Studies of oxide-cathode/low pressure discharge lamps in a manufacturing test cell

Abstract

A UHV manufacturing test cell (MTC) has been constructed for in-situ studies of the preparation, processing, activation and operation of BaSrCa triple oxide and other cathodes in gas discharge lamps and vacuum tubes. A wide range of variables critical to cathode/device performance (e.g. cathode processing, gas pressure and composition, component configuration and electrical parameters) can be established accurately and altered systematically under highly controlled conditions. A wide range of diagnostic techniques, including gas analysis, plasma emission spectroscopy, noise analysis of radiant emission and plasma power, spectrally resolved imaging and laser based diagnostics of both the plasma and the cathodes surface, are incorporated into, or have access to, the MTC. The MTC's capabilities are illustrated by several results from a study of low pressure deuterium (D 2) gas discharge lamps, namely: (i) gas analysis during cathode breakdown and activation; (ii) emission spectroscopy of the negative glow and positive column and (iii) instabilities in the UV output. The MTC is giving insight into critical aspects of gas discharge device design, processing and operation.