A computer program simulating the quench of superconducting magnet systems

A computer program for testing coil and protection design of a composed magnet system is presented. We consider small high field magnets composed of two uniaxial cylindrical coils of different superconducting materials (e.g. NbTi and V3Ga or Nb3Sn). Each coil consists of several sections protected by shunts. The whole system is driven by one power supply. In order to take into account quench propagation due to thermal conduction and also that due to rapid current increase which is important in inductively coupled systems a one-dimensional thermodiffusion equation is solved. Field and temperature dependence of the critical current of every layer of the magnet system are regarded. Current sharing as well as the temperature dependence of specific heat, of resistivity and of thermal conductivity are taken into account. The program calculates the time dependence of currents, of external and internal voltages, of resistances of the sections and of the radial temperature distribution. Calculations for an 11 T V3Ga-NbTi magnet system agree well with experimental results. The influence of a subdivision of a magnet into several sections protected by shunts is discussed.