Analysis of the higher-harmonics radiation suppression in tapered free-electron lasers with phase shifters

Abstract

Abstract The article presents a study of the higher-harmonics radiation suppression in tapered free-electron lasers (FELs) with phase shifters. To increase the power and efficiency of the FEL, tapering is used —a decrease in the parameter K along the laser axis. Undulator tapering is one of the methods for designing multi-terawatt X-ray FELs (XFELs), which are necessary for research in the field of non-linear optics. In the FELs, in addition to the fundamental harmonic there are also higher harmonics of the radiation field. In this article, we propose methods to suppress the higher harmonics of radiation to improve the quality of radiation for the study of the higher-harmonic generation in crystals, etc. Our method can be transferred to other systems as well.