| Paper |
Title |
Page |
| TUPLS107 |
Operation of the Opposite-Field Septum Magnet for the J-PARC Main-Ring Injection
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1750 |
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- I. Sakai, Y. Arakaki, K. Fan, Y. Saito, M. Tomizawa, M. Uota
KEK, Ibaraki
- A.K. Kawasaki, H. Mori, A. Tokuchi
NICHICON, Shiga
- Y. Morigaki, A. Nishikawa
IHI/Yokohama, Kanagawa
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The opposite field septum magnet system has been applied to the injection system of the J-PARC 50-GeV proton synchrotron. The features of the system are a force-free structure, easy pulse excitation and the possibility of a large-aperture, thin-septum structure. The septum magnet has the structure of an inside-vacuum to eliminate the thickness of the vacuum-chamber walls and electric-insulation layer to make the septum thickness as thin as possible. However the magnet cores and return coils are outside of the vacuum to reduce the out-gassing rate of the vacuum system. Finally, the larger beam aperture than the full acceptance of the ring and larger separation angle can be obtained at the septum magnet for low-loss injection. In this paper we will introduce the methods to eliminate the error fields caused by fabrication errors and eddy current with pulse excitation and stability of high current power supply of 50 kA.
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| WEPCH028 |
Position Shuffling of the J-PARC Main Ring Magnets
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1984 |
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- M. Tomizawa, K. Fan, S. Igarashi, K. Ishii, H. Kobayashi, A.Y. Molodozhentsev, K. Niki, E. Yanaoka
KEK, Ibaraki
- Y. Irie
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Machida
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
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The J-PARC 50GeV main ring has 96 dipole, 216 quadrupole with 11 families and 72 sextupole magnets with 3 families. Magnets installation in the tunnel started last year and will be planed to finish by the end of next fiscal year. Field measurements of all magnets will soon finish by this March. Deviations for BL, B'L, B"L in dipole, quadrupole and sextupole magnets make COD, beta beat and third integer stopband, respectively. They can be reduced by choosing a pair of magnets with similar field deviation and by positioning them so as to cancel each other considering betatron phase (shuffling). In this paper, we will report our shufflling scheme chosen under the given schedule for installation and field measurements and also will show performances expected by the shufflings.
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| WEPCH029 |
Injection and Extraction Orbit of the J-PARC Main Ring
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1987 |
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- M. Tomizawa, Y. Kamiya, H. Kobayashi, I. Sakai, Y. Shirakabe
KEK, Ibaraki
- S. Machida
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
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The J-PARC main ring (MR) accelerates a high intensity proton beam and deliver to the neutrino experimental hall by the fast extraction and to the hadron experimental facility by the slow extraction. The beam from the rapid cycle synchrotron (RCS) is injected by the bunch to bucket transfer into the MR. The MR has two beam dump lines, the first one is used to dump the beam at injection energy and the second one can be used to abort accelerated beam. The beam loss at the injection and extraction is one of the critical issue for high intensity proton accelerators. We report designed injection and extraction orbits and discuss about the beam apertures and the beam loss.
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| THPCH013 |
Study of Particle Losses Mechanism for J-PARC Main Ring
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2811 |
| |
- A.Y. Molodozhentsev, M. Tomizawa
KEK, Ibaraki
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Detailed understanding as well as confidence in simulation modeling of long-term effects (~ 100'000 turns) of high intensity proton beam is crucial for Main Ring (MR) of the J-PARC project, where it is necessary to hold the high-intensity beam over typically ~ 2 sec with a loss level less than 1%. The major focus of such study is the combined effect of space charge and nonlinear resonances and its impact on halo formation and/or beam loss. In frame of this report, the tracking results for the injection process including realistic representation of the ring's focusing structure are discussed. Optimization of the working point during the injection process is presented. The halo formation and particle losses during the injection and acceleration for MR have been estimated for realistic magnetic field errors.
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