  In preparation for the MMS mission we ask the question: how common are
bipolar signatures linked to the presence of electron holes along separatrices
emanating from reconnection regions? To answer this question, we conduct
massively parallel simulations for realistic conditions and for the hydrogen
mass ratio in boxes larger than considered in similar previous studies.
  The magnetic field configuration includes both a field reversal and a out of
plane guide field, as typical of many space situations. The guide field is
varied in strength from low values (typical of the Earth magnetotail) to high
values comparable to the in plane reconnecting field (as in the magnetopause).
In all cases, along the separatrices a strong electron flow is observed,
sufficient to lead to the onset of streaming instabilities and to form bipolar
parallel electric field signatures. The presence of bipolar structures at all
guide fields allows the control of the MMS mission to consider the presence of
bipolar signatures as a general flag of the presence of a nearby reconnection
site both in the nightside and in the dayside of the magnetosphere.
