Plasma Oscillations Some New Experiments

Download or read book Plasma Oscillations; Some New Experiments written by and published by . This book was released on 1962 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report deals with four features of self-generated u.h.f. oscilations in the gigacycle region in electron beam maintained plasmas in helium, neon, argon and mercur, at pressures of a few microns, operated at up to about 100 volts with an oxide coated thermionic cathode. (1) Frequency pulling has been found when the anode to cathode spacing is varied within certain limits, and is the more marked the less the divergence of the beam; production of a return beam from the anode may be enhanced if it is contaminated with cathode material. (2) The position of sharp onset of oscillatins along the beam has been measured from the abrupt appearence there of the 'spark' spectra He(II), Ne(II) and Hg(III), and has been found in this way to be determined roughly by the product of pressure, current and beam velocity. (3) Part at least of the fine structure of plasma concentration versus position curves along the beam has been shown to be due to falsification of probe data by the oscillating fields. (4) Results of some direct electron energy distribution measurements are given, which are in general accord with the theory of beam excitation of oscillations.