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Type of Document	Dissertation
Author	Nickel, John C.
URN	etd-10182002-102050
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-10182002-102050
Title	Experimental study of plasma wave resonances in a hot nonuniform plasma column
Degree	PhD
Option	Physics
Advisory Committee	Advisor Name Title Unknown Committee Member
Keywords	None
Date of Defense	1964-05-27
Availability	unrestricted
Abstract NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The relative frequency spectrum [...] of plasma wave resonances in the positive column of a low pressure mercury discharge tube has been shown to depend upon the parameter [...] where r[subscript w] is the radius of the column, [...] is the Debye length defined in terms of the average electron density, and [...] is the square of the average plasma frequency. This paper presents observations of both dipole and quadrupole resonance spectra made on several discharge tubes with r[subscript w] ranging from 0.30 to 0.87 cm. For these measurements [...] varies from about 10[superscript 2] to 10[superscript 5], and the best fit electron temperatures are found to be of the order of 3 ev. The average electron densities are directly measured using a cavity perturbation technique. The results of these observations are found to be in good agreement with the theory (1,2) based upon the first two moments of the correlationless Boltzmann equation in conjunction with Parker's electron density profile (3) for a low density positive column. The results of a preliminary investigation of the effects of an axial, static magnetic field on the dipole resonance spectrum are also presented. These results indicate that in the presence of an axial magnetic field not only does the lowest resonance (approximately predicted by the cold plasma theory) split, but the next higher order resonance also splits. For the lowest resonance, it is found that [...], while for the next higher order resonance [...], where [...] is the cyclotron frequency. These preliminary results are in good accord with calculations made by Parker (1), again using the moment equation approach. (1) J.V. Parker, PhD Thesis, California Institute of Technology, June 1964. (2) J.C. Nickel, J.V. Parker, R.W. Gould, Phys. Rev. Letters 11, 183 (1963). (3) J.V. Parker, Phys. Fluids 6, 1957 (1963)
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