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Recent developments in the modeling of dense plasmas

Recent experiments using intense laser pulses on thin targets have produced spectra in which it has been speculated that certain features are due to multiple ionization or recombination events. To explore this possibility, the rate coefficients for collisional double ionization and its inverse proce...

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Bibliographic Details
Main Authors: Colgan, J, Fontes, C J, Abdallah Jr, J, Streufert, B
Format: Conference Proceeding
Language:English
Subjects:
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Summary:Recent experiments using intense laser pulses on thin targets have produced spectra in which it has been speculated that certain features are due to multiple ionization or recombination events. To explore this possibility, the rate coefficients for collisional double ionization and its inverse process, four-body recombination, have been added to the collisional rate matrix computed within the Los Alamos plasma kinetics code ATOMIC. The collisional double ionization cross sections are obtained from semi-empirical fits to experimental measurements, and the corresponding four-body recombination rates are derived from detailed-balance considerations. We have examined emission spectra produced from solving the coupled rate equations, including the double ionization and four-body recombination rate coefficients, for an Ar plasma in which various fractions of hot electrons are present. We have also explored the sensitivity of our results to the approximations made for the ionization cross sections used in our calculations. We find that inclusion of these multiple-electron effects can make appreciable differences to the average ionization stage of the plasma and the resulting emission spectra at moderately high electron densities, but is strongly dependent on the form of the differential cross sections used in our model.
ISSN:0094-243X
1551-7616
DOI:10.1063/1.2768850