Theoretical computation of the polarization characteristics of an X-ray Free-Electron Laser with planar undulator

OPTICS COMMUNICATIONS

卷:356

Article

Geloni, Gianluca¹  Kocharyan, Vitali²  Saldin, Evgeni² 

[1] European XFEL GmbH, Hamburg, Germany

[2] Deutsch Elektronen Synchrotron DESY, Hamburg, Germany

关键词: Free-electron laser (FEL);    X-rays;    Degree of polarization;   

DOI  :  10.1016/j.optcom.2015.07.048

来源: Elsevier

【 摘 要 】

We show that radiation pulses from an X-ray Free-Electron Laser (XFEL) with a planar undulator, which are mainly polarized in the horizontal direction, exhibit a suppression of the vertical polarization component of the power at least by a factor lambda(2)(w)(4 pi L-g)(2), where lambda(w), is the length of the undulator period and L-g is the FEL field gain length. We illustrate this fact by examining the XFEL operation under the steady state assumption. In our calculations we considered only resonance terms: in fact, non-resonance terms are suppressed by a factor lambda(3)(w)/(4 pi L-g)(3) and can be neglected. While finding a situation for making quantitative comparison between analytical and experimental results may not be straightforward, the qualitative aspects of the suppression of the vertical polarization rate at XFELs should be easy to observe. We remark that our exact results can potentially be useful to developers of new generation FEL codes for cross-checking their results. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

Free