Stabilization, protection and current density: some general observations and speculations

Abstract

There is a need for improved stability in large superconducting magnets where the overall current density is too high for cryogenic stabilization. Adopting the hypothesis that most of the trouble is caused by transient point disturbances, one may characterize stability in terms of the energy, E MPZ, needed to set up a minimum propagating zone (MPZ). Because several of the factors involved in E MPZ have an effect on magnet protection it is helpful to define a goodness factor, G = E MPZ/θ max, where θ max is the maximum temperature rise following a quench. The factor with the single largest potential for improving G is the transverse thermal conductivity of the winding. This factor raises the prospect of using inorganic insulating materials in place of organic polymers.