Analysis of Radiation Focusing and Guiding in the Free Electron Laser by Use of a Source Dependent Expansion.
BERKELEY SCHOLARS INC CA
Pagination or Media Count:
In the free electron laser FEL the resonant interaction between the radiation field and electron beam can result in radiation focusing optical guiding. If the centroid of the electron beam is transversely displaced off aixs, the radiation field, under certain conditions, will follow and be steered by the electron beam. The effect of a spatial modulation on the electron beam envelope can also modify the propagation characteristics of the radiation. These and other phenomena are analytically and numerically studied using a novel source dependent Laguerre-Gaussian modal representation of the fully three dimensional radiation field. Unlike the vacuum Laguerre-Gaussian modal expansion, the longitudinal spatial dependence of the radiation waist and curvature are determined and characterized by the source term in the wave equation. Among the advantages of this general source dependent expansion SDE approach is that few modes are needed to accurately describe the radiation. Hence, fast and accurate numerical solutions of the fully three-dimensional FEL problem can be obtained over distances of many Rayleigh lengths. Furthermore, this expansion enables us to drive an envelope equation for the radiation beams as well as an expression for the centroid of the beam. Keywords Focusing Guiding Free electron laser Radiation.
- Lasers and Masers