Numerical simulations of plasma working fluid compression of a cylindrical copper target liner

Summary form only given, as follows. Experiments performed by Degnan et al. Have been carried out to study the compression of a cylindrical copper target with a hydrogen working fluid. The working fluid is produced by a 350 kJ electrical discharge through a hydrogen gas that is initially at room temperature and 40 torr in a coaxial plasma gun. This discharge pushes the hydrogen gas from the plasma gun into a dynamic chamber that is formed by a quasi-spherical aluminum outer liner, a cylindrical copper inner liner, and converging electrodes at /spl plusmn/45/spl deg/ with respect to the equator of the quasi-spherical liner. The discharge heats and compresses the hydrogen gas-which we now refer to as the working fluid-as it pushes it into the chamber. A second electrical discharge of about 5 MJ from the Shiva Star capacitor bank compresses the quasi-spherical aluminum liner that is filled with the working fluid. The temperature of the working fluid is made sufficiently high by the first discharge-on the order of 1 eV-that the sound speed is faster than the implosion speed of the quasi-spherical liner. This allows for ´shockless´ compression of the inner cylindrical copper target. Most previous numerical simulations of this system with the MHD code MACH2 have included only the compressing liners, and not the plasma gun. Therefore, these simulations assumed the compressing working fluid to be of uniform temperature and mass density. Recent simulations have been made for the entire coupled system of plasma gun and compressing liners as illustrated in the top figure. As a consequence, the effect of nonuniform working fluid on the system has been investigated, and results will be presented for the first time.