PRODUCTION AND CHARACTERIZATION OF LARGE PLASMAS FROM GAS BAG TARGETSON NOVA

Large plasmas are created by illuminating gas-filled thin-walled ballo on-like targets using the Nova laser [E. Campbell et al., Rev. Sci. In strum. 57, 2101 (1986)]. The targets consist of a 5000-6000 Angstrom s kin surrounding 1 atm of neopentane, which, when ionized, becomes a pl asma with an electron density of 10(21) electrons/cm(3). X-ray images of the gas bag target are used to evaluate the size and uniformity of the plasma by comparison with LASNEX [R. M. More, J. Quant. Spectrosc. Radiat. Transfer 27, 345 (1982)] simulations. The gas bags are heated with converging and diverging beam spots. The most uniform plasmas ar e created by illuminating the target with large converging beam spots that overlap to cover most of the surface of the gas bag. The gas bag plasma is heated to a peak temperature of approximately 3.5 keV, with 25 kJ of 3 omega laser light in a 1 ns square pulse. (C) 1995 American Institute of Physics.