Coherent parametric X-radiation by the train of charged particles bunches: Conditions of observation

The problem of coherent parametric X-radiation (PXR) by the electron bunch is considered. The PXR by different electrons could be coherent at small bunch dimensions. Conditions for this kind of radiation - coherent PXR (CPXR) - were considered. Features of CPXR by the bunch as well as by the train of bunches are demonstrated.