Enhanced IFEL performance using a novel wiggler

Abstract

In the conventional inverse free electron laser (IFEL), electron acceleration is done via the interaction of an intense laser beam and a wiggler with a sinusoidal field variation.We have studied the effect on IFEL performance usins a wiggler that creates a nearly squarewave periodic field pattern [1.2]. A novel numerical technique is described which models this wiggler [I]. We find stable orbits and an improvement in IFEL acceleration -gradient, resulting in a gain in energy by as much as a factor of two (equivalent to four times the laser power), when compared with the conventional IFEL with a sinusoidal field wiggler [3]. In an experiment, the magnetic field can be synthesized by running a conventional ferromagnetic wiggler into saturation.

Intensification of harmonic spontaneous radiation with a novel undulator

“…However, one need not limit the choice of undulator field profile to the sinusoid, providing other profiles result in significant advantages. In connection with the IFEL accelerator, in the past we have pointed out [1] that the use of an undulator profile that approximates a" square wave" will result in an enhanced acceleration gradient, by as much as a factor of two (equivalent in effect to an increase of laser drive intensity by a factor of four), similar to the helical undulator. This improvement (essentially at the fundamental FEL resonance) results largely from the fact that, for a given peak undulator field amplitude, the rms electron acceleration obtained from the square wave undulator is larger than that from the sinusoid; furthermore, the electron orbit is stable as well.…”