Observation of far infrared coherent synchrotron radiation at UVSOR-II

At a 750 MeV electron storage ring, UVSOR(Ultraviolet Synchrotron Orbital Radiation)-II, possible coherent synchrotron radiation was observed in the wavelength region between 0.2 and 3.0 mm. Bursts of far infrared emission were detected when the ring was operated in single bunch mode and the beam current exceeded a certain threshold current, typically around 100 mA. Typical duration and interval of the bursts are about 200 μsec and 10 - 15 msec, respectively. Each burst contains many peaks and shows quasi-periodicity of about 30 μsec. The peak intensities of the bursts are 10000 times higher than that of normal synchrotron radiation in the same wavelength region. The threshold current depends on the operation condition of the storage ring, especially that of the RF system. (author)