On numerical simulation of traveling Langmuir waves in warm plasma

Numerical simulation of traveling Langmuir waves in a warm plasma is carried out 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. An important aspect of the work is the comparison of kinetic and hydrodynamic models on the example of the considered problem. 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.