Quench propagation velocities in an epoxy-impregnated Nb3Sn superconducting winding model

A computer code to describe the quench process in multisection, epoxy-impregnated superconducting solenoids has been described (ibid., vol.24, no.2, p.1559-62, 1988) that relies on one experimental input: field- and current-dependent transverse (turn-to-turn) quench propagation velocity. Quench propagation velocity data for longitudinal and transverse waves is presented herein for a Nb₃Sn superconducting winding model. A preliminary analysis of the data indicates that both NbTi data obtained earlier and the present Nb₃Sn data confirm the validity of the basic premise that a quench code for epoxy-impregnated three-dimensional windings can be based on a single thermal parameter in the form of transverse propagation velocity. Furthermore, this transverse velocity is related to longitudinal velocity through a universal correlation constant. This correlation between transverse and longitudinal velocities depends principally on the turn-to-turn thermal conduction.