Quench Transient Simulation in a Self-Protected Magnet with a 3D Finite-Difference Scheme

The quench process in a superconducting magnet is inherently transient and three-dimensional (3D). In many cases, such as magnets protected by active protection systems, this transient can be accurately simulated with a two-dimensional model. However, a more complex 3D model is required in the case of a self-protected magnet. Simulations are particularly challenging due to physical and geometrical features, such as highly non-linear material properties, sudden appearance of localized heat generation, non-isotropic conductors, and relatively thin insulation layers. In this work, it is shown how the quench and heat diffusion in 3D geometry can be accurately yet rapidly simulated using the finite-difference method. The coupled electro-thermal problem is solved with a semi-implicit Euler method. This 3D approach is included as a new feature in the STEAM-LEDET quench simulation software. As a study case, a simulation of the transient following a quench occurring in one of the self-protected LHC magnets is presented. Simulation results are found in excellent agreement with experimental results. The influence of 2D and 3D geometry, inter-filament coupling loss, and quench location on the simulated transient is discussed.