Dissertation Defenses

Doctoral Dissertation Announcement

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Candidate: Shahin Ahmed Abdel Naby

Degree of: Doctor of Philosophy

Department: Physics

Title: Dielectronic Recombination for Aluminum-Like Ions and Photo-absorption Cross Sections for Magnesium Ions at the K-Edge

Committee:
Dr. Thomas W. Gorczyca, Chair
Dr. Dean W. Halderson
Dr. John A. Tanis
Dr. Kirk T. Korista
Dr. Manuel Bautista
Dr. John B. Miller

Date: Thursday, July 22, 2010 3:00 p.m. - 5:00 p.m.
2202 Everett Tower

Abstract:
Accurate and reliable recombination data are needed for modeling the ions in the finite-density plasmas that may take place in solar flares and in divertors of magnetically confined fusion devices such as the International Thermonuclear Experimental Reactor (ITER). Dielectronic recombination (DR) is the dominant recombination mechanism in photoionized and collisionally-ionized plasmas. DR rate coefficients for M-shell argon ions have been calculated using a configuration-average approach. DR rate coefficients for the aluminum-like isoelectronic sequence are instead calculated using the state-of-the-art multi-configuration Breit-Pauli (MCBP) atomic structure and collision code AUTOSTRUCTURE. Good agreement is obtained with the measurements from the Heidelberg heavy-ion Test Storage Ring facility. The Maxwellian-averaged DR rate coefficients are fitted into a simple formula for efficient dissemination of data and ease of use in plasma modeling codes.
K-shell photoabsorption cross sections are required for determining the chemical abundances of the interstellar medium. As a secondary project, K-shell photoabsorption cross sections for magnesium ions have been calculated using the Belfast R-matrix computer package.