Patent ID: 7196883

Claim:
A superconducting magnet system with a quench protection circuit, comprising: a superconducting magnet having a plurality of series-connected superconducting coils; a persistent current switch connected in parallel with the superconducting coils; and first and second quench protection circuits connected in parallel with the superconducting coils and the persistent current switch; wherein the first quench protection circuit comprises anti-parallel diodes and parallelly connected resistive heaters and shunt resistors, and the resistive heaters and the shunt resistors are each connected in series with the diodes; wherein the second quench protection circuit has a diode and a metal of copper connected with the diode; and wherein a turn-on voltage of the diode in the second quench protection circuit is lower than a turn-on voltage of the diodes in the first quench protection circuit.