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Wang, S.

Paper Title Page
MOPCH126 Accelerator Research on the Rapid Cycling Synchrotron at IPNS 339
 
  • G.E. McMichael, F.R. Brumwell, L. Donley, J.C. Dooling, W. Guo, K.C. Harkay, Q.B. Hasse, D. Horan, R. Kustom, M.K. Lien, M.E. Middendorf, M.R. Moser, S. Wang
    ANL, Argonne, Illinois
  
  The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a national user facility for neutron scattering. Neutrons are produced by 70 ns pulses of protons (~3x 1012 protons per pulse) impacting a depleted-uranium target at a pulse repetition rate of 30 Hz. Three accelerators in series (a 750 keV Cockcroft-Walton, 50 MeV Alvarez linac accelerating H- ions, and a 450 MeV rapid-cycling proton synchrotron) provide the beam that is directed to the target. New diagnostics and a third rf cavity that can be operated at either the fundamental or second harmonic of the ring frequency have recently been installed and an experimental program established to try to gain understanding of an instability that limits the charge-per-bunch in the RCS. This program will be described, and preliminary results presented.  
MOPCH137 An Anti-symmetric Lattice for High Intensity Rapid-cycling Synchrotrons 369
 
  • 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
  
  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.  
TUPLS115 Transverse Phase Space Painting for the CSNS Injection 1774
 
  • J. Qiu, J. Tang, S. Wang
    IHEP Beijing, Beijing
  • J. Wei
    BNL, Upton, Long Island, New York
  
  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.  
TUPLS116 Extraction System Design for the CSNS/RCS 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
  
  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.  
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
  
  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.  
WEPCH033 Single Particle Beam Dynamics Design of CSNS/RCS 1996
 
  • S. Wang, S.X. Fang, Q. Qin, J. Tang
    IHEP Beijing, Beijing
  • J. Wei
    BNL, Upton, Long Island, New York
  
  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.  
WEPCH065 Lattices for High-power Proton Beam Acceleration and Secondary Beam Collection, Cooling, and Deceleration 2074
 
  • S. Wang
    IHEP Beijing, Beijing
  • K.A. Brown, C.J. Gardner, Y.Y. Lee, D.I. Lowenstein, S. Peggs, N. Simos, J. Wei
    BNL, Upton, Long Island, New York
  
  Rapid-cycling synchrotrons are used to accelerate high-intensity proton beams to energies of tens of GeV for secondary beam production. After primary beam collision with a target, the secondary beam can be collected, cooled, accelerated or decelerated by ancillary synchrotrons for various applications. In this paper, we first present a lattice for the main synchrotron. This lattice has: a) flexible momentum compaction to avoid transition and to facilitate RF gymnastics b) long straight sections for low-loss injection, extraction, and high-efficiency collimation c) dispersion-free straights to avoid longitudinal-transverse coupling, and d) momentum cleaning at locations of large dispersion with missing dipoles. Then, we present a lattice for a cooler ring for the secondary beam. The momentum compaction across half of this ring is near zero, while for the other half it is normal. Thus, bad mixing is minimized while good mixing is maintained for stochastic beam cooling.