Laser-Direct-Drive Cryogenic Implosion Performance on OMEGAand Improvements to Illumination Uniformity and Ablation Pressure

Statistical modeling of direct-drive cryogenic implosions on OMEGA has led to substantial improvements in nuclear yield and metrics related to alpha-heating.^1,2 Techniques like these depend on the quality and range of data, and can be used to motivate experiments that refine further analyses. We report on studies in beam to target radius (R_b/R_t), in-flight aspect ratio (IFAR), and target radius (R_t) that reduce sources of uncertainty to enhance understanding. A similar approach might be used at facilities capable of high shot rates. New regression formulae are derived with respect to hydrodynamic seeds, growth, and effects, and degradations to yield and areal density, providing new perspectives on design. Optimization and extrapolation of these data motivate the development of future targets and laser systems, and suggest Lawson parameters >~1 are possible at incident energies at/below 2.6 MJ. Improvements in pressure and uniformity of the drive with R_b/R_t ~ 1 are found to be crucial. Since these experiments provide reference data for code validation studies, we also present comparisons with 2D DRACO, to be followed by detailed design studies and calculations in 3D HYDRA. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Numbers DE-NA0003856 and DE-NA0003868.

 

[1] V. Gopalaswamy et al., Nature 565, 581 (2019).

[2] A. Lees et al., Phys. Rev Lett. 127, 105001 (2021).