Author: Kim, C.
Paper Title Page
WEOA01
Femtosecond Synchronization of PAL-XFEL  
 
  • C. Kim, H.-S. Kang, I.S. Ko, C.-K. Min
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The PAL-XFEL achieved a 20 fs jitter in the bunch arrival time at the end of undulators and its pump-probe system, which is extremely useful for maintaining a high stability of machine and time-resolved experiments with high time resolution. A low phase noise timing system and high stability high power RF system enable this low jitter. The measurement result shows 10 fs jitter of bunch arrival time at the injector and it increased ~ 20 fs due to the bunch energy variation. The possibility of improving the final jitter is described based on the optimization of bunch compressors and a longitudinal feedback.  
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WEPA15 Development of BAM Electronics in PAL-XFEL 400
 
  • D.C. Shin, J.H. Hong, H.-S. Kang, C. Kim, G. Kim, C.-K. Min
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  We describe an electronics for electron bunch arrival time monitor (BAM) with a less than 10 femtosecond resolution, which was developed in 2017 and is currently in use at PAL-XFEL. When electron bunches go through an S-band monopole cavity, about 1 us long RF signal can be obtained to compare with a low phase noise RF reference. The differential phase jitter corresponds to the arrival time jitter of electron bunches. RF front-end (F/E) which converts the S-band pickup signal to intermediate frequency (IF) signal, is the essential part of a good time resolution. The digitizer and the signal processor of the BAM electronics are installed in an MTCA platform. This paper presents the design scheme, test results of the BAM electronics and future improvement plans.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA15  
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WEPA16 Micro-Bunching Instability Monitor for X-ray Free Electron Laser 404
 
  • C. Kim, H.-S. Kang, G. Kim, I.S. Ko
    PAL, Pohang, Kyungbuk, Republic of Korea
  • J.H. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
 
  A direct method was developed to measure the micro-bunching instability in the X-ray Free Electron Laser (XFEL). The micro-bunching instability comes from the interaction between the electron beam and the coherent synchrotron radiation (CSR), and the FEL intensity can be affected significantly by the micro-bunching instability. However, no effective method had been introduced to monitor the micro-bunching instability, so that we installed a CCD camera to measure the micro-bunching instability after the bunch compressor. The CCD camera showed the micro-bunching instability successfully, and more interesting features of the micro-bunching instability were revealed from it.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA16  
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WEPB09 Wire Scanner Measurements at the PAL-XFEL 445
 
  • G. Kim, H.-S. Kang, C. Kim, B.G. Oh, D.C. Shin
    PAL, Pohang, Republic of Korea
 
  The PAL-XFEL, an X-ray Free electron laser user facility based on a 10 GeV normal conducting linear accelerator, have been operational at Pohang, South Korea. The wire scanners are installed for transverse beam profile measurement of the Linac and the Hard X-ray undulator section. The wire scanner is a useful device for emittance measurements in the Hard X-ray undulator section. In this paper, we describe the details of the wire scanner and the results of the measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB09  
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