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| MOPC117 | Hybrid Snake Spin Resonance in RHIC | resonance, lattice, coupling, betatron | 337 | ||
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Simulations reveal a potential polarization loss during low beta squeeze. This depolarization appears to be driven by a spin tune modulation caused by spin precession through the strong low beta quads due to the vertical fields. The modulation of the spin tune introduces an additional snake resonance condition at νs0 ± n νx - νz l = integer which while the same numerology as the well known sextupole resonance, can operate in the absence of sextupole elements.
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| MOPC129 | Lattice without Transition Energy for the Future PS2 | dipole, lattice, betatron, quadrupole | 370 | ||
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The Large Hadron Collider (LHC) will be commissioned very soon. Improvements of the LHC injection complex are considered in the upgrade possibilities. In the injection complex it is considered that the aging Proton Synchrotron (PS) would be replaced with a new fast cycling synchrotron PS2. The energy range would be from 5-50 GeV with a repetition rate of 0.3 Hz. This is a report on the PS2 lattice design using the Flexible Momentum Compaction (FMC) method*. The design is trying to fulfill many requirements: high compaction factor, racetrack shape with two long zero dispersion straight sections, circumference fixed to a value of 1346 meters (CPS2=15/77 CPS), using normal conducting magnets and avoiding the transition energy.
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*D. Trbojevic et al. ”Design Method for High Energy Accelerator Without Transition Energy”, EPAC 90, Nice, June 12-16 (1990) pp. 1536-1538. |
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| MOPC153 | Construction and Test of the Superconducting Coils for RIKEN SC-ECR Ion Source | ion, ion-source, factory, cyclotron | 433 | ||
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A superconducting ECR ion source is under development to increase the intensity of the beams with high charge state such as U35+ provided to the RI-beam factory at RIKEN. The ion source consists of six superconducting solenoids and a set of superconducting sextupoles. The axial magnetic fields are 3.8 T at the injection peak and 2.2 T at the extraction peak. The sextupole magnetic field is 2.0 T on the inner surface of the plasma chamber with a diameter of 15 cm. The conductors use NbTi/copper wires with copper/SC ratio of 1.3 and size of 1.25 mm x 0.92 mm. The sextupole coils are difficult to design and fabricate because the maximum experience magnetic field is about 7.3 T and the magnetic force acting on the coils changes by the strength of the radial field of the solenoids along the axis. The design, construction and the results of the excitation test will be presented in this paper.
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| MOPP030 | ATF2 Final Focus Orbit Correction and Tuning Optimisation | quadrupole, linear-collider, collider, dipole | 613 | ||
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ATF2 is an upgrade to the ATF facility at KEK, Japan consisting of a replacement to the current ATF extraction line and the addition of a final focus section. The final focus system has been designed, and is aiming to test, the local chromaticity correction scheme as proposed for future linear colliders. The final focus system focuses the ultra-low emittance beams at the collision point in the linear collider. To provide the required small beam sizes and to maintain the beam sizes to nanometer level requires optimised orbit correction and tuning procedures. In this paper, the optimisation of the orbit correction using a global SVD method is discussed, along with the progress on final focus tuning knob analysis. The tuning algorithms used at ATF2 will provide an important feedback for future linear colliders (including the ILC and CLIC).
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| MOPP059 | Study for ILC Damping Ring at KEKB | emittance, electron, damping, optics | 676 | ||
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ILC damping ring consists of very low emittance electron and positron storage rings. It is necessary for ILC damping ring to study electron cloud effects in such low emittance positron ring. We propose a low emittance operation of KEKB to study the effects.
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| MOPP061 | Non Linear Dynamics Study of the CLIC Damping Rings Using Sympletic Integrators | damping, wiggler, resonance, emittance | 682 | ||
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A class of symplectic integrators with positive steps (SABA2) is applied to investigate the non-linear dynamics of the CLIC damping rings. The detrimental effect of the chromaticity sextupoles is studied using frequency and diffusion maps and verified with MADX ptc dynamic aperture tracking. The reduction of the dynamic aperture for off-momentum particles is also investigated.
