PIC simulations of the wake-fields generated by the propagation of intense ultra-short pulse lasers through underdense plasmas

Summary form only given. PIC (particle-in-cell) simulations are being used to investigate the interaction of a ultrashort high-intensity laser pulse in a plasma. A linearly polarized laser pulse with a Gaussian intensity profile in the transverse direction with a half-width of 8 /spl mu/m is injected into a cold (T/sub e/=10 eV) plasma with a uniform density of n/sub e/=6.25/spl times/10/sup 18/ cm/sup -3/. The laser has a wavelength of 3200 nm, a pulse length of approximately 25 fs, and an intensity of 2.5/spl times/10/sup 18/ W/cm/sup 2/. In the present case, the spatial pulse length is comparable with the transverse dimension of the laser pulse. Longitudinal oscillations at 2/spl Omega//sub o/ are observed in the leading edge of the pulse as well as a net drift due to the large radiation pressure associated with the laser pulse. The ponderomotive force expels electrons from the main body of the pulse. Electron bunches with densities 10n/sub e/4 are generated when the channel collapses in the tail of the laser pulse.