HIGH-FREQUENCY SCATTERING BY AN IMPENETRABLE SPHERE.
Abstract
The scattering of a scalar plane wave by a totally reflecting sphere (hard-core potential) at high frequencies is treated by a modified Watson transformation. The behavior of the solution both in the near and far regions of space is discussed, as well as the accuracy and domain of applicability of the WKB approximation and classical diffraction theory. It is shown that different transformations are required in the forward and backward half-spaces, and corresponding integral representations for the primary wave are derived. The transformations are rigorously proved and the convergence of the residue series is discussed. In the shadow region, the physical interpretation of the complex angular momentum poles in terms of surface waves is in agreement with Keller's geometrical theory of diffraction. In the lit region, sufficiently far from the shadow boundary, the WKB expansion for the wave function is confirmed up to the second order. On the surface of the sphere, Kirchhoff's approximation is accurate, except in the penumbra region, where the behavior is described by Fock's function. The diffraction effects in the neighborhood of the shadow boundary are investigated and the corrections to classical diffraction theory are obtained.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1965
- Accession Number
- AD0615755
Entities
People
- H. M. Nussenzveig
Organizations
- New York University