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Temperature and ionization balance dependence of O VII line ratiosThe forbidden-plus-intersystem to resonance line ratio (G) for the heliumlike ion O VII is calculated, taking into account cascades, blended satellite lines, and radiative plus dielectric recombination. It is noted that G is of particular use for investigating radiative-transfer effects and nonequilibrium ionization in the solar corona and that the calculations are applicable to a low-density optically thin Maxwellian plasma. The temperature dependence of G is considered for the case of a steady-state equilibrium plasma, and the effect of departures from ionization equilibrium on G is examined. It is found that G is quite insensitive to temperature over the range from 600,000 to 6 million K for a steady-state plasma, but that recombinations may be suppressed or dominant, depending on the relative abundance of O VIII, for a plasma in which the state of ionization is not in equilibrium with the electron temperature. This latter effect is shown to be capable of causing large variations in G that are dependent on electron temperature.
Document ID
19790029709
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Acton, L. W.
(Lockheed Missiles and Space Co. Palo Alto, CA, United States)
Brown, W. A.
(Lockheed Research Laboratories Palo Alto, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
November 1, 1978
Publication Information
Publication: Astrophysical Journal
Subject Category
Solar Physics
Accession Number
79A13722
Funding Number(s)
CONTRACT_GRANT: NAS2-9181
CONTRACT_GRANT: NGR-12-001-075
Distribution Limits
Public
Copyright
Other

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