Advanced Photonics Nexus, Volume. 2, Issue 3, 036004(2023)

High-repetition-rate seeded free-electron laser enhanced by self-modulation On the Cover

Hanxiang Yang1,2, Jiawei Yan3, and Haixiao Deng4、*
Author Affiliations
  • 1Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China
  • 2University of Chinese Academy of Sciences, Beijing, China
  • 3European XFEL, Schenefeld, Germany
  • 4Chinese Academy of Sciences, Shanghai Advanced Research Institute, Shanghai, China
  • show less
    Figures & Tables(14)
    Bunching factor versus energy modulation amplitude A at various harmonic numbers. Each line corresponds to the maximum bunching factor at the optimal dispersion strength.
    Schematic layout of the self-modulation HGHG setup. A self-modulation HGHG includes extra dispersive chicane and self-modulator, further amplifying laser-induced energy modulation to obtain a higher harmonic bunching factor.
    The seed laser power ratio of the standard HGHG and self-modulation HGHG in different cases. The blue dot, red cross, and yellow circle correspond to the nominal case of beam size of 100 μm and peak current of 700 A, the second case of beam size of 50 μm and peak current of 700 A, and the third case of 100 μm and 1400 A, respectively. The dotted line corresponds to the scaling curve.
    The energy spread ratio of the standard HGHG and self-modulation HGHG in different cases. The blue dot, red cross, and yellow circle correspond to the nominal case of beam size of 100 μm and peak current of 700 A, the second case of beam size of 50 μm and peak current of 700 A, and the third case of 100 μm and 1400 A, respectively.
    Optimization for the R56 of two chicanes by GENESIS simulations to obtain the 13th harmonic bunching factor of 8% and corresponding energy modulation amplitude A2 of the entrance of the radiator in different beam sizes. (a), (b) Beam size of 100 μm; (c), (d) beam size of 50 μm.
    Comparison of the FEL performance between self-modulation HGHG (blue) and standard HGHG (red) at the 13th harmonic of the 266-nm seed laser in the cases of different beam sizes. (a), (b) Beam size of 100 μm; (c), (d) beam size of 50 μm.
    Optimization of the R56 of two chicanes toward the 30th harmonic of the seed laser. The self-modulator resonates at (a), (b) the fundamental wavelength; (c), (d) the second; (e), (f) the third harmonics of the seed laser, respectively.
    The longitudinal phase space of the electron beam in one seed laser wavelength λs at the entrance of the (a) self-modulator and (b) radiator, where the self-modulator is tuned at the third harmonic of the seed laser.
    The output FEL performance at the 30th harmonic of the seed laser in the third-harmonic self-modulation. (a) 8.87-nm radiation gain curve in the radiator. (b), (c) The power profile and spectrum after six radiator modules, respectively.
    Bunching factor after the second chicane as a function of the harmonic number in various cases, including without self-modulator and the resonance of the self-modulator tuned at the fundamental wavelength, second, and third harmonic of the seed laser, respectively.
    The typical setup of the SXFEL-TF adopted a cascaded EEHG–HGHG scheme. In the self-modulation experiment, modulator 1, with a period of 80 mm in the first stage EEHG, was used as the first modulator. Chicane 3 is the fresh bunch chicane used as the first chicane. A modulator of the second stage HGHG with a period of 55 mm was the self-modulator. Chicane 4 was regarded as the second chicane. X-band transverse deflection structure (XTDS) section was used to measure the longitudinal phase space of the electron beam.
    The measured intensity of the coherent radiation at various harmonic numbers in the first undulator segment of the radiator, under different R56 values of the second chicane of (a) 0.038 mm and (b) 0.048 mm, respectively. The points represent the measurement results, and the curve represents the envelope obtained by smoothing the measurement data.
    • Table 1. Main electron beam parameters of the SXFEL-UF.

      View table
      View in Article

      Table 1. Main electron beam parameters of the SXFEL-UF.

      ParameterValueUnit
      Beam energy1.4GeV
      Slice energy spread50keV
      Normalized emittance1mm·mrad
      Bunch charge600pC
      Bunch length (FWHM)800fs
      Peak current (Gaussian)700A
      Beam size (RMS)100μm
    • Table 2. Main simulation parameters of the seed laser and the undulators.

      View table
      View in Article

      Table 2. Main simulation parameters of the seed laser and the undulators.

      ParameterValueUnit
      Seed laser
      Wavelength266nm
      Peak power (standard HGHG)17 to 75MW
      Peak power (self-modulation HGHG)0.019 to 1.6MW
      Pulse duration (FWHM)150fs
      Rayleigh length5m
      Spot size (RMS)325μm
      Modulator
      K9.891
      Period8cm
      Length1.6m
      Self-modulator
      K5.593 to 9.891
      Period8cm
      Length1.6 or 2m
      Radiator
      K1.823 to 4.239
      Period5cm
      Length3m
    Tools

    Get Citation

    Copy Citation Text

    Hanxiang Yang, Jiawei Yan, Haixiao Deng, "High-repetition-rate seeded free-electron laser enhanced by self-modulation," Adv. Photon. Nexus 2, 036004 (2023)

    Download Citation

    EndNote(RIS)BibTexPlain Text
    Save article for my favorites
    Paper Information

    Category: Research Articles

    Received: Dec. 4, 2022

    Accepted: Mar. 27, 2023

    Published Online: Apr. 19, 2023

    The Author Email: Deng Haixiao (denghx@sari.ac.cn)

    DOI:10.1117/1.APN.2.3.036004

    Topics