Stress Analysis of Cylindrical Superconductors Based on Viscous Flux Flow and Flux Creep in the Demagnetization Process After ZFC

Abstract

In this paper, the magnetoelastic problem of a long cylindrical superconductor placed in a time-dependent external magnetic field during the unloading phase after zero field cooling (ZFC) is investigated. The flux distribution equation considering the viscous flux flow effect and the flux creep effect is established, and the stress distribution equation of the long cylinder obtained by the strain method is modified on this basis. The results show that in the external magnetic field both viscous flux flow velocity and flux creep velocity will affect the stress distribution during low-frequency excitation, while the internal field flux distribution and stress distribution are mainly dominated by the viscous flux flow velocity during high-frequency excitation. In addition, the relationship between the viscous flux flow velocity and the external field excitation velocity and the relationship between the position r0 and the magnitude σr, max(r) of the local stress peak and the action parameter (v0, v1, dBa/dt, n) of the two effects are investigated.