Astron. Astrophys. Suppl. Ser. 142, 95-106

Laboratory observation and modeling of extreme ultraviolet spectra of highly ionized calcium

V.A. Soukhanovskii¹ - S. Lippmann² - M.J. May¹ - M. Finkenthal^1,5 - H.W. Moos¹ - K.B. Fournier³ - W. Goldstein³ - D. Pacella⁴ - G. Mazzitelli⁴

Send offprint request: V.A. Soukhanovskii, e-mail: vlad@jhu.edu

1 - Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, U.S.A.
2 - 2714 Fairview Ave. E. # 101, Seattle, Washington 98102, U.S.A.
3 - Lawrence Livermore National Laboratories, P.O. Box 808, Livermore, California 94550, U.S.A.
4 - Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, CP 65-00044 Frascati Roma, Italy
5 - Permanent address: Racah Institute of Physics, The Hebrew University, Jerusalem, Israel

Received October 8; accepted November 23, 1999

Abstract:

Benchmarking and validation of atomic calculations are crucial for understanding the properties of astrophysical and fusion plasmas. An extended re-evaluation of a previous experimental study of the Ca XVIII - Ca XII extreme ultraviolet (XUV) spectra is presented. CaF₂ was introduced into tokamak plasmas and the spectra of the calcium ions were recorded by a photometrically calibrated grazing incidence time-resolved spectrometer. The local plasma electron temperature and density were measured independently. Nearly all features of the line-of-sight integrated spectra were identified. Atomic data for this work were generated ab initio with the HULLAC suite of codes. The results of collisional-radiative (CR) modeling for individual charge states agree with the measured spectral line intensities within the experimental accuracy for most lines, thus validating the electron temperature and density diagnostic potential of the L-shell lines. In addition, we compare experimentally measured and calculated line intensities with those calculated using the CHIANTI database.

Key words: atomic processes, Sun: UV radiation, Sun: flares