Use of A 12 cm Dia. Nozzle for argon Z-pinches

We report the X-ray output of an argon Z-pinch as a function of the radial gas distribution. The tests, conducted on the Double-EAGLE simulator at ~3.5 MA peak current, utilized a large 12 cm diameter double-shell nozzle that was designed for use with the 300 ns rise-time pulse of the DECADE QUAD (DQ) pulsed power machine. By varying the plena gas pressures of the inner and outer shells, the net radial gas distribution could be changed as a function of radius. Previous work [1] has shown that a semi-uniform (in radius) distribution gives higher X-ray output than thin shell-like flows for gas Z-pinches. The present work reinforces that observation and demonstrates that the K-shell yield has a broad optimum (and the relative strength of the K continuum >;4 keV systematically changes) as the mass distribution becomes more peaked near the axis. Very high-quality K-emitting volumes (<; 5 ns pulse width from <;1 mm diameters) were achieved.