Applicability of the Bourret and Kraichnan approximations to solving problems of the propagation of coherent waves in a medium with strong random inhomogeneities

Armand and Sekistov (1981, 1982) have derived an exact system of moment equations for all the statistical moments of a field of waves from a point source propagating in a Gaussian randomly inhomogeneous medium. In the present paper, this system is used to analyze the applicability of the Bourret and Kraichnan approximations to solving problems of the propagation of a coherent microwave field in a medium with strong random inhomogeneities of permittivity. Conditions are established under which these approximations can be used not only for qualitative but also for satisfactory quantitative calculations of the behavior of an average microwave field in a medium the relative permittivity fluctuations of which can take large values, commensurable with unity.