Macroscopical model of streamer coronas around a spherical electrode

We present a model for streamer coronas emerging from a spherical electrode at high electrostatic potential. By means of a macroscopic streamer model and approximating the corona as a set of identical streamers with a prescribed spatial distribution around the electrode, we establish that coronas more densely packed with streamers are slower and more efficient at screening the electric field inside the streamers. We also apply our model to investigate the electrostatic potential at the boundary of the corona sheath that surrounds a leader and we underline the relevance of the rise-time of the leader potential during a leader step. (paper)