We analyze, by numerical simulation, an inverse free-electron-laser accelerator for the purpose of accelerating electrons from 1.5 MeV to about 20 MeV in a 1.5 m long undulator (∼13 MeV/m). The initial phase distribution of injected electrons is chosen to lie in a small ‘‘phase window’’ from -π/8 to -3π/8 so that all the electrons can be trapped in the accelerating bucket. In this case, there is little particle spread in phase space and the electron energy spectrum is a narrow spike.

• Received 22 March 1994

DOI:https://doi.org/10.1103/PhysRevE.50.1491