TU1P03
KEK, Ibaraki, Japan
Sokendai, Ibaraki, Japan
Energy Recovery Linac can realize a linac-type beam at a high current. An ERL test accelerator, cERL, has been constructed in KEK. Utilizing these features of the ERL beam, low emittance, short bunch, and high repetition rate, we have been developing a unique terahertz radiation source of resonant coherent diffraction radiation. An optical resonant cavity consists of two concave mirrors with a beam hole at the center was installed in the return-loop of cERL. When the multi-bunch electron beam passes through the cavity, it radiates coherent diffraction radiation in the cavity. If the round-trip time of the cavity precisely matches the beam repetition, the radiation of the bunches are stacked coherently and stimulates the energy conversion process from the beam to the radiation. Measuring the terahertz radiation power while scanning the cavity length, we observed a sharp resonance peak showing the realization of the stimulated emission. The cavity was carefully designed to tune the carrier-envelope-offset to be zero. It allows to excite wide-band longitudinal modes simultaneously, and realize a mode-locked terahertz pulse.
HU/AdSM, Higashi-Hiroshima, Japan
KEK, Ibaraki, Japan
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
Northern Illinois University, DeKalb, Illinois, USA
ANL, Argonne, Illinois, USA
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
RISE, Tokyo, Japan
IMP/CAS, Lanzhou, People’s Republic of China
Linear colliders is the only way to realize e+ e− collision at higher energy beyond the limit of ring colliders by the huge synchrotron radiation energy loss. In the linear collider, the beam current should be much smaller comparing to the ring collider to save the required electricity. A way to realize an enough luminosity with the small beam current and less energy spread by Beamstrahlung, is collision in flat beam. This high aspect ratio beam can be made by phase-space rotation technique instead of the conventional way with DR (Damping Ring). We present a simulation of this technique and pilot experiments at KEK-STF and ANL WFA.