Spatial characteristics of the optogalvanic effect in striated rare-gas discharges

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Abstract
The spatial variation of the optogalvanic (OG) signal resulting from visible laser irradiation of rare-gas positive column discharges has been investigated for the case of standing striations. The OG signal was observed to periodically change polarity as the laser was scanned transversly across the bright and (relatively) dark regions of the column. Transitions involving the 3P2,0 metastable levels were found to be everywhere opposite in polarity to those originating on freely radiating levels. The effects of trapped resonance level emission, and collisions of the second kind involving metastables are proposed to be important in determining the OG signal polarity for excitation in certain discharge regions.