Spectroscopy of highly charged ions in Solar and astrophysical plasmas

Abstract

Spectroscopic observation of EUV emission lines in the transition-region and corona provide unique information on physical conditions in these outer atmospheres of the Sun. The EUV Imaging Spectrometer (the EIS) on board the Hinode mission is capable of observing, for the first time in Solar EUV observations, spectra and monochromatic images of possibly non-ionization-equilibrium plasmas in the solar transition-region and corona at two-wavelength bands of 170 - 210Å and 250 - 290Å, with typical time-resolutions of 1 -10 seconds. Dynamic plasma acceleration and heating are found to take place in the solar atmospheres, and they are confined in tiny structures. A time-dependent collisional-radiative model for the iron plasmas is developed to diagnose temperatures and densities in the outer atmospheres of the Sun; no systematic models yet exist for iron ions at the ionization stages of L- and M-shells, which are very important for coronal plasma diagnostics. Adopting the best available theoretical calculations of atomic parameters of these iron ions, as well as generating the experimental data by a compact electron beam ion trap (EBIT), is essential to one of the aims of our research that the mechanism of coronal heating is explored via accurate diagnostics information obtained by the EIS instrument.