Study of Transient Spark Discharge Properties Using Kinetic Modeling

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The kinetic model simulating plasma chemistry induced by Transient Spark (TS) discharge in air is presented in this paper. TS is a dc-driven self-pulsing discharge of streamer-to-spark transition type. The presented kinetic model defines the temporal evolution of reduced electric field strength $E/N$ , gas temperature, and density of neutrals $N$ during the evolution of TS discharge, so that calculated electron density is in agreement with experimental results. We studied the mechanism of the streamer-to-spark transition and breakdown in TS using this model. We assume that the breakdown mechanism in TS is based on the gas density decrease and can be summarized as follows: heating of the channel $\rightarrow $ increase in the pressure $\rightarrow $ hydrodynamic expansion $\rightarrow $ decrease in $N$ in the core of the channel $\rightarrow $ increase in $E/N~\rightarrow $ acceleration of ionization processes. However, this mechanism is influenced by species accumulated due to previous TS pulses at higher TS repetition frequencies. Sensitivity analysis focused on major electron loss and production processes indicates an important role of the amount of O2 dissociated by the previous pulses. A lower density of O2 means a lower rate of electron attachment, while accumulated atomic oxygen atoms lead to acceleration of electron detachment processes.