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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg

[1.52] Atomic Models for Non-LTE Simulations

D. T. Woods (SSL/UCB), J. I. Castor (LLNL), G. H. Fisher (SSL/UCB)

We describe our atomic physics data base for use in future non-LTE simulations of the solar atmosphere. Self-consistent atmospheric models require a treatment that is valid from the photosphere to the corona. We therefore need a vast array of atomic data from many elements spanning the widest range of ion stages. We have therefore been developing atomic models of the most important radiators and absorbers in the Sun. We have used a suite of atomic physics codes at Lawrence Livermore National Lab to produce atomic models for all ion stages of H, He, C, N, O, Ne, Mg, Si, S, Ca, and Fe. The atomic structure calculation is based upon a Multi-Configuration Dirac-Fock method. We have invested considerable time in overcoming the effects of electron correlation which make the solution of near neutral ions difficult. As such we have now produced detailed models for even the neutral species. For example, for neutral iron (the most difficult ion in our set) we have produced a converged solution involving over 5000 levels. We have calculated a large number of oscillator strengths. For neutral iron alone, more than 3 million electric dipole oscillator strengths have been computed.

To augment our calculations we have performed extensive literature searches to assemble the results from the best atomic physics calculations for these species, and have incorporated these results (where possible) into our models. Our models include the detailing of many inner-shell vacant states so that these models can be used in the modeling of flaring atmospheres where it is necessary to account for the absorption of X-rays and EUV radiation in the chromosphere. We present the ionization equilibrium and radiative loss curves in coronal equilibrium and compare them with existing results.

This research is supported by NASA grant NAGW-3429, and NSF grants AST-9528474 and ATM-9505182.

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