X-ray radiation from ions with K-shell vacancies

Abstract New types of space resolved X-ray spectra produced in light matter experiments with high intensity lasers have been investigated experimentally and theoretically. This type of spectra is characterised by the disappearance of distinct resonance line emission and the appearance of very broad emission structures due to the dielectronic satellite transitions associated to the resonance lines. Atomic data calculations have shown, that rather exotic states with K-shell vacancies are involved. For quantitative spectra interpretation we developed a model for dielectronic satellite accumulation (DSA-model) in cold dense optically thick plasmas which are tested by rigorous comparison with space resolved spectra from ns-lasers. In experiments with laser intensities up to 10 19 W/cm 2 focused into nitrogen gas targets, hollow ion configurations are observed by means of soft X-ray spectroscopy. It is shown that transitions in hollow ions can be used for plasma diagnostic. The determination of the electron temperature in the long lasting recombining regime is demonstrated. In Light-matter interaction experiments with extremely high contrast (up to 10 10 ) short pulse (400 fs) lasers electron densities of n e ≈3×10 23 cm −3 at temperatures between kT e =200–300 eV have been determined by means of spectral simulations developed previously for ns-laser produced plasmas. Expansion velocities are determined analysing asymmetric optically thick line emission. Further, the results are checked by observing the spectral windows involving the region about the He α -line and the region from the He β -line to the He-like continuum. Finally, plasmas of solid density are characteristic in experiments with heavy ion beams heating massive targets. We report the first spectroscopic investigations in plasmas of this type with results on solid neon heated by Ar-ions. A spectroscopic method for the determination of the electron temperature in extreme optically thick plasmas is developed

Strongly coupled laser produced plasmas: investigation of hollow ion formation and line shape analysis

International audienceX-ray line emission originating from hollow ions has been identified in dense laser-produced plasmas by means of two-dimensional X-ray optics and spectral simulations performed by the code MARIA. It is shown that for plasma coupling parameters gamma>1 excited states correlation effects of hollow ion configurations exceed the usual ground-state population channel by many orders of magnitude. The intensity of the emission of these excited-state hollow ions can be stronger than those of the usual satellite or resonance line transitions and lead to a remarkable distortion of the spectral emission. Detailed spectral simulations for the K-shell spectral interval are carried out for the 1s2lnl'-Rydberg configurations as well as the K1L0M1N1, K1L0M1N0O1, K1L0M1N0O0P1 hollow ion configurations. Population kinetics, Stark broadening and spectral analysis are discussed along with experimental results of silicon laser-produced plasmas