On the relativistic plasma-dynamical and hydrodynamical normal modes

A plasma and a neutral fluid behave in very different ways in the so-called hydrodynamical limit, when submitted to a long-wavelength disturbance. Both cases can be treated however in the same way if the plasma-dynamical equations are properly regularized. The frequencies and damping rates of both relativistic neutral-fluid modes and relativistic plasma modes are discussed in detail. A new relativistic plasma effect is exhibited as an anomalous, wavelength-independent damping coefficient of longitudinal and transverse plasma oscillations. This effect originates from the contribution of the electric field to the heat flow in a relativistic plasma.