Breaking of a Langmuir wave in cold electron–positron–ion plasmas

The space–time evolution of a given density perturbation in cold homogeneous electron–positron–ion plasma is investigated with an assumption of infinitely massive ions by employing a numerical calculation method. The phase-mixing time and wave-breaking time can be effectively distinguished with this method. It is found that an increase of the ratio of equilibrium ion density to equilibrium electron density can attenuate plasma oscillations, leading to a delay in wave breaking. The dependence of the phase-mixing and wave-breaking times on the amplitude of the initial perturbation is also discussed.