Off-On Characteristics of Magnetically Controlled Superconducting Switch

Abstract

This paper describes structure of an experimental switch, the experimental results and the theoretical approach for the off-on characteristics of the switch. The experimental magnetically controlled superconducting switch, which is composed of superconducting gate wire (NbZr/CuNi) and superconducting field coil (NbTi/CuNi), has been made. Some experiments on the switching characteristics of the switch have been carried out. The experimental results show special characteristics of switching: l)at failure of switching-on, the gate current at zero magnetic induction is independent of the initial current and is constant and 2)the gate current at the off-on transient state, that is, from the normal state to the superconducting state of the superconducting gate wire, does not depend on the voltage across the gate wire, but depends uniquely on the magnetic field around the gate wire. The gate current can be explained to be a minimum normal-zone propagation current given by the equal-area theorem on cryogenic stabilization.