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Huang, J. Y.

 
Paper Title Page
WEC3H102 Fabrication and Performance Test of the Cavity BPM for KEK ATF2 and PAL XFEL 336
 
  • J. Y. Huang, W. H. Hwang, S. H. Kim, S. J. Park, Y. J. Park
    PAL, Pohang, Kyungbuk
  • Y. Honda, I. Y. Inoue, T. Tauchi, J. Urakawa
    KEK, Ibaraki
  • M. C. Ross
    Fermilab, Batavia, Illinois
  
  Precise, single shot measurement of the beam position with a sub-micrometer resolution is required for the next generation linear accelerators such as International Linear Collider (ILC) and X-ray Free Electron Laser (XFEL). As a pill-box cavity structure is sensitive to the transverse offset of the beam at the dipole-mode resonance, e.g., TM110-mode, a pill-box type cavity is a good candidate for the sub-micrometer beam position monitor (BPM). Test cavity BPM had been designed and tested in KEK successfully, and miscellaneous improvements for the final prototype fabrication and beam tests are performed in collaboration between KEK, SLAC and PAL. With the successful results of beam test in ATF, 41 cavity BPMs will be produced by PAL and installed in ATF2, which is an advanced beam-test line under construction as the extension of existing ATF for the beam studies on the final focus of the planned ILC program. Technical design considerations, fabrication and test results are described in this paper.  
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WEPMA050 BPM (Beam Position Monitor) in the PAL Linac and BTL 393
 
  • S.-C. Kim, J. Choi, Y. J. Han, J. Y. Huang, D. T. Kim, W. W. Lee, H. J. Park
    PAL, Pohang, Kyungbuk
  
  In Aug. 2004, thirteen BPMs are installed at BTL (Beam Transport Line), and later in Aug. 2005, three BPM installed at main linac for beam trajectory measurement and feedback. BPMs for the BTL consist of 100mm strip-line electrodes in 150mm long chamber and uses SMA-R type feed-throughs. BPMs of the Linac consist of 57mm strip-line electrodes in 100mm short chamber and SMA-R type feed-throughs. 500MHz log-ratio signal processing circuits are used for the Linac and BTL BPM electronics. BPM data acquisition system is developed as an EPICS IOC by using NI S-series DAQ board and NI LabView 7.1. Best read-out accuracy of BPM system is measured as 20mm including BPM electronics. In this paper, we describe on the status of the BPM and its characteristics for PAL Linac and BTL.  
WEPMA054 Photon Beam Position Monitor with Hydraulic Level System 398
 
  • Y. J. Han, J. Choi, J. Y. Huang, S. N. Kim, Y.-C. Kim
    PAL, Pohang, Kyungbuk
  • I. S. Ko
    POSTECH, Pohang, Kyungbuk
  
  In a synchrotron radiation source like the Pohang Light Source (PLS), a great effort has been made on beam stability improvements. For the beamline user-sided orbit feedback, Photon Beam Position Monitor(PBPM) provides more practical informations on the position and angle of the electron beam at the center of the bending magnet, compared the closed orbit data. For improvement of the orbit stability, PBPMs are used in PLS. However, as the ground of PLS moves about 2mm every year, we also monitor the level difference between the storage ring and the beamline floor with Hydraulic Level System (HLS). The design and experimental results of PBPM with HLS will be presented.  
WEPMA080 Control System for the Bending MPS at PLS Linac 437
 
  • J. H. Kim, J. Choi, K. M. Ha, J. Y. Huang, H.-S. Kang, J. M. Kim, S.-C. Kim, I. S. Ko
    PAL, Pohang, Kyungbuk
  
  The former control system of the bending MPS (Magnet Power Supply) has a three-layered architecture. It was developed by in-house members in early 1993. It is upgraded based on EPICS as the protocol for the full upgrade of the PLS control system. We have replaced the former VME 68K CPU boards with OS-9 to new Power CPU boards operated by VxWorks as IOC in the linac klystron gallery. The upgraded bending MPS control system consists of a MVME5100 EPICS IOC core in the lower level control. It is implemented with the MEDM tool of EPICS to provide friendly Graphical User Interfaces. This paper describes the VME IOC and OPI and embedded local controller in MPS cabinet used for the bending MPS control in the PLS linac

Pohang Accelerator Laboratory, Pohang, 790-784, KoreaThis works supported by the Ministry of Science and Technology, Korea.

 
WEPMA103 The Design And Performance of the Prototype Digital Feedback RF Control System For the PLS Storage Ring 464
 
  • I. H. Yu, J. Y. Huang, H.-S. Kang, D. T. Kim, H. Y. Kim, S.-C. Kim, I. S. Park
    PAL, Pohang, Kyungbuk
  
  The digital feedback RF control system for the Proton Engineering At the Pohang Light Source (PLS) Storage Ring, the low level RF system based on analog technique provides RF field control for the 4 RF stations, and each station drives each RF cavity at 500.082MHz. To achieve better control system stability and accuracy, the prototype digital feedback RF control has been developed in Pohang Accelerator Laboratory (PAL). In addition to RF field control, it provides cavity resonance control, and incorporates the personnel and machine protection functions. An accelerator electric field stability of ± 0.5% in amplitude and ± 0.5° in phase is required for the RF system. In order to accomplish these requirements, a digital feedback control technique is adopted for flexibility of the feedback and feed forward algorithm implementation. In this paper, the design and performance of this system will be presented with the performance test results.  
THPMA063 Energy Stabilization of 2.5 GeV Linac using DeQing 717
 
  • S. H. Kim, Y. J. Han, J. Y. Huang, S.-C. Kim, S. H. Nam, S. S. Park
    PAL, Pohang, Kyungbuk
  
  The 2.5 GeV electron linac of Pohang Accelerator Laboratory (PAL) employs 80 MW klystrons with matching 200 MW modulators as RF sources. Beam voltage stability of the klystron is directly related to a PFN (pulse forming network) charging voltage of the modulator. Therefore, a good regulation of a PFN charging voltage is essential in the modulator. The regulation of the klystron pulse voltage amplitude is made by controlling the PFN charging voltage. In a conventional resonant charging pulse modulator, the regulation is usually achieved by using a deQing circuit. The required beam voltage regulation of less than ± 0.5 %, without deQing circuit, has been achieved by using a SCR phase controller with a voltage regulator. For further improvement of the beam voltage stability for the PAL XFEL (x-ray free electron laser) linac, PAL is studying a deQing circuit aiming at the stabilization of less than 0.02%. A new deQing circuit has been developed with a compensation function which can reduce a charge voltage fluctuation by about several times. The design concept and performance of the deQing circuit will be discussed.  
THPMA074 Operational Analysis of Klystron-Modulator System for PLS 2.5-GeV Electron Linac 740
 
  • S. S. Park, J. Y. Huang, S. H. Kim, S.-C. Kim
    PAL, Pohang, Kyungbuk
  
  The klystron-modulator(K&M) system of the Pohang Accelerator Laboratory (PAL) generates high power microwaves for the acceleration of 2.5 GeV electron beams. There are 12 modules of K&M system to accelerate electron beams up to 2.5 GeV nominal beam energy. One module of the K&M system consists of the 200 MW modulator and an 80 MW S-band (2856 MHZ) klystron tube. The total accumulated high-voltage run-time of the oldest unit among the 12 K&M systems has reached nearly 92,300 hours as of June 2006. The overall system availability is well over 95%. In this paper, we review overall system performance of the high-power K&M system and the operational status of the klystrons and thyratron lifetimes, and overall system's availability will be analyzed for the period of 1994 to June 2006.