A Test System for Superconducting Joints Based on GM Cryocooler

A helium-free superconducting joints test system based on a 1.5 W GM cryocooler has been built in the Institute of Modern Physics, CAS. The resistance and the critical-current of a joint at a particular magnetic field and a particular temperature can be measured synchronously. This system consists of a device on the second stage of the cryocooler and an instrumentation system. The basic method of this system is inductive technique and the current-decay method. The main components of the device include a drive coil, a sample holder, and a background magnet. The measurement process is operating by a LabView program. It has been used to test the NbTi wire joints of the Lanzhou penning trap magnet; it seems reliable and convenient. The principles of main design and some results are presented in this paper.