Relativistic modeling capabilities in perseus extended MHD simulation code for HED Plasmas

Summary form only given. We discuss the incorporation of relativistic modeling capabilities into the PERSEUS extended MHD simulation code for high-energy-density (HED) plasmas, and present the latest simulation results. The use of fully relativistic equations, in conservation form with source terms, enables the model to remain self-consistent when velocities and pressures become relativistic in simulations of such phenomena as X-pinches, hybrid pinches, and laser-plasma interactions. One of the most challenging aspects of a relativistic implementation is the recovery of primitive variables (density, velocity, pressure, etc.) from the conserved quantities, which must be performed at each time step of a simulation in order to compute the flux quantities. In non-relativistic simulations, this recovery can be accomplished using straightforward algebra. When the equations are made relativistic, the primitive variable recovery is much more complicated, and has thus far been a major impediment to nonlinear two-fluid simulations of relativistic HED plasmas. We have recently reduced the central part of this recovery problem to the algebraic solution of a fourth-order polynomial, which not only enables relativistic simulations, but improves their efficiency and accuracy. Our code recovers expected results in the non-relativistic limit, and, we expect, will reveal new physics in the relativistic regime.