Soliton formation of a linearly polarised laser beam in relativistic thermomagnetic plasma

Abstract In this paper, the interaction of a linearly polarized laser beam with a semi-bounded weak relativistic thermomagnetized plasma is investigated. As the laser enters the plasma, its linear polarization is transformed into right-handed (RCP) and left-handed (LCP) circular polarizations, a phenomenon arising from the magnetic field generated by the electric field gradient of plasma particles and the applied external magnetic field. This nonlinear environment leads to the formation of soliton waves. By employing the relativistic momentum and continuity equations, an appropriate dielectric function was derived to analyze the nonlinear dynamics of the coupled system, and soliton solutions were analytically obtained for both polarizations. The results indicate that the soliton characteristics in relativistic thermomagnetized plasmas are highly sensitive to the polarization state, magnetic field strength, laser frequency and electron thermal velocity. RCP solitons, due to stronger coupling with the external magnetic field, are taller and narrower, whereas LCP solitons, with weaker nonlinearity, are broader and shorter. An increase in magnetic field strength enhances nonlinearity, producing taller and narrower solitons, while an increase in electron thermal velocity strengthens the effect of the pressure term, reduces nonlinearity, and results in broader and lower solitons; this effect is stronger for RCP solitons than for LCP ones. Within the range of parameters considered, increasing the laser frequency leads to stronger energy localization, resulting in narrower and taller solitons. The mutual coupling of the real and imaginary parts of the electric field in both polarizations occurs without any energy exchange.