Electro-Thermal Analysis of NI/PI DEMO TF Coils with Fixed and Non-Linear Inter-Layer Bridges

This paper presents an extension of previous numer ical analyses on Non/Partially-Insulated (NI/PI) DEMO Toroidal Field (TF) coils by introducing fixed resistance bridges between coil layers (RL) and non-linear RMIT resistance models. Using an upgraded 3D MATLAB electro-thermal model with refined mesh discretization, the effect of RL and RMIT bridges on temperature maxima (T<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub>), coil maximum voltage (Vcoil), and current redis tribution is assessed. Results show that implementing RL bridges in place of RT ones yields modest reduction in Tmax (10–30%), while coupling these with RMIT provides stronger thermal flat tening (∼35% T<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> reduction) and faster redistribution, at the cost of increased V<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">coil</sub>. These findings confirm the potential of partial-insulation strategies in improving the thermal stability of large-scale fusion magnets, while highlighting design trade-offs requiring further mechanical and experimental validation.