Model soft X-ray spectra for different solar activity conditions

Soft X-ray flux levels in 0.5-3 A, 1-8 A and 8-20 A bands representative of a variety of solar flare conditions have been obtained from an examination of extensive data over the period, 1964-1974. Model spectral distributions corresponding to these conditions have been obtained from the selected flux values using theoretical thermal emission spectra that include X-ray emission lines in addition to free-free and free-bound continuum as well as temperature dependent emission measure representing multithermal plasma responsible for soft X-ray emission. The models are useful in calculations of ionospheric ion production rates in the D-region. (author)