  Recent advances in the understanding of the properties of supernova remnant
shocks have been precipitated by the Chandra and XMM X-ray Observatories, and
the HESS Atmospheric Cerenkov Telescope in the TeV band. A critical problem for
this field is the understanding of the relative degree of dissipative
heating/energization of electrons and ions in the shock layer. This impacts the
interpretation of X-ray observations, and moreover influences the efficiency of
injection into the acceleration process, which in turn feeds back into the
thermal shock layer energetics and dynamics. This paper outlines the first
stages of our exploration of the role of charge separation potentials in
non-relativistic electron-ion shocks where the inertial gyro-scales are widely
disparate, using results from a Monte Carlo simulation. Charge density spatial
profiles were obtained in the linear regime, sampling the inertial scales for
both ions and electrons, for different magnetic field obliquities. These were
readily integrated to acquire electric field profiles in the absence of
self-consistent, spatial readjustments between the electrons and the ions. It
was found that while diffusion plays little role in modulating the linear field
structure in highly oblique and perpendicular shocks, in quasi-parallel shocks,
where charge separations induced by gyrations are small, and shock-layer
electric fields are predominantly generated on diffusive scales.

Astrophysics