Cathode Sheath Effects in Externally-Ionized Gas Discharges.
Abstract
Lowke's theoretical investigation of gas discharges sustained by an external ionization source was extended. In addition to the processes of electron diffusion, electron-ion combination, and ionization of the ground state considered by Lowke, electron-impact ionization of metastable states and secondary emission from the cathode were included in the present analysis. Current-voltage (I-V) characteristics were obtained for discharges in argon and methane. At current densities of 1A/sq cm, Townsend ionization in the cathode sheath resulted in positive-ion number densities which significantly exceeded those in the positive column. I-V characteristics obtained revealed a sharp rise in the current at an 'ignition' voltage. The slope of the high-current region of the characteristic increased for an increase in secondary emission. With the addition of metastable ionization, the ignition voltage and the entire I-V voltage and at low external ionization source strengths, an unstable region of negative differential conductivity was observed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1981
- Accession Number
- ADA115513
Entities
People
- Marc R. Hallada
Organizations
- Air Force Institute of Technology