Multi-pulse Modeling of Self-pulsating DC Streamer Discharges*

Simulation of streamer discharges over long timescales (>100 ns) has proven challenging, due to the high stiffness of the governing drift-diffusion equations, as well as large changes in behavior as the streamer bridges the electrode gap and transitions from a propagation phase into longer current-flow and inter-pulse phases. This presentation describes a numerical model that has been developed to simulate streamer discharges over long timescales of several hundred microseconds. The model is 1.5D - charged particle densities are modeled in 1D, whilst the electric field is modeled in 2D, to include the effects of electric field curvature, of both the propagating streamer tip and the sharp electrode. The model is coded in Julia language and has been optimized for numerical efficiency by using a `stack' of 3 different transient solvers, along with CUDA GPU acceleration. This has enabled the simulation of a single streamer filament from initiation; through propagation and bridging of the electrode gap; development of the cathode sheath and the current flow phase. Current work focuses on simulating the inter-pulse phase (~100 micro-s), up to and including initiation of a second streamer and its current pulse. Compared to a first streamer burst, modeling the subsequent current pulse may improve the predictions of the model, when compared to experimental data. In addition, modeling the subsequent streamer burst will inform the mechanisms driving the self-pulsation of the discharge and the corresponding frequency.