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| WEPMA050 |
BPM (Beam Position Monitor) in the PAL Linac and BTL
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393 |
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- S.-C. Kim, J. Choi, Y. J. Han, J. Y. Huang, D. T. Kim, W. W. Lee, H. J. Park
PAL, Pohang, Kyungbuk
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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.
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| WEPMA054 |
Photon Beam Position Monitor with Hydraulic Level System
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398 |
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- Y. J. Han, J. Choi, J. Y. Huang, S. N. Kim, Y.-C. Kim
PAL, Pohang, Kyungbuk
- I. S. Ko
POSTECH, Pohang, Kyungbuk
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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.
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| THPMA063 |
Energy Stabilization of 2.5 GeV Linac using DeQing
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717 |
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- S. H. Kim, Y. J. Han, J. Y. Huang, S.-C. Kim, S. H. Nam, S. S. Park
PAL, Pohang, Kyungbuk
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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.
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