Study of humid nitrogen plasma chemistry in a glow discharge by laser diagnostics and modeling*

Plasma-liquid interactions have gained significant attention in the low-temperature plasma community in recent decades. Much interest is focused on the dynamic chemical reactions initiated by the energetic plasma electrons near the plasma-liquid interface. In particular, the plasma-assisted transformation of molecular nitrogen and water is interesting for the sustainable and distributed production of ammonia and other chemicals.

In this work, we studied a direct current glow discharge formed in a background of humid nitrogen gas at atmospheric pressure as a model system for a nitrogen plasma interacting with liquid water. Densities of several intermediate species (N, NH, H, and OH) were quantitatively measured by laser and optical emission spectroscopic methods at various degrees of relative humidity. The measured densities were used to benchmark a zero-dimensional (0-D) model. The validated model was subsequently used to calculate the densities of additional molecular species and elucidate the developing chemical pathways.

In addition, a brief review will be given, describing selected collaborative research projects on plasma-liquid interactions, amalgamated by the utilization of resources at Princeton Collaborative Research Facility.