Computational modeling of long implosion time aluminum z-pinches on the Saturn generator

Summary form only given. Long implosion time aluminum experiments have been carried out on the 7-MA Saturn accelerator at Sandia National Laboratories´. Such experiments are motivated by the incentive that longer implosion times translate to reduced cost and power flow risk to existing and future, high current generators. However, to achieve similar implosion velocities and subsequent powers as in the short pulse mode, i.e., 50 ns implosion time, simple scaling estimates indicate larger diameter loads are necessary (P/spl prop/mv/sup 3///spl Delta/r, v/spl prop/R//spl tau//sub imp/). This may lead to poor pinch performance: modification of initial conditions and instability growth over larger distances can comprise pinch quality. To investigate these issues, a wire number and radius scan were performed on Saturn maintaining a nominal implosion time of /spl sim/160 ns. The wire number scan was carried out with a 40 mm diameter array and wire numbers ranging from 32 to 282. The mass was essentially constant. Results indicate that although the radiated energy was basically the same for all cases, the FWHM and risetimes of the radiated power showed a substantial jump near the interwire gap spacing of 3 mm. In the radius scan, both the mass and radius of the inner array were varied to maintain a similar implosion time. The load diameter ranged from 32 to 50 mm. This approach allowed larger diameters to be explored while varying the implosion velocity to find the optimum peak power in K-shell emission. The radius scaling showed a general trend towards higher powers at larger diameters.