ABSTRACT
The Free Electron Laser (FEL) is a device that uses a relativistic beam of electrons passing through a transverse periodic magnetic field (the wiggler) to amplify electromagnetic radiation. It is a tunable and efficient radiation source, driven by electron beams with energy ranging from hundreds of kilovolts to hundreds of megavolts. As the radiation wavelength depends on the electron energy as well as on the period and the magnetic field of the wiggler, the FEL can be continuously tuned in frequency, ideally ranging from the microwave to the soft x-ray regions.
