Damping of an electron plasma wave with detrapping of the electrons

A self-consistent calculation of the damping of an electron plasma wave is presented including, for the first time, the contribution of all electrons (untrapped, detrapped, and trapped). The effect of the detrapped electrons, which is strong at the higher damping rates, is to lower the first minimum of the amplitude after the initial stage of Landau damping and the general level of its oscillation afterward. At γLτ0≊−0.75, a qualitative change is observed from amplitude oscillation to near-plateau behavior. The existence of an important secularity in the Vlasov–Poisson system is pointed out.