Development and Test of High-Temperature Superconductor Harness for Cryogenic Instruments on Satellites

Extremely sensitive X-ray or infrared detectors that have to be cooled to temperatures well below 1 Kelvin will be used in a number of future satellite missions within ESA's Cosmic Vision and Voyage 2050 program, e.g., ATHENA. To provide sufficient cooling power at different temperature levels, complex cryogenic chains are being developed with different types of coolers. Adiabatic demagnetization refrigerators (ADRs) can be used to reach the lowest temperatures in the range of 50 mK – 100 mK. Due to the limited electrical power available on satellites and other space constraints, superconducting ADR magnets are usually operated with dc currents of only a few Amps. Despite the low currents, the current leads connecting the power supply at a higher temperature stage to the magnet at the cold stage contribute with a high heat load to the limited thermal budget. In this paper we present the design, manufacturing and first tests of a high-temperature superconducting current lead harness which is designed to operate up to a temperature as high as 85 K with a nominal current of 2 A and a maximum current of 5 A. Design choices based on characterization of laser-cut
RE
BCO tapes from different suppliers, characterization of structure materials and on thermal and mechanical simulations are presented. First test results for the assembled harness are discussed. They include current and bending tests, as well as insulation resistance tests.