Power enhancement via an ion-channel in a Raman free-electron laser

As a high-power and high-efficiency coherent radiation source, the free-electron laser extends to two unique spectra: the region in the ultra-violet, x- and -rays, and the range in the millimeter- and terahertz-waves. Based on credible simulations, it is shown that the nonlinear power of a Raman free-electron laser in a millimeter wave range goes up and gets an increase of at least 9% when an ion-channel is applied to the beam-wave interaction chamber. A physical explanation is that the ion-channel weakens the velocities spread over the electron beam and, therefore, improves the electron-beam transportation quality and the beam-wave interaction. (paper)