Thermal stability for Ti-22 atomic percent Nb superconducting cables and solenoids

Thermal stability and supercurrent recovery levels are reported for composite copper, Ti-22 atomic percent Nb cables. Cable sizes vary from 0.06 to 0.17-inch diameter and current levels from 200 to 1800 A. Magnet and small coil tests show that cable magnet performance is consistent with short gap cable tests. It is concluded that thermal stability for cables in liquid helium occurs only for temperature rises less than\sim0.8\degK; thus, the critical temperature of the superconductor is not an important factor in the design of totally protected solenoids. Magnet design recommendations are made which define the limit for stabilized currents as the superconducting critical current or the copper-limited current, whichever is lower. Copper-limited values are determined by cooling conditions and normal cable resistance.