Scattering of a dipole field by a moving plasma column

The problem of scattering of a dipole field by a plasma column moving uniformly in the axial direction is treated. In order to know the effect of the motion of the plasma on the scattering pattern, first the scattering properties of the dipole field by a stationary plasma with the aid of numerical examples are discussed. In this case two kinds of scattering patterns are illustrated: one in a cross section of the column and the other in the longitudinal section of the column. Then the scattering pattern of the dipole field by the moving plasma is investigated. From the numerical examples for the stationary plasma it is found that the scattering patterns are well-classified into three typical patterns by investigating the ratio of the backward scattering to the forward scattering with respect to the parameters which govern the scattering properties. In the case of moving plasma, it is shown that the scattering pattern in the longitudinal section will have a characteristic directional pattern, which does not appear in the case of stationary plasma, at a frequency lower than the plasma frequency.