Abstract

We discuss the transition from simple undulator radiation to more fully developed coherent radiation of high gain free electron lasers. In a simple undulator the radiation from different electrons add incoherently. For a long undulator and a high brightness electron beam, the cumulative effect of the radiation-beam interaction leads to development of regions of periodic density variation in the electron beam, resulting in an exponential amplification of the radiation intensity. The amplification eventually stops because the induced momentum spread counteracts the effects of electron correlation. A high gain free electron laser operating in a bypass of a 1 GeV, high brightness electron storage ring is based on this principle, and can potentially generate tens of megawatts of partially coherent power at wavelengths shorter than 1000Å.

© 1986 Optical Society of America