NIF Characterization of Hot Electrons Applied to Shock Ignition, using 3D Monte-Carlo Tracking within 2D ALE Simulations*

When simulated hydrodyamically, shock ignition (SI) achieves the highest fusion energy gain at the scale of current inertial confinement fusion (ICF) facilities [1]. This gain is critical if ICF is to be used for energy generation. The National Ignition Facility (NIF) is the world's largest laser facility, with 1.8MJ of laser energy. The NIF has not yet achieved ignition and, although not designed for spherical direct drive, simulations indicate that polar direct drive (PDD) [2] could be used to ignite an implosion [3]. Scaled down SI experiments have shown that hot electrons generated from laser plasma instabilities (LPI) can degrade implosion performance. Hot electrons are a significant unknown that cannot be captured by hydrodynamics alone.

In this talk, the effects of hot electrons on a cryogenic SI implosion will be analysed using a 3D Monte-Carlo hot electron scattering and energy deposition model integrated into a 2D radiation hydrodynamics ALE code (Odin). The talk will focus on the key areas of hot electron preheat, shock support and shock timing. The hot electron source is based on a NIF experiment which used PDD illumination of a solid target to achieve SI-relevant ablation-plasma and intensity conditions, in addition to characterizing the hot electron population.

[1] Betti, R., et al. Physical review letters 98.15 (2007): 155001.

[2] Skupsky, S., et al. Physics of Plasmas 11.5 (2004): 2763-2770.

[3] Anderson, K. S., et al. Physics of Plasmas 20.5 (2013): 056312.