Contrib. Plasma Phys. 46, No. 7-9, 655 – 660 (2006) / DOI 10.1002/ctpp.200610059 Double Excited High-n Spin Dependent Atomic Structure Scaling Laws for HeI: Application to Radiative Properties for Edge Plasma Conditions E. H. Guedda ∗1,2 , F. B. Rosmej 1 , P. Genesio 1 , R. Stamm 1 , L. A. Vainshtein 3 , M. F. Gu 4 , E. Lindroth 5 , and F. Khelfaoui 2 1 Universit´ e de Provence et CNRS, UMR6633, Laboratoire de Physique des Interactions Ioniques et Mol´ eculaires, Centre Saint-J´ erˆ ome, Service 232, F-13397 Marseille Cedex 20, France 2 Centre Universitaire d’El oued, ISET, 39000 El oued, Algeria 3 P. N. Lebedev Physical Institute, Russian Academy of Science, Moscow 11924, Russia 4 KIPAC, Department of Physics, Stanford University, USA 5 Stockholm University, Atomic physics, 10691 Stockholm, Sweden Received 19 October 2005, accepted 9 February 2006 Published online 22 August 2006 Key words He atomic structure, dielectronic recombination rates, diagnostics, magnetic fusion plasmas. PACS 32.70.Fw, 32.80.Dz, 52.55.Fa, 52.25.Vy We present our numerical calculations of dielectronic recombination rate coefficients which are spin dependent (2lnl ′ -1snl 1 L, 1snl 3 L) and develop scaling relations which are converging for all spin (S), angular (L) and main (n) quantum numbers. The influence of atomic data inaccuracies, spin dependent channelling of dielectronic recombination rates and collisions on the atomic/ionic fractions is discussed. c  2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction The radiation emission of helium (He) in magnetic fusion plasma is of manifold interest. In ITER recombining α-particles from fusion reactions lead to the formation of He 1+ and He 0+ and the corresponding line emission. In divertor simulator experiments [1] , He plasmas and He gas puffing are used to provide a basic understanding of the phenomenon of plasma detachment. A large impact of the spectroscopic analysis stems from the fact that it is based essentially on a collisional radiative approach and therefore provides an information on plasma conditions independent of plasma models [2]. Recombination process are important: Dielectronic recombination (DR) influences on the atomic/ionic balance in plasmas [3] and the corresponding dielectronic satellite emission originating from the autoionizing states plays a central role for diagnostic purposes of complex phenomena: e.g., charge exchange and diffusion in tokamaks [4-5], radiation cooling in magnetic fusion plasma [6], temperature determination [7], etc. However, the data available in the literature for He describe only the total recombination rate coefficient. These data ignore excited state coupling effects in the singlet and triplet structure of neutral helium, the corresponding cascading into different spin-states and collisional redistribution. These effects, however, turned out to be very important for typical plasma parameters in magnetic fusion research. In this paper, we present our results for numerical calculations of neutral helium DR rate coefficients which are spin dependent (1s + e → 2lnl ′ → 1snl 1 L + hν, 1snl 3 L + hν ′ ) and develop scaling relations which are converging for all spin (S), angular (L) and main (n) quantum numbers. The influence of DR rate coefficient for low density isolated atoms and for typical densities encountered in magnetically confined fusion plasmas on the atomic/ionic balance will be discussed. ∗ Corresponding author: e-mail: elh - guedda@yahoo.fr, Phone: +33 491 288 625, Fax: +33 491 670 222 c  2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim