On the stability of superconducting magnet systems subject to weak random thermal disturbances

Abstract

The problem of the stability of superconducting magnets influenced by weak random thermal disturbances is considered. These disturbances correspond to sudden energy releases due to epoxy cracks, fractures, microdeformations etc. The authors applied the theory of stochastic processes to assess the permissible level of thermal noise. Criteria of stability for Gaussian and Poissonian thermal disturbances are obtained, and the permissible level of the temperature fluctuations at a given current is determined. They considered two extreme limits of distributed and point transient disturbances. For point disturbances the quenching of a magnet is due to statistical creation of the minimum propagating zone (MPZ). The stability criteria depend on the effective spatial dimensionality of the MPZ and the statistics (Gaussian or Poissonian) of disturbances. The results of the paper may be used for an estimation of the noise resistance of superconducting magnets.