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| TUPC122 | Feedback Corrections for Ground Motion Effects at ATF2 | feedback, quadrupole, optics, coupling | 1353 | ||
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Ground motion will over time produce beam misalignments and size increases at the IP of the ATF2 beam line. The spatial and temporal characteristics of the vibrations measured on the site have been studied and model parameters have been fitted to allow reliably simulating the effects induced on the beam. A feedback loop to minimise the residual beam motion at the IP is considered, based on optimising the coefficients of a PID controller on both short and long time-scales.
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| WEPC003 | Coupling Control at the SLS | coupling, quadrupole, emittance, betatron | 1983 | ||
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The vertical beam size measurement at the Swiss Light Source (SLS) is based on vertically polarized visual light and allows to verify a vertical emittance of a few pm rad, resp. an emittance ratio in the 10-4 range obtained in 400 mA top-up user operation mode by tuning the lattice by means of 24 skew quadrupoles. Suppression of betatron coupling by local and global coupling correction prevents losses of Touschek scattered particles at the narrow vertical gaps of the in-vacuum undulators and thus protects these devices and increases beam lifetime, resp. the top-up interval. We will report on our experience with the beam size monitor, on the method of coupling control and on the achievements in vertical emittance and beam lifetime.
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| WEPC011 | Using Multi-bend Achromats in Synchrotron Radiation Sources | lattice, vacuum, dipole, emittance | 2007 | ||
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Multi-bend achromats offer small electron beam emittance, large energy acceptance and a good dynamic aperture. Two examples are discussed in the article, each using 7-bend achromats; a 12 achromat lattice and a 20 achromat one. Some possible technical solutions associated with the dense lattices are discussed: magnet technology, vacuum system and RF system. Some characteristics of the two rings are also presented; effects of Intra Beam Scattering, Touschek life-time and the electron beam parameter values.
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| WEPC042 | Commissioning of the SSRF Storage Ring | storage-ring, closed-orbit, emittance, optics | 2079 | ||
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The Shanghai Synchrotron Radiation Facility (SSRF) is a 3.5GeV synchrotron radiation light source under commissioning in Shanghai, China. The SSRF accelerator complex consists of a 150MeV linac, full energy booster and a 3.5GeV storage ring. The commissioning of the SSRF storage ring began on Dec. 21st evening, 2007, the first turn and 150 turns was observed in less than 12 hours with RF off and then the stored beam of 5 mA was achieved on Dec. 24th. On Jan. 3rd, 2008, the 100mA stored beam current were obtained in the machine for the first time. Since then, the storage ring has been brought close to the design parameters, and frequent operation with 100mA beam current has been down for making the vacuum chamber cleaning. In this paper, commissioning results of the machine is presented.
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| WEPC044 | Top-Up Safety Simulations for the Diamond Storage Ring | electron, simulation, storage-ring, quadrupole | 2085 | ||
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To ensure that it is not possible for a train of injected electron bunches to pass down an open beam-line during top-up operation at the Diamond Light Source, an extensive program of tracking studies has been performed. Various error scenarios have been investigated, with realistic magnetic field, trajectory, aperture and energy errors all taken into account. We describe the tracking methods used, scenarios considered and the interlocks required in order to maintain user safety during top-up operation.
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| WEPC045 | Alternative Lattice Settings for ALBA Storage Ring | lattice, optics, dynamic-aperture, resonance | 2088 | ||
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ALBA is a 3 GeV synchrotron light source under construction in Spain. The lattice for the standard operational mode is based in a DBA-like structure, with finite dispersion in the straight sections and extra space in the arcs. This solution provides small emittance with a large available space for insertion devices, RF and diagnostic components, and large dynamic aperture and energy acceptance. Other optic modes has been investigated, in order to facilitate the commissioning procedure or to provide different operating modes to the users: pure achromatic lattice, without dispersion in the straight section; achromatic arcs, where the dispersion is zero in the long straight; or a relaxed lattice, offering higher emittance. This paper review the performance of this alternative options, including the non-linear performance.
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| WEPC051 | Upgrade Plans for the ESRF Storage Ring Lattice | lattice, quadrupole, resonance, simulation | 2106 | ||
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The lattice of the ESRF storage ring is of the Double Bend Achromat type with 32 straight sections of alternating high and low horizontal beta values, currently providing 5 m of available space for insertion devices. As part of the ESRF Upgrade Programme, it is proposed to increase the length of selected insertion device straight sections from 5 to 7 m. In this paper, we will describe the different steps towards longer straight sections: implementation of a new lattice in which the straight section quadrupole triplets are replaced by doublets, design of modified straight sections with replacing the long quadrupoles by shorter ones and moving the adjacent sextupoles, experiments carried out to simulate the lattice symmetry breaking induced by a 7 m long straight section.
