Author: Kang, H.-S.
Paper Title Page
MOICNO02
 Control of Electron Beam Longitudinal Phase Space With a Novel Compact De-chirper for PAL-XFEL  
 
  • H.-S. Kang, M.S. Chae, T. Ha, J.H. Hong, W.W. Lee, S.J. Park, H. Yang
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  The PAL-XFEL adopts a de-chirper system to remove the residual beam chirps with wakefield in corrugated pipes for the soft X-ray FEL line which is branched at 3 GeV point of the 10-GeV linac and does not have enough length of accelerating structures. The corrugated structure which is about 20 m long is designed to have the rectangular geometry and adjust the gap from 2 to 30 mm. We carried out the elegant code simulations using the wake formulas of G. Stupakov and K. Bane for the rectangular geometry to find the optimum parameters of corrugation using longitudinal wakes as well as to find the tolerance of vertical offset using transverse wakes. A 1-m long test de-chirper module is being designed and will be tested experimentally in July 2013 at the injector test facility in Pohang Accelerator Laboratory, which is a collaborative R&D with LBNL and SLAC.
Recommended by Zhirong Huang 		 
slides icon Slides MOICNO02 [10.661 MB]  
 
TUPSO28 Development of Photocathode RF-gun at PAL 279
 
  • J.H. Hong, J.H. Han, H.-S. Kang, Y.W. Parc, S.J. Park, Y.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  • I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  
  We are developing two types of S-band photocathode RF-guns for the X-ray free electron laser (XFEL) at Pohang Accelerator Laboratory (PAL). One is a 1.6-cell RF-gun with a dual side coupler and two pumping ports. This RF-gun is similar to the earlier guns developed at PAL. The other one is a 1.5-cell RF-gun with a coaxial coupler and a cathode preparation system. This RF-gun is similar to the DESY-type L-band RF-gun. We have designed and fabricated two types of RF-guns. In this paper we introduce and compare two different RF-guns.  
 
WEPSO33 Remote RF Synchronization With Femtosecond Drift at PAL 570
 
  • J. Kim, K. Jung, J. Lim
    KAIST, Daejeon, Republic of Korea
  • L. Chen
    Idesta Quantum Electronics, New Jersey, USA
  • S. Hunziker
    PSI, Villigen PSI, Switzerland
  • F.X. Kaertner
    CFEL, Hamburg, Germany
  • H.-S. Kang, C.-K. Min
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Funding: This research was supported by the PAL-XFEL Project, South Korea.
We present our recent progress in remote RF synchronization using an optical way at PAL. A 79.33-MHz, low-jitter fiber laser is used as an optical master oscillator (OMO), which is locked to the 2.856-GHz RF master oscillator (RMO) using a balanced optical-microwave phase detector (BOM-PD). The locked optical pulse train is then transferred via a timing-stabilized 610-m long optical fiber link. The output is locked to the 2.856 GHz voltage controlled oscillator (VCO) using the second BOM-PD, which results in remote synchronization between the RMO and the VCO. We measured the long-term phase drift between the input optical pulse train and the remote RF signals using an out-of-loop BOM-PD, which results in 2.7 fs (rms) drift maintained over 7 hours. We are currently working to measure the phase drift between the two RF signals and reduce the phase drift over longer measurement time. 		 
 
WEPSO47 Simulation Results of Self-seeding Scheme in PAL-XFEL 606
 
  • Y.W. Parc, J.H. Han, I. Hwang, H.-S. Kang
    PAL, Pohang, Kyungbuk, Republic of Korea
  • I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • J. Wu
    SLAC, Menlo Park, California, USA
  
  There are two major undulator lines in Pohang Accelerator Laboratory XFEL (PAL XFEL), soft X-ray and hard X-ray. For the hard X-ray undulator line, self-seeding is the most promising approach to supply narrow bandwidth radiation to the users. The electron energy at hard X-ray undulator is 10 GeV and the central wavelength is 0.1 nm. We plan to provide the self-seeding option in the Phase I operation of PAL-XFEL. In this talk, the simulation results for the self-seeding scheme of hard X-ray undulator line in PAL XFEL will be presented.