Interpretation of High Resolution X-Ray Observations of Coronal Plasmas

Abstract

Soft X-ray spectra with high resolution represent a rich source of information on the nature of solar plasma as well as on the power loss of the fusion plasma due to impurity radiation. These emission spectra correspond to mutliply ionized atoms and for their interpretation in terms of physical parameters it is necessary to understand the atomic processes involved and to compute the corresponding parameters. These X-ray diagnostic techniques are used mainly for active region and flare plasmas and have determined the design of the X-ray Polychromator (XRP) flown on the NASA Solar Maximum Mission. Spectra from calcium and iron have been observed and fitted with the best available theoretical spectra giving the temperature and density, ionization state, abundances, velocity,... A similar analysis of the iron spectrum emitted from the PLT (Princeton Large Torus) tokamak plasma has confirmed the precision of the electron temperature diagnostic. Experience with such high resolution X-ray spectroscopy offers the possibility of extension to the analysis of optically thin astronomical plasmas such as stellar coronal and wind, supernovae remnants,...