A hydrogen plasma waveguide for high-intensity laser pulses is described. T
he guiding channel is formed by a small-scale discharge in a hydrogen-fille
d capillary. The measured lifetime of the capillary is inferred to be great
er than 10(6) shots. The results of interferometric measurements of the ele
ctron density in the capillary are presented. The guiding channel is found
to be highly ionized with an axial electron density of 2.7 x 10(18) cm(-3),
and parabolic, the curvature corresponding to a matched spot-size of 37.5
mum.