Hotspot Parameter Scaling with Velocity and Yield for High Adiabat Layered Implosions on the National Ignition Facility

Abstract

This paper presents a study on hotspot parameters in indirect-drive inertially confined fusion implosions as they proceed through the self-heating regime. The implosions with increasing nuclear yield would reach the burning plasma regime, hotspot ignition and finally propagating burn and ignition. These implosions span a wide range of alpha heating from a yield amplification of 1.7 to 2.5. We show that the hotspot parameters are explicitly dependent on both yield and velocity and that by fitting to both of these quantities the hotspot parameters can be fit with a single power law in velocity. The yield scaling also enables the hotspot parameters extrapolation to higher yields. This is important as various degradation mechanisms can occur on a given implosion at fixed implosion velocity which can have a large impact on both yield and the hotspot parameters. The yield scaling also enables the experimental dependence of the hotspot parameters on yield amplification to be determined. The implosions reported have resulted in the highest yield(1.73x10^16+/-2.6%), yield amplification, pressure and implosion velocity yet reported on the National Ignition Facility.