High temperature superconductor current leads for fusion machines

All large fusion experimental machines presently under construction like the tokamak ITER, the stellarator Wendelstein 7-X (W7-X), and the satellite tokamak JT-60SA will use high temperature superconductor (HTS) current leads to reduce the cryogenic load and operational cost. The Karlsruhe Institute of Technology (KIT which is a merger of former Forschungszentrum Karlsruhe and University Karlsruhe) designed, constructed and successfully tested a 68 kA HTS current lead demonstrator for ITER which led to the decision by ITER IO to use HTS current leads for the ITER magnet system, and the Chinese Domestic Agency is in charge of providing these leads as a part of the superconducting feeder system. KIT is in charge of design, construction and test of HTS current leads for W7-X and JT-60SA. The paper discusses the status of the current lead development and describes the results of the W7-X prototype test which has been performed recently.