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Quasi‐particle method for propagation in inhomogeneous media
Author(s) -
Marcuvitz N.
Publication year - 1984
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs019i005p01139
Subject(s) - caustic (mathematics) , physics , range (aeronautics) , amplitude , phase space , computational physics , point source , gravitational singularity , space (punctuation) , wave propagation , classical mechanics , excitation , phase velocity , optics , quantum mechanics , linguistics , philosophy , materials science , composite material , mathematical physics
In the conventional geometric‐optic approximation to wave propagation excited by a source of finite extent, each source point emits rays that transport wave energy along well‐defined trajectories, but with transport properties exhibiting singularities in caustic regions where the cross section of ray bundles vanishes. In the first‐order quasi‐particle approximation the extended source is viewed as a phase space distribution of point quasi‐particles whose space‐time dependent kinetic properties such as density, average velocity, etc., provide nonsingular measures of the space‐time transport of amplitude, wave number, frequency, etc., of the wave train modulation even in caustic regions. The range of ap‐ plicability of the quasi‐particle method is examined in terms of relative space‐time scales characteristic of the excitation and medium.