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The velocity of a wave packet in an anisotropic absorbing medium

Published online by Cambridge University Press:  13 March 2009

Kurt Suchy†
Kurt Suchy†
Affiliation:
Groupe de Recherches Ionosphériques du Centre National de la Recherche Scientifique 4 avenue do Neptune, 94 Saint-Maur, France
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Abstract

The field of a pulsed beam (a ‘wave packet’), travelling through a medium with moderate absorption, is calculated by the saddle-point method. The packet velocity (i.e. the velocity of the spatial amplitude maximum) has the same direction as the velocity Re (∂ω/∂k), a generalization of the group velocity ∂ω/∂k in non-absorbing media. It differs from the absolute value of this velocity by a correction factor depending on the absorption, beam width and pulse duration. This factor is unity for vanishing absorption and infinite beam width. The velocity Im (∂ω/∂k) has no apparent physical meaning.

Type
Research Article
Information
Journal of Plasma Physics , Volume 8 , Issue 1 , August 1972 , pp. 33 - 51
Copyright
Copyright © Cambridge University Press 1972

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