Properties of diffraction radiation in practical conditions: Finite size target effect, surface roughness and pre-wave zone

Diffraction radiation (DR) is very suitable for electron beam diagnostics for next generation collider and the fourth generation light source due to its noninvasive, multi-parameter and on-line features. In this paper, several properties of DR in practical conditions are studied with diffraction model based on which analytical formulae for describing the finite size target effect on spectral angular distribution of DR from circular aperture are obtained. Some pre-wave zone properties of DR that may play great role in real measurements are also studied. It is shown the requirement for wave zone approximation to be valid is more stringent for DR than transition radiation (TR). It is concluded that the diffraction model can handle TR and DR from any shape of target in both wave zone and pre-wave zone. As an example, DR from a striped target that can generate TR-like spectrum and TR from rough-surfaced target which may be important in beam diagnostics with optical TR and DR are studied. Finally, a weakly modulated target is suggested to suppress the pre-wave zone effects.