What is a Free Electron Laser or FEL?
A Free Electron Laser or FEL is a very special laser that uses very-high-speed electrons that move freely through a magnetic structure, hence the term free electron as the lasing medium and shares many of the characteristics of a synchrotron radiation facility. The free-electron laser has the widest frequency range of any laser type, and can be widely tunable, currently ranging in wavelength from microwaves, through terahertz radiation and infrared, to the visible spectrum, ultraviolet, and X-ray. Moreover it can be used as a pulsed light source with a very short pulsewidth allowing for dynamic studies on timescales hitherto unachievable in the study of materials or of atomic and molecular processes, which for an x-ray free electron laser is of the order of attoseconds.
For an overview of the free electron laser light sources of the world visit lightsources.org to see the locations of more than 12 free electron laser sources worldwide, of which 6 are in Europe. Of the list worldwide Irish research groups currently use 4 of these sources.
X-ray Free Electron Laser – XFEL: “The European X-ray Free Electron Laser”