Impact of external LEH hardware on implosion shape and laser-to-hohlraum coupling in indirect drive implosions at the National Ignition Facility*

In order to simplify and speed up integrated hydrodynamic simulations of indirect drive implosion experiments, such simulations historically have not included target components outside of the hohlraum near the laser entrance hole (LEH). More sophisticated simulations have shown evidence that aluminum ablated from the LEH washer enters into the laser beam paths, in particular in the presence of a large (4.0 mm diameter) LEH where the inner diameter (ID) of the washer is exposed to hohlraum wall emission. In order to quantify the impact of this effect on implosion velocity and shape, we are fielding an experiment where the washer ID was increased from 4.04 to 4.88 mm compared to its predecessor experiment [1]. Results and conclusions will be discussed.

 

[1] Kritcher et al. PoP, accepted (2021), DOI: 10.1063/5.0047841