8 is a diagram showing a sectional constitution of a multi-core MgB₂ wire prepared in the embodiment of the present invention;

FIG. 9 is a diagram showing a result of a test performed in the embodiment of the present invention; and

FIG. 10 is a diagram showing a result of a test performed in the embodiment of the present invention.

Claims

1. A permanent current switch having a coiled superconducting wire and a heater wire which switches the superconducting wire between a superconducting state and a normal conducting state, the superconducting wire being a magnesium diboride superconducting wire having a high-resistance metal on an outer side and a magnesium diboride superconducting portion on an inner side and prepared by forming a superconducting metal on a layer between the high-resistance metal and the magnesium diboride superconducting portion,the permanent current switch further comprising:a superconductive connecting section superconductively connected to a lead wire guided from the superconducting wire and a superconducting wire for a wiring line.

2. The permanent current switch according to claim 1, wherein the superconductive connecting section superconductively connects the magnesium diboride superconducting portion or the superconducting metal with which the magnesium diboride superconducting portion is coated to a superconducting core portion of the superconducting wire for the wiring line via a low-melting superconducting metal or a low-melting superconducting alloy.

3. A permanent current switch having a coiled superconducting wire and a heater wire which switches the superconducting wire between a superconducting state and a normal conducting state, the superconducting wire being a multi-core magnesium diboride superconducting wire having a plurality of magnesium diboride superconducting cores formed by coating magnesium diboride superconducting portions with a superconducting metal and prepared by arranging the plurality of magnesium diboride superconducting cores in a high-resistance metal,the permanent current switch further comprising:a superconductive connecting section superconductively connected to a lead wire guided from the superconducting wire and a superconducting wire for a wiring line.

4. The permanent current switch according to claim 3, wherein the superconductive connecting section superconductively connects the magnesium diboride superconducting portion or the superconducting metal with which the magnesium diboride superconducting portion is coated to a superconducting core portion of the superconducting wire for the wiring line via a low-melting superconducting metal or a low-melting superconducting alloy.

5. The permanent current switch according to claim 1, wherein the high-resistance metal is an alloy containing Cu as a main component.

6. The permanent current switch according to claim 1, wherein the superconducting metal is an alloy containing Nb as a main component.

7. The permanent current switch according to claim 2, wherein the low-melting superconducting metal or the low-melting superconducting alloy is made of at least one or more metals of Sn, Mg, In, Ga, Pb, Te, Tl, Zn, Bi and Al.

8. The permanent current switch according to claim 3, wherein the high-resistance metal is an alloy containing Cu as a main component.

9. The permanent current switch according to claim 3, wherein the superconducting metal is an alloy containing Nb as a main component.

10. The permanent current switch according to claim 4, wherein the low-melting superconducting metal or the low-melting superconducting alloy is made of at least one or more metals of Sn, Mg, In, Ga, Pb, Te, Tl, Zn, Bi and Al.

11. A superconducting magnet comprising a superconductivity coil, a power supply, and a permanent current switch connected in parallel with said superconductivity coil and said power supply, said permanent current switch having a coiled superconducting wire and a heater wire which switches the superconducting wire between a superconducting state and a normal conducting state, the superconducting wire being a magnesium diboride superconducting wire having a high-resistance metal on an outer side and a magnesium diboride superconducting portion on an inner side and prepared by forming a superconducting metal on a layer between the high-resistance metal and the magnesium diboride superconducting portion,the permanent current switch further comprising:a superconductive connecting section superconductively connected to a lead wire guided from the superconducting wire and a superconducting wire for a wiring line.

12. A superconducting magnet comprising a superconductivity coil, a power supply, and a permanent current switch connected in parallel with said superconductivity coil and said power supply, said permanent current switch having a coiled superconducting wire and a heater wire which switches the superconducting wire between a superconducting state and a normal conducting state, the superconducting wire being a multi-core magnesium diboride superconducting wire having a plurality of magnesium diboride superconducting cores formed by coating magnesium diboride superconducting portions with a superconducting metal and prepared by arranging the plurality of magnesium diboride superconducting cores in a high-resistance metal,the permanent current switch further comprising:a superconductive connecting section superconductively connected to a lead wire guided from the superconducting wire and a superconducting wire for a wiring line.