Tunable UV upgrade on OMEGA EP

Abstract

The OMEGA EP laser has been upgraded to provide a UV wavelength-tunable beam to support the study of wavelength detuning for the mitigation of cross-beam energy transfer in direct-drive inertial confinement fusion. The beamline delivers up to 0.5 TW in pulses up to 1-ns duration (0.1 TW up to 2.5 ns), to either the OMEGA or OMEGA EP target chambers with wavelength tunable from 350.2 to 353.4 nm. The upgrade leverages the existing optical parametric amplification (OPA) system in the short-pulse front end of OMEGA EP Beamline 1 for amplification of a new tunable, narrowband fiber front end over a broad spectral range. The tunable OPA output is spatially shaped to form a round OMEGA-like beam, which is amplified in the OMEGA EP beamline, then frequency tripled and characterized using the existing OMEGA EP long-pulse infrastructure. A new 3ω beam-transport system intercepts the tunable UV beam near the OMEGA EP target chamber and image relays it to the P9 port of the OMEGA target chamber for joint shots with the OMEGA 60-beam laser. Commissioning of the tunable UV capability has been completed, and four experimental campaigns have been supported with the tunable beam