Complete theory for Langmuir envelope solitons in dusty plasmas

A complete theory for Langmuir envelope solitons in an unmagnetized dusty plasma is presented, taking into account interactions between finite amplitude Langmuir waves and fully nonlinear dust ion-acoustic (DIA), dust acoustic (DA), and ion hole (IH) perturbations. For this purpose, a nonlinear Schrödinger equation is employed for the Langmuir wave envelope and expressions for plasma slow responses are derived, including a modified (by the Langmuir wave ponderomotive force) Boltzmann electron distribution and appropriate ion and dust density distributions for fully nonlinear dispersive DIA, DA, and IH perturbations, which include departure from the quasi-neutrality condition. In the stationary frame, the governing equations can be cast in the form of a Hamiltonian which is used to check the accuracy of the numerical scheme predicting stationary localized solutions of our governing nonlinear equations. Numerical results reveal different classes of Langmuir envelope solitons (cavitons) whose features differ from those in an electron-ion plasma without dust. Ion and dust thermal effects for the DIA and DA waves, respectively, have been included. It is suggested that new beam-plasma experiments in laboratory dust plasmas should be conducted to verify our theoretical predictions of cavitons.