Electron acceleration and the propagation of ultrashort high-intensity laser pulses in plasmas

Reported are interactions of high-intensity laser pulses (lambda = 810 nm a nd I less than or equal to 3 X 10(18) W/cm(2)) with plasmas in a new parame ter regime, in which the pulse duration ( tau = 29 fs) corresponds to 0.6-2 .6 plasma periods. Relativistic filamentation is observed to cause laser-be am breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 de grees is generated in the forward direction, which is correlated to the gro wth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long pulse results.