Europhys. Lett.
Volume 73, Number 3, February 2006
Page(s) 342 - 348
Section Atomic and molecular physics
Published online 23 December 2005
Europhys. Lett., 73 (3), pp. 342-348 (2006)
DOI: 10.1209/epl/i2005-10405-7

Convergent coupling of helium to the H/D background in magnetically confined plasmas

F. B. Rosmej1, R. Stamm1 and V. S. Lisitsa2

1  Université de Provence et CNRS, UMR6633, Centre St. Jérôme, PIIM Av. Escadrille Normandie Niemen, 13397 Marseille Cedex 20, France
2  Russian Research Center "Kurchatov" - 123182 Moscow, Russia

received 27 October 2005; accepted 2 December 2005
published online 23 December 2005

The alpha particles are coupled to the hydrogen/deuterium background plasma via charge exchange processes. Population kinetics calculations show that in the framework of standard models, the charge transfer from hydrogen/deuterium excited states to helium leads to a strong divergence of the atomic populations and to a critical dependence on the number of quantum states retained in the simulations. The divergence is related with the large cross-sections for charge transfer from excited states of the background atoms. For typical parameter conditions (e.g., ITER) the charge-exchange-induced population flow may even reach the level of flow typically induced by turbulent diffusion. A self-consistent excited-states coupling approach of atomic kinetics is proposed, which avoids divergences and critical dependence on the number of states. This approach also removes free parameters from the system and provides therefore the ideal basis for a pure diffusion analysis in space which is requested to test global effects of turbulent transport theories.

32.70.Fw - Absolute and relative intensities.
52.25.Vy - Impurities in plasmas.
52.25.Ya - Neutrals in plasmas.

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