Long time implosion experiments with double gas puffs

Long time implosion experiments with argon double gas puffs have been conducted on the GIT-12 [S. P. Bugaev et al., Izv. Vyssh. Uchebn. Zaved., Fiz. 40, 38 (1997)] generator at the current level of 2.2–2.4 MA. A double gas puff was used as one of the alternative ways to improve implosion stability at implosion times from 230 to 340 ns. The results of these experiments were compared with two-dimensional snowplow simulations. The experiments and the simulations show that the final pinch is sufficiently stable when the inner-to-outer shell mass ratio is greater than 1. The maximum argon K-shell yield obtained in the experiments is 740 J/cm with 220 GW/cm radiation power. At the long implosion times, the K-shell yield obtained in the double gas puff implosion is twice the K-shell yield of a 4-cm-radius single gas puff, with more than an order of magnitude increase in radiation power.