Characteristics of polarized coherent radiation in THz region from a crossed-undulator (2)

A variable polarized THz light source using a crossed-undulator configuration has been developed at Research Center for Electron Photon Science (ELPH), Tohoku University. A demonstration experiment will be carried out using newly constructed compact planar undulators at a test linear accelerator called t-ACTS in ELPH. The magnetic field measurement has been performed. The measured fields of the two undulators were in good agreement with each other. A variable R₅₆ triple bend lattice has been studied for the electron beam line as a phase shifter. Assuming an expected setup (a distance between the centers of each undulator, 5 m and the fundamental frequency, 1.94 THz), degree of circular polarization larger than 0.9 can be obtained in the angular range of 2.0 mrad, i.e. 12% of the radiation angular spread. Only the central part of the radiation will be used in the demonstration experiment. (author)