Vaughan H. Weston

Oblique Incidence of an Electromagnetic Wave on Plasma Half‐Space

A radio frequency electromagnetic wave, polarized in the plane of incidence is incident obliquely upon a plasma half‐space, where the equilibrium plasma is taken to be homogeneous and isotropic. Employing the specular boundary condition, an exact solution of the coupled Maxwell‐Vlasov equations is derived, yielding both transverse and longitudinal waves in the plasma region. The reflection coefficient is derived, and approximately evaluated.

Oblique Incidence of an Electromagnetic Wave on a Plasma Layer

A plane electromagnetic wave is obliquely incident upon a plasma layer of finite thickness, where the equilibrium plasma is taken to be homogeneous and isotropic. The electric vector of the wave is assumed polarized in the plane of incidence. The specular boundary condition for the distribution function is employed and an exact solution of the coupled Maxwell‐Vlasov equations is derived as an expansion in normal modes, yielding coupled tranverse and longitudinal waves in the plasma region. Temperature effects on the reflection coefficient are investigated.

Diffraction of a plane wave by an almost circular cylinder

The two-dimensional problem of an E-polarized plane wave incident on a perfectly conducting cylinder of almost circular cross-section is treated , the maximum deviation of the perimeter of the cross-section from a strict circle being regarded mathematically as an infinitesimal quantity whose second and higher powers are neglected. In the body of the paper the method of solution uses infinite Fourier transform techniques, but an analysis involving a Watson transformation, more traditional in this type of problem , is given in appendix A. Attention is for the most part directed to the case in which the mean radius of the cylinder is large compared to the wavelength, and the form of the solution then appropriate is examined in some detail. In particular, initial terms of asymptotic expansions in inverse powers of the mean radius to wavelength ratio are obtained for the ‘specular’ and for the ‘creeping’ contributions to the far field. It is shown that the former contributionis in agreement with that derived by the Luneberg—Kline method, and the latter with the prescription proposed by Keller. Various Bessel function results are required, some of which are derived in appendices.

High-frequency scattering from a metal-like dielectric lens

The scattering of a plane electromagnetic wave by a dielectric lens which behaves like a metal reflector is considered. At short wavelengths, the leading term of the backscattered field cannot be determined entirely through simple geometrical optics considerations; instead, it is obtained by means of a modified Watson transformation of the exact solution. The difficulties that arise in applying this technique to other lenses are discussed.

Near-zone Back-scattering from large spheres

SummaryFor an incident electromagnetic plane wave, the near-zone behaviour of the backscattered field produced by a perfectly conducting sphere is investigated for small wavelengths. The backscattered cross-section becomes appreciably different when the receiver approaches to within a distance of several radii from the center of the sphere, and in fact becomes the cross-section of a flate plate for the receiver very near the sphere.

Representation of Fields in a Relativistic Plasma by a Surface Integral

The collective motion of electrons in a relativistic isotropic plasma which is described by the linearized Maxwell‐Boltzmann equations is treated with time harmonic dependence. It is shown that the electric intensity at any point in an enclosed volume, can be determined when the tangential components of the electric and magnetic field are prescribed along with the electronic distribution function, on the surface enclosing the volume.