Propagating characters of Gaussian laser beam in plasmas with non-homogeneous radial temperature distribution

We investigate the propagation regimes of laser beam in plasmas with radial distribution of electron temperature, characterized by ratio parameter of radial Gaussian distribution. By following the WKB method and paraxial approximation, the propagation equations of laser beam are derived and discussed for two nonlinearity mechanisms respectively. Both the critical curves for different ratio parameters are plotted, and it is proved that the self-focusing or self-trapping mode could be realized only when the ratio parameter excesses 1. The variations of laser beam-width are calculated, which indicates the feasibly effective modification of propagation characters by radial distribution of electron temperature. -- Highlights: ► Radial Gaussian distribution of plasma temperature in laser–plasmas interaction. ► Two dynamic mechanisms of collisional and ponderomotive nonlinearities are involved. ► Propagating characters of laser beam for different ratio parameters are discussed. ► Divergence mode is accessible with severer variation of radial temperature. ► Self-trapping or self-focusing mode could occur when ratio parameter excesses 1.