ABSTRACT
After discussing of the basic properties of the radiation emitted by accelerated charges, this chapter analyses the consequences of emitting synchrotron radiation on the beam. The average radiated power causes oscillations of beam particles to exponentially damp, whereas the quantum nature of the emission excites the particles. The balance of both effects determines the beam sizes and emittances in electron storage rings. In the following section the temporal and spectral characteristics, as well as the power radiated by dipole magnets, wigglers, and undulators are discussed. The joint dynamics of electrons and fields in free-electron lasers is the topic of the next section and found to be equivalent to the motion of particles in longitudinal phase space. Therefore, also here the equations of motion can be fully integrated and give a comprehensive description of the process. Moreover, the Matlab code from Chapter 5 can be reused. If the beam currents are extremely large, a collective instability develops, the SASE process, and leads to an exponential increase of the radiation power. The variations on the emitted power, due to the stochastic nature of the startup from noise, are discussed. The final section of this chapter addresses the challenges to build accelerators suitable to drive free-electron lasers.
