| Terascale
Atomic Physics for Controlled Fusion Energy
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| Figure
16 Electron probability cloud following
a head-on collision between a proton and a lithium atom
at 15 keV incident energy. The large peak at the center
represents excitation of the lithium target, the narrow
peak at right center represents charge transfer to the
proton projectile, while the many plains and valleys represent
ionization of the lithium target. |
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Modeling the electron-impact ionization of atomic and molecular
constituents is a key to understanding many astrophysical and
laboratory plasmas. The goal of this collaboration is to implement
state-of-the-art atomic collision codes on the newest generation
of terascale computing facilities. Studies will then ensue on
a wide range of atomic collision processes present in the edge
region of controlled fusion plasmas. Computational research
advances will be applied to other general science areas, including
laser interactions with atoms and molecules, atomic physics
near compact stars, and the dynamics of cold atom gases.
Colgan et al. have conducted three independent nonperturbative
calculations for the electron-impact ionization of both the
ground and first excited states of the neutral lithium atom
(Figure 16). The time-dependent close-coupling, the R
matrix with pseudostates, and the converged close-coupling
methods yield total integral cross sections that are in very
good agreement with each other, while perturbative distorted-wave
calculations yield cross sections that are substantially higher.
These nonperturbative calculations provide a benchmark for
the continued development of electron-atom experimental methods
designed to measure both ground and excited state ionization.
INVESTIGATORS
M. S. Pindzola and F. J. Robicheaux, Auburn University; D.
R. Schultz, Oak Ridge National Laboratory; D. C. Griffin,
Rollins College, Winter Park, Florida; N. R. Badnell and H.
P. Summers, University of Strathclyde, Glasgow; P. G. Burke,
Queen’s University of Belfast; C. J. Noble, Daresbury
Laboratory, Warrington, England.
PUBLICATION
J. Colgan, M. S. Pindzola, D. M. Mitnik, D. C. Griffin, and
I. Bray, “Benchmark nonperturbative calculations for
the electron-impact ionization of Li(2s) and Li(2p),”
Phys. Rev. Lett. 87, 213201 (2001).
URL
http://www.physics.auburn.edu/~scidac/ |
