Distributed Inter-Strand Coupling Current Model for Finite Element Simulations of Rutherford Cables

TL;DR

This paper introduces the DISCC model, a finite element homogenization approach that efficiently simulates the transient magnetic response of Rutherford cables, capturing inter-strand coupling currents and losses with reduced computational effort.

Contribution

The paper presents a novel FE homogenization model for Rutherford cables that accurately reproduces inter-strand coupling currents without explicit strand modeling, significantly reducing computational time.

Findings

DISCC accurately models inter-strand coupling currents.

The model reduces simulation time compared to detailed FE models.

It can be integrated into magnet cross-section simulations for transient analysis.

Abstract

In this paper, we present the Distributed Inter-Strand Coupling Current (DISCC) model. It is a finite element (FE) model based on a homogenization approach enabling efficient and accurate simulation of the transient magnetic response of superconducting Rutherford cables without explicitly representing individual strands. The DISCC model reproduces the inter-strand coupling current dynamics via a novel mixed FE formulation, and can be combined with the Reduced Order Hysteretic Magnetization (ROHM) and Flux (ROHF) models in order to reproduce the effects of internal strand dynamics: hysteresis, eddy, and inter-filament coupling currents, as well as ohmic effects. The DISCC model offers a massive reduction of the computational time compared to fully detailed FE models and still accounts for all types of loss and magnetization contributions. As a result, Rutherford cables homogenized with the DISCC model can be directly included in FE models of magnet cross-sections for efficient electro-magneto-thermal simulations of their transient response. We present two possible FE formulations for the implementation of the DISCC model, a first one based on the h-phi-formulation, and a second one based on the h-phi-a-formulation, which is well suited for an efficient treatment of the ferromagnetic regions in magnet cross-sections.