Hannover 2016 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 2: Plasma Diagnostics I
P 2.2: Fachvortrag
Montag, 29. Februar 2016, 11:30–11:55, b305
Charge-exchange from fast atoms in X-ray spectra — •Tobias Schlummer1, Oleksandr Marchuk1, Dave Schultz2, Günter Bertschinger1, Wolfgang Biel1, and Detlev Reiter1 — 1Institut für Energie- und Klimaforschung, Plasmaphysik, Forschungszentrum Jülich GmbH, 52425 Jülich — 2Department of Physics, University of North Texas, Denton, TX 76203, USA
Charge exchange recombination (CX) is an important atomic process in astrophysical and laboratory plasmas. It describes the capture of a bound electron from an atom A by an ion Xz: [Xz + Aq → Xz−1+Aq+1]. The newly formed ion Xz−1 is preferentially in a highly exited state causing subsequent line emission. This line emission strongly depends on the final-state-resolved CX cross sections. However, the available theoretical data sets diverge significantly restricting the accuracy of spectroscopic measurements. Recently, a first experimental testing of the high energy final-state-resolved CX cross sections was performed at the TEXTOR tokamak using X-ray spectroscopy. The Rydberg series and the Kα spectrum of He-like argon were measured in the beam path of a 50 keV neutral hydrogen injector. The observed line enhancement caused by the interaction of H-like argon ions with the fast neutrals shows good agreement with the theoretical expectation based on one set of CX cross sections. The CX contributions from H(n=1) and H(n≥1) atoms are clearly separable in the spectra. It is shown that the number of beam excited states is limited to principal quantum numbers n≈ 10 confirming recent models for fast atoms in fusion plasmas using parabolic quantum states.