Design of a 20 T Class REBCO Insert in a 15 T Low Temperature Superconducting Magnet

Abstract

A 20 T REBCO insert magnet has been designed considering a 15 T/150 mm background field generated by an LTS magnet. A two-nested-coil structure was chosen. The target of this project is to generate a 20 T/80 mm user field by inserting the outer MI-REBCO coil (Coil 2) first, then try to reach 35 T by inserting the inner NI-REBCO test coil (Coil 1). Coil 2 will be wound by copper packed, 185-μm thick REBCO tapes co-wound with 50-μm thick Hastelloy tapes. Coil 1 will be no-insulated wound by 65-μm thick REBCO tapes. Two mechanical models were built to estimate the stress distribution inside the HTS coils during operation. The influence of the screening current distribution on stress was discussed. The unbalanced force caused by the coil misalignment was also simulated. The 20 T HTS insert magnet is planned to be built and tested in 2021. The progress of coil winding and preliminary test results at 77 K were presented.

Progress of ultra-high-field superconducting magnets in China

“…The purpose of using MI and no-insulation (NI) coil in the insert magnet simultaneously is to generate a 20 T/80 mm user field by the 5 T MI-REBCO coil first, then reach the 35 T allsuperconducting field by a 15 T NI-REBCO test coil. MI-REBCO coil has a smaller charging-delay time constant compared to NI coils, and the co-wound layer can help to compact the coil and reduce the hoop stress compared to insulated coils [45]. NI-REBCO coil can generate a much higher engineering current density to reach the 35 T target, but it suffers a much bigger magnetic force with a greater chance of damage, so coil 1 was designed to be easy to replace.…”

Experimental study on screening-current induced strain in REBCO insert coils: under critical current control and operation current cycles

“…Notable works include the 'little big coil' REBCO insert [2] and the 32 T all-superconducting magnet [3][4][5] developed by the National High Magnetic Field Laboratory (NHMFL), the 800 MHz REBCO insert magnet by MIT [6][7][8][9], the 32.35 T magnet [10] by the Institute of Electrical Engineering, Chinese Academy of Science (IEECAS), and the 26.4 T all-HTS magnet by SuNAM Co., Ltd and MIT [11,12]. Several ultra-highfield magnets are being developed, including the 40 T allsuperconducting user magnet by NHMFL [13], the 835 MHz REBCO magnet by MIT [14,15], the 35 T all-superconducting magnet by the Institute of Plasma Physics, Chinese Academy of Science (ASIPP) and Tsinghua University [16][17][18], and the 35 T all-REBCO magnet by SuNAM [19].…”

“…To address the SCS issue, numerical models are being developed to calculate the SCS level during the electromagnetic design of high-field REBCO magnet projects [16,29,30]. An electromagnetic-mechanical coupled model was developed to estimate SCS results with better precision [31,32].…”

Electro-thermal modelling by novel variational methods: racetrack coil in short-circuit

“…The design of superconducting applications containing windings of superconducting wires or tapes requires electro-thermal modelling. Indeed, electrothermal quench is a main concern for magnets [1][2][3][4][5][6][7][8][9] and the stator or rotor windings of motors and generators [10].…”