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Some Anomalies in the Raman spectrum from laser-produced plasmas

Published online by Cambridge University Press:  09 March 2009

T. J. M. Boyd
Affiliation:
Department of Physics, University of Wales, UCNW, Bangor LL57 2UW, Wales, UK
G. A. Gardner
Affiliation:
Department of Physics, University of Wales, UCNW, Bangor LL57 2UW, Wales, UK
G. A. Coutts
Affiliation:
Department of Physics, University of Wales, UCNW, Bangor LL57 2UW, Wales, UK

Abstract

Many experiments show features of the Raman spectrum at variance with the predictions of conventional theory. One persistent discrepancy, the cut-off in the spectrum of scattered light at about 1·5λ0, led Simon and Short to postulate that the scattered spectrum is not Raman light as such, but derives from enhanced Thomson scattering from plasmas in which a population of suprathermal electrons is present. We describe a set of simulations which model the propagation of a light wave through a plasma characterized by two electron temperatures with the hot electron fraction varying between 0 and 0·05. The results show that enhanced Thomson scattering will contribute to the spectra observed in some experiments at least and confirm the contention that the spectrum of the scattered light is not especially sensitive to the width of the suprathermal electron feature. We have also examined the effect of a finite quiver velocity on the enhanced Thomson spectrum as a function of the population of suprathermal electrons, in particular its effect on the wavelength bands.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1988

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