Investigation of a hydrogen plasma waveguide.

A hydrogen plasma waveguide for high-intensity laser pulses is described. The guiding channel is formed by a small-scale discharge in a hydrogen-filled capillary. The measured lifetime of the capillary is inferred to be greater than 10(6) shots. The results of interferometric measurements of the electron density in the capillary are presented. The guiding channel is found to be highly ionized with an axial electron density of 2.7x10(18) cm(-3), and parabolic, the curvature corresponding to a matched spot-size of 37.5 microm.