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 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.

Subjects

Boris integrator

DIII-D

Fast ions

JET

Neutral beam injection

Particle tracking

Spectral deferred corrections

Physics - Computational Physics

Computer Science - Numerical Analysis

Mathematics - Numerical Analysis

DDC Class

004: Informatik

510: Mathematik

530: Physik

Publication version

publishedVersion

Lizenz

https://creativecommons.org/licenses/by/4.0/

Name

2021_CPC_Final.pdf

Size

3.16 MB

Format

Adobe PDF

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