A 100-MW, electron-beam-pumped, argon fluoride laser for driving metal photo-cathodes

摘要

Summary form only given, as follows. A reliable and repeatable electron beam pumped ArF laser system to drive bare aluminum metal photo-cathodes is described. The system consists of a seven stage Marx generator charged to 65 kV/stage that in-turn pulse charges a 150-ns-long, 5.5-ohmm water PFL to voltages as high as 750 kV. The PFL utilizes a low-jitter, self-breaking SF/sub 6/ switch and is terminated in an adjustable radial resistor to match varying diode impedances and voltages from 250- to 375-kV. The optimized diode geometry consists of a flat velvet emitter (7.6 cm high /spl times/ 98 cm long) operated at 275 kV with an AK gap of 3.3 cm. The goal of attaining this 10-ohmm diode geometry at 275 kV was to match a sly developed thyratron based, 11-ohmm, 300-kV Blumlein driver. The velvet diode delivers 28 kA of current through a 3-mil Kapton foil into the 6.5-cm-diam by 100-cm-long laser gas region at 1500 torr. In order to achieve long foil lifetimes /spl sim/500 pulses, a pair of Helmholtz coils are used to guide, compress, and profile the electron beam. The output laser energy, power, and spatial profile from a stable resonator configuration have been shown to be reproducible to less than 5 percent over any 50 shot sequence without any adjustment to the system.