# Hannover 2010 – wissenschaftliches Programm

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# P: Fachverband Plasmaphysik

## P 2: Diagnostics

### P 2.11: Vortrag

### Montag, 8. März 2010, 17:00–17:15, B 305

**Effective rate coefficients for charge-exchange recombination spectroscopy of hydrogen-like ions** — •Tobias Schlummer^{1}, Oleksandr Marchuk^{1}, Yuri Ralchenko^{2}, Wolfgang Biel^{1}, and Detlev Reiter^{1} — ^{1}Plasmaphysik, Institut für Energieforschung, FZ Jülich, 52428 Jülich, Germany — ^{2}Physics Division, National Institute of Standards and Technology, Gaithersburg, MD 20886, USA

For ITER a charge exchange recombination (CXR) spectrometer is planned to measure the densities of impurity ions. A neutral H-beam is injected into the plasma. During a CX reaction the beam atom donates its electron to the bare nucleus of the impurity ion. The highly excited state of the resulting H-like ion decays quasi instantaneously emitting characteristic light. The number of emitted photons is directly proportional to the population of excited states. CXRS diagnostics therefore provides one of the most reliable methods for local density measurements of bare nuclei. In this work the intensity of the CX spectral lines is calculated in terms of effective rate coefficients. The data have been obtained for transitions in the visible spectral range using the validated collisional radiative model NOMAD resolved in nl quantum numbers up to n=20. The new set of CX cross-sections was used as a major source of population of excited states. The corresponding populations of the H-like ions and consequently the rate coefficients are calculated by solving the rate balance equations for H-like and bare nucleus ions at the condition of quasi steady state. The rate coefficients have been obtained for impurities of interest like He and Ar as a function of plasma density, temperature and beam energy.