3D Modeling of the Magnetization of Superconducting Rectangular-Based Bulks and Tape Stacks

TL;DR

This paper compares three numerical methods for 3D modeling of the magnetization in superconducting bulks and tape stacks, focusing on current constraints and energy dissipation, to improve understanding of their electromagnetic behavior.

Contribution

It introduces a 3D modeling approach for superconducting stacks with current constraints, comparing MEMEP, H-formulation, and VIM methods for the first time.

Findings

Different current density profiles observed between methods.

Energy dissipation varies with current constraints.

Computational effort differs significantly among models.

Abstract

In recent years, numerical models have become popular and powerful tools to investigate the electromagnetic behavior of superconductors. One domain where this advances are most necessary is the 3D modeling of the electromagnetic behavior of superconductors. For this purpose, a benchmark problem consisting of superconducting cube subjected to an AC magnetic field perpendicular to one of its faces has been recently defined and successfully solved. In this work, a situation more relevant for applications is investigated: a superconducting parallelepiped bulk with the magnetic field parallel to two of its faces and making an angle with the other one without and with a further constraint on the possible directions of the current. The latter constraint can be used to model the magnetization of a stack of high-temperature superconductor tapes, which are electrically insulated in one direction. For the present study three different numerical approaches are used: the Minimum Electro-Magnetic Entropy Production (MEMEP) method, the $H$-formulation of Maxwell's equations and the Volume Integral Method (VIM) for 3D eddy currents computation. The results in terms of current density profiles and energy dissipation are compared, and the differences in the two situations of unconstrained and constrained current flow are pointed out. In addition, various technical issues related to the 3D modeling of superconductors are discussed and information about the computational effort required by each model is provided. This works constitutes a concrete result of the collaborative effort taking place within the HTS numerical modeling community and will hopefully serve as a stepping stone for future joint investigations.