Overview of results from Wendelstein7-X HTS current lead testing

The High Temperature Superconductor (HTS) current leads (CL) for the Wendelstein 7-X stellarator (W7-X) with a maximum current of 18.2 kA are designed and manufactured by the Karlsruhe Institute of Technology (KIT). In addition the acceptance tests of the W7-X HTS CLs are performed at KIT. Therefore the existing TOSKA facility has been extended by a test cryostat connected to the main vacuum vessel. After the extensive prototype CL test campaigns in 2010 the final acceptance tests of 14 series CLs started in 2011. The estimated completion of the routine test campaign is in December 2012. The main parts of each acceptance test are the determination of the heat load at the 4.5 K level, of the necessary 50 K He mass flow rate through the heat exchanger as well as the simulation of a loss of flow accident of the 50 K He mass flow at full current (18.2 kA). The tests also include a long-time operation at the maximum current of 18.2 kA to demonstrate the steady state operation capability of the HTS CLs. In the present paper an overview of all conducted HTS CL acceptance tests is given. The results for the different CLs are summarized and compared to the specifications.