Author: Nam, I.H.
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Hard X-Ray Self-Seeding at PAL-XFEL  
  • C.-K. Min, M.H. Cho, H. Heo, H.-S. Kang, C. Kim, G. Kim, M.J. Kim, J.H. Ko, D.H. Na, I.H. Nam, B.G. Oh, S.Y. Rah, C.H. Shim, Y.J. Suh, H. Yang
    PAL, Pohang, Kyungbuk, Republic of Korea
  • K. Kim, D. Shu, Yu. Shvyd’ko
    ANL, Lemont, Illinois, USA
  A hard X-ray self-seeding utilizing time-delayed forward Bragg diffracted photons from thin diamond crystals has been successfully commissioned in a broad spectral range (3.5~14.4 keV), and will be soon provided to user experiments. In the self-seeded mode, the spectral bandwidth is typically 0.2~0.5 eV FWHM in contrast to SASE mode, in which the spectral bandwidth is around 20 eV. This implies that the seeded FEL can be a single longitudinal mode laser since the number of longitudinal mode is 100~200 in the SASE operation. In this case, the photon number of filtered FEL is expected to be fluctuated 100% from the narrow bandwidth filtering out of random and spiky SASE spectra. We found that our energy stability of electron bunches (10-4) do not degrade much the seeding performance and the large variation of the seeded FEL intensity will be from the seeding probability. The advantages of 30 um thin diamond crystal and diagnostic tool for the self-seeding will be also presented.  
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THP051 Generating Trains of Attosecond Pulses with a Free-Electron Laser 692
  • S. Serkez, G. Geloni
    EuXFEL, Schenefeld, Germany
  • M.H. Cho, H.-S. Kang, G. Kim, J.H. Ko, C.-K. Min, I.H. Nam, C.H. Shim
    PAL, Pohang, Republic of Korea
  • F.-J. Decker
    SLAC, Menlo Park, California, USA
  • J.H. Ko, C.H. Shim
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • Yu. Shvyd’ko
    ANL, Lemont, Illinois, USA
  Recently, a Hard X-ray Self-Seeding setup was commissioned at PAL XFEL. Its main purpose is to increase the temporal coherence of FEL radiation in an active way. We report another application of this setup to generate trains of short sub-femtosecond pulses with linked phases. We discuss preliminary results of both experiment and corresponding simulations as well as indirect diagnostics of the radiation properties.  
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About • paper received ※ 20 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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