Time-step dependent force interpolation scheme for suppressing numerical Cherenkov instability in relativistic particle-in-cell simulations

TL;DR

The paper introduces the WT scheme, a time-step dependent force interpolation method that effectively suppresses the lowest order numerical Cherenkov instability in relativistic PIC simulations, enhancing simulation stability and flexibility.

Contribution

The WT scheme is a novel interpolation approach that reduces NCI growth rates for arbitrary time steps in relativistic PIC simulations.

Findings

WT scheme removes lowest order NCI growth rate

Numerical tests show slower instability growth with smaller time steps

WT scheme improves simulation quality and flexibility

Abstract

The WT scheme, a piecewise polynomial force interpolation scheme with time-step dependency, is proposed in this paper for relativistic particle-in-cell (PIC) simulations. The WT scheme removes the lowest order numerical Cherenkov instability (NCI) growth rate for arbitrary time steps allowed by the Courant condition. While NCI from higher order resonances is still present, the numerical tests show that for smaller time steps, the numerical instability grows much slower than using the optimal time step found in previous studies. The WT scheme is efficient for improving the quality and flexibility of relativistic PIC simulations.