Masters Theses

Chaoyu Liu

Date of Award

12-1995

Degree Type

Thesis

Degree Name

Master of Science

Major

Electrical Engineering

Major Professor

J. Reece Roth

Committee Members

I. Alexeff, W. L. Green

Abstract

In 1990, Prof. Roth and his graduate students and associates at the University of Tennessee's Plasma Science Laboratory started the experimental and theoretical study of one atmosphere pressure plasma generation and its industrial applications. Significant results have been achieved in both experiment and theory. This work includes research on atmospheric plasma generation; atmospheric plasma applications in the textile industry; surface treatment by atmospheric plasma; and atmospheric plasma applications to fluid mechanical control. We have developed a new type of one atmosphere uniform glow discharge plasma in parallel plate and modified geometries. This plasma is neither a corona discharge nor a filamentary discharge. It is an RF electrical discharge, and it has been shown experimentally that it can operate at one atmosphere pressure in the steady state. Good agreement between experiment and theoretical predictions have been obtained. It has been shown that the physical processes which make this discharge possible are based on an RF ion trapping mechanism. Our experimental study showed that there exists a certain range of RF frequency, electric field intensity and electrode separation which is required to maintain this discharge. The operating parameters characterizing the plasma in air at one atmosphere obtained experimentally are: RF frequency, under about 10 kHz; RMS electric field about 9kV/cm; plasma number density about 1010 electrons/cm3 and the input power density is about 10~200 milliwatts/cm3 (Ref 12). These parameters imply a great potential for industrial application of this new type of plasma. In industrial applications, the one atmosphere uniform glow discharge plasma not only would allow many plasma-related surface modification processes to be carried out under production line conditions, rather than in expensive vacuum systems, that increase the budget and make the processes complicated, but also could perform tasks that can be achieved in no other way. The quality of the wettable and wickable polymer fabrics which have been treated by our one atmosphere glow discharge, for example, has been greatly improved. Another important line of exploratory research has been initiated. We have been able to demonstrate the creation of a one atmosphere uniform glow discharge plasma on a planar surface several millimeters thick. The electric field in this surface plasma layer can provide an electrostatic body force which might find application to boundary layer control, turbulence suppression, drag reduction, and noise reduction in aircraft and aerodynamic flow.

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