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.

1 . 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.   
   
   
       2 . The superconducting magnet 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 . The superconducting magnet according to  claim 1 , wherein the high-resistance metal is an alloy containing Cu as a main component. 
   
   
       4 . The superconducting magnet according to  claim 1 , wherein the superconducting metal is an alloy containing Nb as a main component. 
   
   
       5 . The superconducting magnet 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, Ti, Zn, Bi and Al. 
   
   
       6 . 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.   
   
   
       7 . The superconducting magnet according to  claim 6 , 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. 
   
   
       8 . The superconducting magnet according to  claim 6 , wherein the high-resistance metal is an alloy containing Cu as a main component. 
   
   
       9 . The superconducting magnet according to  claim 6 , wherein the superconducting metal is an alloy containing Nb as a main component. 
   
   
       10 . The superconducting magnet according to  claim 7 , 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.