Oscillations in Plasma II

Abstract

As previously reported, two or three plasma-electron oscillations of slightly different frequencies are simultaneously generated in a hot cathode discharge. The filled gas is mercury vapour at pressures of order of 1 micron. These oscillations can be observed by a Yagi antenna set apart from the discharge tube as well as by a probe in it. In the discharges the primary electrons form convergent and divergent beams. The oscillation of the highest frequency is generated by the convergent beam in the central part of the tube and this is that observed by many authors. The oscillation of the lowest frequency seems to be generated near the wall of tube by the divergent beam. Another oscillation having a middle frequency is often observed. This is generated at the periphery of the convergent beam.