Streamers and transition to breakdown

In this paper processes preceding breakdown are described; the so-called prebreakdown phenomena. It deals with a time-resolved optical and electrical study of the avalanche and streamer formation in atmospheric nitrogen and dry air. With the results from experiments and two-dimensional model simulations the formation of avalanches and streamers, and the dominant processes involved are illustrated and discussed. A fast experimental setup is used to measure the discharge current and the optical discharge activity