Experimental determination of interaction between the radiation fields of Dragonfly's MMRTG and Titan's environment II: Gamma induced atmospheric conductivity

Abstract

The apparatus described in part I of this investigation was filled with various blends of ultra high purity nitrogen and a mixture of 95% nitrogen/5% methane, simulating Titan's atmosphere with up to 50% relative methane humidity, as well as an Earth atmosphere for comparison, with a source of gamma rays suspended therein. Readings were taken from a plate immersed in the atmosphere at the top of the chamber connected to a conductivity probe, with the source at various distances from the plate. Gamma-induced conductivity was not found to be significant at a distance from the source equivalent to that on the surface of the hull segment on Dragonfly containing the radioisotope generator when gamma ray energies and field geometry were corrected for, however ion buildup in the experiment chamber indicated the possibility of similar buildup within the hull segment itself. The effect of methane in the atmosphere was statistically indeterminate, reflecting earlier simulation results, however molecular ions were shown more likely to be the predominant carriers of charge than the free electrons measured in the simulation.