Instability Growth in Cylindrical Implosions at Convergence Ratio 5

Hydrodynamic instability growth is a key factor limiting performance in inertial confinement fusion implosions, and growth is further enhanced in convergent geometry due to Bell-Plesset effects. Direct measurements in spherical systems are challenging, but cylindrical systems include the effects of convergence while retaining diagnostic access to the unstable interface. We present results from laser-driven cylindrical implosions at convergence ratio CR=5 (CR=initial radius/final radius), the highest yet achieved in these experiments, for three different sizes of target. Hydrodynamic growth of an initial perturbation occurs through a mix of the buoyancy-driven Rayleigh-Taylor instability during the deceleration phase and Bell-Plesset effects, and analytic models are employed to identify key differences in these targets and previous experiments at lower CR. The experimental results compare favorably with radiation-hydrodynamics modeling. Designs that push to higher CR through the use of gas-filled cylinders are presented.