Formation of Ammonia through Meteoritic Atmospheric Shock*

Here we present results from Frontiers experiments at the DIII-D tokamak, which studied ammonia formation in plasma conditions reminiscent of those in the tails of meteoroids entering the Early Earth atmosphere. The formation of ammonia in fusion plasmas has been observed in the past [1]. However, here, we argue that the range of heating conditions achievable in the DIII-D divertor, ~30MW/m^2 near the outer strike point (OSP) to ~1MW/m^2 away from the OSP, allows for the study of ammonia formation in environment like the one expected during meteoroid ablation. Here, the DIII-D’s Divertor Material Evaluation System (DiMES) was used to expose SiO2-coated graphite rods to the edge plasma. To mimic various conditions in Earth’s history, different gases were puffed in the divertor region near the rods (N2-only, N2-H2 mixture, and N2-CH4 mixture). Upon collection and chemical analysis of the rods, different amounts of ammonium (the cation of ammonia) were detected, allowing to assess ammonia formation with different seeded gases. Our experiment demonstrates that it is plausible for meteoroids ablation to generate ammonia in several different stages of the Earth’s history, which could have been used in prebiotic chemical processes.

[1] https://doi.org/10.1016/j.jnucmat.2015.01.010

Work supported by US DOE under DE-SC0022554, DE-SC0021338, DE-SC0023375, DE-SC0023367, and DE-FC02-04ER54698