Über den Zusammenhang von Rauschen und Schichtungen der positiven Säule beim kataphoretischen He-Cd-Laser / Correlation of Noise and of Striations in the positive Column of the cataphoretic He-Cd-Laser

Abstract

The noise of the laser signal of the cataphoretic He-Cd-Laser (441,6 nm) and the spontaneous emission are investigated spectroscopically in end on and side on observation as function of Cd and He atom density. Commencing with Cd atom densities of 5 · 1014 cm-3 witish and blue striations of the positive column develop, that are directly connected with a sinoidal modulation of the voltage and the Cd, Cd+, and He emission. Electron temperature and Cd+ density are higher in the whitish zones than in the blue zones. The noise is attributed to plasma disturbations, for example Cd density fluctuations. The striations are explained on the basis of Wojaczek's theory of electron temperature waves.