Stability of cable-in-conduit superconductors

Abstract

The stability margin of a single triplex of NbTi/Cu strands soldered around a heater wire, sheathed in a stainless-steel tube, and cooled by pressurized helium is found to be multivalued for certain combinations of transport current, ambient helium pressure, and externally imposed helium flow. A qualitative model based on the idea that good recovery in stagnant or slowly flowing helium is due to heating-induced flow accounts well for the complex multivalued behavior of the stability margin.