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| WEPC059 | Lattice Design of PEP-X as a Light Source Machineat SLAC | wiggler, emittance, injection, dynamic-aperture | 2127 | ||
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The lattice study for converting the High Energy Ring (HER) of PEP-II into a light source machine with minimal modifications is reported. In this design, a higher phase advance is used in the HER FODO lattice which reduces the emittance to 5 nm at 4.5 GeV without a damping wiggler, and to 0.4 nm with 116 m damping wiggler included in two straight sections out of six. We also study the possibility of replacing one of the six FODO arcs with eight DBA cells to provide additional dispersion free straight sections for the experimental beam lines. The DBA cells will reuse the existing HER and LER (Low Energy Ring) magnets for a minimal cost of the modification. The main parameters and beam dynamics properties of these lattices are presented.
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| WEPC067 | Optics for the ALBA Booster Synchrotron | booster, dipole, quadrupole, lattice | 2148 | ||
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The ALBA booster is a full energy injector of 3 GeV for top-up operation that will be installed in the same tunnel as the Storage Ring. Its large circumference of 249.6 m and the magnetic lattice with combined function bending magnets provide an equilibrium emittance as low as 9 nm rad. In this paper the linear optics functions, the aperture requirements and the gradient error tolerances in the dipoles and quadrupoles are discussed. The closed orbit correction scheme consists of 44 horizontal and 28 vertical correctors and 44 BPMs. A solution that requires a reduced number of BPMs has been studied as well. Chromaticity correction and dynamic aperture during the ramping have been also investigated. Finally, the injection and extraction schemes are described.
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| WEPC091 | Beam Injection by Use of a Pulsed Sextupole Magnet at the Photon Factory Storage Ring | injection, storage-ring, pulsed-power, power-supply | 2204 | ||
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We will install a pulsed sextupole magnet (PSM) in order to test a new injection system for the top-up injection at the Photon Factory storage ring (PF ring) in the spring of 2008. A parabolic magnetic field of the PSM can give an effective kick to the injected beam that passes a distant region from the field center. And there is little modulation of the orbit of the stored beam because it passes around the center of the PSM. To achieve the beam injection at the PF ring, the PSM has a length of 0.3m, a magnetic field of 400 Gauss at a peak current of 3000A and a pulse width of 2.4μsec in a half-sine form. We already made the PSM and measured the magnetic field. We will report the result of the PSM beam injection at the PF ring.
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| WEPC122 | Magnetic Characterization of an APPLE-II Undulator Prototype for FERMI@Elettra | undulator, quadrupole, controls, multipole | 2294 | ||
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The FERMI@Elettra free electron lasers will use APPLE-II undulators in the radiating sections to provide variably polarized photon beams. In preparation of the manufacturing of the final devices a prototype has been developed in order to test different methods of magnetic field optimization. For this purpose, an existing variable-gap support structure was equipped with a new mechanical interface providing the required longitudinal shifting of the magnetic arrays. Permanent magnet blocks were mounted on short modules and their field integrals measured using a stretched wire system. Field optimization was iteratively performed by proper selection of the modules to be mounted based on measurements of the partially assembled undulator structure. The results of the final magnetic field characterization are presented showing the achieved trajectory, phase and multipole errors. These results are compared with those of a previous assembly where the same modules were mounted in random order. Further improvements obtained by shimming and application of “magic fingers” are finally described.
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| WEPC144 | Test Results of the AC Field Measurements of Fermilab Booster Corrector Magnets | booster, quadrupole, dipole, pick-up | 2347 | ||
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Multi-element corrector magnets are being produced at Fermilab that will enable correction of orbits and tunes through the entire cycle of the Booster, not just at injection. The corrector package includes six different corrector elements - normal and skew orientations of dipole, quadrupole, and sextupole - each independently powered. The magnets have been tested during typical AC ramping cycles at 15Hz using a fixed coil system to measure the dynamic field strength and field quality. The fixed coil is comprised of an array of inductive pick-up coils around the perimeter of a cylinder which are sampled simultaneously at 100kHz with 24-bit ADC’s. The performance of the measurement system and a summary of the field results are presented and discussed.
