Hybrid Simulation Algorithms for Plasma Accelerators and Fast Ignition

Summary form given only. We describe hybrid PIC algorithms which are used to model plasma jet accelerators for use in fusion energy research and other HEDP applications. An electron-magnetohydrodynamics (EMHD) model has been developed and ported to the 3-D EM-PIC code Lsp to allow for modeling of dense plasma jets. This model, which uses PIC particles for ions and assumes that the electrons form a fluid which maintains the quasi-neutrality of the plasma, circumvents the need for prohibitively small timesteps needed to resolve electron plasma frequencies at high densities. Hall physics, important to the description of plasma jets, but usually neglected in standard MHD, are retained in this formulation. Plasma jet simulation results using the EMHD algorithm are presented and are compared to implicit PIC simulations at intermediate plasma densities (~10¹⁶ cm^-3). We have also ported a radiation transport model into Lsp for use in hybrid simulations of fast-ignition (FI) plasmas. The radiation energy density is described by a single diffusion equation with spectrum-averaged opacities and absorption coefficients ("single-group" model). The source term is a sum over integrated Planck functions at the local temperature of each plasma species. A flux-limiter is used to bound the radiation flux in the low-opacity limit. The radiation equation is solved simultaneously with the plasma equations. We will show results applying the model to sample FI calculations.