Speaker
Description
Ultra-high field magnets are being developed for various applications in fundamental-physics experiments, materials sciences, and nuclear magnetic resonance (NMR). Here we report our recent R&D work focused on conceptual design and enabling technologies for a 40 T all-superconducting solenoid magnet with a 20-mm warn bore, intended for potential high-energy partial physics experiments. Adopting commercial REBCO conductors, we propose the Extreme-no-insulation (NI) winding technique to enhance the mechanical integrity and thermal self-protecting ability through an extra low-resistance shunting layer on the winding surfaces of the REBCO coils, along with copper cooling sheets attached to them. A small-scale Extreme-NI magnet will be wound and tested in a conduction-cooling cryostat to demonstrate high mechanical integrity and improved over-current/quench stability. To mitigate the screening-current effect, we have investigated two practical methods: the temperature-controlled charging sequence (TCCS) and the vertical-field-first charging sequence (VFCS), both of which will be tested to reduce the locally concentrated magnetic stress during charging. Based on these results, we present a conceptual design for the Extreme-NI HTS magnet for the 40 T user solenoid magnet. By employing the TCCS and/or VFCS methods, we expect the maximum hoop strain in the REBCO winding to remain below 0.5%, achieving an anticipated ~20% reduction in peak strain compared to conventional charging sequences.