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| WEPC153 | Dipole Magnet for Use of RHIC EBIS HEBT Line | multipole, dipole, quadrupole, octupole | 2365 | ||
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We present the design optimization of a dipole magnet for use of RHIC EBIS HEBT line. This magnet provides a total bending angle of 145 degrees by two identical magnets and it is used to guide H+ to Au32+ beam with energy of 2 MeV/amu. Magnetic field is required to change within 1 second corresponding to the ion species, so magnet body has the laminated structure to suppress eddy current. Effective length and field quality within a radius of 5 cm was optimized separately. Effective length was optimized by adjusting end shape not to change the beam orbit between low and high field operation more than 1 mm from intended beam orbit after bending. Then field quality was optimized by changing the shim position and additional bump. After modification, all multipole coefficients along the beam trajectory were reduced to within 10x10-4.
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| WEPC164 | Development of Modulating Permanent Magnet Sextupole Lens for Focusing of Cold Neutrons | focusing, dipole, scattering, permanent-magnet | 2392 | ||
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A modulating permanent magnet sextupole lens that can focus pulsed cold neutrons is under development. It is based on the extended Halbach configuration to generate stronger magnetic field. In order to adjust the strength, the magnet is divided into two co-axial nested rings, where the inner ring is fixed and the outer ring can be rotated. Synchronizing the period of the modulation with that of pulsed neutron beam suppress the chromatic aberration. We have fabricated a half-scale model and studied the strength, the torque and the temperature rise caused by eddy current. Now we are developing the full-scale model improving such problems. These two scale models of magnet are described.
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| WEPC165 | Magnetic Measurements of the SSRF Storage Ring Magnets | quadrupole, storage-ring, multipole, dipole | 2395 | ||
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The SSRF storage ring comprises a total of 460 magnets which has four types and eight different effective magnetic lengths. The magnetic measurements of all the production magnets including 40 bending magnets with a maximum field of 1.2726 T, 200 quadrupoles divided in Three families with a maximum gradient of 20 T/m, 140 sextupoles with a maximum second order differential of 460 T/m, and 80 correctors with a maximum kick capability of 1.2 mrad. For the dipoles a long coil system has been used to measure the magnetic field while for the quadrupoles and sextupoles a rotating coil system has been used to determine the magnitude of the high order multipoles. In this paper the analysis of these data is discussed and results for measured magnets are presented.
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| WEPD028 | Performance of the Superconducting Corrector Magnet Circuits during the Commissioning of the LHC | acceleration, target, extraction, cryogenics | 2470 | ||
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The LHC is a complex machine requiring more than 7400 superconducting corrector magnets distributed along a circumference of 26.7 km. These magnets are powered in 1380 different electrical circuits with currents ranging from 60 A up to 600 A. Among the corrector circuits the 600 A corrector magnets form the most diverse and differentiated magnet circuits. About 60000 high current connections had to be made. A minor fault in a circuit or one of the superconducting connections would have severe consequences for the accelerator operation. All magnets are wound from various types of Nb-Ti superconducting strands, and many contain resistors to by-pass the current in case of the transition to the normal conducting state in case of a quench, and hence reduce the hot spot temperature. In this paper the performance of these magnet circuits is presented, focussing on the quench current and quench behaviour of the magnets. Quench detection and the performance of the electrical interconnects will be dealt with. The results as measured on the entire circuits will be compared to the test results obtained during the reception tests of the individual magnets.
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| WEPD031 | Dependence of the Static and Dynamic Field Quality of the LHC Superconducting Dipole Magnets on the Pre-cycle Ramp Rate | injection, dipole, multipole, acceleration | 2479 | ||
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The allowed multipoles in the Large Hadron Collider (LHC) superconducting dipole magnets decay whilst on a constant current plateau. It is known that the decay amplitude is largely affected by the powering history of the magnet, and particularly by the pre-cycle flat top current and duration and the pre-injection preparation duration. Recently, it was observed that the decay amplitude is also highly dependent on the pre-cycle ramp rate, which has an indirect effect also on the sample of data taken at constant field along the magnet loadlines. This is an important consideration to be included in the Field Description for the LHC (FiDeL), to cope with the difference between the test procedure followed for series tests and the expected cycles during the machine operation. This paper presents the results of the measurements performed to investigate this phenomenon and describes the method included in FiDeL to represent this dependence.
