Finite Element Study of the Quench Behavior of a Solenoid for SSC Detector

When a superconducting magnet starts to quench, the resistivity of the normal zone of the superconductor increases greatly and the current moves into the stabilizer. Ohmic heating results and the temperature of the quench initiation site begins to rise very quickly. Therefore, the magnet and quench protection system must be designed so that this “hot spot” does not reach a damaging temperature. The work described in this paper is part of the R&D effort leading toward the design of a thin solenoid for an experiment at the SSC. The 4 m diameter x 8 m x 2 T magnet has a single layer of aluminum-stabilized Cu/Nb-Ti superconductor cooled indirectly. Quench protection is through a room temperature dump resistor. The behavior of a quench has been extensively studied by a computer simulation using three methods. In the first, one dimensional model, it is assumed that the heat flows only in the circumferential direction along the conductor. In the second model turn to turn heat conduction is added with one thermal conductivity along conductor and another transverse to it. In the third model current diffusion is also included. The calculations are done with the commercial finite-element program ANSYS.