I. "Murakami

K. Moribayashi

T. Kato

U." Safronova

National Institute for Fusion Science (NIFS-Repository)

§12. Effect of Recombination on Line Intensities of Be-like Ions Murakami, I., Kato, T., Moribayashi, K. Safronova, U. (Institute of Spectroscopy, Rus-sian Academy of Sciences, Russia) We have constructed a collisional-radiative model ( CRM) for Be-like ions to calculate the spectral line intensities in non equilibrium ion-ization plasma. In the CRM we take into ac-count recombination processes from the ground state of a Li-like ion to the excited states of a Be-like ion as well as ionization from the excited states of the Be-like ion. We focused on Be-like Fe (Fe22+) and Be-like Ne (Ne6+) ions to build the CRM with their atomic data [1,2,3,4,5]. Since the dielectronic recombination process populates the electron density much more at higher excited states and cascades are impor-tant, we consider many excited states in the CRM: 2snl with n :::; 70 and 2pnl with n :::; 11 for Fe22+; and 2snl with n :::; 20 and 2pnl with n :::; 6 for N e6+. The dielectronic recomi bation is more important for Be-like ions than the ra-diative recombination or the three body recom-bination at high temperature and low density plasma, however, the rate coefficients are not available. So we have calculated the recombina-tion rate coefficient with the Cowan's code, con-sidering the dielectronic recombination through doubly excited states, 2pnl and 3lnl', to each excited state. Using the constructed CRM, we have cal-culated the spectral line intensities and the radiative power losses as functions of the electron density and temperature from Fe22+ and Ne6+ ions (Figs.1 and 2). The radia-tive power loss is Ploss(ionizing)n(Be-like) + Ploss(recombining)n(Li-like). If the Li-like ion is more abundant than the Be-like ion or the electron temperature is low, the recombining component [Ploss( recombining)] becomes impor-tant. The ionizing component [Ptoss(ionizing)] of Fe22+ ion has weak temeperture dependence at around 1ke V where the ion is the most a bun-dant, and the recombining component is about one tenth when the ion abundance ratio is unity. 11 o-,a t::'T"'--r-T""T"'1rTTTr--""""T"'-.-.-r-T"TT"'~ f"'·lo-u' en ..,E u ~ v 1·to-20 a.. 1000 10000 T.(eV) Figure 1: Radiative power loss of Be-like Fe ion as a function of an electron temperature. Ioniz-ing plasma component and recombining plasma component are shown together with the power loss due to the bremsstrahlung and the loss of the ionizing plasma component of Li-like Fe ion. 710-18 en ..,E u 10-20 E' ~ 1 o-~ L--.L.......L....L.I...LI..I..I.l.---L.....L..L..LLU.I.L-~....L...LL.L.ll.l 1 10 100 1000 T. (eV) Figure 2: The radiative power loss of Be-like Ne ion as, a function of an electron temperature. References 1) Murakami, I., Kato, T., and Dubau, J., NIFS-DATA-35 ( 1996) 2) Zhang, H.L. and Sampson, D.H., A.D.N.D.T., 52 (1992) 143 3) Sampson, D.H., Goett, S.J., and Clark, R.E.H., A.D.N.D.T., 30 (1984) 125 4) Mewe, R., Astron. Astrophys., 20 (1972) 215 5) Clark, R.E.H., Cowan, R.D., and Bobrowicz, F.W., A.D.N.D.T., 34 (1986) 415 291 

Effect of Recombination on Line Intensities of Be-like Ions

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