Speaker
Description
Fast-ramping REBCO HTS magnets are required for the central solenoid and poloidal field coils of spherical tokamaks. Beyond fusion, this class of magnets has broad relevance to a range of emerging applications including motors and generators, space propulsion, manufacturing and other sectors. These magnets cannot adopt no-insulation (NI), which offer the most compact route to high fields using HTS coils, due to well-established charging-delay limitations. Various technical challenges are therefore faced associated with quench protection, stress management and thermal management, all of which traditionally result in significantly reduced engineering current density compared to NI coils.
This presentation will describe the development of compact, fast-ramping, conduction-cooled HTS coils based on “ultra-compact insulation” technology developed recently by TE Magnetics. The work has been conducted by rapid prototyping, involving the manufacture and test of some tens of HTS coils throughout 2024 and 2025, at 100 – 300 mm diameter scale. The presentation will include the results of cryogenic testing at 20-50 K at multi-kilo-amp currents. This explores aspects such as transient field stability, linearity of field vs current response, field homogeneity, and the resilience of the coils against thermal cycling, electromagnetic cycling, and intentionally induced quenches. These experimental test results will be presented alongside the predictions of our modelling software. The talk will also cover the coil development approach and choices made to optimise the design for volume manufacturability within live commercial projects. The readiness of this technology to meet the needs of various emerging commercial applications will be highlighted.
