(303a) Effect of Pulse Delivery Modes and Electrode Polarity on Production of Reactive Nitrogen Species (RNS) in a Nanosecond Pulse Discharge Plasma Gas-Liquid Reactor

Plasma interacting with liquid water has been investigated for many applications in chemical, environmental, materials, and electrical engineering. The plasma reactor used in this study, utilizes flowing gas and liquid streams whereby a thin liquid film is formed, and the electrical discharge propagates along the interface of this film. The interaction of air plasma with water molecules (H­₂O) leads to NO₂^- and NO₃^- in the liquid phase and NO and, NO₂ in the gas phase. Previous work has shown that the production rates of NO and NO₂^- increased linearly, while those for NO₂ and NO₃^- followed a bilinear trend with increase in pulse frequency from 1kHz-10kHz with input voltage and pulse width constant at 16kV and 40ns respectively.

In this work, the effects of changes in mode of pulse delivery method i.e., (a) uniform pulsing and (b) burst mode and, the effects of electrode polarity were studied. The pulse frequency was varied between 1-10kHz at 16kV (input voltage) and 40ns (pulse width). A “burst” train of high-voltage pulses was introduced by varying the (a) number of pulses in a burst (N-cycles) between 1-50 (b) time between the pulses in a burst (internal frequency) between 1kHz-1MHz and (c) time between the bursts (burst period) between 0.1ms-1ms. Formation of H₂O₂, NO₂^-, NO₃^-, NO, and, NO₂ were studied with variation of pulse delivery method and changes in electrode polarity.

**This work is partially supported by the US Department of Energy (DOE) under Contract No. DE-SC0025438.