Tretiak, KrasymyrKrasymyrTretiakBuchanan, JamesJamesBuchananAkers, RobRobAkersRuprecht, DanielDanielRuprecht2021-04-142021-04-142021-07Computer Physics Communications 264: 107876 (2021-07)http://hdl.handle.net/11420/9256Modelling neutral beam injection (NBI) in fusion reactors requires computing the trajectories of large ensembles of particles. Slowing down times of up to one second combined with nanosecond time steps make these simulations computationally very costly. This paper explores the performance of BGSDC, a new numerical time stepping method, for tracking ions generated by NBI in the DIII-D and JET reactors. BGSDC is a high-order generalisation of the Boris method, combining it with spectral deferred corrections and the Generalized Minimal Residual method GMRES. Without collision modelling, where numerical drift can be quantified accurately, we find that BGSDC can deliver higher quality particle distributions than the standard Boris integrator at comparable cost or comparable distributions at lower cost. With collision models, quantifying accuracy is difficult but we show that BGSDC produces stable distributions at larger time steps than Boris.en0010-46552021North Holland Publ. Co./Elsevierhttps://creativecommons.org/licenses/by/4.0/Boris integratorDIII-DFast ionsJETNeutral beam injectionParticle trackingSpectral deferred correctionsPhysics - Computational PhysicsPhysics - Computational PhysicsComputer Science - Numerical AnalysisMathematics - Numerical AnalysisInformatikMathematikPhysikJournal Article10.15480/882.342410.1016/j.cpc.2021.10787610.15480/882.34242005.07705v2Journal Article