Beschreibung:
<jats:p>Using the relativistic Vlasov equation and the appropriate Maxwell–Boltzmann–Jüttner distribution for the unperturbed plasma thermal equilibrium state, it is demonstrated that the longitudinal dispersion relation in warm isotropic Maxwellian plasmas has two real roots with superluminal phase speed below a characteristic wave number kc that is determined by the plasma frequency and the plasma temperature. The superluminal oscillations undergo no Landau damping. The relativistically correct analysis leads to markedly different results than previous nonrelativistic work which incorrectly yielded a nonzero imaginary part of the roots for all phase speeds.</jats:p>