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| WEPD033 | A Demonstration Experiment for the Forecast of Magnetic Field and Field Errors in the Large Hadron Collider | dipole, controls, multipole, quadrupole | 2482 | ||
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In order to reduce the burden on the beam-based feedback, the Large Hadron Collider (LHC) control system is embedded with the Field Description for the LHC (FiDeL) which provides a forecast of the magnetic field and the multipole field errors. FiDeL has recently been extensively tested at CERN to determine main field tracking, multipole forecasting and compensation accuracy. In this paper we describe the rationale behind the tests, the procedures employed to characterize and power the main magnets and their correctors, and finally, we present the results obtained. We also give an indication of the prediction accuracy that the system can deliver during the operation of the LHC and we discuss the implications that these will have on the machine performance.
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| WEPP036 | DAΦNE Setup and Operation with the Crab-Waist Collision Scheme | luminosity, injection, collider, vacuum | 2599 | ||
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In the second half of 2007 a major upgrade has been implemented on the Frascati DAΦNE collider in order to test the novel idea of Crab Waist collisions. New vacuum chambers and permanent quadrupole magnets have been designed, fabricated and installed to realize the new configuration. At the same time the performances of relevant hardware components, such as fast injection kickers and shielded bellows have been improved relying on new design concepts. The collider has been successfully commissioned in this new configuration. The paper describes the new layout as well as several experimental results about linear and non-linear optics setup and optimization, damping of beam instabilities and discusses the obtained luminosity performances.
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| WEPP040 | New Low Emittance Lattices for the SuperB Accelerator Project | emittance, lattice, luminosity, polarization | 2608 | ||
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New low emittance lattices (1.6 nm at 7 GeV, 2.8 nm at 4 GeV) have been designed for the asymmetric SuperB accelerator aiming at a luminosity of 1036 cm-2 s-1. Main optics features are two alternating arc cells with different horizontal phase advance, in order to decrease beam emittance and allow at the same time for easy chromaticity correction in the arcs. Emittance can be further reduced by a factor of two for luminosity upgrade. New beam parameters have been chosen to fulfill the transparency conditions for 4x7 GeV beams, different from the asymmetric currents used in operating B-Factories. Beam polarization schemes have been studied and will be implemented in the lattice.
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| WEPP045 | Suppression of Beam-beam Resonances in Crab Waist Collisions | luminosity, resonance, betatron, collider | 2620 | ||
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The recently proposed Crab Waist scheme of beam-beam collisions can substantially increase the collider luminosity since it combines several potentially advantageous ideas. One of the basic ingredients of the scheme is the use of dedicated sextupoles in the interaction region for the vertical beta function waist rotation at the interaction point. In this paper we show how this nonlinear focusing helps to suppress betatron and synchrobetatron resonances arising in beam-beam collisions due to particles’ vertical motion modulation by their horizontal oscillations.
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| WEPP156 | Spherical Aberrations-free Wiggler | wiggler, quadrupole, multipole, octupole | 2853 | ||
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We represented details of design of a wiggler with linear piecewise longitudinal field dependence. This type of field distribution eliminates spherical aberrations in wiggler. This wiggler can be recommended for usage in cooler rings including ILC ones.
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| THPC008 | Constants and Pseudo-constants of Coupled Beam Motion in the PEP-II Rings | betatron, coupling, quadrupole, lattice | 2990 | ||
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Constants of beam motion help as cross checks to analyze beam diagnostics and the modeling procedure. Pseudo-constants, like the betatron mismatch parameter or the coupling parameter det C, are constant till certain elements in the beam line change then. This can be used to visually find the non-desired changes, pinpointing errors compared with the model.
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| THPC024 | Closed Orbit Correction at the LNLS UVX Storage Ring | coupling, storage-ring, optics, feedback | 3029 | ||
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The orbit correction of stored electrons in the LNLS storage ring often needs a few iterations to converge to the smallest distortion. This is caused in part by the residual coupling between transverse planes. This coupling effect can be included in the correction algorithm leading to the best orbit in just one iteration. However, in the LNLS ring, the number of monitors equals the number of vertical correctors but surpasses the number of horizontal correctors. This means that the vertical orbit can be corrected to zero at the position monitors in the decoupled situation but the horizontal orbit cannot. For the coupled case, the incapacity of zeroing the horizontal orbit leaks into the vertical plane. This problem can be addressed by the eigenvector method with constraints.
