Transition Undulator Radiation (TUR) as a beam diagnostics and a high brilliance infrared source

The Transition Undulator Radiation (TUR), introduced by K.J. Kim, is obtained as interference between two bremsstrahlung amplitudes at the entrance and exit of the undulator. sult is applied to the TTF FEL experiment, for which this radiation, in the visible bandwidth, may be used as an electron beam non-intercepting diagnostics, while in the far infrared region, due to the coherent emission by each microbunch, is a high-brilliance source synchronized with the higher-energy FEL radiation.