Accession Number : ADA115513

Title :   Cathode Sheath Effects in Externally-Ionized Gas Discharges.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Hallada,Marc R

PDF Url : ADA115513

Report Date : Dec 1981

Pagination or Media Count : 167

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)

Descriptors :   *Switches, *Gas discharges, Ionization, Mathematical analysis, Cathodes, Conductivity, Secondary emission, Voltage, Ground state, Argon, Methane, Metastable state, Ignition, Weapon systems, High energy, Density, External, Equations, Poisson equation, Theory, Theses

Subject Categories : Numerical Mathematics
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE