Chemical Modeling of a Pulsed Glow Discharge Plasma at Low Temperature with Applications to Saturn's Moon Titan

The Cassini spacecraft measured the molecular mass of ions for the first time in the atmosphere of Saturn’s largest moon, Titan^[1]. These observations uncovered the complexity of Titan’s upper atmospheric chemistry, which results in the production of radicals, ions and aerosols^[2]. Photochemical models have helped explain the gas phase chemistry involved in the production of organic aerosols^[3]. Alongside those models, laboratory experiments have helped fill gaps in the reaction networks through detailed studies of the effects of precursors and energy source(s) on the chemical pathways leading to aerosol production. Here we present a new study using an existing 1D model^[4], which simulates the plasma chemistry in the Titan Haze Simulation (THS) experiment developed on the COsmic Simulation Chamber (COSmIC) at NASA Ames Research Center. THS uses a pulsed plasma discharge in the stream of a supersonic jet expansion to simulate the different steps in Titan’s atmospheric chemistry at low (~150 K) Titan-like temperature^[5]. Using newly published reaction rates^[3], we have updated the model and report new computational results and their comparison to experimental mass spectra obtained with THS in two gas mixing ratio conditions (N₂-CH₄ and N₂-CH₄-C₂H₄) relevant to Titan's ionosphere.