Long time implosion experiments with double gas puffs

Long time implosion experiments with argon double gas puffs have been condu cted on the GIT-12 [S. P. Bugaev , 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 impl osion times from 230 to 340 ns. The results of these experiments were compa red with two-dimensional snowplow simulations. The experiments and the simu lations 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 o btained in the experiments is 740 J/cm with 220 GW/cm radiation power. At t he 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. (C) 2000 Amer ican Institute of Physics. [S1070-664X(00)02604-5].