Effect of Current Pulses on the Resistivity of a Cryogenic High Purity Aluminum Conductor

Abstract

Cryogenic high-purity aluminum conductors offer greatly reduced resistive energy losses and conductor mass for high energy pulsed power systems. These benefits result from high RRR (residual resistivity ratio) or low electrical resistivity of these conductors. Previous experiments have shown significant reductions in RRR of conductors exposed to cyclic strain. For pulsed power applications, it is important to know whether RRR might also be degraded by high current density pulses and the associated thermal cycling. This paper presents experimental data on the electrical resistance of high-purity aluminum conductors exposed to thermal cycling caused by pulsed heating at high current densities (~ 109 A/m2) and cooling between pulses by liquid neon coolant (at ~ 27 K). A composite conductor consisting of high purity aluminum filaments in a Al-Fe-Ce matrix was used. The conductor was exposed to about 12000 pulses of 10 ms duration and about 3000 pulses of 20 ms duration at a repetition rate of 1 pulse per second. The experiments showed no significant change in the DC resistance of the composite conductor as a result of the current pulses and the thermal cycling.