• Advanced Photonics
  • Vol. 3, Issue 4, 045003 (2021)
Jiawei Yan1、2, Nanshun Huang1、2, Haixiao Deng3、*, Bo Liu3, Dong Wang3, and Zhentang Zhao3、*
Author Affiliations
  • 1Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China
  • 2University of Chinese Academy of Sciences, Beijing, China
  • 3Chinese Academy of Sciences, Shanghai Advanced Research Institute, Shanghai, China
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    As a new-generation light source, free-electron lasers (FELs) provide high-brightness x-ray pulses at the angstrom-femtosecond space and time scales. The fundamental physics behind the FEL is the interaction between an electromagnetic wave and a relativistic electron beam in an undulator, which consists of hundreds or thousands of dipole magnets with an alternating magnetic field. We report the first observation of the laser–beam interaction in a pure dipole magnet in which the electron beam energy modulation with a 40-keV amplitude and a 266-nm period is measured. We demonstrate that such an energy modulation can be used to launch a seeded FEL, that is, lasing at the sixth harmonic of the seed laser in a high-gain harmonic generation scheme. The results reveal the most basic process of the FEL lasing and open up a new direction for the study and exploitation of laser–beam interactions.

    1 Introduction

    A charged particle radiating energy in the form of an electromagnetic wave when it is accelerated is the basic principle behind modern accelerator-based light sources. Among such sources, synchrotron radiation and free-electron lasers (FELs) have played key roles in numerous scientific fields by providing high-brightness electromagnetic waves over a wide spectral range. X-ray FELs,1,2 which are considered to be the next generation of light sources, are capable of providing femtosecond x-ray pulses with a peak brightness 10 orders of magnitude higher than third-generation synchrotron light sources. Compared to synchrotron radiation, the amplification of the FEL pulse comes from the strong and continuous interaction between an electromagnetic wave and a relativistic electron beam in a periodic lattice of alternating dipole magnetic fields known as an undulator.

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    Jiawei Yan, Nanshun Huang, Haixiao Deng, Bo Liu, Dong Wang, Zhentang Zhao. First observation of laser–beam interaction in a dipole magnet[J]. Advanced Photonics, 2021, 3(4): 045003
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    Category: Letters
    Received: May. 12, 2021
    Accepted: Jul. 8, 2021
    Published Online: Aug. 17, 2021
    The Author Email: Deng Haixiao (denghaixiao@zjlab.org.cn), Zhao Zhentang (zhentangzhao@zjlab.org.cn)