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Title: Beam-Optics Analysis and Periodicity Restoration in the Storage Ring of the Pohang Light Source

Abstract

In this paper, we examine numerically and experimentally the linear beam optics distortion in the storage ring of the Pohang Light Source (PLS), and the correction of optics using a number of quadrupole magnets installed in the storage ring. The measured orbit-response matrices were fitted to the model-response matrices to obtain {beta} and dispersion functions in storage ring. By readjusting currents of quadrupole-magnet power supplies, optics parameters were successfully restored to the values very close to the design ones. After the optics correction, it is expected that the performance of the storage ring is better than the present one.

Authors:
;  [1];  [2]
  1. Department of Physics, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, Gyeongbuk 790-784 (Korea, Republic of)
  2. Department of Physics, Kyungpook National University, Sangyuk-dong, Bukgu, Daegu 702-701 (Korea, Republic of)
Publication Date:
OSTI Identifier:
21049216
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436018; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM OPTICS; CORRECTIONS; DESIGN; ELECTRIC CURRENTS; MAGNETS; ORBITS; PERFORMANCE; PERIODICITY; POHANG LIGHT SOURCE; POWER SUPPLIES; QUADRUPOLES; STORAGE RINGS

Citation Formats

Shin, S. H., Yoon, M., and Kim, E.-S. Beam-Optics Analysis and Periodicity Restoration in the Storage Ring of the Pohang Light Source. United States: N. p., 2007. Web. doi:10.1063/1.2436018.
Shin, S. H., Yoon, M., & Kim, E.-S. Beam-Optics Analysis and Periodicity Restoration in the Storage Ring of the Pohang Light Source. United States. doi:10.1063/1.2436018.
Shin, S. H., Yoon, M., and Kim, E.-S. Fri . "Beam-Optics Analysis and Periodicity Restoration in the Storage Ring of the Pohang Light Source". United States. doi:10.1063/1.2436018.
@article{osti_21049216,
title = {Beam-Optics Analysis and Periodicity Restoration in the Storage Ring of the Pohang Light Source},
author = {Shin, S. H. and Yoon, M. and Kim, E.-S.},
abstractNote = {In this paper, we examine numerically and experimentally the linear beam optics distortion in the storage ring of the Pohang Light Source (PLS), and the correction of optics using a number of quadrupole magnets installed in the storage ring. The measured orbit-response matrices were fitted to the model-response matrices to obtain {beta} and dispersion functions in storage ring. By readjusting currents of quadrupole-magnet power supplies, optics parameters were successfully restored to the values very close to the design ones. After the optics correction, it is expected that the performance of the storage ring is better than the present one.},
doi = {10.1063/1.2436018},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • After three years of upgrading work, the Pohang Light Source-II (PLS-II) is now successfully operating. The final quantitative goal of PLS-II is a top-up user-service operation with beam current of 400 mA to be completed by the end of 2014. During the beam store test up to 400 mA in the storage ring (SR), it was observed that the vacuum pressure around the radio frequency (RF) window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. Although available beam current is enhanced by setting a higher RF accelerating voltage, it is bettermore » to keep the RF accelerating voltage as low as possible in the long time top-up operation. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. In our simulation, an equivalent physical modeling was developed using a finite-difference time-domain code. The simulation revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window, which comes with the rapid increase of window vacuum pressure. The RF accelerating voltage of PLS-II RF system was set to 4.95 MV, which was estimated using the maximum available beam current that works as a function of RF voltage, and the top-up operation test with the beam current of 400 mA was successfully carried out.« less
  • We measured the spatial coherence length and incoherent source size of a hard x-ray undulator beamline at Pohang Light Source-II, the stored electron energy of which has been increased from 2.5 GeV to 3 GeV. The coherence length was determined by single-slit measurement of the visibility of the Fresnel diffraction pattern. The correlated incoherent source size was cross-checked for three different optics: the single slit, beryllium parabolic compound refractive lenses, and the Fresnel zone plate. We concluded that the undulator beamline has an effective incoherent source size (FWHM) of 540 μm (horizontal) × 50 μm (vertical)
  • Beam sizes of the stored electron beam at the APS storage ring were measured using pinhole optics and bending magnet x-rays in single-bunch and low-current mode. A white-beam pinhole of 25 {mu}m and a fast x-ray imaging system were located 23.8 m and 35.4 m from the source, respectively. The x-ray imaging system consists of a CdWO{sub 4} scintillation crystal 60 {mu}m thick, an optical imaging system, and a CCD detector. A measurement time of a few tenths of a second was obtained on a photon beam of E{approx_gt}30 keV produced from a 7-GeV electron beam of 2-mA current. Themore » resolution of the pinhole imaging system was evaluated to be 16 {mu}m. The measured vertical and horizontal sizes of the electron beam were in reasonable agreement with the expected values. {copyright} {ital 1996 American Institute of Physics.}« less
  • Beam sizes of the stored electron beam at the Advanced Photon Source storage ring were measured using zone-plate optics and undulator radiation. A gold Fresnel zone plate (3.5 {mu}m thick) located 33.9 meters from the x-ray source focused radiation of 18 keV, selected by a cryogenically cooled Si(111) crystal in horizontal deflection, and formed a source image in a transverse plane 2.41 m downstream. The sizes of the source image were determined from measured intensity profiles of x-ray fluorescence from a smooth nickel edge (1.5 {mu}m thick), fabricated using a lithographic technique, while the nickel edge was scanned across overmore » the beam in the transverse plane. The measured vertical and horizontal sizes of the electron beam were 60{plus_minus}4.3{mu}m and 300{plus_minus}13{mu}m, respectively, in reasonable agreement with the expected values. {copyright} {ital 1997 American Institute of Physics.}« less
  • Beam sizes of the stored electron beam at the Advanced Photon Source storage ring were measured using zone-plate optics and undulator radiation. A gold Fresnel zone plate (3.5 {mu}m thick) located 33.9 meters from the x-ray source focused radiation of 18 keV, selected by a cryogenically cooled Si(111) crystal in horizontal deflection, and formed a source image in a transverse plane 2.41 m downstream. The sizes of the source image were determined from measured intensity profiles of x-ray fluorescence from a smooth nickel edge (1.5 {mu}m thick), fabricated using a lithographic technique, while the nickel edge was scanned across overmore » the beam in the transverse plane. The measured vertical and horizontal sizes of the electron beam were 60{+-}4.3 {mu}m and 300{+-}13 {mu}m, respectively, in reasonable agreement with the expected values.« less