A Novel Pseudo-Spectral Method to Suppress Numerical Cherenkov Instabilities in Particle-in-Cell Plasma Simulations*

The Lorentz-boosted frame technique can successfully speed up plasma acceleration simulations with the electromagnetic particle-in-cell (PIC) method by orders of magnitude. However, the speedup may be affected if the simulation timestep becomes limited by the Courant condition. This occurs when the grid cell size in the transverse direction becomes smaller than in the longitudinal direction in the boosted frame of the simulation. In this work, we present a novel formulation of the pseudo-spectral PIC method that allows us to overcome this limitation while preserving accuracy and stability with regard to the numerical Cherenkov instability (NCI). The details of the method and its applications to the modeling of plasma accelerators will be presented.