Persistent current effects in highly homogeneous superconducting magnets

Abstract

Many factors affect the magnetic field quality of superconducting magnet, among which the persistent current originating from the inherent attribute of superconducting material exists for a long time and has a greater influence on the magnetic field quality, and its influence on the magnetic field of highly homogeneous magnets has not been reported yet. Based on the critical state model, the magnetization curve of a single superconducting wire, as well as the variation of the higher-order magnetic field components with current of a typical pre-cycle are simulated for a 7 T highly homogeneous magnet. For the validation, the magnetization curves of a single superconducting wire are measured, and the superconducting magnet is subjected to a cool-down test. Compared to zonal harmonics, more obvious hysteresis phenomena for tesseral harmonic components are observed and validated, which confirmed the effectiveness of this methodology.