High Convergence Gas-Filled Cylindrical Implosions at the OMEGA Laser Facility

Deceleration-phase Rayleigh-Taylor instability (RTI) growth during the inertial confinement fusion (ICF) implosions affects the implosion performance significantly as it mixes the cold ablator material into the fuel. Precise measurements of such instability growth are essential for both validating the existing simulation codes and improving our predictive capability. RTI measurements on the inner surface of a spherical shell are limited and are often inferred indirectly at limited convergence. In contrast, cylindrical implosions allow for direct and precise measurements of the inner surface while retaining the effects of convergence, which are known to modify RTI growth rates through Bell-Plesset effects. Earlier we have demonstrated RTI growth to be scale-invariant between the cylindrical targets at OMEGA and similar targets at the NIF that are scaled up by a factor of 3 in the radial dimension at a relatively low convergence of CR~2.5 using 300 mg/cc foam filled cylindrical implosions. Here we demonstrate 10 mg/cc propane gas filled cylindrical implosions at the OMEGA laser facility reaching a CR of 7 at re-shock. We compare the RTI growth measurements to 2D xRAGE calculations. Designs for similar higher convergence cylindrical implosions at NIF are currently underway.