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Title: Indirect processes in electron impact ionization of Kr[sup 24+] and Kr[sup 25+]

Electron-impact ionization cross sections have been calculated for magnesiumlike Kr[sup 24+] and sodiumlike Kr[sup 25+]. Electron-impact ionization is an important atomic process in hot dense plasmas. It can affect the ionization balance, electron temperature, electron density, and level population in the plasma. In the past decade, theoretical and experimental studies have revealed that indirect processes can make significant contributions to the cross sections for electron impact ionization of positive ions. The most important indirect process is excitation of an inner-shell electron followed by Auger emission. Higher-order processes such as resonant excitation followed by sequential double Auger emission, can also contribute significantly. The contributions of excitation-autoionization and resonant excitation double autoionization (REDA) were included, in addition to the cross sections for direct ionization of a 3s electron. The calculations were carried out using the relativistic distorted wave methods and the multiconfiguration Dirac-Fock model. For Kr[sup 25+], the total cross section is about 5 times the direct ionization cross section. For the Kr[sup 24+], the indirect contribution is about 2.5 times the direct ionization cross section. The REDA process produces many strong resonances and contributes about 20% to the average ionization cross section.
Authors:
;
Publication Date:
OSTI Identifier:
6521293
Report Number(s):
UCRL-JC-111717; CONF-920948--13
ON: DE93014129
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 6. international conference on physics of highly charged ions, Manhattan, KS (United States), 28 Sep - 2 Oct 1992
Research Org:
Lawrence Livermore National Lab., CA (United States)
Sponsoring Org:
DOE; USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; INNER-SHELL EXCITATION; AUTOIONIZATION; CALCULATION METHODS; KRYPTON IONS; CROSS SECTIONS; ELECTRON-ION COLLISIONS; IONIZATION; AUGER EFFECT; DISTORTED WAVE THEORY; EXCITATION; CHARGED PARTICLES; COLLISIONS; ELECTRON COLLISIONS; ENERGY-LEVEL TRANSITIONS; ION COLLISIONS; IONS 664300* -- Atomic & Molecular Physics-- Collision Phenomena-- (1992-)