Numerical analysis of non-insulated DEMO TF coils

TL;DR

This paper introduces a new 3-D numerical model for simulating charge, discharge, and quench processes in DEMO TF coils, coupling electrical and thermal physics to assess thermal stability and safety features.

Contribution

It presents an original, efficient numerical simulation tool specifically designed for large-scale DEMO TF coils, enabling detailed analysis of quench dynamics and thermal behavior.

Findings

The model successfully simulates charge/discharge and quench scenarios.

Localized bridges significantly affect current redistribution and thermal response.

Initial results highlight the importance of design features on coil safety.

Abstract

The design of small solenoids without/with-partial insulation among turns or layers has been proven to grant higher thermal stability than for standard insulated cases. This technology implies higher safety standards, by allowing for 1-100 V highest voltage in the single TF coil; at the same time, a passive/simpler quench protection systems (QPS) becomes a concrete opportunity. Besides, experiments and simulations on large-scale solenoids do not guarantee yet the same advantages, as the redistribution of currents after quench is not yet clear and the temperature margins allowed by LTS are narrower. The possibility for full internal energy dissipation is here discussed analytically, highlighting the already high final temperatures being reached and the limits of the held hypotheses. \\ This study presents therefore a new effective 3-D original numerical model, developed for simulating in a fast fashion charge/discharge and quench of a EUROfusion DEMO toroidal field (TF) coil, by coupling both electrical and thermal physics in the same solver. Its structure is explained as well as its first benchmarks. Finally, the first results are reported of a parametric study where only turn-turn localized bridges are considered, discussing the consequences and the future outlook for this simulation work.