Radiation of non-relativistic particle on a conducting sphere and a string of spheres

The radiation resulting from the uniform motion of a charged particle by (or through) metal sphere is considered. The simple but rigorous description of the radiation process is developed for the case of non-relativistic particle and perfectly conducting sphere by the way of the method of images known from electrostatics. The spectral-angular and spectral densities of the diffraction and transition radiation on the single sphere are computed. The Smith-Purcell radiation caused by motion of the particle parallel to the periodic string of spheres is also considered.