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P: Plasmaphysik

P 13: Entladungen III

P 13.1: Fachvortrag

Thursday, March 18, 1999, 14:00–14:30, ZO 2

Direct Current Atmospheric Pressure Glow Discharges — •Robert H. Stark and Karl H. Schoenbach — Physical Electronics Research Institute, Old Dominion University, Norfolk, VA 23529, USA

A novel plasma cathode for the sustainment of large volume, high pressure dc glow discharges has been developed. A microhollow cathode discharge (MHCD) with 100 micrometer diameter cathode and anode holes was used to provide electrons for a large volume glow discharge, sustained between the hollow anode of the MHCD and a third electrode. Current and voltage characteristics, and the visual appearance of the glow discharge and MHCD were studied in argon and air. We are able to get stable dc operation in argon and air up to 1 atm. The glow discharge is ignited when the current in the plasma cathode (MHCD), which is on the order of mA, reaches a threshold value. This threshold current increases with reduced applied voltage across the main gap. Above this transition the current in the glow discharge is identical to the MHCD current and can be controlled by varying the MHCD voltage. Then the electrical characteristic of this system of coupled discharges resembles that of a vacuum-triode. The electron density in the plasma column is on the order of 1011 to 1013 cm-3. Parallel operation of microhollow cathode discharges have indicated that large area high pressure stable glow discharges can be obtained by using arrays of MHCDs as electron sources.

This work was funded by the Air Force Office of Scientific Research (AFOSR) in cooperation with the DDR&E Air Plasma Ramparts MURI Program, and the National Science Foundation (NSF).