Highly Ionized ca X-Ray Spectra from Flares Seen with the Diogeness Spectrometer

X-ray lines of helium-like calcium (Ca XIX) and nearby Ca XVIII dielectronic satellites have been observed in solar flares with a number of high-resolution spectrometers. The DIOGENESS instrument on the CORONAS-F spacecraft, a scanning crystal spectrometer which operated in 2001, observed these lines but in addition satellites of lower ionization stages of Ca as well as ionized Ar lines in the spectral range 3.05-3.35 Angstroms. In this work, spectra from flares including the X5 flare on 2001 August 25 are analyzed and compared with synthetic spectra. The latter were generated with a specially written code based on various theoretical data including results from the Cowan Hartree-Fock pseudo-relativistic code run for satellite lines. Solar flare spectra taken with the P78-1 SOLFLEX instrument in 1980-1981 are also analyzed. There is close agreement between the solar flare and synthetic spectra for the Ca XIX lines and Ca XVIII satellites (3.17-3.21 Angstroms) and also the Ca XVII satellites at 3.215-3.235 Angstroms clearly seen in DIOGENESS and some SOLFLEX spectra. In addition, fainter line emission at longer wavelengths (λ> 3.24 Angstroms) in DIOGENESS spectra is identified with Ca XVI satellites and with the Ca XVIII "o" and "p" satellites as well as a feature due to Ar XVI. These identifications are confirmed by recent analysis of X-ray Ar and Ca spectra from the Alcator-C Mod tokamak high-temperature plasmas. The synthetic code developed for this work will be used for analysis of X-ray spectra, recently characterized with new calibration data, from the Solar Maximum Mission Bent Crystal Spectrometer, and spectra expected from the Polish high-resolution ChemiX spectrometer/dopplerometer, due to fly on the [two] Russian Interhelioprobe spacecraft in 2025/2026.