Weakly ionized plasmas, generated in high pressure glow discharges, are able to reflect or absorb electromagnetic radiation and consequently act as temporally controllable barriers for this radiation. It is proposed to study the physics of do glow discharges in atmospheric air, particularly the cathode fall of these discharges. Instabilities which evolve from the cathode fall, have so far been the major obstacle for do operation of high pressure glow discharges. We propose to explore the use of microhollow electrode discharges as stabilizing elements for the cathode fall. In addition to the stabilizing effect, microhollow electrode arrays serve as highly emissive cathodes for the main discharge. Temporal control of the main discharge should be possible by pulsing the microhollow cathode discharge affay at voltages low compared to the sustaining voltage of the main discharge. Electrical and optical diagnostic methods, such as open shutter and streak photography and spectroscopy, will be used to obtain information on the microhollow electrode discharges The electron emission of microhollow plasma cathodes will be measured by means of a differentially pumped retarding field analyzer. The use of thin film technologies for the development of microelectrode panels will be explored. Efforts to reduce the power losses in the main discharge through reduction of electron attachment as a result of combustion chemistry are under way at Stevens Institute of Technology, Hoboken, NJ. supported by AFOSR. Cooperation with this research group is intended and will be facilitated through a consulting agreement with the P.L, E. Kunhardt. The proposed reach has relevance for other applications besides plasma barriers. Examples are controllable plasma cathodes for agile mirrors, and the use of plasma sheaths, generated by hollow eletrode discharge arrays for drag reduction of air flow along surfaces. ***
