At exceeding the gas-specified critical field strength the
attachment-detachment processes reach a point from
which the ionization dominates (effective ionization
coefficient αeff > 0). Now the electron avalanches can
shape, and the number of charge carriers grows
exponentially. When the ion concentration at the head of
the avalanche exceeded 108
a steep rise in current,
known as a streamer, happened and breakdown of the
gap in uniform filed followed [3]. On account of the
electron-to-ion mass ratio the electrons travel faster to
anode and leave slow ions at the place of their
formation. That leads to the alteration of field in the gap
and yields in further excitation processes at avalanche’s
head. When the streamer reached the opposite electrode
it was heated instantaneous and thermally ionized.
Finally the streamer breakdown occurs by means of this
highly conductive “kanal”.