Scaling of nested wire array Z-pinches on the Z accelerator

Summary form only given, as follows. Davis et al. (1997) Douglas et al. (1997) and Hammer et al. (1997) have shown the advantages of nested configurations for high current Z-pinches. Experiments have begun on the 20-MA Z accelerator to study these configurations using two nested wire arrays. For the first set of experiments, the outer array was chosen to be a 40 mm diameter with 240 wires which has been found to be the optimum single array which produced 200/spl plusmn/30 TW of X-rays. A second array was mounted internal to this array at a diameter of 20 mm. An initial scan keeping the final implosion time constant but varying the masses of the inner and outer arrays produced 250/spl plusmn/40 TW and reduced the X-ray pulsewidth from 6.5 to 4.8 ns for the lightest internal array, 470 /spl mu/g/cm. In this scan, the early implosions of the outer array, as its mass was decreased as the inner mass was increased, caused power coupling issues. A subsequent series of experiments kept the outer array mass constant at 1850 /spl mu/g/cm and varied the inner mass. This methodology revealed a new optimum inner mass of 1030 /spl mu/g/cm with a peak X-ray power of 290/spl plusmn/40 TW in a 4 ns pulse. The effects of wire array dynamics have also been studied by varying the number of wires in the inner array from 60 to 240 wires. In this paper, these results will be reviewed and compared to different 2D (r-z) radiation MHD codes and to results from a wire code.