The Removal Of The Screening Current Induced Field

910 WordsOct 11, 20154 Pages
This paper presents the details of a recent study on the removal of the screening-current-induced field (SCIF) in a pancake-type noninsulated high-temperature superconductor (HTS) coil (NI coil). To determine the SCIF in the NI coil, the magnetic flux density (Bz) was calculated using the equivalent circuit model of the coil and compared to Bz obtained empirically. The experimental results exhibited that the SCIF elimination in the NI coil enhanced upon increasing the amplitude and frequency of the AC current being supplied to the background coil. Moreover, the SCIF in the NI coil could be successfully removed by applying the appropriate intensity of an external AC magnetic field. This is because the magnetization direction of SCIF completely changed from radial to spiral, and the phenomenon is termed the “vortex shaking effect.” Overall, this study confirmed that the SCIF in a pancake-type NI coil can be effectively removed by exposing the coil to an external AC magnetic field. 1. Introduction The second-generation (2G) high-temperature superconductor (HTS) coated conductor (CC) is regarded as a promising material for the development of ultrahigh-field magnets for use in nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) applications. This is because the dependence of the critical current (Ic) in the CC on external magnetic fields is lower than those in its low-temperature counterparts [1–4]. However, in the case of a quench, the 2G HTS magnet is

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