Channeling of neutral particles in micro- and nanocapillaries

After a brief review of the main areas of research in X-ray optics and an analysis of the development of capillary optics, a general theory of radiation propagation through capil- lary structures is described in both geometrical optics and wave optics approximations. Analysis of the radiation field structure inside a capillary waveguide shows that wave propagation in channels can be of a purely modal nature, with the transmitted energy mostly concentrated in the immediate neighborhood of the capillary inner walls. A qualitative change in radiation scattering with decreasing channel diameter — namely, the transition from surface channeling in microcapillaries to bulk channeling in nanocapillaries — is discussed.