Open AccessResearch of coherent edge radiation generated by electron beams oscillating free-electron lasers
Author(s) -
N. Sei,
Hiroshi Ogawa,
Toshinari Tanaka,
Yasushi Hayakawa,
Takeshi Sakai,
Yoske Sumitomo,
Y. Takahashi,
Katsumi Hayakawa,
Keiji Nogami,
Heishun Zen,
Hideaki Ohgaki
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1350/1/012039
Subject(s) - free electron laser , physics , optics , desy , synchrotron radiation , undulator , radiation , electron , transition radiation , laser , beam (structure) , cathode ray , terahertz radiation , radiant intensity , infrared , nuclear physics
We have studied far-infrared coherent radiation with S-band linacs at Laboratory for Electron Beam Re-search and Application (LEBRA) at Nihon University and at Kyoto University Free Electron Laser. We have already developed a couple of terahertz-wave sources based on coherent synchrotron radiation and coherent transition radiation, which have been applied to spectroscopic research. Moreover, we developed coherent edge radiation (CER) at the downstream bending magnets in the FEL sections. Because the edge radiation has an annular shape distribution characterized by the asymmetric first-order Laguerre-Gaussian mode, the CER can be extracted from an optical cavity of the FEL system without a diffraction loss of the FEL beam. The root-mean-squared bunch length of the electron beam was evaluated by measuring the CER spectra, which was about the same level as the FEL micropulse width. Although the infrared FELs at LEBRA had a long slippage length, the FEL energy became higher as the bunch length was shorter. The CER intensity can be a guidepost enhancing the FEL power because of the existence of their correlation.