Development of cryogen free Ic measurement system

The increasing use of high-temperature superconducting (HTS) materials for advanced power applications has generated much interest in the acquisition of the voltage–current ( V – I ) characteristic curve to measure the critical current ( I c ) of HTS tape. Cryogen free I c measurement system for HTS wires or coils was designed and fabricated by using a GM-cryocooler and two HTS current leads. The sample cools conductively by 2nd stage of SRDK-408D cryocooler manufactured by Sumitomo Heavy Industries Ltd. (SHI). Each high temperature end of HTS current leads is thermally connected to 1st stage of the cryocooler and electrically disconnected. HTS tape samples cooled down by about 10 K. I c measurements were conducted on a BSCCO-2212 tape, a BSCCO-2223 tape with joints and a BSCCO-2223 small coil under self-field. A description of cryogen free I c measurement system design and results from a series of measurements will be presented.