Author: Kang, H.-S.
Paper Title Page
Progress of the PAL-XFEL Undulator System  
  • D.E. Kim, Y.-G. Jung, H.-S. Kang, H.-G. Lee, S.B. Lee, W.W. Lee, B.G. Oh, K.-H. Park, H.S. Suh
    PAL, Pohang, Kyungbuk, Republic of Korea
  • M.-H. Cho, I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • S. Karabekyan, J. Pflüger
    XFEL. EU, Hamburg, Germany
  Pohang Accelerator Laboratory (PAL) is developing 10 GeV, 0.1 nm SASE based FEL for high power, short pulse X-ray coherent photon sources named PAL-XFEL. At the first stage PAL-XFEL needs two undulator lines for photon source. PAL is developing undulator magnetic structure based on EU-XFEL design. For hard X-ray lines, we need 18 26.0 mm period hybrid type planar undulator structures, and for soft X-ray lines, 6 planar undulator with 37 mm period is planned with a couple of EPUs for polarization control. In this report we summarize the progress in the undulator system. Particular emphasis will be the results of the local-K correction, which is essential to speed-up the pole tuning process.  
MOP032 PAL-XFEL Magnet Power Supply System 87
  • S.-H. Jeong, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park, H.S. Suh, Y.G. Young-Gyu
    PAL, Pohang, Kyungbuk, Republic of Korea
  This paper presents an overview of the magnet power supply(MPS) for the PAL-XFEL. The number of total MPS is 628 and they will be installed along the accelerator and the undulator sections. The power capacity of the MPS was ranging from about 1 A to 300 A. These MPSs were required to meet the high stability that was subjected from the beam dynamics specifications. This paper described the overall MPS requirements, MPS assembling, test process, control scheme, installation plan and so on.  
MOP033 Design, Fabrication, and Performance Tests of Dipole and Quadrupole Magnets for PAL-XFEL 90
  • H.S. Suh, M.-H. Cho, S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  PAL-XFEL is now being constructed in Pohang, Korea. This facility will consist of a 10 GeV linac and five undulator beamlines. As the first phase we will construct one hard X-ray and one soft X-ray beamlines which require 7 different families of dipole magnets, and 11 families of quadrupole magnets. We are designing these magnets with considering the efficient manufacturing and the proper power supplies. In this presentation, we describe the design features of the magnets, the manufacturing, and the thermal analysis with the test results.  
TUP093 A Beam Test of Corrugated Structure for Passive Linearizer 593
  • H.-S. Kang, J.H. Hong
    PAL, Pohang, Kyungbuk, Republic of Korea
  A dechirper which is a vacuum chamber of two corrugated, metallic plates with adjustable gap was successfully tested at Pohang, in August 2013. Another beam test was carried out to test the same structure to see if the corrugated plates may work as a linearizer. The test result will be presented together with the simulation result.  
WEB02 Beam Operation of the PAL-XFEL Injector Test Facility 615
  • J.H. Han, S.Y. Baek, M.S. Chae, H. J. Choi, T. Ha, J.H. Hong, J. Hu, W.H. Hwang, S.H. Jung, H.-S. Kang, C. Kim, C.H. Kim, I.Y. Kim, J.M. Kim, S.H. Kim, I.S. Ko, H.-S. Lee, J. Lee, S.J. Lee, W.W. Lee, C.-K. Min, G. Mun, D.H. Na, S.S. Park, S.J. Park, Y.J. Park, Y.G. Son, H. Yang
    PAL, Pohang, Kyungbuk, Republic of Korea
  The Pohang Accelerator Laboratory X-ray Free electron Laser (PAL-XFEL) project was launched in 2011. This project aims at the generation of X-ray FEL radiation in a range of 0.1 to 10 nm for photon users with a bunch repetition rate of 60 Hz. The machine consists of a 10 GeV normal conducting S-band linear accelerator and five undulator beamlines. The linac and two undulator beamlines will be constructed by the end of 2015 and first FEL radiation is expected in 2016. As a part of preparation for the project, an Injector Test Facility was constructed in 2012. Since December 2012, beam commissioning is being carried out to find optimum operating conditions and to test accelerator components including RF, laser, diagnostics, magnet, vacuum and control. We present the status of beam commissioning and components tests at the test facility.  
