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

Liangjun Shao,Yufan Yan,Xintao Zhang,Huajun Liu,Timing Qu,Haoyuan Wang

doi:10.3390/electronics10141741

Liangjun Shao, Yufan Yan + Show 4 more

Open Access

https://doi.org/10.3390/electronics10141741

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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.

Highlights

REBa2Cu3O7−x (REBCO), a high-temperature-superconducting (HTS) material, is believed to be the main candidate conductor for high field magnets [1]
A 32 T all-superconducting magnet was successfully tested in 2017, which consists of a 17 T HTS insert and a 15 T LTS background magnet [4,5,6,7,8]
A 100-μm thick Cu stabilizer layer was chosen for the REBCO conductors to control the copper current density in the range of 400–450 A/mm2 [10]

Summary

Introduction

REBa2Cu3O7−x (REBCO), a high-temperature-superconducting (HTS) material, is believed to be the main candidate conductor for high field magnets [1]. The Grenoble/CEA group makes great effort in the metal-as-insulation (MI) winding technique, which can decrease the time constant while having the same self-protection aspect compared with the NI winding technique [16,17] Based on this, they tested an MI HTS insert called the NOUGAT magnet to reach 32.5 T in a 20 T background resistive magnet [18]. In their design, ‘double-winding’ technique was applied to effectively increase the electromagnetic operation margin in local regions This winding method was firstly tested in a prototype coil that obtained 11.2 T central field at a transport current of 167 A in a 15 T background magnet [22]. The self-protection merit of NI technology is the key issue to maintain the safe running of Coil 1 [26]

Critical Current Level

Hoop Stress

Conceptual Mechanical Design

Conclusions