User defined elements in ANSYS for 2D multiphysics modeling of superconducting magnets

Abstract

Dynamic simulation of superconducting magnets is critical for the design of quench protection systems to prevent potentially damaging temperatures and high voltage from developing after magnet quench. Modeling these scenarios is challenging due to the many multiscale phenomena which impact magnet behavior. These range from conductor scale effects of quench and interfilament coupling currents up to the behavior of the magnet in its powering and protection circuit. In addition, a strong coupling between electromagnetic and thermal domains is required to capture temperature and field dependent material properties and quench behavior. We present a finite element approach which integrates the various effects into the commercial software ANSYS by means of programming new element types. This is shown capable of simulating the strongly coupled transient electromagnetic, thermal, and circuit behavior of superconducting magnets required for quench protection studies. A benchmarking study is presented which shows close agreement between the new ANSYS elements and a COMSOL Multiphysics implementation developed at CERN for dump resistor and Coupling Loss Induced Quench (CLIQ) based magnet protection of a Nb 3 Sn block dipole. Following this, the ANSYS implementation is shown reproducing strongly coupled quench back behavior observed during the test of a Nb 3 Sn superconducting undulator prototype at Lawrence Berkeley National Laboratory.

Overview of Identified Challenges in the Development Process of Superconducting Accelerator Magnets

“…The fast transients in superconducting magnets during a quench can induce high mechanical stress, and protecting against quenching becomes more complex as the quest for higher magnetic fields intensifies [44]. The challenges require interconnected simulation models across domains, emphasizing the increasing relevance of multi-physics numerical models that link thermal, mechanical, and electromagnetic components [45]. The issue of simulating non-linear transient effects in superconducting accelerator magnets is characterized as multi-domain, multi-physics, multi-rate, and multi-scale, involving the magnet, its circuits, and the power converter controller [46].…”

“…These domains involve multiple interconnected physical phenomena demanding a simulation infrastructure allowing model-order reduction while facilitating information exchange between different software packages. Quenches in the operation of superconducting magnets can cause damage to the surrounding infrastructure and circuitry, requiring special protection systems whose interactions with the magnet must be simulated, incorporating multi-physical properties, heat propagation equations, and mechanical models [45,47]. This modeling process, complicated by domain coupling and multiscale phenomena, necessitates using multiple simulation tools like Ansys ® and COMSOL ® in tandem to model the electromagnetic and thermal domain couplings.…”

Magnetization Current Simulation of High-Temperature Bulk Superconductors Using the ANSYS Iterative Algorithm Method

“…Research and development work on implementing self-developed numerical methods into the finite-element method (FEM) software ANSYS is ongoing at the Paul Scherrer Institute (PSI) for the purpose of modelling and optimizing the short-period and high-field staggered-array high-temperature superconductor (HTS) bulk undulators which are highly appreciated for the construction of compact free electron lasers (FELs) [1]- [3]. The idea of developing ANSYS comes from its powerful capability for mechanical or multiphysics-coupled simulations and its parametric design language (APDL) which allows the secondary development or the user-defined element [4]. Our ambitious goal is to develop adaptive numerical algorithms which could allow the electromagnetic modelling of HTS obeying the critical state model or the flux creep model (e.g., E-J power law), but with This work is supported by European Union's Horizon2020 research and innovation program under grant agreement No.…”

COMSOL implementation of the H-$ϕ$-formulation with thin cuts for modeling superconductors with transport currents

“…This issue did not emerge in our recent works [11], [14], since the non-conducting domains did not surround any net current in the models considered. Nonetheless, in many applications of interest, a net current is needed in the HTS domains [15]- [19].…”