Long plasma channels in segmented capillary discharges

Guided propagation of ultrashort (100 fs) high intensity (10 ¹⁶ W cm ^-2) laser pulses over distances up to 12.6 cm using optimized segmented capillary is reported. A new diagnostic technique is presented in which the transport of a guided laser pulse at different delay times from the initiation of the discharge is sampled on a single discharge shot. The current waveform was optimized to obtain a long lasting, deep radial profile. Radial profiles with the maximal electron density from 4 × 10 ¹⁷ to 2 × 10 ¹⁸ cm ^-3 and up to 25% deep were obtained thereby, whereas longitudinal profiles were found to be remarkably uniform. The potential application of these long channels to the laser wake field accelerator is discussed.