Streamer inception and imaging in various atmospheres

Streamers are the first stage of many discharges involving high voltages.
They consist of a propagating ionization front leaving behind a
trail of conductive, quasi-neutral plasma. In this contribution we will
show experiments on streamers revealing some of their most important
properties: their inception and their propagation and branching
behaviour.
We study streamer inception by applying repetitive high voltage
pulses and studying the statistics of inception delay. By means of small
bias pulses between the high voltage pulses, we are able to manipulate
these statistics, which reveals a lot on the processes governing the
inception.
Secondly, we study the propagation and branching of streamers by
a combination of stereoscopic and stroboscopic measurements of ’low
complexity’ streamer discharges. We have developed automated routines
which can determine propagation velocities, branching angles and
much more from these and can directly compare these against numerical
results, thereby also giving unprecedented insights into the fundamentals
of such discharges.