COHERENT SYNCHROTRON RADIATION AT SUBMILLIMETER AND MILLIMETER WAVELENGTHS

To study the coherence effect of synchrotron radiation (SR), light emission from the Tohoku 300 MeV linac, whose energy and bunch length of electrons were 180 MeV and a few millimeters, was observed in the submillimeter and millimeter wavelength regions by using a grating spectrometer. The absolute intensity of ordinary SR in the visible region was also measured. In comparison with ordinary SR, the absolute intensity of SR in the millimeter wavelength region was enhanced by about a factor of 10(6), which corresponded roughly to the number of electrons in one bunch. The intensity of enhanced SR showed the quadratic dependence on the beam current. The enhanced SR was strongly polarized in the electron orbital plane. The relation between the electron distribution in a bunch and the spectra of coherent SR is discussed.