High Temperature Superconductors for Fusion Applications

Recent improvements in the superconducting performance and technical maturity of high-temperature-superconductors (HTS) lead to considerations of using HTS in future fusion magnets in addition to the presently used low-temperature superconductors (LTS). Compact high field magnet systems entirely made of HTS for compact tokamaks, hybrid HTS-LTS magnets for enhanced operational capabilities (e.g. larger flux swing) in conventional tokamaks and future stellarator devices with HTS magnet systems are presently investigated.
An overview of recent concepts, developments and designs of HTS-based future fusion magnet systems will be given and a number of physical and technical challenges will be addressed, too:
In particular, the so-called second generation HTS Rare-Earth-Barium-Copper-Oxide (REBCO) shows an excellent superconducting performance over a wide range of magnetic fields and temperatures. The layered architecture of these technical REBCO conductors and the ceramic nature of REBCO lead to mechanical challenges at high Lorentz forces, which is relevant for cable-in-conduit-conductors (CICC) of future fusion magnets due to the high currents and high field strengths. ... mehrDifferent high-current cable concepts for future fusion magnets will be discussed.
High loads are not only a challenge for potential future HTS conductors but also for the conductor jackets and the coil casing of the magnet systems. An increase of the numbers of load cycles on the path towards a future fusion power plant requests superior mechanical strength. Recent developments on structural materials for use in future fusion magnets will be presented.
The high critical temperature of HTS materials allow to design HTS CICC with to a noticeably higher minimum quench energy and temperature margin compared to LTS conductors – but leads inevitably to substantially slower quench propagation velocity and challenges related to quench detection. Recent results on numerical modelling and experimental investigation of quench in high-current HTS CICC will be addressed.
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.