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Lee, T.-Y.

Paper Title Page
MPPP003 FALSE BPM READINGS AFFECTING ORBIT FEEDBACK 847
 
  • H.-S. Kang, J. Choi, M.-H. Chun, K.M. Ha, J.Y. Huang, Y.-C. Kim, E.-H. Lee, T.-Y. Lee, W.W. Lee, J.-H. Suh
    PAL, Pohang, Kyungbuk
  
  Funding: Ministry of Science and Technology, Korea.

A slow global orbit feedback (SOFB) is routinely operating in the usual user service operation at PLS. The orbit feedback uses 22 correctors in each plane which have 20-bit capability for the vertical plane and 16-bit capability for the horizontal plane, and the feedback speed is 4 seconds. The orbit stability in RMS was maintained below 1 mm in both planes for one hour and 3 mm for a 12-hour operation. The BPM chamber movement due to the change of synchrotron radiation heat load mainly limits the SOFB performance. The intensity dependence of BPM electronics is well compensated by a look-up table of BPM.

 
TPAT010 Practical Definitions of Beam Lifetimes in an Electron Storage Ring 1216
 
  • T.-Y. Lee
    PAL, Pohang, Kyungbuk
  
  Derived are simple definitions of beam lifetimes in an electron storage ring. They are defined in terms of measured beam lifetime and its time derivative. They are practical rather than theoretical. The only condition required is suppression or saturation of the radiative polarization.  
RPAE046 Operational Status at the PLS: Recent Improvements and Changes 2923
 
  • E.S. Park, J. Choi, H.-S. Kang, M. Kim, E.-H. Lee, T.-Y. Lee
    PAL, Pohang, Kyungbuk
  
  PLS has been operated 10 years since 1994. A few improvements has been made to stabilize the reference orbit drifts caused by insertion devices and other sources: The control system has been upgraded to 20 bit capability from 12 bit. The slow global orbit feedback is employed routinely in the user run times. These improvements and the operational status changes will be presented in this report.  
RPPT017 Wake Field Effect on the SASE Performance of PAL XFEL 1549
 
  • J.-S. Oh, I.S. Ko, T.-Y. Lee, W. Namkung
    PAL, Pohang, Kyungbuk
  
  Funding: Supported by the POSCO and the MOST, Korea.

The PAL XFEL will supply coherent radiations from VUV to X-rays. X-ray FEL for 0.3 nm lasing requires a 3-GeV driver linac and a 60-m long in-vacuum undulator with a narrow variable gap. The linac should supply highly bright beams with emittance of 1.2 mm-mrad, a peak current of 3.5 kA, and a low energy spread of 0.03%. The beam quality is degraded along the undulator trajectory due to the energy loss, the wake field, and the magnetic field errors, etc. Especially the wake field effect is most sensitive parameter due to the narrow gap of the undulator. The preliminary design details of undulators for PAL-XFEL are presented with parametric analysis. The temporal SASE performance is analyzed using simulation tools such as GENESIS and SIMPLEX.