  Two charge- and current neutral plasma beams are modelled with a
one-dimensional PIC simulation. The beams are uniform and unbounded. The
relative speed between both beams is 0.4c. One beam is composed of electrons
and protons and one out of protons and negatively charged oxygen (dust). All
species have the temperature 9 keV. A Buneman instability develops between the
electrons of the first beam and the protons of the second beam. The wave traps
the electrons, which form plasmons. The plasmons couple energy into the ion
acoustic waves, which trap the protons of the second beam. A proton phase space
hole grows, which develops through its interaction with the oxygen and the
heated electrons into a rarefaction pulse. This pulse drives a strong ion
acoustic double layer, which accelerates a beam of electrons to about 50 MeV,
which is comparable to the proton kinetic energy. The proton distribution
eventually evolves into an electrostatic shock. Beams of charged particles
moving at such speeds may occur in the foreshock of supernova remnant shocks.
This double layer is thus potentially relevant for the electron acceleration
(injection) into the diffusive shock acceleration by supernova remnants shocks.
