Paper | Title | Other Keywords | Page |
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MOPC009 | Experiments on LHC Long-Range Beam-Beam Compensation and Crossing Schemes at the CERN SPS in 2004 | emittance, simulation, resonance, hadron | 686 |
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Experiments with two prototype long-range beam-beam compensators (current-carrying wires) during the 2004 CERN SPS run explored the efficiency of a proposed long-range beam-beam compensation for the LHC. In addition, the SPS compensators were also used to 'simulate' the effect of different planes of crossing at two LHC interaction points. We present the experimental results and compare them with computer simulations. | |||
MPPE005 | Dynamic Aperture and Resonance Correction for JPARC-RCS | resonance, sextupole, injection, quadrupole | 979 |
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Main intrinsic field nonlinearities, which are common for synchrotrons with large aperture, are the nonlinear field of the bending magnets, the fringing field of the magnets and the sextupole field nonlinearity, used for the chromaticity correction. The particle motion in the ring bending magnets has been analyzed by two methods: (1) by direct integration of the particle motion equations in the 3D magnetic field (Tosca output), based on the 4th order Runge-Kutta integrator and (2) by determination the transfer 8th order map of the bending magnet by using the Gaussian wavelet in the 3D space. The second technique allows us to use powerful tools such as the normal form analysis, to define the resonance driving terms, which can be used for the resonance correction. As the result of this study it was shown that the main limitation of the RCS dynamic aperture can be caused by the structure normal sextupole-order resonance and the normal octupole-order resonance. Other high-order resonances have smaller effects on the particles motion than the resonances mentioned above. The correction scheme to improve the dynamic aperture near the normal sextupole-order resonance has been analyzed. | |||
MPPE025 | Dynamical Effects Due to Fringe Field of the Magnets in Circular Accelerators | quadrupole, resonance, dipole, multipole | 1907 |
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Funding: Work supported by the Department of Energy under Contract No. DE-AC02-76SF00515. The leading Lie generators, including the chromatic effects, due to hard edge fringe field of single multipole and solenoid are derived from the vector potentials within a Halmitonian system. These nonlinear generators are applied to the interaction region of PEP-II to analyze the linear errors due to the feed-down from the off-centered quadrupoles and solenoid. The nonlinear effects of tune shifts at large amplitude, the synchro-betatron sidebands near half integer and their impacts on the dynamic aperture are studied in the paper. |
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MPPE064 | Dynamic Aperture Study and Lifetime Improvement at the Advanced Photon Source | sextupole, coupling, resonance, injection | 3632 |
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. Over past few years, the optics of the Advanced Photon Source storage ring was optimized to provide lower natural emittance. Presently, APS operates at 2.5 nm-rad emittance. The optimization was done at the expense of stronger sextupoles and shorter lifetime. Here we present our work on measurement and understanding the dynamic aperture of APS in low-emittance mode. We found good agreement between the dynamic aperture measurements and that of the model derived from the response matrix analysis. Based on the model, we were able to increase the lifetime significantly by optimizing sextupoles, correcting optics, moving working point, and adjusting rf voltage. The higher lifetime allowed us to decrease operating coupling from 2.5% to 1%. |
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MPPE075 | Simulation of the Effect of an In-Vacuum Undulator on the Beam Dynamics of the ALS | undulator, simulation, injection, lattice | 3949 |
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Funding: Work supported by the Director, Office of Energy Research, Office of Basic Energy Science, Material Sciences Division, U.S. Department of Energy, under Contract No. DE-AC03-76SF00098. The femtosecond slicing project at the Advanced Light Source (ALS) requires that a short period (3 cm) and narrow gap (5.5 mm) in vacuum undulator to be installed. The combination of the short period and the narrow gap raised concern of the impact on the beam dynamics. A 3D field model was established based on numerical data using 8 longitudinal and 4 transverse harmonics. At first fourth-order symplectic integrator was used. It was to our surprise that the dynamic aperture decreased by a fact of 3. To understand the cause of the drastic change in the dynamic aperture, the field model was implemented in a differential algebraic code and the Taylor map of the undulator was obtained. Tracking result using the Taylor map showed little change in the dynamic aperture, which was latter corroborated by that using the symplectic integrator with 150 slices per period (as opposed to 10 before). Yet it is simply too time consuming to use the symplectic integrator with such thin slices. For this case, Taylor proves to be a much faster alternative. |
