Phase shift errors associated with the WKB approximation

A numerical technique is presented which yields an exact solution to the one dimensional scattering problem. The algorithm is used to compute phase shift error curves associated with the WKB approximation. A variety of scattering potentials are considered and cover cases for which the WKB solution varies from extremely good to poor. It is shown that some commonly assumed forms for ionospheric electron density profiles yield phase responses which are discontinuous functions of wavenumber. Implications of these results to the inverse scattering problem are discussed.