Experimental study of relativistic self-focusing and self-channeling of an intense laser pulse in an underdense plasma

This paper reports on experimental investigations on relativistic self-focusing and self-channeling of a terawatt laser pulse (0.7 TW/spl les/P/spl les/15 TW) in an underdense plasma. We present results obtained with picosecond (/spl tau/=1 ps) and subpicosecond (/spl tau/=0.4 ps) pulses. In the "long pulse" regime, modifications in the laser propagation are observed for P