X-ray radiation from ions with K-shell vacancies

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 1019 W/cm2 focused into nitrogen gas targets, hollow ion con"gurations are observed by means of soft X-ray spectroscopy. It is shown that transitions in hollow ions can be used for *Corresponding author. Tel.: #49-6151-16-6593; fax: #49-6151-16-4321. E-mail address: [email protected] (F.B. Rosmej) 1Permanent address: P.N. Lebedev Physics Institute, Russian Academy of Science, 118927 Moscow, Russia. 0022-4073/00/$ see front matter ( 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 2 4 0 7 3 ( 9 9 ) 0 0 0 9 1 6 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 1010) short pulse (400 fs) lasers electron densities of n % +3]1023 cm~3 at temperatures between k1 % "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 a -line and the region from the He b -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 "rst 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. ( 2000 Elsevier Science Ltd. All rights reserved.