Spectroscopic study of the fast gas-filled-capillary discharge

The capillary experiment CAPEX was reconstructed to approach conditions suitable for creation of population inversion in Ne-like Ar. The reconstruction consisted in substitution of a ceramics capillary for former plastic one, in remarkable reduction of the pre-ionization current, and in change of Ar filling and pumping geometry. The soft X-ray spectroscopic measurements prior to and after this reconstruction are described. It is shown that the reconstruction resulted in appearance (under certain conditions) of the strong spectral line at the wavelength of laser transition (46.9 nm) that dominates the spectrum even at exposition 50 ns.