A hydrodynamic simulation is used to show that intense laser pulses propagating in underdense plasmas create stable, long-lived, and completely evacuated channels. At low intensities, ${I=10\mathrm{}}^{17}$ ${\mathrm{W}/\mathrm{c}\mathrm{m}}^2,$ self focusing seriously distorts the temporal envelope of the pulse, but channeling still occurs. At high intensities, ${I=10\mathrm{}}^{19}$ ${\mathrm{W}/\mathrm{c}\mathrm{m}}^2,$ channeling can proceed over many diffraction lengths with significant distortion restricted to the leading edge of the pulse.

• Received 29 April 1997

DOI:https://doi.org/10.1103/PhysRevE.56.R2394