Quantitative insight into the influence of previous discharge on the subsequent discharge

Previous discharge significantly influences the subsequent discharges and this is particularly pronounced for repetitively pulsed discharges, due to the residual charges and species created by the previous discharge
^[1–3]
. In this work, we built a two-step simulation model (combining 2D fluid dynamics and zero-dimension plasma kinetics) to quantitatively explain how residual charges and species created by the previous streamer discharge affect the initiation and propagation of the subsequent discharge in pure nitrogen $\left(\mathrm{N}_{2}\right)$ and artificial air $\left(20 \% \mathrm{O}_{2}+80 \% \mathrm{~N}_{2}\right)$ at 100 mbar pressure The 2 D simulation results show that after the first pulse discharge, the migration of negative ions under the electric field inside the streamer channel and the adsorption reaction of electrons, resulting in a significantly higher concentration of negative ions near the anode than that in other parts. The electric field of the selected reference point near the interface is obtained by 2D model and transmitted into the OD model. The numerical results of OD model show that the electron density within the previous discharge plasma channels remains sufficiently high $\left(2 \times 10^{18} \mathrm{~cm}^{-3}\right)$, allowing the second pulse streamers to reignite their paths from the stopping points of the previous streamer rather than that from the tip. The high concentration of negative oxygen ions at the head of the needle tip inhibits the formation of new streamer or causes them to propagate laterally. A high density of positive ions, e.g., N+ 4 patches, would increase the likelihood of the secondary streamer to branch. A competitive mechanism between the density of net positive charges and the existing density of electrons plays a role in enhancing or mitigating the subsequent positive discharge.