Modeling of discharges generated by electron beams in dense gases: Fountain and thunderstorm regimes

In this paper we present an analysis of the predicted dynamics of plasmas g enerated in air and other gases by injecting beams of high-energy electrons . Two distinct regimes are found, differing in the way that the excess nega tive charge brought in by the ionizing electron beam is removed. In the fir st regime, called a fountain, the charge is removed by the back current of plasma electrons toward the injection foil. In the second, called a thunder storm, a substantial cloud of negative charge accumulates, and the increase d electric field near the cloud causes a streamer to strike between the clo ud and a positive or grounded electrode, or between two clouds created by t wo different beams. A quantitative analysis, including electron beam propag ation, electrodynamics, charge particle kinetics, and a simplified heat bal ance, is performed in a one-dimensional approximation. (C) 2001 American In stitute of Physics.