To date, quite a number of no-insulation (NI) REBCO magnets have been designed and constructed, and all of them successfully generated their target fields. Some magnets experienced a quench at their full fields and survived without damage. The results have shown a potential of the NI REBCO winding technique for high field user magnets. Motivated by the recent progress, a 20 T all-superconducting user magnet project was launched in early 2016 at the National High Magnetic Field Laboratory, where a 13 T 52 mm NI REBCO insert has been designed and constructed with support from the University of Florida to purchase the REBCO conductors. The insert will be installed in a cold bore of a 7 T low temperature superconductor background magnet to complete the 20 T all-superconducting system. The insert consists of a stack of 24 double pancake coils wound with multi-width (MW) REBCO tapes manufactured by the SuNAM, Co., Ltd. It is expected to generate a target field of 13 T at an operating current of 213 A that corresponds to a current density of the narrowest-tape-wound coil of 433 A/mm2. We plan to apply the active feed-back control method, recently proposed by our team, to precisely control the steady-state field generation as well as to reduce the charging time delay. This paper presents design and construction details of the 13 T insert and operation results and user feedback of the complete 20 T system.
ACKNOWLEDGMENTS: This work was supported by the National High Magnetic Field Laboratory (which is supported by the National Science Foundation under NSF/DMR-1157490), and by the State of Florida.