Hannover 2016 – scientific programme

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P: Fachverband Plasmaphysik

P 6: Low temperature plasmas I

P 6.2: Fachvortrag

Tuesday, March 1, 2016, 11:30–11:55, b302

On the role of three-body electron attachment for gaseous high voltage insulation — •Alise Chachereau, Mohamed Rabie, and Christian Franck — Power Systems and High Voltage Laboratories, ETH Zurich, Physikstr. 3, 8092 Zurich, Switzerland

The electron swarm parameters such as the electron drift velocity and the effective ionization rate constant are required for modeling low temperature plasmas in general, and in particular for obtaining the breakdown strength of gases at ambient temperature stressed with high electric fields. It is common practice to calculate these using electron-neutral scattering cross sections obtained e.g. in electron beam experiments. The ion kinetic processes are often neglected due to the lack of ion scattering data. Another option is to derive electron swarm parameters using a swarm experiment, e.g. a Pulsed Townsend experiment. Here, mainly electronegative gases and gas mixtures are investigated, having in mind the objective to assess their performance in high voltage insulation applications. In many gases, the effective ionization rate constant strongly depends on the gas pressure, due to three-body electron attachment. Since the measurements are limited to relatively low pressures compared to the typical pressures used in high voltage insulation, kinetic models are needed to predict the value of the effective ionization rate at higher pressures. In this talk, the basic kinetic processes in swarms are introduced and it is shown how a pressure dependence can result from three-body collisions.