On the Numerical Simulation of Traveling Langmuir Waves in Warm Plasma

Traveling Langmuir waves are numerically simulated in a warm plasma using a kinetic description of the process. Waves of this type can be excited by a powerful short laser pulse (the so-called wake wave). It is shown that the propagation velocities of perturbations at the moments of the distribution function of the second and third orders significantly exceed the propagation velocity of the charge density wave. The comparison of kinetic and hydrodynamic models on the example of the considered problem is the important aspect of this study. It is shown that the hydrodynamic model without taking into account the heat flux does not give a good approximation to the solution of the kinetic Vlasov equation. As a result, the closure problem for moment equations remains open.