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

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 μs-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 (τstag) and average stagnation pressure (Pstag, the pressure at the origin, averaged over τstag) are determined by evaluating a wide range of liner initial conditions. For high-M flows, τstag ∼ ΔR/v0, where ΔR and v0 are the initial liner thickness and velocity, respectively. Furthermore, for argon liners, Pstag scales approximately as v015/4 over a wide range of initial densities (n0) and as n01/2 over a wide range of v0. The approximate scaling Pstag ∼ M3/2 is also found for a wide range of liner-plasma initial conditions.