2D r-z Analysis of Hohlraum Experiments on Sphinx Machine using Axial Radiation from a Wire Array Z-pinch

Axial radiation flux from an aluminum Z-pinch on SPHINX machine is used to drive 5 mm diameter, 7 mm height hohlraums. 2006 results demonstrated that >200 GW power in 10 ns could be achieved creating >35 eV radiation temperatures. A 20-30 ns delay between the axial power starting time and the temperature rise had, however, to be explained. In this paper, analysis of this behaviour based on 2D r-z hydroradiative simulations is shown. A mobile source with plasma starting from 3 to 10 mm upstream of the holhlraum and with ~30 cm/mus velocity is an essential feature. This hypothesis of a mobile source is also inferred by Z-pinch zipper effect measurements and by pictures of Z-pinch implosion which show edge effects on the same spatial scale. Improvement of the configuration is considered, like using a conical pedestal to limit edge effects on the Z-pinch or using a power improved Z-pinch source. First experimental results with tins improved configuration are shown.