Design, construction and performance of the current lead test facility CuLTKa

Abstract

The Karlsruhe Institute of Technology (KIT) has a longtime experience in the development of High Temperature Superconductor (HTS) Current Leads (CLs) for high currents leading to several contracts with national and international partners. Within these contracts series production and cold acceptance tests of such CLs were required. The cold test of a large number of CLs requires the availability of a flexible facility which allows fast and reproducible testing.With the Current Lead Test Facility Karlsruhe (CuLTKa) a versatile and flexible test bed for CLs was designed and constructed. The facility consists of five cryostats including two test boxes and is directly connected by a transfer line to a refrigerator with a capacity of 2kW at 4.4K. The refrigerator supplies supercritical helium at two different temperature levels simultaneously. Each of the two test cryostats can be equipped with a pair of CLs which is short-circuited at the low temperature level via a superconducting bus bar. For current tests a power supply can provide DC currents up to 30kA. If required, the facility design offers the potential of withstanding high voltages of up to 50kV on the test objects.The commissioning of the facility started in July 2014. In total a series of acceptance tests of the CLs for the Japanese JT-60SA will be carried out until second half of 2017 to qualify six CLs with a current of 26kA and 20 CLs with a current of 20kA. In the meantime, six CLs@26kA and 16 CLs@20kA have been tested in CuLTKa which demonstrates the very effective operation of the facility.This paper describes the setup of the facility from cryogenic, electrical and process control point of view and will highlight the design of particular technical aspects. Furthermore, an overview of the performance during the commissioning phase will be given.