Electron-beam produced air plasma: Electron density and momentumtransfer collision rate measurements

Summary form only given. A 100-keV 5-mA electron beam is used to generate air plasma in a test cell with a pressure between 1 mTorr and 638 Torr. The beam propagates through a 12.7-I????m thick aluminum transmission window into a 400-liter test cell. Microwave measurements at 10 GHz and nitrogen positive- ion emissions are observed on the optical midplane 12 in into the test cell. A 10-GHz in-phase and quadrature measurement system is used to measure the real and complex components of the wavenumber. The wavenumber is used to evaluate the electron number density and momentum-transfer collision rate. Optical emissions using eight telescopic collimators positioned perpendicular to the RF propagation path quantify the volumetric ionization rate. From this ionization rate and an iterative estimation of the electron density using an air- chemistry code, the electron-density profile along the RF propagation path is deduced. This profile is used to quantify the path length used for RF measurements. Representative electron density and momentum-transfer collision rate measurements for air plasma from 1 mTorr to 638 Torr will be discussed as well as the RF measurement technique, optical technique, and evaluation of the electron-density profile from the volumetric ionization rate.