PULSED ALKALI-VAPOR LAMPS.
ARMY ELECTRONICS COMMAND FORT MONMOUTH N J
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The development of nonreactive tube bodies, such as lucalox and sapphire, has in recent years resulted in increased alkali-metal-vapor lamp research. Presently, sodium vapor lamps are available for lighting applications. Cesium, sodium, potassium, rubidium, and some mixtures of these gases were studied. These studies were directed toward pulse operation, which has been generally neglected by investigators because it was considered unfeasible. The reason for this is the requirement for high-temperature operation to maintain high gas pressures for efficient light output and the belief that this is inconsistent with achieving a high degree of depth of modulation. Greater than 95 depth of modulation was demonstrated without sacrificing efficiency. The influence of the environmental and operating conditions on the tube design has been determined. Careful consideration has to be given to atmospheric oxidation problems, thermal shocking of the envelope, and selection of electrode materials. These factors can cause early failure owing to end cap leakage, body cracks, or sputtering that reduces the light output. The influence of the mode of operation on the tube design and the failure mechanisms will be discussed. Author
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