Abstract: This invention relates to transversely-excited gas lasers, in which the gas may be at atmospheric or greater pressure and in which the gas is excited by means of a distributed electric discharge between two electrodes. The electrodes, which are preferably elongate, are such that an initial trigger discharge occurs between minor trigger portions of the electrodes which conditions the discharge gap between the electrodes resulting in a distributed, preferably glow-type discharge, between the major portions of the electrodes causing lasing action in the gas. The trigger discharge preferably generates electro-magnetic radiation of high intensity to cause volume photo-ionization of the gas. The electrodes may be composite in form, each having a trigger electrode and a main discharge electrode that are directly electrically connected to each other.

Abstract: This invention provides a compact high voltage electric switch having a fast switching time. The switch comprises two spaced-apart main electrodes defining a breakdown gap, in which an insulating gas is present, and a trigger means in close proximity to the gap to provide electrically generated electro-magnetic radiation of high intensity which causes large-scale volume photo-ionization of the gas and thus breakdown of the gap. The trigger means may conveniently be one or more trigger electrodes, with a trigger discharge occurring between the trigger electrode and one of the main electrodes or between two trigger electrodes. In a preferred embodiment, the main electrodes are flat and the trigger means is a surface gap spark plug centrally mounted in one of the main electrodes, with the trigger discharge occurring between the spark plug and the main electrode in which it is mounted.