The anticipated behavior of uranium oxide vapor bubbles produced by the capacitor discharge vaporization (CDV) method in the Fuel Aerosol Simulant Test (FAST) Facility is discussed on the basis of relatively simple physical models. Results of calculations for the rate of bubble rise and for heat and mass transfer rates are presented. Parametric studies indicate that future analysis efforts should emphasize the diffusion condensation process and the loss of heat from the bubble by radiation. Transfer of heat in the surrounding sodium is rapid enough that simplified models should be adequate. No important effects were noted in connection with bubble depth, initial quantity of UO/sub 2/, or initial superheat.

Recent experiments with high Z disks on the Argus facility have exteanded our knowledge of the temperature (inferred from the slope of the hard x-ray spectrum) of laser generated suprathermal electrons, from the previous regime of 1 less than or equal to Z less than or equal to 30 to the Z approx. = 80 regime. The systematic rise of temperature with Z is theoretically analyzed. We believe that material albedoes (electron reflectivity) which increase with Z can account for this behavior, since electrons can make multiple passes through the region of resonant electric fields and are thus reheated. We treat this effect quantitatively and obtain reasonable agreement with experiment. The effects of magnetic fields and filamentation are also examined.