Development of a 12 cm diameter nozzle for argon Z-pinches on the decade quad

We report on the initial tests of a large diameter (12 cm) double shell nozzle designed for use with the 300 ns rise-time current pulse (>6 MA) of the DECADE QUAD (DQ) pulsed power machine. The nozzle employs unique features to simplify construction, enhance gas flow reproducibility, and reduce fabrication costs. With a large 4 cm recess, the gas flow at the pinch location is well collimated and nearly a uniform fill, a flow condition that has been shown Coleman, PL et al. (2001) to give better output than shell-like flows for gas z-pinches. Results with this nozzle on the double eagle simulator indicate that such long implosion time pinches are not hopelessly unstable. K-shell emission is at the levels expected from empirical scaling at other peak currents and implosion times. The overall morphology (pulse width and spatial extent) of the pinch can be varied from tight and concentrated to broad and extended by the choice of relative pressures in the plenums that drive the two nozzle shells.