| Paper |
Title |
Page |
| MOPCH137 |
An Anti-symmetric Lattice for High Intensity Rapid-cycling Synchrotrons
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369 |
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- J. Wei, Y.Y. Lee, S. Tepikian
BNL, Upton, Long Island, New York
- S.X. Fang, Q. Qin, J. Tang, S. Wang
IHEP Beijing, Beijing
- S. Machida, C.R. Prior, G. Rees
CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
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Rapid cycling synchrotrons are used in many high power facilities like spallation neutron sources and proton drivers. In such accelerators, beam collimation plays a crucial role in reducing the uncontrolled beam loss. Furthermore, the injection and extraction section needs to reside in dispersion-free region to avoid couplings; a significant amount of drift space is needed to house the RF accelerating cavities; orbit, tune, and chromatic corrections are needed; long, uninterrupted straights are desired to ease injection tuning and to raise collimation efficiency. Finally, the machine circumference needs to be small to reduce construction costs. In this paper, we present a lattice designed to satisfy these needs. The lattice contains a drift created by a missing dipole near the peak dispersion to facilitate longitudinal collimation. The compact FODO arc allows easy orbit, tune, coupling, and chromatic correction. The doublet straight provides long uninterrupted straights. The four-fold lattice symmetry separates injection, extraction, and collimation to different straights. This lattice is chosen for the Beijing Spallation Neutron Source synchrotron.
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| TUPLS115 |
Transverse Phase Space Painting for the CSNS Injection
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1774 |
| |
- J. Qiu, J. Tang, S. Wang
IHEP Beijing, Beijing
- J. Wei
BNL, Upton, Long Island, New York
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The CSNS accelerators consist of an 80 MeV proton Linac, and a 1.6 GeV rapid cycling synchrotron (RCS). The ring accumulates 1.88*1013 protons via H－stripping injection in the phase CSNS-I. The injected beam is painted into the large transverse phase space to alleviate space-charge effects. The uniformity of beam emittance is important in reducing the tune shift/spread due to space charge effect. The paper introduces two parameters to evaluate the uniformity of a distribution. To satisfy the low-loss design criteria, extensive comparison of different painting scenarios has been carried out by using the simulation code ORBIT. This paper gives detailed studies on painting schemes and the dependence on the lattice tune, the injection peak current, and also chopping rate.
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| TUPLS116 |
Extraction System Design for the CSNS/RCS
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1777 |
| |
- J. Tang, Y. Chen, Y.L. Chi, Y.L. Jiang, W. Kang, J.B. Pang, Q. Qin, S. Wang, W. Wang
IHEP Beijing, Beijing
- J. Wei
BNL, Upton, Long Island, New York
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The CSNS extraction system takes use one of the four dispersion-free straight sections. Five vertical kickers and one Lambertson septum magnet are used for the one-turn extraction. The rise time of less 250 ns and the total kicking angle of 20 mrad are required for the kickers that are grouped into two tanks. The design for the kicker magnets and the PFN is also given. To reduce the low beam loss in the extraction channels due to large halo emittance, large apertures are used for both the kickers and septum. Stray magnetic field inside and at the two ends of the circulating path of the Lambertson magnet and its effect to the beam has been studied.
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| TUPLS117 |
Beam Transport Lines for the CSNS
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1780 |
| |
- J. Tang, G.H. Wei, C. Zhang
IHEP Beijing, Beijing
- J. Wei
BNL, Upton, Long Island, New York
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This paper presents the design of two beam transport lines at the CSNS: one is the injection line from the linac to the RCS and the other is the target line from the RCS to the target station. In the injection beam line, space charge effects, transverse halo collimation, momentum tail collimation and debunching are the main concerned topics. A new method of using triplet cells and stripping foils is used to collimate transverse halo. A long straight section is reserved for the future upgrading linac and debuncher. In the target beam line, large halo emittance, beam stability at the target due to kicker failures and beam jitters, shielding of back-scattering neutrons from the target are main concerned topics. Special bi-gap magnets will be used to reduce beam losses in the collimators in front of the target.
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| TUPLS118 |
Injection System Design for the CSNS/RCS
|
1783 |
| |
- J. Tang, Y. Chen, Y.L. Chi, Y.L. Jiang, W. Kang, J.B. Pang, Q. Qin, J. Qiu, L. Shen, S. Wang
IHEP Beijing, Beijing
- J. Wei
BNL, Upton, Long Island, New York
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The CSNS injection system is designed to take one uninterrupted long drift in one of the four dispersion-free straight sections to host all the injection devices. Painting bumper magnets are used for both horizontal and vertical phase space painting. Closed-orbit bumper magnets are used for facilitating the installation of the injection septa and decreasing proton traversal in the stripping foil. Even with large beam emittance of about 300 pmm.mrad used, BSNS/RCS still approaches the space charge limit during the injection/trapping phase for the accumulated particles of 1.9*1013 and at the low injection energy of 80 MeV. Uniform-like beam distribution by well-designed painting scheme is then obtained to decrease the tune shift/spread. ORBIT code is used for the 3D simulations. Upgrading to higher injection energy has also been considered.
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| WEPCH033 |
Single Particle Beam Dynamics Design of CSNS/RCS
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1996 |
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- S. Wang, S.X. Fang, Q. Qin, J. Tang
IHEP Beijing, Beijing
- J. Wei
BNL, Upton, Long Island, New York
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Rapid Cycling Synchrotron (RCS) is a key component of Beijing Spallation Neutron Source (BSNS). It accumulates and accelerates protons to design energy of 1.6 GeV and extracts high energy beam to the target. As a high beam density and high beam power machine, low beam loss is also a basic requirement. An optimal lattice design is essential for the cost and the future operation. The lattice design of BSNS is presented, and the related dynamics issues are discussed. The injection/extraction scheme and the beam collimation system design are introduced.
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