Ignition Designs*

The three-shell Revolver target[1] proposed for direct-drive ignition at the National Ignition Facility (NIF) utilizes a large 6-mm beryllium shell as an ablator. This ablator will be subjected to significant levels of laser imprint arising directly from the NIF laser beams illuminating the target without sufficient laser smoothing. Initial studies[2] have indicated that such imprint can severely distort the incoming shell and lead to ignition failure. Two-dimensional simulation results, employing nonlocal electron thermal transport and cross‑beam energy transport, will be presented investigating the implementation of several laser-smoothing techniques, as well as tamper layers within the target, to evaluate their efficacy in limiting the ensuing perturbation growth.

[1] K. Molvig et al., Phys Rev. Lett. 116, 255003 (2016).

[2] P. W. McKenty et al., Bull. Am. Phys. Soc. 62, BAPS.2017.DPP.NO7.5 (2017).