Simulation of the Quenching of the Cyclotron Gas Stopper Magnet at MSU

The cyclotron gas stopper magnet at Michigan State University (MSU) consists of two superconducting coils, each in its own cryostat. The two cryostats are mounted in the two warm iron poles of a sector cyclotron magnet used to control the orbit of heavy ions as the particle energy is being removed by circulating the ions through helium gas. The two coils are connected in series to 200-A power supply. The magnet current leads are protected by cold silicon diodes in series with a resistor. The coils are attached to a stainless steel mandrel. As a result there is no magnet quench-back from the mandrel. There is quench-back from the resistor in series with the diodes that is wound on the outside of the solenoid coil. This causes the magnet coils to quench more rapidly reducing both the hot-spot temperature and the peak voltages in the circuit. This report presents a simulation of the quench process for this magnet.