Open AccessElectron‐bunch lengthening on higher‐harmonic oscillations in storage‐ring free‐electron lasers
Author(s) -
Sei Norihiro,
Ogawa Hiroshi,
Okuda Shuichi
Publication year - 2017
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s160057751700916x
Subject(s) - lasing threshold , storage ring , harmonics , physics , harmonic , laser , electron , atomic physics , free electron laser , optics , cathode ray , resonator , high harmonic generation , free electron model , beam (structure) , nuclear physics , quantum mechanics , voltage
The influence of higher‐harmonic free‐electron laser (FEL) oscillations on an electron beam have been studied by measuring its bunch length at the NIJI‐IV storage ring. The bunch length and the lifetime of the electron beam were measured, and were observed to have become longer owing to harmonic lasing, which is in accord with the increase of the FEL gain. It was demonstrated that the saturated FEL power could be described by the theory of bunch heating, even for the harmonic lasing. Cavity‐length detuning curves were measured for the harmonic lasing, and it was found that the width of the detuning curve was proportional to a parameter that depended on the bunch length. These experimental results will be useful for developing compact resonator‐type FELs by using higher harmonics in the extreme‐ultraviolet and the X‐ray regions.