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MPPT057 | Design of a Magnet System for a Muon Cooling Ring | closed-orbit, lattice, dipole, simulation | 3366 |
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Funding: This work was performed with the support of the U.S. DOE under Contract No. DE-AC02-98CH10886. A hydrogen gas filled muon cooling ring appears to be a promising approach to reducing the emittance of a muon beam for use in a neutrino factory or a muon collider. A small muon cooling ring is being studied to test the feasibility of cooling by this method. This paper describes the magnet system to circulate the muons. The magnet design is optimized to produce a large dynamic aperture to contain the muon beam with minimum losses. Muons are tracked through the field to verify the design. |
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TOAB006 | SPEAR 3 - The First Year of Operation | feedback, injection, optics, power-supply | 505 |
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Funding: Work supported in part by Department of Energy Contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences. The first electrons were accumulated in the new 3-GeV SPEAR 3 storage ring in December, 2003, five days after the beginning of commissioning. By mid-January of 2004, the phas·10^{-1} current of 100 mA were stored. Ring characterization and tuning continued until early March when the first photon beam line was opened for users. By the end of the first run in July, SPEAR 3 beam properties and ring performance had been extensively measured by the accelerator and beam line groups. These included micron stability using slow orbit feedback, an emittance coupling of ~0.1% and 30-h lifetimes at 100 mA. During the present 2005 user run, turn-by-turn BPMs, fast orbit feedback, a high resolution UV synchrotron light monitor, and beam scrapers are being commissioned and 500-mA operation will be established. A modified lattice that will incorporate a double vertical waist chicane has been designed that will enable future installation of two small gap insertion devices. A study of top-off injection modes will also commence this year. The performance of SPEAR 3 during its first year of commissioning and operation, together with plans to improve performance, are described. |
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TPPP001 | Design of Damping Ring for SuperKEKB | emittance, damping, linac, positron | 773 |
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In the SuperKEKB, a plan upgrading the KEKB to higher luminosity of (2.5-5) x10^{35} cm^{2}/sec, the beam currents are 9.4 A for the LER (3.5 GeV-electrons) and 4.1 A for the HER (8 GeV-positrons). In order to supply the HER with the positron beam, which is currently injected to the LER, the field gradient of the injector linac has to be increased. To meet this requirement, the S-band accelerating structures placed at the beam energy greater than 1 GeV, after the positron target, are replaced with C-band structures. A damping ring (DR) is indispensable since the aperture of the C-band structure is much smaller than the beam emittance. In this paper, we describe on the design of DR. We adopt a new cell structure for DR; FODO cell with alternating bends, where one of two bends in a cell is reversed. One of advantages of the proposed ring is that very small, even negative, momentum compaction factor is easily achieved by properly choosing the bend-angle ratio of the reverse bend to the main bend. Tracking simulation for the proposed DR has shown that it has very large dynamic aperture in both transverse and longitudinal phase space, for very wide tune space. | |||
TOPA010 | Photonic Crystal Laser-Driven Accelerator Structures | lattice, focusing, laser, simulation | 731 |
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Funding: Work supported by Department of Energy contract DE-AC03-76SF00515 (SLAC). We discuss simulated photonic crystal structure designs, including two- and three-dimensional planar structures and fibers. The discussion of 2D structures demonstrates guiding of a speed-of-light accelerating mode by a defect in a photonic crystal lattice and reveals design considerations and trade-offs. With a three-dimensional lattice, we introduce a candidate geometry and discuss beam dynamics, coupling, and manufacturing techniques for that structure. In addition we discuss W-band scale tests of photonic crystal structures. The computational methods are also discussed. |
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WOAB004 | Applying Frequency Map Analysis to the Australian Synchrotron Storage Ring | sextupole, resonance, synchrotron, quadrupole | 407 |
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The technique of frequency map analysis has been applied to study the transverse dynamic aperture of the Australian Synchrotron Storage Ring. The results have been used to set the strengths of sextupoles to optimise the dynamic aperture. The effects of the allowed harmonics in the quadrupoles and dipole edge effects are discussed. | |||
WOAC003 | Effects of Fringe Fields and Insertion Devices Revealed Through Experimental Frequency Map Analysis | sextupole, storage-ring, undulator, insertion | 266 |
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Funding: This work was supported by the Bundesministerium für Bildung und Forschung and by the Land Berlin.
