Experimental study of the effect of the current sweep cycle on the magnetic field stability of a REBCO coil

Abstract

This paper reports the effects of a current sweep cycle method on reducing the screening current induced field (SCF) in a (RE)Ba2Cu3Ox (REBCO) coil. The screening current induced field in a REBCO coil causes two major problems: temporal magnetic field drift and a reduction of the central magnetic field. This is a critical problem in relation to REBCO coils, which require a homogeneous and stable magnetic field, during, for instance, nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) applications (Itoh et al., 2013; Hemmi et al., 2005; Hahn et al., 2008; Amemiya et al., 2008; Otsuka et al., 2011; Yang et al., 2013; Ahn et al., 2009; Koyama et al., 2009; Kajikawa et al., 2015). In an effort to circumvent the SCF problem, the current sweep cycle method is investigated based on experiments in this study. The experimental results show that a greater SCF reduction in a REBCO coil can be obtained by increasing the overshooting of the current sweep cycle.