Application of the energy conservation law in the cold plasma model

For the two-fluid hydrodynamic cold plasma model, differential relations characterizing the energy conservation law are derived. The case when the motion of the heavier ions can be neglected as compared with the electrons and the situations with and without allowance for the relativistic factor in the electron dynamics are considered separately. For the problem of free plasma oscillations initiated by a short intense laser pulse, numerical results concerning the fulfillment of the energy conservation law in all above-mentioned situations are presented. The main result is that the reliability of the computations can be improved substantially via the standard theoretical study of the approximation and stability, together with experimental observation of energy conservation.