Following the pioneering work at the ALS* frequency map analysis was performed at the light source BESSY. With altogether 7 families of sextupole magnets available in the storage ring, amplitude dependent tune shifts can be made rather small. Therefore, the impact of fringe fields of dipole and quadrupole magnets as well as systematic octupole and decapole field components of the quadrupole and sextupole magnets used in addition as horizontal, vertical and skew gradient correctors are clearly visible in the measured maps. Insertion devices with their known systematic and usually unknown random non-linear field components impact the appearance of the frequency maps even more strongly. In the talk the current status of the experiments as well as the results of the theoretical modeling will be presented.
*"Global Dynamics of the Advanced Light Source Revealed through Experimental Frequency Map Analysis," D. Robin, et al., Phys. Rev. Lett. 85, 558 (2000). |
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ROAA003 | Proposal of an Experiment on Bunch Length Modulation in DAFNE | synchrotron, storage-ring, luminosity, factory | 336 |
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Obtaining very short bunches is a challenge for colliders and Coherent Synchrotron Radiation sources as well. The modulation of the bunch length in a strong RF focusing regime has been proposed, corresponding to a large value of the synchrotron tune. A ring structure where the dependence of the longitudinal position of a particle on its energy (R56) along the ring oscillates between large positive and negative values can produce a bunch length modulation. The synchrotron frequency can be tuned both by means of the rf voltage and by the integral of R56, down to the limit of zero value corresponding to the isochronicity condition. We present here the proposal of bunch length modulation along the DAFNE rings. Its lattice can be tuned to positive or negative momentum compaction, or to structures in which the two arcs are alternately set to positive/negative integrals of R56. With the proposed installation of an extra RF system at 1.3 GHz, experiments on bunch length modulation both in the high and low synchrotron tune regimes can be realized. | |||
RPAE006 | Feasibility Study on Introducing a Superconducting Wiggler to Saga Light Source | lattice, multipole, quadrupole, wiggler | 1021 |
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Saga light source (SAGA-LS) is the synchrotron radiation facility, which consists of 250 MeV electron linac and 1.4 GeV storage ring. We have a plan to introduce an existing superconducting wiggler, which has been developed for other project by National Institute of Radiological Sciences. The superconducting wiggler consists of a main pole of 7T and two side poles of 4T. Each pole is composed of a racetrack-shaped coil and an iron core. We have examined the effects of the wiggler on the beam optics when it is introduced into SAGA-LS. The distribution of multipole components in the planes perpendicular to the electron orbit, which is deformed by the wiggler fields, have been calculated using magnetic field calculation code RADIA. Then the lattice function and the dynamic aperture of the ring have been calculated by the lattice calculation code SAD. The results show that the tune shift due to the quadrupole component of the wiggler field is as large as to make horizontal beam orbit unstable. The dynamic aperture after the tune correction becomes small by about 20%. These effects due to multipole field are considered to be tolerable for the SAGA-LS. | |||
RPAE047 | Lattice Study for the Taiwan Photon Source | emittance, sextupole, lattice, photon | 2989 |
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The feasibility study for the new 3.0~3.3 GeV Taiwan synchrotron light source, dubbed Taiwan Photon Source, was initiated in July, 2004. The goal is to construct a high performance light source with extremely bright X-ray in complementary to the existing 1.5 GeV light source in Taiwan. The ring circumference is 518.4 m and a 24-cell DBA lattice structure is chosen. The natural emittance with distributed dispersion is less than 2 nm-rad. A large booster ring of 499.2 m sharing the storage ring tunnel will be adopted. | |||
RPPP007 | CLIC Damping Ring Optics Design Studies | wiggler, damping, emittance, sextupole | 1060 |
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In this paper the nonlinearities induced by the short period NbFeB permanent wiggler optimized for the CLIC damping ring and their influence to the beam dynamics are studied. | |||
RPPP008 | The Short Circumference Damping Ring Design for the ILC | wiggler, damping, emittance, scattering | 1126 |
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The ILC damping ring tentative design is driven by the operational scenario of the main linac, the beam-dynamics demand of producing a stable and high-quality beam, the injection/extraction scheme and the kicker performance. In this paper, a short circumference damping ring design based on TME cells is described. The ring accommodates injection kickers which provide a flat top of 280 nsec and a 60 nsec rise and fall time and very fast strip-line kickers for beam extraction with a 2 nsec rise and fall time for 3-MHz operation. The potential impact of collective effects and the possible degradation of the dynamic aperture by nonlinear-wiggler fields are estimated. | |||
RPPP023 | A Compact Damping Ring Using RF Deflectors for the International Linear Collider | damping, kicker, quadrupole, extraction | 1811 |
