The coronal X-spectrum: Problems and prospects

Major attention is given to high-resolution observations of the spectrum of the nonflaring sun. The spectra below 25 A and from 25 to 400 A, the spatial distribution of the coronal emission, identification of spectral lines, and absolute intensity measurements are considered. The theoretical basis for the interpretation of the observed spectra is discussed in terms of the population and the deexcitation of excited states, recombination process and the X-ray continuum, techniques for the direct measurement of physical parameters, and the relative importance of emission processes in the coronal spectrum. The structure of the quiet corona is treated, taking account of elemental abundances and temperature and density structure. Recent observational results and prospects are discussed.