Radial density profile and stability of capillary discharge plasma waveguides of lengths up to 40 cm

Abstract We measured the parameter reproducibility and radial electron density profile of capillary discharge waveguides with diameters 650 $\mathrm{\mu} \mathrm{m}$ to 2 mm lengths 9 40 cm. To best authors’ knowledge, cm is longest plasma waveguide date. This length important for $\ge$ 10 GeV energy gain in a single laser-driven wakefield acceleration stage. Evaluation variations showed that their focusing strength was stable reproducible $<0.2$ % average on-axis $<1$ %. These explain only small fraction bunch observed experiments Measurements laser pulse centroid oscillations revealed channel rises faster than parabolic excellent agreement magnetohydrodynamic simulation results. show effects non-parabolic contributions on Gaussian propagation were negligible when approximately matched channel. However, they affected non-matched configuration which used as telescope change focused spot size.