  Spontaneous branching of discharge channels is frequently observed, but not
well understood. We recently proposed a new branching mechanism based on
simulations of a simple continuous discharge model in high fields. We here
present analytical results for such streamers in the Lozansky-Firsov limit
where they can be modelled as moving equipotential ionization fronts. This
model can be analyzed by conformal mapping techniques which allow the reduction
of the dynamical problem to finite sets of nonlinear ordinary differential
equations. The solutions illustrate that branching is generic for the intricate
head dynamics of streamers in the Lozansky-Firsov-limit.
