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http://dx.doi.org/10.9714/psac.2018.20.4.065

Current overshoot operation of a REBCO magnet to mitigate SCF  

Lee, Changhyung (School of Mechanical Engineering, Changwon National University)
Hahn, Seungyong (Department of Electrical and Computer Engineering, Seoul National University)
Bang, Jeseok (Department of Electrical and Computer Engineering, Seoul National University)
Cho, Jeonwook (Korea Electrotechnology Research Institute (KERI))
Kim, Seokho (School of Mechanical Engineering, Changwon National University)
Publication Information
Progress in Superconductivity and Cryogenics / v.20, no.4, 2018 , pp. 65-69 More about this Journal
Abstract
Due to large in-field current carrying capacity and strong mechanical strength, a REBCO wire has been regarded as a viable high temperature superconductor (HTS) option for high field MRI and > 1 GHz (>23.5 T) NMR magnets. However, a REBCO magnet is well known to have an inherent problem of field inhomogeneity, so-called 'Screening Current induced magnetic Field (SCF)'. Recently, 'field shaking' and 'current overshoot operation' techniques have been successfully demonstrated to mitigate the SCF and enhance the field homogeneity by experiments. To investigate the effectiveness of current overshooting operation technique, a numerical simulation is conducted for a test REBCO magnet composed of a stack of double pancake coils using '2D edge-element magnetic field formulation' combined with 'domain homogenization' scheme. The simulation result demonstrates that an appropriate amount of current overshoot can negate the SCF. To verify the simulation results, current overshoot experiments are conducted for the REBCO magnet in liquid nitrogen. Experimental results also demonstrate the possible application of current overshoot technique to mitigate the SCF and enhance the field homogeneity.
Keywords
REBCO magnet; field homogeneity; screening current induced field; current overshoot; field shaking;
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