  The behaviour of a strongly-magnetized collisional electron-positron plasma
which is optically thin to cyclotron radiation is considered, and the
distribution functions accessible to it on the various timescales in the system
are calculated. Particular attention is paid to the limit in which the
collision time exceeds the radiation emission time, making the electron
distribution function strongly anisotropic. Indeed, these are the exact
conditions likely to be attained in the first laboratory electron-positron
plasma experiments currently being developed, which will typically have very
low densities and be confined in very strong magnetic fields. The constraint of
strong-magnetization adds an additional complication in that long-range Coulomb
collisions, which are usually negligible, must now be considered. A rigorous
collision operator for these long-range collisions has never been written down.
Nevertheless, we show that the collisional scattering can be accounted for
without knowing the explicit form of this collision operator. The rate of
radiation emission is calculated and it is found that the loss of energy from
the plasma is proportional to the parallel collision frequency multiplied by a
factor that only depends logarithmically on plasma parameters. That is, this is
a self-accelerating process, meaning that the bulk of the energy will be lost
in a few collision times. We show that in a simple case, that of straight
field-line geometry, there are no unstable drift waves in such plasmas, despite
being far from Maxwellian.
