An investigation of the resonance cone structure in a warm anisotropic plasma

Citation

Burrell, Keith Howard (1974) An investigation of the resonance cone structure in a warm anisotropic plasma. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/HD16-SA13. https://resolver.caltech.edu/CaltechETD:etd-10252005-155445

Abstract

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This work presents a detailed theoretical and experimental investigation of the resonance cone pattern excited by a small antenna in a warm, magnetized plasma.

The warm plasma theory is developed for an infinite, uniform plasma for arbitrary incident frequency [...] in the limit that [...] and [...]. Here, [...] and [...] are the electron plasma and cyclotron frequencies, respectively, while [...] is the Debye length, [...] is the Larmor radius, and [...] is the distance from the source to the point of observation. The theory predicts the functional dependence of the angular position of the main resonance cone peak and the angular spacing between interference peaks on the physical parameters. The theory for plasmas with nonuniform density is also developed, but in the cold plasma limit, leading to predictions that the resonance cones can reflect off of density gradients.

Experimental work verifying the theoretical picture is presented. The main cone angle is found to depend on [...], [...], [...], and [...] in a manner consistent with the theory, as is the angular interference spacing. The idea of resonance cones reflecting from density gradients can explain features of the data that are otherwise incomprehensible.

From the data, values for [...] are obtained in two independent ways, and the results are consistent. The data also yield a value for the temperature that is appropriate for the afterglow plasma used in the experiment. Since both density and temperature can be obtained from the same data, resonance cone measurements are a useful diagnostic for plasmas in which antennas can be inserted.

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