Target designs for energetics experiments on theNational Ignition Facility

摘要

The goal of the first hohlraum energetics experiments on the National IgnitionrnFacility (NIF) [G. H. Miller et al , Optical Eng. 43, 2841 (2004)] is to select the hohlraum designrnfor the first ignition experiments. Sub-scale hohlraums heated by 96 of the 192 laser beams onrnthe NIF are used to emulate the laser-plasma interaction behavior of ignition hohlraums. Thesern“plasma emulator” targets are 70% scale versions of the 1.05 MJ, 300 eV ignition hohlraumrnand have the same energy-density as the full-scale ignition designs. Radiation-hydrodynamicsrnsimulations show that the sub-scale target is a good emulator of plasma conditions inside thernignition hohlraum, reproducing density ne within 10% and temperature Te within 15% along arnlaser beam path. Linear backscatter gain analysis shows the backscatter risk to be comparablernto that of the ignition target. A successful energetics campaign will allow the National IgnitionrnCampaign to focus its e?orts on optimizing ignition hohlraums with e±cient laser coupling.