Investigation of a discharge-ablated capillary waveguide for high-intensity laser pulses

Summary form only given. Many areas of current research, such as novel short-wavelength lasers, high-harmonic generation, and plasma accelerators, require the propagation of intense laser pulses through plasmas. However, the interaction length in such applications is limited to the confocal parameter of the driving beam, and often to even shorter lengths because of strong defocusing by transverse electron density gradients induced by the laser pulse. One technique for channelling high-intensity pulses through plasmas is the discharge-ablated capillary waveguide. In this approach, a current of /spl sim/500 A is passed through an initially-evacuated capillary. Ablation of the capillary wall fills the capillary with plasma, and forms an electron density profile with an axial minimum, leading to guiding of optical pulses injected into the capillary. We have performed experiments to investigate the temporal behaviour of a discharge ablated capillary waveguide.