Large diameter copper wire array implosions for K-shell x-ray generation on the refurbished Z machine

Summary form only given. Copper wire arrays have previously been fielded in large diameter (up to 70 mm) nested configurations on the 20 MA Z machine, with average Cu K-shell (8.4 keV) yields of 20 kJ typical. More recently, Cu K-shell source development studies have been performed on the refurbished Z machine, which in initial commissioning shots has produced just over 20 MA current in these loads. At full capability, the refurbished Z is anticipated to drive 25 MA z-pinch implosions with double the stored energy as previously available at the facility. Loads of 65 mm and 80 mm initial diameter have been studied to date at masses of 2-3 mg. The large diameter is required to obtain the high specific kinetic energy and the 5 keV electron temperature needed to generate appreciable K-shell excitation in Cu. Double and triple nested wire arrays were employed to mitigate the magnetic Rayleigh-Taylor instability which can dominate the implosion at these large diameters. Cu K-shell yield up to 25-30 kJ has been obtained along with time-gated pinhole images and K-shell spectroscopy. These data, along with plans for additional experiments on Z, will be discussed in the context of K-shell yield scaling impacted by energy loss through L-shell radiative cooling.