Synchrotron Radiation and Free-Electron Laser -Tutorial-

摘要

This paper reviews the amplification mechanism for the free-electron laser from the single-particle point of view. We consider a model of the free-electron laser which consists of an electron accelerator, an array of permanent magnets (called a wiggler or an undulator), and a resonator composed of two reflecting mirrors. We first find the frequency spectrum for the synchrotron radiation emitted by a single electron passing through an undulator with relativistic velocity. Then, we clarify the mechanism for the stimulated emission by which a particular frequency component wave of the synchrotron radiation can be amplified through the interaction with a relativistic electron beam under the influence of a periodic static magnetic field generated by the undulator.