Three-dimensional particle-in-cell simulations of ion-driven parametric instabilities

HERCULES, a massively parallel three-dimensional hybrid particle-in-cell (PIC) code, implemented on the CRAY-T3D, is presented. The code is based on a physical model, described in a previous report, where the electrons are modeled as an adiabatic fluid with an arbitrary ratio of specific heats γ, and the electromagnetic field model is based on a temporal WKB approximation. On a CRAY-T3D with 512 processors, the code requires about 0.6 μs/particle/time step. The largest test problem performed with this code consists of a computational mesh of 4096×64×64 (16 million) cells, and a total of 256 million particles, and corresponds to a plasma volume of 250 μm×62.5 μm×62.5 μm. This code is the first PIC code capable of simulating ion-driven parametric instabilities in a large plasma volume, and it offers a unique opportunity for examining issues that are potentially vital to inertial confinement fusion (ICF), e.g., nonlinear ion kinetic effects and their role in nonlinear saturation mechanisms. Applications of H...