The effect of chirp parameter on laser propagation in collisional quantum plasma

Abstract

This manuscript investigates the effect of the chirp factor on the relativistic self-focusing of a Gaussian chirped pulse laser in collisional quantum plasmas. Nonlinear equations are derived to describe the propagation of a linear chirped laser frequency; afterward, by considering dielectric function obtained by quantum kinetic equation and BGK collision integral in coordinate space, evolution differential equations of laser beam width are found; and numerically solved by the fourth-order Runge-Kutta method. It studies oscillations of the beam width along the propagation direction for different values of collision frequency, chirp parameter, plasma density, and laser intensity. Numerical analyses show that a laser beam is defocused after focusing on a definite value; nonetheless, the positive chirp parameter could reduce the defocusing and strengthen the self-focusing in collisional quantum plasma. Also, the higher chirp value leads to a smaller oscillation amplitude and a greater oscillation rate. Furthermore, the self-focusing effect becomes stronger by increasing plasma density and laser intensity. These consequences could be beneficial in the improvement of fast ignition experiments.