Extreme ultraviolet plasma spectroscopy of a pseudospark XUV source

The development of extreme ultraviolet (XUV) sources for tabletop operation has enabled a range of new applications in nano-structuring and spectroscopy. The quantitative characterization of the XUV emission obtained from a pseudospark hollow cathode lamp (HCL) was carried out with a self-developed flat-field spectrometer for the lambda< 25 nm spectral range. The wavelength calibration in XUV spectroscopy is challenging, because of the poor grating resolving power for ultrashort wavelengths, which propagate only in a vacuum. Among three alternative methods, flat-field calibration showed the highest accuracy over a wider range. The plasma parameters were extracted from the calibrated spectra. The electron temperatures of the discharged N-2, O(2)and Ar gases in the HCL are consistent in the range of 17-22 eV. The intensity of the XUV radiation decreased with the increase of working gas pressure, due to self-absorption. A self-developed one-hole HCL exhibited three orders of magnitude higher electron density (N-e= 1.5 x 10(19)cm(-3)) compared to the state-of-the-art three-hole HCL design (N-e= 10(16)cm(-3)), as confirmed by means of collisional-radiative modelling. These results, along with a comparable spectral fingerprint, suggest more extensive and homogeneous excitation across the entire plasma body in the own design.