The Nike KrF laser facility: Performance and initial target experiments

TLDR

Krypton‑fluoride lasers are attractive for fusion because their large bandwidth (~THz) enables rapid beam smoothing and their short wavelength (¼ µm) ensures good laser–target coupling, and the Nike facility is a newly completed 56‑beam KrF laser at the Naval Research Laboratory. Nike was built to investigate hydrodynamic instabilities in ablatively accelerated planar targets, and this review reports on its ability to deliver uniform illumination and uniform target acceleration. Nike’s 1 THz bandwidth yields highly uniform focal spots, and early experiments demonstrate spatially uniform ablation pressures (Δp/p < 2 %) and target acceleration over distances adequate for studying hydrodynamic instability while preserving planarity.

Abstract

Krypton-fluoride (KrF) lasers are of interest to laser fusion because they have both the large bandwidth capability (≳THz) desired for rapid beam smoothing and the short laser wavelength (1/4 μm) needed for good laser–target coupling. Nike is a recently completed 56-beam KrF laser and target facility at the Naval Research Laboratory. Because of its bandwidth of 1 THz FWHM (full width at half-maximum), Nike produces more uniform focal distributions than any other high-energy ultraviolet laser. Nike was designed to study the hydrodynamic instability of ablatively accelerated planar targets. First results show that Nike has spatially uniform ablation pressures (Δp/p&amp;lt;2%). Targets have been accelerated for distances sufficient to study hydrodynamic instability while maintaining good planarity. In this review we present the performance of the Nike laser in producing uniform illumination, and its performance in correspondingly uniform acceleration of targets.