Electron avalanches influenced by detachment and conversion processes

The authors analyze the avalanche growth in electronegative gases which exhibit detachment and conversion processes in addition to ionization and attachment processes. The study is based on an evaluation of the model of H.F.A. Verhaart and van der Laan (1982). Humid air is taken as an example to demonstrate, with this model, the effects of detachments and conversion processes on the avalanche electron distribution across the gap and on the external current waveform. The model is also used to determine swarm parameters from fast swarm experiments. The results show that detachment and conversion affect the electron distribution in the avalanche and can thereby influence the streamer breakdown threshold. The neglect of these process in the analysis of swarm experiments results in measured values for the effective ionization coefficient that can may substantially differ from the true values.<>