Envelope electron-acoustic solitary waves and their modulational instability in electron beam plasmas with superthermal electrons

The electron-acoustic (EA) envelope solitons and their modulational instability in multicomponent unmagnetized plasma (consisting of a cold electron fluid, hot electrons obeying a superthermal distribution, an electron beam and stationary ions) are theoretically investigated. A one-dimensional nonlinear Schrödinger equation, which governs the slow modulation of electron-acoustic wave packets, is derived by using a reductive perturbation method. It is seen that the plasma system under consideration supports two types of envelope solitons (bright and dark). It is also obvious that the bright (dark) envelope solitons are modulationally unstable (stable) according to instability condition. The variation of the growth rate of the unstable bright envelope solitons with various plasma parameters (e.g. wave number, temperature of superthermal electrons, etc.) is observed to be significant. The modulational instability criterions of the electron acoustic envelope solitons are also found to be influenced due to the variation of the intrinsic plasma parameters. So, the real application of our model might be particularly interesting in space plasmas environment such as auroral zone plasma and controlling plasma energy in laboratory.