U.S. Particle Accelerator School

Intro to Synchrotron Radiation and Free Electron Lasers course

Sponsoring University:

University of California, Santa Barbara


Intro to Synchrotron Radiation and Free Electron Lasers


Kwang-Je Kim, ANL and Zhirong Huang, SLAC

This course is an introduction to the physics of high-brightness radiation beams, the performance of which have been increased remarkably recently by use of insertion devices in synchrotron radiation facilities and by the development of free electron laser (FEL) oscillators and high-gain amplifiers. The course consists of four parts: the first part is a review of fundamental concepts in beams, brightness, and coherence. The second part is a discussion of basic properties of synchrotron radiation by relativistic electron beams in magnetic devices and the enhanced brightness of partially coherent radiation from periodic magnetic devices known as undulators. The third part is a discussion of how the electromagnetic field of radiation generated by the electrons in undulators influence the electron motion leading to density modulation in electron beams, which in turn leads to an amplification of the radiation intensity. Free electron laser oscillators utilizing such amplification to generate fully coherent radiation in the visible and the infrared wavelength regions where the oscillator mirrors are available. The fourth part is a discussion of principles of high-gain free electron lasers in which the gain in single pass is made to be extremely high by use of high-brightness electron beams and long undulators. High-gain FELs are important as next generation radiation devices in x-ray region since optical cavity is not necessary and the initial noise signals are amplified to intense coherent radiation known as the self-amplified spontaneous radiation (SASE). After a discussion of basic concept, a more rigorous treatment of the high-gain FELs and SASE process will be given based on Maxwell-Vlasov equations. We study radiation properties in start-up, exponential growth and saturation regimes, including temporal and transverse coherence, intensity fluctuation and harmonic generation. Novel schemes for coherence enhancement and short pulse generation will also be discussed. Prerequisites: Classical Mechanics and Electromagnetism.