Effect of radiation losses on the compression of hydrogen by imploding solid liners

Summary form only given, as follows. Quasispherical solid liner implosions with little or no instability growth have been achieved experimentally. Applications for such implosions include the uniform, shock-free compression of some sort of on-axis target. One proposed means of obtaining such compression is to inject a 1 eV hydrogen plasma "working fluid" between the liner and the target, and imploding the liner around it. The high initial temperature assures that the sound speed within the liner is always greater than the inner surface implosion velocity of the liner, and the initial density is chosen so that the volume of the working fluid at peak compression is sufficiently large so that perfectly spherical convergence of the liner is not required. One concern with such an approach is that energy losses associated with ionization and radiation will degrade the effective gamma of the compression. To isolate and, therefore, understand these effects we have developed a simple "zero-dimensional" model for the liner implosion that accurately accounts for the shape and thickness of the liner as it implodes and compresses the working fluid. Based on simple considerations we make a crude estimate of the range of initial densities of interest for this technique. We then observe that within this density range, for the temperatures of interest, the lines are strongly self-absorbed so that the transport of radiation is dominated by bound-free and free-free processes. This approximate opacity is coupled to the simple model to determine the extent that radiation losses affect implosion dynamics. We find that over the density range of interest radiation loss effects are not significant.