Semi-Retractable Current Lead Cooled by a Cryocooler for High Field Magnet

The semi-retractable current lead cooled by a cryocooler is designed for a high field superconducting magnet system. The semi-retractable current lead is composed of a normal metal element, conducting the current from room temperature to an intermediate temperature, and an HTS element, conducting the current down to liquid helium temperature. An HTS element and the joint between the normal metal and HTS element are connected to a two-stage cryocooler. The intermediate joint carries current through a strip of louvered material. After charging the normal metal element is disengaged from the HTS element without breaking vacuum in the insulating space. The semi-retractable current lead is fabricated and assembled with a two-stage cryocooler for feasibility test. The adaptability and reliability of the lead are tested during engage and disengage performance. The electrical contact resistance is also measured in the intermediate joint with respect to the vacuum level and temperature has been measured.