Some Nonlinear Phenomena in a Preformed Underdense Plasma

The propagation of a laser pulse with a peak intensity 10¹⁹W/cm² through the preformed underdense plasma with the density 0.014n_c are studied by using two-dimensional particle-in-cell simulations. The longitudinal electron heating is identified and verified, and its major property agrees with the theoretical prediction. The electron distributions in phase space, patterns of the electric fields, profiles of the ion or electron density and other plasma nonlinear phenomena are presented and discussed.