A laser efficiency of 4.2% at 4.2-J output has been obtained from a self-sustained discharge-pumped XeCl laser using a novel high-voltage prepulse technique to provide efficient energy transfer from a low-impedance transmission line to the load. High-pressure discharge-pumped lasers now offer a reliable, efficient, and scalable alternative to e beams for many applications in the visible and ultraviolet regions of the spectrum.

Polycrystalline GaAs layers have been deposited on sapphire substrates by the AsCl3-Ga-H2 vapour transport method, and treated with caesium and oxygen. A layer 0·6 μm thick when operated as a photocathode has shown a luminous sensitivity of 70 μA lm−1, in transmission. Thicker layers have shown lower sensitivities. Spectral response curves are given for layers 0·6 and 0·8 μm thick and show yields out to 1·4 ev.An attempt has been made to relate the results to an elementary theory for transmission photocathodes.

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We have obtained nearly 1 J of blue-green radiation in 60-nsec pulses by Raman shifting an injection-locked XeCl laser in Pb vapor. The measured 50% Raman energy conversion has been observed in both oscillator and oscillator-amplifier experiments. These results indicate that an XeCl/Pb blue-green laser efficiency of >1.4% should be possible.

A verylowinductance triggered multichannel surface switch Rev. Sci. Instrum. 61, 852 (1990); 10.1063/1.1141453 Multichannel switch triggered by saturable reactorinduced voltage pulse Rev. Sci. Instrum. 54, 765 (1983);