Non-planckian equilibrium radiation of plasma-like media

Consideration of equilibrium radiation of plasma-like media shows that the spectral distribution of such radiation differs from that of Planckian equilibrium radiation (blackbody radiation). The physical reason for this difference consists in the impossibility of propagation of photons with the dispersion law ω = ck in systems of charged particles. The thermodynamics of equilibrium electromagnetic radiation in plasma is also considered. It is shown that the difference of the thermodynamic properties of such radiation from those of Planckian radiation is characterized by the parameter a = ℏΩp/T. This difference is especially pronounced in plasma media in which a ≥ 1. Applications of the results obtained to plasmas of metals (first of all, liquid metals in which charged particles have no distant order) and to the plasma model of the early Universe are discussed.