Theoretical model for the effect of dust grains on self‐filamentation of a gaussian electromagnetic beam in a fully ionized plasma

Abstract

A theoretical model for the effect of dust grains on the self-filamentation of a Gaussian electromagnetic beam propagating in a fully ionized plasma has been developed by employing the energy balance of the plasma constituents, perturbed electron and ion concentrations, and temperature. In this model, neutral atom ionization, re-integration and accumulation of electrons and ions, photoelectric emission of electrons from the surface of dust grains, as well as elastic and charging collisions have also been considered. The effective dielectric constant in the presence of dust grains has been constructed. The effect of temporal growth of dust grains on various plasma parameters for different values of the dust density has been explored. The variation of the beam width with the normalized channel of propagation has been observed for distinct dust densities and dust charge states. It is observed that the non-linearity induced by the effective dielectric constant in the presence of dust grains increases the self-filamentation of the beam, thus enhancing the effective critical power with the dust density. Some of the outcomes of our approach are in line with experimental observations. These outcomes may be useful for explaining space and laboratory plasma experiments as well as for future studies in complex plasmas. KEYWORDScritical power, dusty plasmas, fully ionized plasma, propagation of beam, self-filamentation INTRODUCTIONSeveral investigations [1][2][3][4][5] have been carried out on complex plasmas because of their exclusive characteristics. Especially, self-filamentation has been attracting a lot of of interest in recent years because of the non-linear interaction of an electromagnetic (EM) beam in complex plasmas. Non-linearity appears because of the non-linear radial distribution of the intensity of the beam in complex plasmas and modifies the electron concentration, electron temperature, and dielectric constant. Collisional, relativistic, and ponderomotive non-linearity are the leading factors for carrying out research in the field of plasma applications.Collisional non-linearity appears as a result of heating of the plasma components due to the dissipation of energy of the EM beam propagating through the plasma. The energy gained by the electrons during this process is lost by thermal conduction as well as by electron collisions with ions, dust, and neutral particles. In a fully ionized plasma, the former mechanism becomes predominant because of the higher degree of ionization as 0 ( 2 0 ∕l 2 m ) << 1, where 0 (=2m e /m i ) is the fraction of energy loss due to collisions, m e and m i are the electronic and ionic masses, 0 is the initial width of the beam, and l m is the mean free path of collisions of the electrons.The importance of the subject has been confirmed by various researchers. [6][7][8][9][10][11][12][13][14][15][16][17][18][19] Sharma et al. [20] analysed the non-linear self-modulation of an EM beam in a dusty plasma. They measured the non-linear current density and change in the modulation