PLASMA CHANNEL FORMATION AND GUIDING DURING HIGH-INTENSITY SHORT-PULSE LASER-PLASMA EXPERIMENTS

A plasma channel is formed behind a self-guided, subpicosecond, 2 TW l aser pulse in a hydrogen gas jet plasma. The channel is produced from the radial expulsion of plasma ions due to charge separation created i n the displacement (or cavitation) of plasma electrons by the large po nderomotive force of the laser. Using Thomson scattering diagnostics a nd mode structure measurements, an intense trailing laser pulse (I sim ilar to 5 x 10(16) W/cm(2)) is observed to be guided throughout the le ngth of this channel for about 20 Rayleigh lengths, approximately equa l to the propagation length of the self-guided pump laser pulse.