Data versus Simulations for Gated LEH Images on NIF ICF Campaigns*

Laser entrance hole (LEH) size in a hohlraum has been shown to be important in interpreting the radiation drive [1] in indirect drive ICF experiments. However the time-dependent LEH size has not been routinely measured until the deployment of the G-LEH diagnostic [2] at the National Ignition Facility (NIF), which can provide 4-16 images from a single shot. We present a systematic study of measured data vs. simulations for the CH campaigns on NIF for gas fill densities of 0.3 to 0.6 mg/cc. We compare the measured LEH size vs. time to simulations using several different models for the atomic physics and electron heat transport. The comparison with the growth of the laser-heated gold plasma bubble, the change in brightness of inner beam spots due to time-varying cross beam energy transfer, and plasma instability growth near the hohlraum wall will also be discussed.

[1]. S MacLaren, M. Schneider, K. Widmann, et al., PRL 112 105003 (2014)

[2]. H. Chen, N. Palmer, P. Bell, et al., RSI, in press (2018)