Cyclotron emissivity of a plasma of arbitrary density

The spectral emissivity of a non-relativistic plasma of arbitrary density for frequencies above the electron cyclotron frequency is derived. A general formula is given which then is explicitly discussed for the case of thermal equilibrium. For emission perpendicular to the static magnetic field an analytic formula has been obtained. For arbitrary directions, the results are calculated numerically and given in graphical form. In the limit of vanishing electron density the usual results are recovered.