Two-Dimensional Particle Simulations for Microhollow-Cathode Discharges: Comparison of Secondary Electron Emission Models

Abstract

Cylindrical microhollow-cathode discharges with a diameter D of 100 mu m are analyzed by two dimensional (2d3v) axisymmetric particle-in-cell Monte-Carlo collision simulations. Argon discharges at pressure p of 10 and 100 Torr are generated with a DC current source of 1-10 mA. Under these conditions (pD = 0.1 and 1 Torr.cm), the discharges extend inside the hollow cathode and create a virtual anode along the symmetry axis. Due to the resulting radial electric field, secondary electrons emitted from the cathode surface acquire a pendular motion within the hollow cathode and populate the high energy tail of the electron-energy-probability function. The characteristics of the microhollow-cathode discharge for different secondary electron-emission models are compared. When driven by a constant current source, a low effective secondary electron-emission coefficient results in higher plasma densities and discharge voltages.