Corona discharge and electrostatic precipitation in carbon dioxide under reduced pressure simulating Mars atmosphere

The possibility of using electrostatic precipitation to clean the gas above solar panels on the surface of planet Mars is investigated. Results are presented on corona discharge in carbon dioxide gas under reduced pressure ranging from 5 to 10 mbar with different electrode configurations. The corona discharge inception voltage and the threshold of bipolar discharge have been measured for the three configurations. The charging of suspended particles of micrometer size in the gas by unipolar ions is examined. In the considered reduced pressure, very likely diffusion charging dominates over field charging. The drift velocity of charged particles is then estimated and is found to be not drastically lower than in industrial precipitators for fine particles despite the much lower electric field which can be applied under reduced pressure. Finally the results of a laboratory experiment examining the dust deposit onto photovoltaic cells are presented. It appears that electrostatic precipitation reduces the rate of dust deposit and might be used in order to increase the lifetime of solar panels during Mars missions.