Design Overview of the MIT 1.3-GHz LTS/HTS NMR Magnet with a New REBCO Insert

We present a design overview of the MIT 1.3-GHz LTS/HTS NMR magnet (1.3G) with a newly designed 835-MHz REBCO insert (H835) as a replacement for the 800-MHz REBCO insert (H800) that was damaged when it quenched during opera-tion in 2018. The new H835 is designed to contribute 19.6 T in a background field of 10.93 T by an LTS NMR magnet that normal-ly rated at 11.74 T (500 MHz): combined, 1.3G generates a total field of 30.53 T corresponding to a proton resonance frequency of 1.3 GHz. H835 is designed to operate stably while meeting 1.3G de-sign constraints. We have also designed H835 to protect it from permanent damage in an improbable event like a quench. Key de-sign features are: 1) a single-coil formation, composed of 38 stacked metal-co-wound no-insulation and 2 stacked no-insulation double-pancake coils, all with mechanically improved cross-over sections; 2) enhanced thermal stability; and 3) reduced current margin with a detect-and-heat method. This paper in-cludes: 1) electromagnetic and mechanical design of H835; 2) cryo-genics overview; 3) quench protection strategy; and 3) discussion on the next steps to successfully complete 1.3G.