Evolution of high intensity ultrashort laser pulse spot size propagating through magnetized plasma

Evolution of the spot size of ultrashort laser pulse propagating in underdense magnetized cold plasma has been studied taking into account the effect of nonlinearity up to third order. The plasma is embedded in an external magnetic field with constant strength and variable direction on a plane perpendicular to electric field vector of the laser pulse. The time derivative of the third order nonlinear current density of plasma electron is used in the paraxial wave equation in plasma and the source dependence expansion method is employed to solve the equation. Results show that, influence of the direction of the external magnetic field on spot size is significant. So that, increasing angle between laser pulse magnetic field vector and external magnetic field decreases the effect of external magnetic field and leads to decreasing the focal length of plasma lens. Also, the effects of laser pulse intensity and external magnetic field strength on the self-focusing property of laser pulse for different direction of the external magnetic field have been studied.

► We take into account the effect of nonlinearity up to third order.
► The plasma embedded in an external magnetic field with constant strength.
► We assume that, the direction of the external magnetic field is variable.
► Increasing the strength of the external magnetic field decreases self-focusing property.
► For different direction of the magnetic field both of self-focusing and defocusing is possible.