Author: Heo, H.
Paper Title Page
0.1-nm FEL Lasing of PAL-XFEL  
  • H.-S. Kang, H. Heo, C. Kim, G. Kim, C.-K. Min, H. Yang
    PAL, Pohang, Kyungbuk, Republic of Korea
  The hard X-ray free electron laser at Pohang Accelerator Laboratory (PAL-XFEL) achieved saturation of a 0.144-nm free electron laser (FEL) beam on November 27, 2016, making it the third hard X-ray FEL in the world, following LCLS in 2009 and SACLA in 2011. On February 2, 2017, a saturated 1.52-nm FEL beam was also achieved in the soft X-ray FEL line with an electron beam energy of 3.0 GeV. Finally, saturation of a 0.104-nm FEL beam was achieved on March 16, 2017 using an electron beam energy of 9.47 GeV and K = 1.87. In this paper we present the commissioning result of PAL-XFEL as well as the beamline commissioning results.  
slides icon Slides MOC01 [7.016 MB]  
Demonstration of Harmonic Lasing Self-Seeded Mode for Soft X-Rays Down to 1nm at PAL-XFEL  
  • I.H. Nam, H. Heo, H.-S. Kang, C. Kim, G. Kim, C.-K. Min, H. Yang
    PAL, Pohang, Kyungbuk, Republic of Korea
  Harmonic lasing is a promising way to provide the beams that can be brilliant, stable and narrow-band. We demonstrate the 3rd harmonic lasing operation in the current configuration with gap-tunable planar hybrid type undulators at soft X-ray beam line at PAL-XFEL. In order to suppress the fundamental resonant radiation, we used a set of phase shifters for optimal condition. This new operation mode can improve the spectral brightness compare to Self-Amplified Spontaneous emission (SASE) mode. In this paper, we report the results of these studies of the harmonic lasing mode for soft X-ray in the wavelength down to 1 nm with the electron beam energy of 3 GeV at PAL-XFEL.  
Optimization of PAL-XFEL's 3 Bunch Compressor Linac  
  • H.-S. Kang, H. Heo, C. Kim, C.-K. Min, H. Yang
    PAL, Pohang, Kyungbuk, Republic of Korea
  • D. Khan, T.O. Raubenheimer, J. Wu
    SLAC, Menlo Park, California, USA
  The Pohang Accelerator Laboratory X-Ray Free Electron Laser (PAL-XFEL) consists of a 10 GeV normal-conducting linac delivering an electron bunch to two undulator beamlines and FEL radiation between 0.1 nm (Hard XRay) and 4.5 nm (Soft X-Ray). To provide high quality FEL lasing, it is paramount to optimize the linac settings under the consideration of the collective effects a beam may experience during transport to the undulator. The PAL-XFEL linac consists of four S-band linac sections, an X-band harmonic linearizer proceeding the first linac section, and a three chicane bunch compression system (the very first of its kind in operation). The addition of the third bunch compressor opens the possibility of heightened mitigation of CSR during compression and an increased flexibility of system configuration. In this paper, we outline a procedure to optimize the PAL-XFEL linac under several compression configurations using the particle tracking code Elegant and present its results.