Publications by authors named "Yoon Hyuck Choi"

We present experimental and numerical studies on a method to mitigate screening current-induced field (SCF) for NI REBCO coil. The SCF is the major field error to incorporate a REBCO insert for a high field LTS/HTS magnet. The field-shaking technique is going to be used to mitigate the SCF of 800-MHz REBCO insert magnet (H800) for MIT 1.

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We present assembly and test results of a 3-nested-coil 800-MHz (18.8 T) REBCO insert (H800) for the MIT 1.3 GHz LTS/HTS NMR magnet currently under completion.

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We present a design study of a liquid-helium (LHe)-free 23.5-T, ϕ25-mm RT-bore REBCO magnet for high-resolution 1-GHz microcoil nuclear magnetic resonance (NMR) spectroscopy. A microcoil NMR magnet is compact and thus its cost will be less by nearly an order of magnitude than that of the standard NMR magnet, and placeable on a bench, thereby resulting in a large saving in space.

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Article Synopsis
  • The MIT 800-MHz REBCO insert magnet (H800), designed to achieve 18.7 T and enhance a larger magnet for a proton resonance frequency of 1.3 GHz, unexpectedly quenched during operation in March 2018, leading to more extensive damage than initially assessed.
  • A new design, H800N, is being developed to address flaws identified in the H800 by focusing on improved stability against quenching and minimizing damage during unforeseen events.
  • Key enhancements for H800N include a single solenoid structure with better coil design, improved thermal stability, and reduced current margins for effective quench protection.
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The characteristic features of the collapse of the ground state in trapped one-component attractive Bose-Einstein condensates are studied by applying the catastrophe theory. From numerically obtained stable and unstable solutions of the Gross-Pitaevskii equation, we derive the catastrophe function defining the stability of the stationary points on the Gross-Pitaevskii energy functional. The bifurcation diagram and the universal scaling laws stemming from the catastrophe function show quantitative agreement with the numerical results.

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