Stability of large current aluminium stabilized conductors

Abstract

A complete stability analysis is given for a highly stabilized large current (50–100 kA) conductor cooled by a He II bath. The analysis concentrates on the minimum normalizing energy pulse, the minimum quench energy pulse (transient stability) and the maximum non-propagating current for constant length travelling normal zones (dynamic stability). The minimum normalizing energy pulse is defined as the energy required to raise the strand temperature above the current sharing level. The quench energy pulse is the pulse over which the conductor cannot recover. The dynamic stability is defined as two constant length normal zones travelling at constant velocity in opposite directions and is related to the change in ohmic heat generation following a normalization pulse. The computational model includes thermal conduction in Nb-Ti/Cu strands and the aluminium stabilizer, the thermal and electrical properties of both, heat transfer to helium at the conductor surface and current diffusion.