Synchrotron radiation sources

A relativistic electron passing through a bending magnet emits electromagnetic radiation in the forward direction with an extremely narrow opening angle. The photon density of this 'so-called synchrotron' radiation is correspondingly high and has, in addition, a very broad radiation spectrum. Because of its outstanding properties, synchrotron radiation has become a very powerful tool in basic research and technical applications. The required relativistic electron beam is provided by utilizing modern particle accelerator techniques. Presently the most successful accelerator type used as a dedicated synchrotron radiation source is the storage ring. Very important for a high quality of radiation is strong focusing of the electron beam circulating in the accelerator. The theory of this low-emittance optics is presented, including some important examples of magnet lattices. Inserting special wiggler and undulator magnets into a storage ring gives a significant increase of the photon density. In particular, the undulator magnets provide very high intensities of coherent synchrotron radiation. A logical consequence of the coherent undulator radiation was the development of the free electron laser (FEL), which is described in the last section of this review.