MHD modeling of plasma compression to high pressure with capacitive-driven solid shell implosions

Isotropic high-pressure plasma could be used to compress targets for equation of state studies, for generating fusion reactions, for accelerating projectiles to high speed and for other high-energy density endeavors. One way to generate such high-pressure plasma is to compress a modest pressure gas via implosion of a solid shell by a pulsed electrical discharge. The pressure of an ideal gas characterized by a constant ratio of specific heats Γ that is undergoing adiabatic compression scales as ρ^Γ where ρ is the mass density. Whereas Γ may not be constant for realistic compressing plasmas, it is certainly always greater than unity. Since the ratio of final to initial mass density can be greater for spherical compression than for cylindrical compression, spherical compression offers an opportunity to achieve substantial pressure increase. Quasi-spherical compression of a solid shell has been achieved in the laboratory and, in this paper, we discuss in detail numerical simulations that were used to guide and interpret such experiments. The numerical simulations are performed with MACH2; an unsteady resistive-MHD code for materials that may exist in any of the solid, liquid, gas and plasma states. These simulations illustrate how Mbar pressures can be achieved in the laboratory using presently available pulsed power technology.