Emission and absorption of cyclotron radiation in non-equilibrium plasma

From the kinetic Klimontovich theory we derive the equation of radiative transfer for the case of homogeneous and stationary nonequilibrium plasma in a magnetic fiel. For the sake of simplicity we shall consider only the propagation of cyclotron-radiation in the direction of the magnetic field. Explicit expressions for the coefficients of absorption and spontaneous emission, valid also at the cyclotron frequency, will be obtained. In the final results the plasma is allowed to be weakly inhomogeneous in the z-direction. Application is made of the theory to the simple equilibrium case as a test yields the Rayleigh-Jeans formula of the black-body-radiation.