Plasma diagnostics using a tabletop soft x-ray laser: demonstration of shadowgraphy and interferometry using a Lloyd's mirror

We report the first demonstration of plasma imaging and interferometry using a tabletop soft x-ray laser. A very compact capillary discharge Ne-like Ar laser operating at 46.9 nm was used as a backlighter to study the evolution of the plasma of a micro-capillary discharge. The resulting series of shadowgrams show the plasma created by ablation of the walls of the evacuated micro-capillary rapidly evolves from a non-uniform initial state into a symmetric column with minimum density on axis. In a second experiment we took advantage of the good spatial coherence of the capillary discharge laser to perform interferometry measurements in the plasma of a pinch discharge. In this experiment the laser was used in combination with a wavefront division interferometer based on Lloyd's mirror to map the electron density distribution in the cathode region of the discharge.