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| THPC044 | Accurate Calculation of Higher Order Momentum Compaction Factor in a Small Ring | storage-ring, radiation, synchrotron, synchrotron-radiation | 3074 | ||
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The key issues to obtain short beam bunch in storage ring is to lowering momentum compaction factor. When the linear momentum compaction factor is small, higher order momentum compaction factor can produce significant effects in the longitudinal beam dynamics. In the small storage ring, higher order momentum comaction factor is determined not only by sextupoles, and also by the fringe field of main magnets. In this paper, the higher order momentum factor formula including the effects of fringe field is deduced. As a example, the momentum compaction factor of HLS storage ring was calculated.
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| THPC045 | Beam Uniformization System Using Multipole Magnets at the JAEA AVF Cyclotron | multipole, target, octupole, cyclotron | 3077 | ||
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It has been known that uniformization of a beam with a Gaussian profile is possible utilizing odd-order nonlinear forces*. Here, we investigate uniformization of the transverse beam profile using nonlinear-focusing forces produced by multipole magnets in detail. We show that it is possible to uniformize an asymmetric beam as well as a Gaussian beam utilizing the odd and even-order nonlinear forces in combination**. It enables us to perform high-uniformity irradiation at a constant particle fluence rate over the whole area of a large target. A research and development study of the beam uniformization system composed of sextupole and octupole magnets is now in progress at the JAEA AVF cyclotron facility. Some results of preliminary experiments on beam uniformization are also reported.
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*P. F. Meads, Jr., IEEE Trans. Nucl. Sci. 30, 2838 (1983). |
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| THPC049 | Progress in the Beam Preparation for the Multi-turn Extraction at the CERN Proton Synchrotron | extraction, octupole, proton, resonance | 3089 | ||
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A new type of extraction based on beam trapping inside stable islands in the horizontal phase space will become operational during 2008 at the CERN Proton Synchrotron. A series of beam experiments was carried out to prove loss-less capture with high intensity and multi-bunched beams, up to 1500·1010 protons per pulse, in preparation of the extraction commissioning. These fundamental steps for the new Multi-turn Extraction are presented and discussed in details.
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| THPC050 | Experimental Evidence of Beam Trapping with One-third and One-fifth Resonance Crossing | resonance, octupole, proton, synchrotron | 3092 | ||
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Beam trapping in stable islands of the horizontal phase space generated by non-linear magnetic fields is realized by means of a given tune variation so to cross a resonance of order n. Whenever the resonance is stable, n+1 beamlets are created whereas if the resonance is unstable, the beam is split in n parts. Experiments at the CERN Proton Synchrotron showed protons trapped in stable islands while crossing the one-third and one-fifth resonance with the creation of 3 and 6 stable beamlets, respectively. The results are presented and discussed in details.
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| THPC066 | Measuring Ring Nonlinear Components via Induced Linear "Feed-down" | resonance, simulation, beam-losses, closed-orbit | 3137 | ||
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The knowledge of the distribution in a ring of the non-linear components is important for the resonance compensation. We present a method to measure the lattice nonlinear components based on the non-linear tune response to a locally controlled closed orbit deformation. A test of this concept in the SIS18 synchrotron is presented and discussed.
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| THPC067 | ALBA Dynamic Aperture Optimization | dynamic-aperture, resonance, lattice, betatron | 3140 | ||
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The lattice of ALBA, the 3 GeV synchrotron light source in Spain, provides extremely low emittance of the beam. It is known that such lattices require strong sextupole magnets to compensate natural chromaticities. The paper describes strategy and results of the ALBA dynamic aperture optimization including both tune point selecting and sextupoles arrangement to increase the DA size.
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| THPC068 | Effect of Magnetic Multipoles on the ALBA Dynamic | multipole, dynamic-aperture, quadrupole, dipole | 3143 | ||
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For modern synchrotron light sources the main limitation of dynamic aperture is due to the strong chromatic sextupoles. However, small multipole errors in magnetic elements can reduce the original dynamic aperture by generating high order resonances at the aperture boundary. For the ALBA synchrotron light source a dynamic aperture in the presence of magnetic multipoles in the main magnets was simulated by tracking code. Both systematic and random magnetic errors were taken into account. In this paper we report on the results of our considerations.
