Space charge effects and arc properties of simulated lightning on Venus

Abstract

An experimental investigation of the physical properties of lightning on Venus was carried out by applying fast impulses to a pressurized (1-2.8 atm) CO2-N2 gas mix. The maximum current employed in the experiments was 2.8 kA. It was found that the pressure has a marked effect on the measured electric field. This effect is mostly due to negative ions created by electron attachment. This negative space charge could hamper breakdown on Venus if the clouds are negatively charged. Using a time-resolved spectroscopic technique, the instantaneous temperature of the arc was measured. This varies from 29,000 K soon after the arc appears to 14,000 K some 15 μs later. The arc's linear resistance and the power it dissipates were estimated using the Spitzer resistivity model and the measured temperatures. The linear resistance was found to be in the 17-233 Ωm-1 interval, which is comparable to the values of terrestrial lightning. The by-products of the discharge were analyzed using a mass analyzer, and it was found that the discharge decomposes the CO2 into CO and O at similar rates. Our estimate of the CO yield is 2.7 × 1018 molecules J -1. Copyright 2011 by the American Geophysical Union.