title: Elimination of numerical Cherenkov instability in flowing-plasma particle-in-cell simulations by using Galilean coordinates.
abstract: Particle-in-cell (PIC) simulations of relativistic flowing plasmas are of key interest to several fields of physics (including, e.g., laser-wakefield acceleration, when viewed in a Lorentz-boosted frame) but remain sometimes infeasible due to the well-known numerical Cherenkov instability (NCI). In this article, we show that, for a plasma drifting at a uniform relativistic velocity, the NCI can be eliminated by simply integrating the PIC equations in Galilean coordinates that follow the plasma (also sometimes known as comoving coordinates) within a spectral analytical framework. The elimination of the NCI is verified empirically and confirmed by a theoretical analysis of the instability. Moreover, it is shown that this method is applicable both to Cartesian geometry and to cylindrical geometry with azimuthal Fourier decomposition.
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Remi
authors.initials: R
authors.lastname: Lehe
authors.affiliation: Center for Free-Electron Laser Science & Department of Physics, University of Hamburg, 22761 Hamburg, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Kirchen
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.|University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Brendan B
authors.initials: BB
authors.lastname: Godfrey
authors.affiliation: Center for Free-Electron Laser Science & Department of Physics, University of Hamburg, 22761 Hamburg, Germany.
authors.forename: Andreas R
authors.initials: AR
authors.lastname: Maier
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Vay