AC losses at 4$middot$2 K in heat-treated niobium wire

Abstract

Samples of heavily worked, cold-drawn niobium wire were heat-treated at temperatures between 200 and 700°C to produce changes in the magnetization behaviour of the material. An investigation was then carried out to determine the influence of these changes on the AC power losses produced in the wires at 4·2 K due to 50Hz transport currents of up to 120 A. The results show that the power losses at a particular current increase as the field of initial penetration into the niobium, Hp, decreases.