Safety of superconducting magnets for fusion: Thermal analysis of large cryostable magnets

A thermal analysis program has been developed to study the response of a cryostable fusion magnet to abnormal conditions such as a localized heat input, overcurrent, or uncooled length of conductor. It performs a heat balance on each element. Variation of parameters with temperature, pressure, and magnetic field are incorporated. The program has been applied to a conductor with magnetic field variation along its length, carrying a high current as might occur in one toroidal field toil when a neighboring coil discharges rapidly. It is found that a stable normal region can develop, with possibly serious consequences.