Speaker Li Chao (CWI) presents the algorithms and the simulation results of a 3D hybrid model that can simulate long streamers that are used in industrial applications such as lightning.

Location: CWI, room M279. Tea starting at 10h.

Streamers are used in industrial applications such as lightning, gas and water purification or combustion control, and they occur in natural processes as well such as lightning or transient luminous events in the upper atmosphere. Both fluid and particle models have been developed for streamer simulations.

The particle model is suited to study physical phenomena related to the dynamics of individual electrons, such as the precise electron energy distribution, the generation of run-away electrons, the branching triggered by particle fluctuations, or streamer inception from few electrons. But it demands an enormous computational power and storage to simulate a full long streamer while so-called super-particle methods create numerical artifacts. Fluid models, on the other hand, approximate the electrons and ions as continuous densities. They are computationally efficient in regions with large particle densities like the interior of a streamer finger.

To study the physics phenomena related with individual electron dynamics in an evolving streamer, a hybrid model that couples fluid and particle model in suitable regions, has been developed in a systematical way. Li Chao: "We present the algorithms and the simulation results of the 3D hybrid model. The 3D hybrid model can simulate long streamers while following the real electron motion at the most active region of the streamer head. We also investigate the generation of run-away electrons and present how keV electrons are produced in a growing streamer."

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