| Paper |
Title |
Page |
| 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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| WEPCH079 |
Effects of Intrinsic Nonlinear Fields in the J-PARC RCS
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2104 |
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- H. Hotchi, Y. Irie, F. Noda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Machida
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
- A.Y. Molodozhentsev
KEK, Ibaraki
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In order to accelerate a high intense proton beam with small particle losses, the J-PARC RCS, which is being constructed at JAEA, has a large acceptance. In such synchrotrons, the nonlinear motion of the beam particles, especially moving away from the axis of the elements, is a common issue, and it becomes essential to consider intrinsic field nonlinearities. The main sources of nonlinear magnetic fields in the RCS are as follows: fringes of the main dipole and quadrupole magnets, sextupole fields used for the chromatic correction, leak fields from the injection and extraction beam lines, etc. In this paper, we will discuss influences of the intrinsic field nonlinearities and a cure for the induced betatron resonances, based on single-particle and multi-particle tracking simulations.
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| THPCH013 |
Study of Particle Losses Mechanism for J-PARC Main Ring
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2811 |
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- 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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