Status of electra: a repetitively pulsed, electron beam pumped KrF laser facility

Abstract

Summary form only given. Electra is a repetitively pulsed, electron beam pumped laser system at the Naval Research Laboratory. It is used to develop the technologies required for a large, durable krypton fluoride (KrF) laser driver for Inertial Fusion Energy (IFE). Each of the two pulsed power systems of the main amplifier operates at 400-550 kV, 70-120 kA, and with a 140 ns FWHM pulse duration. The system can run at 5 Hz continuously for 10/sup 5/ shots without refurbishment and has been used to test laser components for up to 10,000 shots per day for several days. This presentation will give an overview on the progress of the Electra Laser Facility and present recent advances that include: (i) high laser output energy of 500 J per shot during a 10 shot burst at 1 Hz with the main amplifier configured as an oscillator; (ii) high electron beam energy deposition efficiency into the laser gas by eliminating the anode foil and by patterning the electron emitter into strips; (iii) elimination of the transit-time instability in a diode with a large area, parallel plate anode/cathode configuration, (iv) cooling of the pressure foil by periodically deflecting the laser gas towards the hibachi, and (v) construction of a pre-amplifier pulsed power system (front end) that will operate with a rep-rate of 5 Hz, at 150-175 kV, 68-80 kA, and a flat-top pulse duration of 40 ns. This system uses a fast gas Marx, a pulse forming line, a single stage magnetic switch, and transit time isolators. In addition, it will also serve as a test bed for a laser gated and pumped thyristor that is currently under development at Titan PSD, Inc.