Accession Number:

ADA045949

Title:

Path Integrals for Waves in Random Media

Descriptive Note:

Technical rept.

Corporate Author:

STANFORD RESEARCH INST MENLO PARK CA

Personal Author(s):

Report Date:

1977-05-01

Pagination or Media Count:

113.0

Abstract:

The problem of wave propagation in a random medium is formulated in terms of Feynmans path integral. It turns out to be a powerful calculational tool. The emphasis is on propagation conditions where the rms multiple scattering angle is small but the log-intensity fluctuations are of order unity - the so-called saturated regime. It is shown that the intensity distribution is then approximately Rayleigh with calculable corrections. In an isotropic medium, the local or Markov approximation which is commonly used to compute first and second at arbitrary space-time separation moments of the wave field is explicitly shown to be valid whenever the rms multiple scattering angle is small. It is then shown that in the saturated regime the third and higher moments can be obtained from the first two by the rules of Gaussian statistics. There are small calculable corrections to the Gaussian law leading to coherence tails. Correlations between waves of different frequencies and the physics of pulse propagation are studied in detail. Finally it is shown that the phenomenon of saturation is physically due to the appearance of many Fermat paths satisfying a perturbed ray equation.

Subject Categories:

  • Statistics and Probability

Distribution Statement:

APPROVED FOR PUBLIC RELEASE