Role of hot electrons in shock ignition constrained by experiment at the National Ignition Facility

Abstract

Shock ignition is a scheme for direct drive inertial confinement fusion that offers the potential for high gain with the current generation of laser facility; however, the benefits are thought to be dependent on the use of low adiabat implosions without laser–plasma instabilities reducing drive and generating hot electrons. A National Ignition Facility direct drive solid target experiment was used to calibrate a 3D Monte Carlo hot-electron model for 2D radiation-hydrodynamic simulations of a shock ignition implosion. The α=2.5 adiabat implosion was calculated to suffer a 35% peak areal density decrease when the hot electron population with temperature Th=55 keV and energy Eh=13 kJ was added to the simulation. Optimizing the pulse shape can recover ∼1/3 of the peak areal density lost due to a change in shock timing. Despite the harmful impact of laser–plasma instabilities, the simulations indicate shock ignition as a viable method to improve performance and broaden the design space of near ignition high adiabat implosions.