Nonlinear harmonic generation in free-electron lasers

摘要

A three-dimensional nonlinear simulation code to treat multiplenfrequencies simultaneously is described and used to study nonlinearnharmonic generation in free-electron lasers (FELs). Strong nonlinearnharmonic gain is found where the gain length varies inversely with thenharmonic number. Substantial power levels are found in the harmonics.nThe odd harmonics are favored with generally higher power levels since anplanar wiggler geometry is employed; however, the second harmonicnexhibits substantial power as well. The analysis is relevant to thenemission expected from self-amplified spontaneous emission (SASE)nfree-electron laser schemes