An Adiabatic Fluid Electron Particle-in-Cell Code for Simulating Ion-Driven Parametric Instabilities

A hybrid particle-in-cell (PIC) method is presented in which the electrons are modeled as an adiabatic fluid with an arbitrary ratio of specific heats ?. The electromagnetic field model is based on a temporal Wentzel?Krammers?Brillouin approximation. The method is a new tool for simulating ion-driven parametric instabili?ties which often exist in laser-produced plasmas. The method is general and does not depend on the number of spatial dimensions. The method will model the plasma behavior correctly even in situations where the electron Debye shielding is not negligible. Test simulations of ion Landau damping in both one and two dimensions are performed, and the results are in excellent agreement with linear Vlasov theory. Test simulations of stimulated Brillouin scattering (SBS) in one and two dimensions are performed, and the results indicate that when the intensity of the driving electromagnetic field is sufficiently high, backscatter SBS is dominant at early time while side-scatter SBS is dominant at late time. For the test cases in which a high-frequency driving electromagnetic field is present, our hybrid PIC method offers a substantial saving in computational time over explicit PIC methods that require the time scale of the driving electromagnetic field to be resolved.