Recent results for a 20 CM diameter, triple shell argon Z-pinch on the sphinx pulsed power generator

The Sphinx generator uses LTD technology to produce >4 MA pulsed power, driving large diameter (>=14 cm), long implosion time (>600 ns) aluminum wire array z-pinch implosions. A large diameter argon gas puff load developed by AASC for Sphinx was given initial testing in 2006. Specifically, we fielded a triple plenum, triple valve system that produces (1) a central 1 cm diameter gas column, (2) a thick "shell" flow between diameters of 1 and 9 cm, and (3) an outer thick "shell" over the diameter range 9 to 20 cm. The large 20 cm initial diameter is needed to get a long implosion time and to extract a significant part of Sphinx\´ stored energy. 0D modeling favors an implosion time of about 500 ns, more than a factor of two larger than previous experience with argon at many megamp currents. Recent testing of the nozzle on Sphinx took advantage of an improved initial radial gas distribution (more on- and near-axis mass). The resulting K-shell emission shows remarkably tight pinches (~2 mm in the K-shell) with < 10 ns overall pulse widths. Corrected for zipper, the intrinsic K-shell pulse width was under 5 ns. Additional results including X-ray and optical framing images will be shown.