Magnetization Modeling of Twisted Superconducting Filaments

Abstract

Abstract-This paper presents a new Finite Element numerical method to analyse the coupling between twisted filaments in a superconducting multifilament composite wire. To avoid the large number of elements required by a 3D code, the proposed method makes use of the energy balance principle in a 2D code. The relationship between superconductor critical current density and local magnetic flux density is implemented in the program for the Bean and modified Kim models. The modeled wire is made up of six filaments twisted together and embedded in a low-resistivity matrix. Computations of magnetization cycle and of the electric field pattern have been performed for various twist pitch values in the case of a pure copper matrix. The results confirm that the maximum magnetization depends on the matrix conductivity, the superconductor critical current density, the applied field frequency, and the filament twist pitch. The simulations also lead to a practical criterion for wire design that can be used to assess whether or not the filaments are coupled.

Coupled axial and transverse currents method for finite element modelling of periodic superconductors

“…The method proposed by T. Satiramatekul and F. Bouillault in [25][26][27] reproduces the effect of coupling currents in the conducting matrix by introducing equivalent resistances between the filaments, accounting for the twist pitch length of the wire. This allows to reproduce uncoupled, partially coupled, and coupled filament regimes without using a 3D model, but a simple, yet appropriate, 2D approach.…”