| Paper |
Title |
Page |
| THOAFI01 |
The Development of Computational Tools for Halo Analysis and Study of Halo Growth in the Spallation Neutron Source Linear Accelerator
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2768 |
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- D.A. Bartkoski, A.V. Aleksandrov, S.M. Cousineau, S. Henderson, J.A. Holmes
ORNL, Oak Ridge, Tennessee
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Computational tools have been developed to quantify the halo in a beam by analyzing beam profiles and identifying the halo particles using the Gaussian area ratio and kurtosis methods. Simulations of various injection quadrupole magnet configurations using three types of initial simulated distributions, along with an analysis of their phase space and rms properties, provides insight into the development of halo in the Spallation Neurton Source linear accelerator. Finally, comparisons with machine beam profile data, taken at the same conditions as that of the simulated data, show how accurately the simulations model the beam and its halo development and provide a better understanding of the best machine configuration with which to minimize beam halo and losses.
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Transparencies
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| THOAFI02 |
Ion Instability Observed in PLS Revolver In-vacuum Undulator
|
2771 |
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- H.-S. Kang, J. Choi, M. Kim, T.-Y. Koo, T.-Y. Lee, P.C.D. Park
PAL, Pohang, Kyungbuk
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Revolver In-Vacuum X-ray Undulator which was designed and fabricated at Spring-8 is under commissioning at PLS. This planar undulator whose permanent magnet array structure is a revolving type with 90-degree step provides 4 different undulator wavelengths of 10, 15, 20, and 24 mm. The minimum gap of the undulator is as small as 5 mm. It was observed that the trailing part of a long bunch train was scraped due to ion instability when the undulator gap was closed below 6 mm. At that time the vacuum pressure in the undulator, which is estimated to be about one order of magnitude lower than that of the undulator gap, increased from 1.4 x 10-10 (gap 20 mm) to 7.9 x 10-10 Torr (gap 6 mm) at the stored beam current of 100 mA. This high vacuum pressure causes fast beam-ion instability: trailing part of a long bunch train oscillates vertically. It was also confirmed that adjusting the orbit along the undulator has improved the situation to some extent. The ion instability measured with a pico-second streak camera and a one-turn BPM as well as the result of orbit adjustment and chromaticity control will be described in this paper.
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Transparencies
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| THOAFI03 |
Global and Local Coupling Compensation in RHIC using AC Dipoles
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2774 |
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- R. Calaga
BNL, Upton, Long Island, New York
- F. Franchi
GSI, Darmstadt
- R. Tomas
CERN, Geneva
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Compensation of transverse coupling during the RHIC energy ramp has been proven to be non-trivial and tedious. The lack of accurate knowledge of the coupling sources has initiated several efforts to develop fast techique using turn-by-turn BPM data to identify and compensate these sources. This paper aims to summarize the beam experiments performed to measure the coupling matrix and resonance driving terms with the aid of RHIC ac dipoles.
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Transparencies
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