Modeling gas and electrode surface chemistry in a plasma discharge in nitrogen and carbon tetrafluoride discharges

Plasma-based switches are frequently used to deliver high currents for pulsed power applications. A switch's effectiveness depends on the reliability of the breakdown voltage. Reliability is hypothesized to depend on surface chemistry-related damage or modifications. Breakdown events at anomalously low voltages may depend on the plasma-induced surface chemistry, such as the formation of insulating layers, necessitating the investigation of the fundamental chemistry of plasma discharges. Modeling gas chemistry can yield insights into how gas composition can influence breakdown voltage and the potential of fluorine-containing compounds to mitigate these events. In this work, a 0D plasma chemistry model investigates plasma chemistry that may influence electrode surface chemistry. The model utilizes a multi-term Boltzmann equation solver, MultiBolt [1], to solve for the electron energy distributions given the gas composition. The reaction rates are implemented to track species density through time on a millisecond (ms) time scale. The species interactions yield insight into the reactive species that play the largest roles in plasma switch discharges. For a test case, N₂ and CF₄ mixtures are modeled with emphasis on radicals that may interact with electrode surfaces. Modeling results will be compared with experimental results. This model yields insights into the lifetimes of chemical species generated by plasma, which affects the reliability of the breakdown voltage of a switch.