Spontaneous electromagnetic fluctuations in unmagnetized plasmas. III. Generalized Kappa distributions

In the first two papers of this series, the general expressions for the spontaneous fluctuations spectra (electric and magnetic field, charge and current densities) from uncorrelated plasma particles are derived and illustrated for a Maxwellian (relativistic or nonrelativistic) plasma close to thermal equilibrium. In this paper, the results are illustrated for the nonideal case of a plasma out of thermal equilibrium and described by the generalized Kappa (power-law) particle distribution function in the nonrelativistic limit. The suprathermal fluctuations of weakly amplified modes and aperiodic modes are provided. Thus, it is shown for the first time the existing finite level of noncollective fluctuations, which are particularly important in the context of plasma fluctuations (collective or noncollective) as the best agent in the energy dissipation and transfer to suprathermal populations. The results obtained in the first paper for an equilibrium plasma are recovered only in the limit of a very large power index κ→∞.