One-dimensional radiation-hydrodynamic scaling studies of imploding spherical plasma liners

Abstract

One-dimensional radiation-hydrodynamic simulations are performed to develop insight into the scaling of stagnation pressure with initial conditions of an imploding spherical plasma shell or "liner." Simulations reveal the evolution of high-Mach-number (M), annular, spherical plasma flows during convergence, stagnation, shock formation, and disassembly, and indicate that cm- and {\mu}s-scale plasmas with peak pressures near 1 Mbar can be generated by liners with initial kinetic energy of several hundred kilo-joules. It is shown that radiation transport and thermal conduction must be included to avoid non-physical plasma temperatures at the origin which artificially limit liner convergence and thus the peak stagnation pressure. Scalings of the stagnated plasma lifetime ({\tau}stag) and average stagnation pressure (Pstag, the pressure at the origin, averaged over {\tau}stag) are determined by evaluating a wide range of liner initial conditions. For high-M flows, {\tau}stag L0/v0, where L0 and v0 are the initial liner thickness and velocity, respectively. Furthermore, for argon liners, Pstag scales approximately as v0^(15/4) over a wide range of initial densities (n0), and as n0^(1/2) over a wide range of v0. The approximate scaling Pstag ~ M 3/2 is also found for a wide range of liner-plasma initial conditions.