National Ignition Facility laser performance status

TLDR

The National Ignition Facility (NIF) is the world's largest laser system. The study reports performance qualification tests of the first eight NIF laser beams. The facility employs a 192‑beam neodymium glass laser that delivers 1.8 MJ at 500 TW at 351 nm, with pulse shaping across two orders of magnitude and focal‑spot fluence control achieved through phase plates, spectral‑dispersion smoothing, and orthogonal‑polarization beam overlap, and performance was measured at 1ω and 3ω with and without focal‑spot conditioning. When scaled to full 192‑beam operation, these results demonstrate that the NIF will meet its laser performance design criteria and can simultaneously meet temporal pulse shaping, focal‑spot conditioning, and peak power requirements for two candidate indirect‑drive ignition designs.

Abstract

The National Ignition Facility (NIF) is the world's largest laser system. It contains a 192 beam neodymium glass laser that is designed to deliver 1.8 MJ at 500 TW at 351 nm in order to achieve energy gain (ignition) in a deuterium-tritium nuclear fusion target. To meet this goal, laser design criteria include the ability to generate pulses of up to 1.8 MJ total energy, with peak power of 500 TW and temporal pulse shapes spanning 2 orders of magnitude at the third harmonic (351 nm or 3omega) of the laser wavelength. The focal-spot fluence distribution of these pulses is carefully controlled, through a combination of special optics in the 1omega (1053 nm) portion of the laser (continuous phase plates), smoothing by spectral dispersion, and the overlapping of multiple beams with orthogonal polarization (polarization smoothing). We report performance qualification tests of the first eight beams of the NIF laser. Measurements are reported at both 1omega and 3omega, both with and without focal-spot conditioning. When scaled to full 192 beam operation, these results demonstrate, to the best of our knowledge for the first time, that the NIF will meet its laser performance design criteria, and that the NIF can simultaneously meet the temporal pulse shaping, focal-spot conditioning, and peak power requirements for two candidate indirect drive ignition designs.