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Accueil > Thèmes de recherche > Physique des collisions ioniques

Diagnostics of Tokamak fusion plasmas

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Beyond the study of electron-ion/atom collisions, which have been at the root of the improved nanoplasma model previously described, we also considered collisional processes devoted to the analysis of diagnostics of Tokamak plasmas.
In the framework of ADSEX-Upgrade programs concerning Ne and Ar seeded plasmas, we have computed Neq+,Arq++(H,D,T) inelastic cross sections that enter the ADAS simulations (H. P. Summers et al., Strathclyde, UK) of the plasma diagnostics. Quantal, semi-classical and classical methods have been used to encompass the wide range of impact energies involved in the diagnostics simulations. We are also concerned with ion collisions on molecules, that take place near the walls of Tokamak fusion devices. A cooperation between France (CELIA, LASIM), Spain (Madrid) and Hungary (Debrecen) has been initiated to consider target molecules of interest in radiation damage of living cells.

Within the collaboration with the atomic physics group at Concepción’s University (ECOS-CONICYT project 2004-2006) and in connection with plasma–walls interactions, we investigate electron transfer mechanisms in grazing incidence low energy ion–metallic surfaces collisions. Our work has been particularly focused on the surface-plasmon assisted electron capture process which is the collective counterpart of the well known Auger mechanism. We have shown that this process plays a significant role in He+/Al and H+/Al interactions by means of comparisons between our theoretical results and experimental outgoing charge fractions and angular distributions provided to us by Pr. H. Winter (Humboldt University – Berlin). Nevertheless, in spite of the advances reached in recent years on a deeper understanding of these interactions, large uncertainties remains on the electronic structure of ions (and atoms) in the very near surface region and consequently on the transition rates of the relevant exchange processes. In the forthcoming years we plan to address this problem which is closely related to the one of atomic structures in plasmas since in the near surface region the moving ion travels inside a strongly non – uniform cold degenerate plasma.