Optogalvanic effects in the obstructed glow discharge

An anomalously strong 594.5-nm optogalvanic effect is observed in an obstructed glow discharge in 1.0 Torr of Ne occurring between plane parallel Al electrodes separated by 1.0 cm. The absolute size of a steady-state optogalvanic effect is characterized by a dimensionless ratio of the change in power delivered to the load resistor over the absorbed laser power. A ratio of −400 for the 594.5-nm effect is observed in the obstructed glow discharge, while ratios of −6 are typical for the 594.5-nm effect in the positive column discharge. The 594.5-nm effect in the obstructed glow discharge results from a laser induced depletion of metastable atoms which play an important role in electron emission from a cold cathode.