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| THPC070 | Symmetry Restoration of the SPring-8 Storage Ring by Counter-sextupole Magnets | dynamic-aperture, electron, lattice, betatron | 3149 | ||
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In the SPring-8 storage ring there are four magnet-free long straight sections of about 30m. These were realized in 2000 by locally rearranging quadrupole and sextupole magnets. In modifying the optics we took care of the periodicity of cell structure, especially of sextupole field distribution along the ring. To keep the periodicity high and hence the dynamic aperture large, we adopted a scheme in which "betatron phase matching" and "local chromaticity correction" are combined. In this scheme the dynamic aperture for on-momentum electrons is kept by the phase matching and that for off-momentum electrons is enlarged by the local chromaticity correction with weak sextupoles (SL). After modifying the lattice, we tried to recover the symmetry of the ring further and found that a harmful effect of nonlinear kick due to SL can be minimized by additional "counter-sextupole magnets" placed 180 degrees apart in horizontal betatron phase from SL. We installed such counter-sextupoles in every long straight sections and confirmed that the aperture was improved. In the paper we discuss these topics showing experimental data of injection efficiency, momentum acceptance, etc.
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| THPC073 | Measurement of Resonance Driving Terms in the ATF Damping Ring | resonance, coupling, simulation, kicker | 3155 | ||
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The measurement of resonance driving terms in the Damping Ring of the Accelerator Test Facility in KEK could help finding possible machine imperfections and even to optimize single particle stability through the minimization of non-linearities. The first experimental attempts of this enterprise are reported in this note.
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| THPC076 | Closed Orbit Correction and Sextupole Compensation Schemes for Normal-conducting HESR | closed-orbit, dipole, electron, lattice | 3161 | ||
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The High Energy Storage Ring (HESR) will be part of the future Facility for Antiproton and Ion Research (FAIR) located at GSI in Darmstadt, Germany. The HESR will be operated with antiprotons in the momentum range from 1.5 to 15 GeV/c, which makes a long beam life time and a minimum of particle losses crucial. This and the demanding requirements of the PANDA experiment lead to the necessity of a good orbit correction and an effective multipole compensation. We developed a closed orbit correction scheme and tested it with Monte Carlo simulations. We assigned different sets of angular and spatial errors to all elements (magnets, bpms, etc.) within the lattice of the HESR. For correction we applied the orbit response matrix method. We carried out investigations concerning higher-order multipoles and created a scheme for chromaticity correction and compensation of arising resonances utilising analytic formulae and dynamic aperture calculations. In this presentation we give an overview of the correction and compensation schemes and of the corresponding results.
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| THPP103 | Design of the Beam Extraction System of the New Heavy Ion Synchrotrons SIS100 and SIS300 at FAIR | extraction, septum, kicker, quadrupole | 3605 | ||
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The proton and heavy ion synchrotrons SIS100 and SIS300 are the heart of the new FAIR facility which is under construction on the site of the present GSI. All ions from protons to uranium will be accelerated up to a magnetic rigidity of 100 Tm and 300 Tm, respectively. The design of the beam extraction system of both synchrotrons is completed and will be presented in this paper. The extraction devices of both synchrotrons are situated in one common straight section and deflect the beam vertically. SIS100 has been optimized for fast extraction by means of a distributed fast bipolar kicker system. However, slow extraction over a few seconds is also foreseen. SIS300 has been optimized for slow extraction and may generate spills of up to 100s. The slow extraction channel combines horizontal deflection by an electrostatic septum in the first stage with vertical deflection by a Lambertson septum magnet and subsequent magnetic extraction septa in the second stage. An emergency beam dumping system could be integrated in the extraction system of both machines.
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| THPP121 | The SSRF Storage Ring Dipole and Sextupole Magnet Power Supplies | power-supply, controls, dipole, storage-ring | 3641 | ||
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SSRF is a third generation synchrotron radiation light source. It has a full energy injection storage ring of 3.5GeV. The storage ring dipole magnet string and sextupole magnets strings are powered by 10 large magnet power supplies. The power supply output current ranges from 250A to 800A, and the output voltage ranges from 140V to 840V. These power supplies are digital controlled, with bridge topology, and diode rectifiers with step-down transformers. In this paper, the commissioning results of these power supplies are presented, together with the circuit topology and the control schemes.
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