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

Abstract

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 of the 800-MHz REBCO insert that was damaged when it quenched during operation in 2018. The new H835 contributes 19.6 T as designed, with an LTS back-ground magnet of 10.9 T, toward a total field of 30.5 T that corre-sponds to a proton resonance frequency of 1.3 GHz. The H835 is de-signed to be stable within 1.3G design constraints. The design also prevents the entire insert from permanent damage in the improba-ble event like a quench. Key design features are: 1) a single-solenoid structure, composed of 38 stacked metal-co-wound no-insula-tion and 4 stacked no-insulation double-pancake coils with mechan-ically improved cross-over sections; 2) enhanced thermal stability; and 3) reduced excessive current margin with a detect-and-activate-the-heater method. This paper includes: 1) electromagnetic and me-chanical design of the H835; 2) cryogenics overview; 3) quench pro-tection schemes; and 3) discussion on the next steps toward the 1.3G.