Published online by Cambridge University Press: 28 February 2011
Spectroscopic diagnostics are used to map key parameters of the cathode fall of a He glow discharge.Optogalvanic spectroscopy on Rydberg atoms is used to perform spatially resolved electric field measurements.The resulting E/N maps provide the ion and electron current densities, which are used to determine the local ionization rates.Local excitation rates are mapped by observing the spectral emission from the discharge.Optogalvanic spectroscopy is also used to observe electron avalanches starting from a well defined position in the cathode fall.These detailed experimental maps will be essential in studies of the nonhydrodynamic electron distribution function.Various theoretical models of the cathode fall will be compared to the experimental results.