Turbulent amplification of magnetic field in laser plasma interaction and astrophysical plasmas

Abstract

The investigation of the nonlinear evolution of magnetosonic wave (MSW) in the presence of density fluctuations at the background has been presented in this paper. The propagation of a single beam or counter propagation of beams is assumed to change the background density accordingly. The model equation for MSW has been obtained by considering the effect of modified plasma density in the background, along with the nonlinear ponderomotive force. The equation so found has been numerically solved to study its effect on the localization of MSW. From the results, the localized and filamentary structures of the MSW can be observed. The effect of variation of the amplitude of density perturbation has been studied on the amplification of magnetic field. To get better insight of these structures, a semi-analytical model with paraxial approximation has been studied. The effect of background density fluctuations on the resulting turbulent spectrum has been evaluated. The results show that the turbulent spectrum gets flattened towards smaller scales as the counter propagation of beams takes place as compared to the single beam propagation. The nonlinear interaction presented here may be important in interpreting the phenomenon of turbulence and magnetic field amplification due to mergers and jets in central galaxy.