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Ion Temperatures in the Plasma Betatron Experiment

by

William W. Zuzak

A thesis submitted to the Faculty of Graduate Studies in partial fulfilment of the requirements for the degree of

Master of Science

in the Department of Physics,

University of Saskatchewan
April, 1965

ABSTRACT

This thesis describes the investigation of the optical radiation emitted during the betatron discharge with the specific purpose of measuring the temperature of the ions during this time. The light intensity as a function of time was measured with a photomultiplier mounted on a Hilger quartz prism spectrometer. The observed spectral lines indicate that the atoms radiating during the discharge are mostly singly ionized. From this fact the electron temperature was estimated to be approximately 22 eV. The Doppler broadening of a spectral line emitted from singly ionized xenon atoms in the torus was measured in three mutually perpendicular directions using a photographic method on a Fabry-Perot interferometer. The broadening measured in the directions perpendicular to the minor axis of the torus was considerably larger than that measured in the direction tangential to the minor axis. An attempt was made to explain this phenomenon in terms of a drift acceleration of the ions to the walls of the torus and in terms of an anomalous diffusion. It was concluded that the broadening in the direction tangential to the minor axis is a result of unidentified collective electron-ion interactions. The ion temperature associated with this broadening turned out to be 26,700 oK or 2.3 ev for a peak accelerating field of 3500 volts/m, a magnetic field of 0.116 webers/m2 and a pressure of 0.35 x 10-3 Torr. Similar measurements of the broadening of nitrogen emissions in the direction tangential to the minor axis gave a temperature of 25,400 oK or 2.2 eV under similar conditions. These ion temperatures are average values over the time of the discharge. It is possible that instantaneous values are much larger.

Acknowledgements are expressed to Dr. H.M. Skarsgard for supervision and assistance, to Department of Physics faculty and staff for equipment and to " M.R. Zuzak who so magnanimously spent considerable time and effort in the preperation of most of the drawings and photographs which appear in this thesis."

Details of the Plasma Betatron and the overall research effort have been published as indicated below:
 Wave-Plasma Interactions involving intense Runaway Electron Streams Proceedings of the Seventh International Conference on Phenomena in Ionized Gases, Vol. 11 (Beograd 1966), H. M. Skarsgard, A. R. Strilchuk and W. W. Zuzak