Performance of the BGSDC integrator for computing fast ion trajectories in nuclear fusion reactors

Modelling neutral beam injection (NBI) in fusion reactors requires computing the trajectories of large ensembles particles. Slowing down times up to one second combined with nanosecond time steps make these simulations computationally very costly. This paper explores performance BGSDC, a new numerical stepping method, for tracking ions generated by NBI DIII-D and JET reactors. BGSDC is high-order generalization Boris combining it spectral deferred corrections Generalized Minimal Residual method GMRES. Without collision modelling, where drift can be quantified accurately, we find that deliver higher quality particle distributions than standard integrator at comparable computational cost or lower cost. With models, quantifying accuracy difficult but show produces stable larger Boris.