Non thermal cyclotron emission and absorption

The problem of emission and absorption in an inhomogeneous, anisotropic plasma out of thermal equilibrium is investigated. We explicitly construct the Green function of the Maxwell equations in the eikonal approximation. Then, considering the fluctuating microcurrents associated with the non thermal component of the electronic population, we give the general expressions for the source function and the optical depth. The theory is then applied to a tokamak plasma whose current is generated by lower-hybrid waves and to the final stage of the Parail-Pogutse instability