Nested stainless steel wire array variations on the Z accelerator

Summary form only given. Nested stainless steel wire arrays have been used extensively on Sandia's Z accelerator as a /spl sim/6.7 keV K-shell source (/spl sim/35 kJ, /spl sim/8 TW) for radiation effects studies. In this work, we discuss variations on the standard load (2:1 mass and radius ratios, total mass 1 mg/cm, 55 mm outer array diameter), pursued with the dual intent of radiation source optimization and investigation of physics issues that influence the K-shell source performance. Results will be presented from experiments in which the mass was varied by changing the wire number, keeping the 2:1 mass ratio and other parameters fixed. The 1 mg/cm total mass appears to produce near-optimal power, yield, and rise time, though the optimum may lie closer to 0.8 mg/cm. Additional experiments will be discussed in which the geometry of the outer array was kept fixed in the standard 55 mm diameter configuration while inner array radii between 25-75% of that of the outer array were fielded. The inner array mass was chosen to hold the implosion time constant. With >1 mm interwire gaps for all of these arrays, the inner array is expected to be transparent to the imploding outer array, and thus the effect of varying mass and velocity of the final implosion on K-shell production is studied. In these experiments, the 2:1 radius ratio of the standard load appears to be optimal. Also presented will be observations of non-0D implosion of the outer array, based on data from optical streak camera, laser shadowgraphy, Z-Beamlet bent crystal backlighting, and electrical circuit inductance diagnostics. The delayed trajectory observed is consistent with an initial ablation phase preceding the implosion, and observations of axially non-uniform ablation and trailing mass will be presented as well. Finally, circuit diagnostics have been used to infer the electrical energy input to the pinch, which can be compared to the X-ray output in order to address energy balance in fast Z-pinches.