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Funding: NSF Current specifications for the International Linear Collider call for bunch trains hundreds of kilometers in length. We describe a scheme for manipulating a compressed bunch train in the damping ring using RF deflectors and multiple transfer lines. The concept is demonstrated in the design of a 4 km damping ring that circulates 2800 bunches spaced 4 ns apart, and we show that injection and extraction of individual bunches is possible with conventional kickers requiring rise/fall times of only 16 ns. The performance and stability of the 4 km damping ring is evaluated and compared with existing machines. |
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RPPP025 | CESR-c Wiggler Studies in the Context of the International Linear Collider Damping Rings | wiggler, damping, emittance, linear-collider | 1880 |
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Funding: Work supported by the NSF. We present a picture of the International Linear Collider (ILC) damping ring wiggler dynamics using the experience gained from the experimental and simulation-based research studying the wigglers used in the current configuration of the Cornell Electron Storage Ring (CESR). CESR is currently running at 1.8 GeV with 12 superconducting wigglers that have been designed, fabricated, tested, and simulated on-site. We will present results which include frequency map analyses and conventional dynamic aperture studies of CESR-c and the ILC damping rings. We will also provide results from an initial look at physical limitations in the design of the ILC damping ring wigglers. |
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RPPP051 | Characterization of a 6-km Damping Ring for the International Linear Collider | lattice, damping, emittance, wiggler | 3147 |
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Several damping ring designs for the International Linear Collider have been proposed recently. One particular design has a circumference of 6 km (hoping to take advantage of future kicker technology advances), TME arc cells, and 77 m of 2 T wigglers. Several beam dynamics characterizations and optimizations are reported. We used the accelerator code elegant for matching and tracking, and a 100-CPU linux cluster to provide high throughput. | |||
RPPP054 | Achieving Large Dynamic Aperture in the ILC Damping Rings | lattice, damping, sextupole, emittance | 3277 |
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Funding: Work supported by US Department of Energy, Director, Office of Science - Contract Nos. DE-AC03-76SF00098 and DE-AC03-76SF00515. The Damping Rings for the International Linear Collider have challenging requirements for the acceptance, because of the high average injected beam power and the large beam produced from the positron source. At the same time, the luminosity goals of the collider mean that the natural emittance must be very small, and this makes it particularly difficult to achieve a good dynamic aperture. We describe a design approach and present a lattice design that meets the emittance specification and has a very promising dynamic aperture. We also discuss the potential impact of the damping wiggler and of magnet errors. |
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FPAT087 | elegantRingAnalysis: An Interface for High-Throughput Analysis of Storage Ring Lattices Using elegant | lattice, storage-ring, simulation, sextupole | 4200 |
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Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. The code {\tt elegant} is widely used for simulation of linacs for drivers for free-electron lasers. Less well known is that elegant is also a very capable code for simulation of storage rings. In this paper, we show a newly-developed graphical user interface that allows the user to easily take advantage of these capabilities. The interface is designed for use on a Linux cluster, providing very high throughput. It can also be used on a single computer. Among the features it gives access to are basic calculations (Twiss parameters, radiation integrals), phase-space tracking, nonlinear dispersion, dynamic aperture (on- and off-momentum), frequency map analysis, and collective effects (IBS, bunch-lengthening). Using a cluster, it is easy to get highly detailed dynamic aperture and frequency map results in a surprisingly short time. |
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FPAT089 | A Parallel Simplex Optimizer and Its Application to High-Brightness Storage Ring Design | storage-ring, emittance, optics, target | 4230 |
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Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. Optimization is commonly used in accelerator design to find linear optics solutions. Such optimizations are usually fairly fast as linear optics computations are themselves fast. For high-brightness storage rings, optimization of nonlinear elements (e.g., sextupoles) is also important in obtaining sufficient dynamic aperture. However, this can be very time onsuming as the basic calculations are time consuming. We have developed an efficient parallel Simplex optimizer that runs on a Linux cluster. It can optimize the result of running essentially any program or script that returns a penalty function value. We have used this optimizer with elegant to optimize dynamic aperture of storage ring designs. We discuss the optimization algorithm and performance, design of penalty functions, and optimization results. |
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