Masters Theses

James R. Carl

Abstract

"A short burst of electromagnetic energy that propagates into and through a plasma medium can react with the plasma medium in several different ways depending on both the characteristics of the plasma and of the pulse. This thesis derives approximations for the plasma transfer function at low pressure (high altitude) and at high pressure (low altitude). The mechanisms that can change the shape of a waveform, in general, are dispersion and breakdown. dispersive distortion at low altitude is shown to exist for electron concentrations well above the resonant concentration for plasma sheaths that are thin compared to one wavelength. Several methods are presented for determining the degree of distortion that will occur. Microwave pulse breakdown at low altitude can occur if the input energy rate of the pulse is high. The energy dissipated by the plasma during the pulse raises the plasma temperature and ambient electron concentration until the latter portion of the pulse is seriously attenuated or blocked. A graphical method is derived for the solution of this problem. Dispersive distortion at high altitude is significant only near the plasma resonant frequency for thin sheaths. Over large distances, however, dispersion can occur where the electron concentration is well below resonance, such as in the ionosphere. Examples of both types are considered herein. In the case of electron concentration being well above resonance, no dispersion occurs (but it is extremely difficult to match the plasma in order to couple electromagnetic energy into it). High altitude breakdown is an avalanche electron build up effect. The altitude region that is most sensitive to breakdown occurs when there are enough particles available to sustain an avalanche reaction but the particles are spaced far enough apart that free electrons can gain sufficient energy to cause a high percentage of ionizing collisions. A method is presented for the solution of breakdown problems caused by pulses of RF energy. This solution is largely based on previous work as referenced in the thesis. Experimental work done in this field is presented"--Abstract, page ii-iii.

Advisor(s)

Boone, Jack L.

Committee Member(s)

Bertnolli, Edward C.
Jawa, M. S.

Department(s)

Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering

Publisher

University of Missouri at Rolla

Publication Date

1968

Pagination

xi, 73 pages

Note about bibliography

Includes bibliographical references (page 61).

Rights

© 1968 James R. Carl, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Microwaves -- Transmission
Plasma diffusion
Plasma sheaths
Pulse techniques (Electronics)

Thesis Number

T 2107

Print OCLC #

5995550

Electronic OCLC #

803525408

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