Protection method for SMES coils

The design of a superconductor which will protect superconducting magnet coils from over-temperature and overvoltage due to cryogenic failure or a massive vacuum failure during the life of the coils is presented. The superconductor is interiorly cooled by helium II, and is surrounded by a finned aluminum alloy structure with liquid nitrogen filling the space between the finned housing and the outer aluminum alloy case. The large heat capacity of nirogen serves to absorb stored energy below 800K. A coil designed with these principles would not suffer mechanical or electrical damage in the event of a forced discharge. No action of switches or electronic sensors are required and the coil would only warm to approx. 800K. Some additional cost would be incurred for the extra plumbing required for the nitrogen and the cool-down time would be increased. Cool-down time for these coils should not be a problem because they will normally be kept cold for years at a time