Mechanical and Electro-Mechanical Investigations of Assembled HTS CroCo Triplets

Abstract

In fusion applications, cables are exposed to high currents and magnetic fields. Cable-in-conduit conductors (CICC) made of several high temperature superconductor (HTS) strands, like the HTS CrossConductor (HTS CroCo), have the ability to meet these requirements. HTS CroCos are made of a cross-shaped stack consisting of two different widths of REBCO and copper tapes embedded in a round solder matrix. The round outer shape allows an easy encapsulation with copper tubes for electrical and mechanical reasons. The triplet-CICC of HTS CroCos is considered as the next step towards a full size fusion conductor. First, a straight triplet sample and later a high field winding demonstrator is planned to be tested at high operational currents (>10 kA) and high magnetic fields (>10 T). Operating the triplet under such conditions will inevitably lead to high Lorentz forces acting on the strands of the triplet-CICC. In order to investigate the electromechanical performance of HTS CroCo triplets, short triplet samples were loaded with transversal mechanical pressure at 77 Kelvin, self-field, to simulate the Lorentz forces of the intended high-current, high-field application. The maximum allowable transversal load was investigated for different triplet configurations in order to determine design limits for the triplet winding demonstrator.