Spherical Rayleigh-Taylor growth of three-dimensional broadband perturbations on OMEGA

Spherical Rayleigh-Taylor (RT) growth experiments of three-dimensional (3D) broadband nonuniformities were conducted in the acceleration phase of spherical implosions on OMEGA [T. R. Boehly, Opt. Commun. 133, 495 (1997)]. The targets consisted of 20- and 24-μm -thick plastic spherical shells having diagnostic openings for backlighter x rays to image shell modulations. Experiments were conducted with square laser pulses at a low drive intensity of ∼2 × 10¹⁴ W/cm², high drive intensity of ∼1 × 10 ¹⁵ W/cm², and a shaped pulse consisting of a low-intensity foot and high-intensity drive part (peak intensity of ∼1 × 10 ¹⁵ W/cm²). In low-intensity experiments, large RT growth was measured, resulting in shells being broken up by 3D modulations at the end of the drive. In the high-intensity experiments, no RT growth of the 3D modulations was detected. In the shaped-pulse experiments, perturbations grew during the low-intensity part of the drive and were stabilized later during the high-intensity part of the drive. The measured RT growth stabilization with the high-intensity drive was similar to previous observations in planar geometry [V. A. Smalyuk, Phys. Rev. Lett. 101, 025002 (2008)].