Abstract
The first results are reported from a repetitively pulsed, electron-beam-pumped angularly multiplexed krypton fluoride (KrF) laser system. This laser system, called Electra, was constructed at the U.S. Naval Research Laboratory. The technologies developed on Electra are scalable to a full-size fusion power plant beam line and should meet the inertial fusion energy (IFE) requirements for durability, efficiency, and cost. As in a full-size fusion power plant beam line, Electra is a multistage laser system that consists of a commercial discharge laser, a 175-keV electron-beam-pumped (40-ns flat-top) preamplifier, and a 500-keV (100-ns flat-top) main amplifier. Angular multiplexing is used in the optical layout to provide pulse length control and to maximize laser extraction from the amplifiers. The laser system initially demonstrated 452 J in a single shot and 1.585 kJ total energy in a one-second, 5-Hz burst. The preamplifier alone produces a 25-J KrF output with two angularly multiplexed beams. Extraction volumes were calculated for both a single-pass and a double-pass angularly multiplexed amplifier. A standard ray trace must be used to calculate the extraction volumes for the double-pass amplifier with focusing elements.
