Issues in the 2-D simulation physics of high-performance Z-pinch experiments

Summary form only given, as follows. Recent experiments conducted on the Sandia Z accelerator have continued the progress which began with the Saturn large-wire-number array implosions. Included in this progress was the discovery that total radiated energy is roughly independent of pinch length leading to improved power/length performance for short length pinches; the use of "nested" arrays to reduce instability effects, increase power and decrease pulsewidth; and the employment of on-axis cylindrical foam targets to create high-temperature (>200 eV) "dynamic hohlraums". Two-dimensional simulations have confirmed and provided an explanation for the results from short length pinches and produced good matches to measured currents, radiation powers and energies for a variety of experimental configurations. Simulations of nested array implosions and dynamic hohlraum experiments have also reproduced important results and in some cases were able to provide accurate predictions of experimental results. In other cases, the experimental performance has not matched the simulation results, at times with better experimental performance than expected. In this presentation, we will review the successful match which has been achieved of 2-D simulations to experimental data and examine the underlying physical mechanisms which appear to be important. In addition, comparisons will be made with experiments which have not been as well matched, and examine possibilities for the underlying physical mechanisms which may be responsible.