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Title: A detailed study of important atomic collision processes for the analysis of astrophysical plasmas
Author: Tyndall, Niall Benjamin
ISNI:       0000 0004 6351 2230
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2016
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In this thesis, we present a number of atomic transitions associated with three astrophysically important systems S9+, Ar2+, and Co2+ . The latter is especially prominent in the study of particular classes of Supernovae (SNe). We also provide an additional collisional-radiative modelling procedure to analyze electron collisions involving Co2+ by implementing an isolated atom approximation. We consider typical temperature and density diagnostics to constrain properties such as SNe evolution and mass-loss processes. Large evaluations for these three systems have been considered using the well studied R-matrix method, where appropriate parallel computer codes DARC and BP have been used to incorporate relativistic effects accordingly. We have studied in detail the photoionization of S8+, both valence and L2-shell photoionization of Ar+, above threshold photoionization of Co+ and the applicable extension to the electron-impact excitation of Co2+ required for the computation of Maxwellian averaged collision strengths. To describe these systems, we have considered various approaches to model such many-body problems. Two computer packages CIV3 and GRASPO have been executed to solve the target state problem, and we apply the theory of configuration-interaction to include sufficient correlation effects to enhance the wavefunctions. Energy levels, oscillator strengths and transition probabilities have been presented here and comparisons are conducted with other works. A systematic analysis has been carried out, and theoretical predictions for our current set of scattering results agree well with other theoretical and experimental measurements. Therefore, we conclude that in this thesis we have presented accurate and extremely useful atomic data for transitions involving electrons and photons essential for spectral modelling.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available