Incorporating Energetic Particle Confinement in the DESC Stellarator Optimization Suite

Energetic particle loss can result in physically unbearable heat fluxes on the diverter and lower overall plasma energy. It has been shown that a proper optimization of the Γ_c metric described by V. V. Nemov et. al. in “Poloidal motion of trapped particle orbits in real-space coordinates” can reduce these losses by nearly a full order of magnitude. We have implemented this metric in the DESC optimization suite which allows for greatly improved multi-objective stellarator optimization because it is written in python using JAX and can be automatic-differentiable.