Speaker
Description
High Temperature Superconductors (HTS) are currently considered as promising candidates for high current Cable-In-Conduit Conductors (CICC) for large high-field magnets. In many cases, these CICC are formed from several HTS strands which themselves are formed from individual HTS tapes. These stranding concepts often use stacks of tapes or wrapped-tape arrangements.
Large effort is presently made to investigate the performance of these conductors during quench by modelling the entire structure. One important parameter which determines the quench performance is the current and heat transfer between the individual elements of the CICC, e.g. HTS REBCO tapes, normal-conducting metal parts (e.g. copper or stainless steel) and combinations thereof. As HTS REBCO tapes for high-field magnet application are usually encapsulated by a copper sheath, the problem reduces to the thermal resistance between pressed copper-copper and copper-stainless steel interfaces, which has been investigated experimentally by measuring the thermal conductivity of stacks made of copper strips and of copper-stainless steel strips as a function of temperature. With the knowledge of the thermal conductivity of copper and stainless steel basic material, the thermal conductivity of the interfaces was evaluated and compared to the values used until now. The resultant thermal resistances will be used in coming modelling, for example in a CICC for future fusion magnets being formed of six HTS CrossConductor (HTS CroCo) strands twisted around a central copper core forming a round cable which is embedded in a stainless steel jacket.