slides icon Slides WEB02 [10.249 MB]  
THB03 Femtosecond-Stability Delivery of Synchronized RF-Signals to the Klystron Gallery over 1-km Optical Fibers 663
  • J. Kim, K. Jung, J. Lim, J. Shin, H. Yang
    KAIST, Daejeon, Republic of Korea
  • H.-S. Kang, C.-K. Min
    PAL, Pohang, Kyungbuk, Republic of Korea
  Funding: This work was supported by the PAL-XFEL Project and the National Research Foundation (Grant number 2012R1A2A2A01005544) of South Korea.
We present our recent progress in optical frequency comb-based remote optical and RF distribution system at PAL-XFEL. A 238 MHz mode-locked Er-laser is used as an optical master oscillator (OMO), which is stabilized to a 2.856 GHz RF master oscillator (RMO) using a fiber- loop optical-microwave phase detector (FLOM-PD). We partly installed a pair of 1.15 km long fiber links through a cable duct to connect and OMO room to a klystron gallery in the PAL-XFEL Injector Test Facility (ITF). The fiber links are stabilized using balanced optical cross- correlators (BOC). A voltage controlled RF oscillator (VCO) is locked to the delivered optical pulse train using the second FLOM-PD. Residual timing jitter and drift between the two independently distributed optical pulse train and RF signal is measured at the klystron gallery. The results are 6.6 fs rms and 31 fs rms over 7 hours and 62 hours, respectively. This is the first comb-based optical/RF distribution and phase comparison in the klystron gallery environment.
slides icon Slides THB03 [7.478 MB]  
THP011 Beam Measurement of Photocathode RF-gun for PAL-XFEL 699
  • J.H. Hong, M.S. Chae, J.H. Han, H.-S. Kang, C.-K. Min, S.J. Park, Y.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  • I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  The Injector Test Facility (ITF) at Pohang Accelerator Laboratory (PAL) was constructed to develop an injector for the PAL X-ray free-electron laser (PAL-XFEL) project. The PAL-XFEL design requires the injector to produce an electron beam with a slice emittance of 0.4 mm-mrad at the charge of 200 pC. A 4-hole type RF-gun has been successfully fabricated and tested at ITF. In this paper we report the recent beam-measurement results using the RF-gun at ITF. Emittance measurements have been carried out by changing laser and RF parameters.  
THP012 Error Analysis for Linac Lattice of Hard X-ray FEL Line in PAL-XFEL* 703
  • H. Yang, J.H. Han, H.-S. Kang, I.S. Ko
    PAL, Pohang, Kyungbuk, Republic of Korea
  Funding: *This work was supported by MSIP, Korea.
PAL-XFEL consists of the hard x-ray line for 0.06 – 1-nm FEL and the soft x-ray line for 1 – 10-nm FEL. The linac of hard x-ray line is designed to generate 10-GeV, 200-pC, and 3-kA electron beam. It consists of S-band accelerating columns, an X-band linearizer, three bunch compressors (BC). We conduct error simulation in order to evaluate the tolerances of machine parameters and alignments. First, the machine tolerances and beam jitter levels are calculated in the simulations with dynamic errors and we find out the optimized lattice to satisfy the target tolerance of machine. Second, we conduct simulations with misalignment. We quantify the emittance dilution by misalignments, especially those of BCs. In order to compensate the misalignments, the methods of beam correction like Beam Based Alignment (BBA) are presented and the effects of emittance improvements are calculated.
poster icon Poster THP012 [0.736 MB]