  The behaviour of a collisional 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. Unusually for
plasma physics, the collision operator can nevertheless be calculated
analytically although the plasma is far from Maxwellian. The rate of radiation
emission is calculated and found to be governed by the collision frequency
multiplied by a factor that only depends logarithmically on plasma parameters.
