Spatially resolved interferometric measurement of a discharge capillary plasma channel

The plasma density distribution within a capillary discharge determines its performance as a waveguide for high intensity laser pulses. This paper describes direct, spatially resolved density measurements of a discharge capillary plasma channel, obtained using transverse interferometry. A transparent glass discharge capillary with square cross section was designed and constructed to provide a clear side view for interferometric imaging. Localized density profiles were reconstructed both inside and outside the capillary. Density channels suitable for high-intensity laser guiding were directly measured, revealing significant axial density gradients inside the capillary near the ends, as well as possible curvature of the channel