Search

A fully nonlinear, time-asymptotic theory of nonlinear Landau damping and resonant particle trapping in finite-amplitude waves is presented. The virial theorem and the conservation of the parallel adiabatic invariant are used to determine the time-asymptotic distribution function. The effect of trapped particles on the nonlinear wave dynamics is highly nontrivial and forces a significant departure from the conventional models of finite-amplitude waves.

Thermodynamic and spectral properties of a photon gas in ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\gamma}$ plasmas are studied. The effect of a finite effective mass of a photon, associated with the plasma frequency cutoff, is self-consistently included. In the ultrarelativistic plasma, the photon spectrum turns out to be universal with the temperature normalized plasma frequency cutoff as a fundamental constant independent of plasma parameters. Such a universality does not hold in the nonrelativistic plasma.