In glow discharges having a positive column with a constant emf and a series resistance, oscillations usually are observed in tube voltage, current, and light intensity. While current and voltage oscillations represent a modulation of only a few percent, the intensity decreases to zero between maxima in the positive column, but there is an appreciable steady component near the cathode. The intensity maxima move as positive striations toward the cathode, or as negative striations with a much higher speed toward the anode. Where positive and negative striations meet they stop for times up to 100 μsec.

The oscillations are often very stable and repeat themselves without change for hours. Often several modes exist and the discharge moves back and forth between them and appears unstable.

The data presented in this paper were obtained chiefly from argon discharges although similar phenomena occur in most other gases over a great range of pressure and current. A discussion of the mechanism producing the phenomena is given.

• Received 29 November 1948

DOI:https://doi.org/10.1103/PhysRev.81.248