Individual project

Funder: German Research Foundation

Period: 2011-2014

URI: https://gepris.dfg.de/gepris/projekt/192988978

Detailed description: 
Ionization and recombination determine the ion charge state distribution in a plasma and hence the emission of electromagnetic radiation from the plasma. In addition, data on atomic structure and decay processes of excited ions are needed for plasma diagnostics and modeling. Available plasma-related data bases for elements with low and intermediate atomic number Z are relatively reliable, however, there are large uncertainties for heavier multi-electron ions, where even the most fundamental atomic processes are not yet sufficiently well understood. In view of the critical importance of tungsten in fusion plasmas it is therefore proposed to make use of the most advanced experimental techniques to study electron-impact ionization and recombination as well as photo-excitation of tungsten ions, representing the more general class of multi-electron atoms, in a wide range of charge states and of electron and photon energies at the best possible energy resolution presently available. The unique expertise of our research group and our collaborators in research applying colliding beams techniques will be exploited to help resolve outstanding problems in modeling the behavior of high-Z atoms in laboratory-based as well as in astrophysical plasma environments. At the same time, using tungsten in different charge states, the physics of a model set of many-electron atoms will be addressed aiming at the understanding of unexplored phenomena, such as the dominance of broad strong resonances, that have occasionally been observed to occur in collisions of complex heavy atoms. Electrons and photons will be used as the finest available probes to elucidate these phenomena that have not yet been systematically studied.