NoncuA Variable Temperature Cryostat to Measure J(T) of ITER Strands up to 20 Teslas

Abstract

The determination of the non-copper critical current density JnonCu is crucial for the development of Nb3Sn strands for ITER coils. The temperature dependence of JnonCu in a magnetic field plays a leading part in determining the operating parameters and stability of the ITER coils. This chapter describes the development of a variable temperature cryostat based on a new concept. This new cryostat allows the measurement of critical current (I < 600 A) to be performed in ITER-type superconducting strands within a large temperature and magnetic field range. It uses a new principle of thermalization of the superconducting strand. This new cryostat is able to measure critical currents up to 600 A in fields up to 20 T in a temperature range of 4.2 K to 20 K range and in magnetic fields up to 20 T. The design allows to insert the cryostat inside the bore of the hybrid magnet of the CNRS High field laboratory.