Axisymmetric fluid streamer model in the AMReX library

We have implemented an axisymmetric fluid model of streamers in the AMReX open-source library. Our implementation is based on the first-order fluid model with a local field approximation. Photoionization is implemented by employing the Zhelenznyak’s model using the Helmholtz approach. We have verified our code in standard conditions by comparing our results for positive streamers in air with the existing benchmarks from the literature. To verify the performance of our code in strongly attaching gases, we compare the properties of negative streamers with those obtained from the Afivo-streamer open-source code. Calculations have been performed in mixtures of carbon dioxide and perfluoro-nitrile with a background number density of electrons and positive ions of 10¹³ m⁻³. We found an excellent agreement between the two sets of results, which indicates the numerical integrity of our code.