Patent ID: 8680716

Claim:
A method of operating a superconducting switch for a persistent mode superconducting magnet system so as to condition the system against quenching of a superconducting magnetic circuit of the system, the method comprising: connecting a main superconducting switch to the magnetic circuit by two connecting parts, the main superconducting switch providing a resistance of a first resistance value between the connecting parts; connecting an auxiliary superconducting switch to the magnetic circuit by the connecting parts, the auxiliary superconducting switch providing a resistance of a second resistance value greater than the first resistance value between the connecting parts; energising the magnetic circuit by means of a power supply connected to the connecting parts; closing the main superconducting switch and the auxiliary superconducting switch so as to cause superconducting current flow through the main superconducting switch within the magnetic circuit and so as to cause the superconducting current flow to persist within the magnet circuit when the power supply is disconnected; carrying out a preconditioning step by opening the main superconducting switch and determining whether the superconducting current flow persists within the magnet circuit by flowing through the auxiliary superconducting switch; closing the main superconducting switch so as to cause the superconducting current flow to revert to flowing through the main superconducting switch as a result of the second resistance value being greater than the first resistance value; and where the determination in the preconditioning step indicates failure of the superconducting current flow to transfer from the main superconducting switch to the auxiliary superconducting switch, repeating the preconditioning step as many times as is necessary to condition the system against quenching.