http://syrinx.gen.u-tokyo.ac.jp/labo/fel/ (PC Press Internet CD, 03/1996)Free-electron laser (FEL) is a coherent radiation emitted by a relativistic electron beam traveling through a periodically alternating magnetic field.
We have demonstrated an FEL lasing using a 15MeV Linac at UTNL (Nuclear Engineering Research Laboratory, University of Tokyo). This is the first lasing of linac FEL in Japan.
Linac at UTNL
Waveform of FEL Lasing