It is shown that during a capillary discharge, plasma channels for guiding
light from high-power lasers are temporarily formed. The experiments are pe
rformed with alumina capillaries of 2-mm radius and 14-cm length filled wit
h about 100 Pa of helium, methane or hydrogen. The transmission of probe li
ght is enhanced due to light guiding by a factor up to 20 during a time win
dow of 5 ns. The results indicate the formation of a first channel, when th
e shock wave reaches the axis, and of a second channel after the reflection
of the shock wave on the axis. Compared to simple focussing by a lens, in
the guiding device the intensity-length product: increases by almost two or
ders of magnitude. Guiding is achieved over 180 times the Rayleigh length.