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Title: Propagation of low frequency waves in a plasma column
Author: Purcell, Jeffrey John
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1968
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In this thesis, an investigation has been made into the propagation of low frequency waves along the positive column of a cylindrical gaseous discharge. The ion acoustic wave has been successfully detected by previous workers and shown to be in good agreement with theoretical predictions. However, it can be shown that under a favourable combination of the type of gas, the pressure and the column geometry, a mode propagates with little or no attenuation in the electron stream directions and with a very high attentuation in the opposite direction. The anode directed wave is of the 'backward' type, as an increase of frequency corresponds to an increase of wavelength. It has been possible to show that by including collisional losses in the equations of motion for the electrons and ions and deriving the appropriate plasma permittivity expression, dispersion solutions for a circularly symmetric longitudinal mode do exhibit a backward slope and anomolous propagation characteristics providing that the electron drift velocity is of the order of the thermal velocity. Experiments have shown that these waves exist in Neon over the pressure range 0.1 to 0.03 mM. Hg. with a discharge current of 100 mA., and measurements of the. plasma parameters have shown that the necessary conditions are satisfied in the discharge system investigated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available