Harald L. Witting

Acoustic resonances in cylindrical high‐pressure arc discharges

Acoustic resonances were observed in high‐pressure (600 Torr) sodium‐mercury‐xenon discharges operated with ac input at power frequencies of 2–120 kHz. Three sizes of cylindrical sapphire arc tubes were operated at constant average powers of 400, 250, and 150 W, respectively. The observed resonance frequencies and arc shapes agree well with a simple analysis of standing pressure waves in cylinders. The results indicate that transverse resonances effectively average the gas temperature across the arc, while longitudinal resonances mainly involve the hot core of the discharge.

Mass‐Spectrometer Analysis of a Cesium Plasma

An experiment has been performed in order to determine the dominant ionic species in a cesium plasma in the Torr pressure range. The device consists of a planar thermionic converter with a small (25 μ diam) hole in the collector. Ions that pass through the hole are accelerated by an ion gun and analyzed in a magnetic mass spectrometer. It is found that atomic cesium ions are the dominant species in both the ignited and unignited modes of operation of the discharge. The molecular cesium ions Cs2+ and Cs3+ were also detected in the ignited mode. In addition, measurements were made of the total ion and electron currents that pass through the collector hole. Here the hole acts as a probe of the plasma adjacent to the collector.

Test results on pulsed cesium amalgam flashlamps for solid state laser pumping

Initial tests on experimental cesium amalgam flashlamps have yielded promising results. These lamps will pump Nd:YAG lasers with efficiencies that are comparable to those of conventional xenon and krypton flashlamps, but with substantially longer lamp life due to the vapor replenishment of the cesium cathode activator.