ABSTRACT
Historically, electron plasma waves, or Langmuir waves, are those Àrst studied by the kinetic plasma model. It might not be these waves which are the most interesting, or the most relevant, for plasmas in nature, but we take these as a model for discussing some of the basic problems distinguishing a Áuid and a kinetic description. We have seen that a dispersion relation obtained from the linearized version of the basic Áuid equations was a very useful device for understanding the plasma dynamics, so we place an emphasis in deriving a dispersion relation also for the kinetic model. For the present purpose, we assume that only high frequency Áuctuations are relevant, taking for simplicity the ion component to be an immobile background of positive charge.
