MuCool Superconducting Solenoid Quench Simulations and Test Stand at FNAL

Abstract

Fabrication and preparation for test of the MuCool superconducting solenoid are now in progress. The solenoid's passive quench protection system is based on cold diodes and shunt resistors. The solenoid does not have heaters, and quench propagation relies on the superconductor quenching and the subsequent “quench back” effect caused by eddy currents in the coil's Al mandrel. The solenoid has a very large inductance of ~600 H and the stored energy is 100% dissipated into the cold mass during a quench. This makes the solenoid protection a challenging task. This paper presents the quench analysis of the solenoid based on a 3-D FEA solution of the coupled transient electromagnetic and thermal properties during the quench. The simulations used the Vector Fields QUENCH code. A new test facility, the solenoid test stand (STS), is being built at Fermilab to test these coils. One of the critical issues regarding the STS is the fringe field produced by the magnet under test, which interacts with the surrounding equipment. In this paper, we present the stray-field analysis and the corresponding magnetic forces. The STS includes a sophisticated DAQ system to carefully monitor quench events and temperatures.