Generation of Coherent Undulator Radiation at ELPH, Tohoku University

A test accelerator as a coherent terahertz source (t-ACTS) has been under development at Tohoku University, in which an intense coherent terahertz (THz) radiation generated by an extremely short electron bunch. Velocity bunching scheme in a traveling accelerating structure is employed to generate femtosecond electron bunches. Spatial and temporal coherent radiation in THz region can be produced by the electron bunches with small transverse emittance. A long-period undulator, which has 25 periods with a period length of 10 cm and a peak magnetic field of 0.41 T, has been also developed and installed to provide intense coherent THz undulator radiation. By optimizing the bunch length, we found that it is possible to generate a coherent undulator radiation that contain only the fundamental wave from numerical studies. We are planning an experiment with 30 MeV beam to generate a coherent undulator radiation of 2.5THz. In the conference, we will report the preliminary experimental results.
Proceedings of the 28th Linear Accelerator Conf., LINAC2016, East Lansing, MI, USA