Effect of linear absorption on self focusing of Hermite Gaussian laser beam in plasma in relativistic and ponderomotive regime

Abstract

Effect of linear absorption, intensity of fundamental laser pulse and plasma frequency on beam width parameter is investigated to study the self-focusing of Hermite-Gaussian(HG) laser beam in plasma under relativistic and ponderomotive regime. Intense short pulse laser propagates through plasma imparts oscillatory velocity to electrons and non linearity arises. Using the paraxial approach we have derived the second order differential equation for beam width parameter and the equation for normalized radius of incident beam is also obtained using the critical condition. The outcome of our study reveals that light absorption and intensity of radiation enhance the self focusing of Hermite-Gaussiam laser beam. It is observed that the beam width parameter shows significant decrease for higher values of linear absorption coefficient and plasma frequency. We also observe that radius of the incident beam decreases sharply with increasing intensity of incident pulse for higher values of plasma frequency.