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SUMMARY:Modelling Ion Populations in Plasmas: the Solar Transition Region 
 - Roger P. Dufresne
DTSTART:20181106T130000Z
DTEND:20181106T140000Z
UID:TALK112090@talks.cam.ac.uk
CONTACT:Dr William Béthune
DESCRIPTION:Ion abundances for each element in a plasma depend on the inte
 rplay of atomic transitions that can take place both within an ion and bet
 ween neighbouring ions. Knowledge of the ion populations present is fundam
 ental for extracting key plasma parameters\, such as temperature\, density
  and elemental abundances\, from lines observed in plasma spectra. In high
  temperature\, medium density plasmas\, such as the solar corona\, modelli
 ng can be greatly simplified owing to the plasma conditions present\, and 
 predicted ion populations agree well with observations. Further down in th
 e solar atmosphere\, in the transition region\, higher densities\, lower t
 emperatures and the dynamic nature of the plasma mean the simplifications 
 used in the modelling no longer apply. Predicted intensities for some ions
  can be up to a factor of ten different from observations. Improvements be
 ing made to the modelling\, using carbon as a test case\, will be presente
 d\, including new atomic calculations. Predictions made by the new modelli
 ng for ion populations will be compared to the existing model\, and a prel
 iminary comparison with observations given. 
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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