Electra: Durable Repetitively Pulsed 700 J, 100 ns Electron Beam Pumped KrF Laser System

摘要

Electra is a repetitively pulsed, electron beam pumped Krypton Fluoride (KrF) laser at the Naval Research Laboratory that is developing the technologies that can meet the Inertial Fusion Energy (IFE) requirements for durability, efficiency, and cost. Electra in oscillator mode has demonstrated single shot and rep-rate laser energies exceeding 700 J with 100 ns pulsewidth at 248 nm. Continuous operation of the KrF laser has lasted for more than 2.5 hours without failure at 1 Hz and 2.5 Hz. The measured intensity and energy per shot is reproducible in rep-rate runs of 1 Hz, 2.5 Hz and 5 Hz for greater than thousand shot durations. The KrF intrinsic efficiency is predicted to be 12% with measurements and modeling (Orestes Code). In addition we have compared Orestes with initial results of 23 J for the Electra Pre-Amplifier. The positive agreement between Orestes and our results lead allow us to predict that large KrF laser systems will meet the efficiency requirements for inertial fusion energy driver. The focal profile measurements show for single shot conditions recovery in less than 200 ms, the time needed for 5 Hz operation. Rep-rate focal profile measurements at 1 Hz show reproducibility in spatial extent and energy.