A Shock-Augmented approach to Laser Inertial Fusion

Shock ignition¹ enables high gain at low implosion velocity, easing the ablative Rayleigh-Taylor instability which degrades conventional direct drive. With this method, driving a strong shock requires high laser power and intensity, resulting in inefficiencies in the drive and the generation of hot electrons that can preheat the fuel. A new ‘shock-augmented ignition’ pulse-shape² is described which, by launching a strong shock, enables the shock-ignition of thermonuclear fuel, but with substantially reduced laser power and intensity requirements. The reduced intensity requirement with respect to shock-ignition limits laser-plasma instabilities, such as Stimulated Raman and Brillouin Scatter, reducing the risk of hot-electron pre-heat and restoring the laser coupling advantages of conventional direct drive. Simulations indicate that, due to the reduced power requirements, high gain (~100) ignition of large-scale direct drive implosions is possible within the power and energy limits of existing facilities such as the National Ignition Facility. Moreover, this concept extends to indirect drive implosions, which exhibit substantial yield increases at reduced implosion velocity. Shock-augmented ignition expands the viable ignition design-space of laser inertial fusion.