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multipole

  
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MOPKF052 Design of an In Archromatic Superconducting Wiggler at NSRRC wiggler, vacuum, synchrotron, storage-ring 425
 
  • C.-H. Chang, H.-H. Chen, T.-C. Fan, G.-Y. Hsiung, M.-H. Huang, C.-S. Hwang, F.-Y. Lin
    NSRRC, Hsinchu
  A 15-pole superconducting wiggler with period length of 6 cm is designed for National Synchrotron Research Center (NSRRC) in Taiwan. The compact superconducting wiggler will be installed near the second bending magnet of the triple bend achromat section in the 1.5 GeV storage ring. This wiggler magnet with maximum peak field of 3.2 T at pole gap width of 19 mm is operated in 4.2 K liquid helium vessel. A 5-pole prototype magnet is tested and measured to verify the magnetic field performance in the testing dewar. Furthermore, the cryogenic considerations and thermal analysis in the 4.2 K wiggler magnet and the 77 K vacuum chamber are also presented in this work.  
 
MOPLT014 Testing of the LHC Magnets in Cryogenic Conditions: Current Experience and Near Future Outlook dipole, injection, instrumentation, sextupole 560
 
  • V. Chohan, M. Buzio, G. De Rijk, J. Miles, P. Pugnat, V. Remondino, S. Sanfilippo, A.D. Siemko, N. Smirnov, B. Vullierme, L. Walckiers
    CERN, Geneva
  For the Large Hadron Collider under construction at CERN, a necessary and primordial condition prior to its installation is that all the main twin-aperture Dipole and Quadrupole magnets are tested in the 1.9K cryogenic conditions. These tests are not feasible at the manufacturers and hence, are carried out at CERN at a purpose built facility on the site. This presentation will give an overall view of the issues related to the operation of the tests facility. In particular, it will give the goals that need to be met to ensure the magnet integrity and performance and the context & constraints on the test programme. Results accumulated from the tested magnets and the ensuing tests stream-lining will be presented, together with some of the explanations and hard limits. Finally, some improvements planned for efficient operation will be given within the confines of the testing programme as was foreseen and the project goals and deadlines.  
 
MOPLT175 A Method to Measure the Focusing Properties (R_Matrix) of a Magnet focusing, ion, heavy-ion, dipole 935
 
  • N. Tsoupas, L. Ahrens, K.A. Brown, D. Gassner, J. Glenn, Y.Y. Lee, T. Roser, P. Thieberger, J. Wei
    BNL, Upton, Long Island, New York
  We discuss a method that may be used to measure the focusing properties of a magnet. This method may prove valuable when applied to non-conventional magnets that deviate from the usual dipole magnets or other multipole magnets which are commonly used in a synchrotron. In this category of non-conventional magnets, fall special magnets, which come under the name Snakes. Such magnets are being used in synchrotron accelerators[*,**] to introduce artificial spin resonances to help overcome the intrinsic and/or imperfection spin resonances. This method of measuring the focusing properties of a magnet requires the use of low energy and high rigidity heavy-ions which may be obtained from the BNL Tandem accelerator.In brief the method consists on, injecting low emittance beamlets of lightly stripped heavy ions into a magnet and measuring the coordinates, of these narrowbeamlets, at the entrance and exit of the magnet.From the measurement of these coordinates of the narrowbeamlets we can deduce information on the R matrix and higher order matrix elements that define the focusing properties of the magnet.

* T. Roser, AIP Conf. Proc. 187 (1988) 1221** H.Huang, et. al. Phys. Rev. Lett. 73 (1994) 2982

 
 
TUPLT028 Development of Finger Drift Tube Linacs booster, quadrupole, focusing, rfq 1204
 
  • K.-U. Kuehnel, A. Schempp
    IAP, Frankfurt-am-Main
  • C.P. Welsch
    MPI-K, Heidelberg
  At higher particle energies the efficiency of RFQs decreases and DTL structures in combination with magnetic quadrupoles are used. One approach at IAP is the combination of RFQ and DTL. To compensate the defocusing effects of a DTL structure, the accelerating gaps of a spiral loaded cavity were equiped with small focusing fingers. These fingers arranged in a quadrupole symmetry provide an additional focusing field component. The beam dynamics of such a cavity has been studied with PARMTEQ. Simulations of the rf properties have been done using microwave studio. A prototype of a spiral loaded cavity with finger drift tubes has been built and low power measurement were made. Results of the calculations as well as low level and bead pertubation measurements are presented in this contribution.  
 
TUPLT092 Optics and Magnet Design for Proton Beam Transport Line at PEFP proton, optics, dipole, extraction 1372
 
  • H.-S. Kang, H.S. Han, S.H. Jeong, Y.G. Jung, D.E. Kim, M. Kim, H.G. Lee, T.-Y. Lee, H.S. Suh
    PAL, Pohang
  The PEFP proton linac is designed to have two proton beam extraction lines at the 20-MeV and 100-MeV end, respectively. Each extraction line has 5 to 6 beamlines for proton beam users. The proton beam transport system for users? experiments will be prepared for this purpose. At the beginning, the beam optics for the proton beam transport system is designed with the TRACE code. The optics should be designed so as to meet the users? various requirements which might be to control the beam size and intensity at the beam target, and the timing of the proton beam. The magnet to distribute the proton beam to many beamlines is an AC magnet which has an AC frequency of 15 Hz, and is powered with a programmable AC power supply. In this paper, the result of the optics design will be presented and the magnet design will be described.  
 
TUPLT189 Dipole and Quaqdrupole Sorting for the SNS Ring quadrupole, dipole, resonance, sextupole 1574
 
  • D. Raparia, A.V. Fedotov, Y.Y. Lee, J. Wei
    BNL, Upton, Long Island, New York
  The Spallation Neutron Source (SNS) accumulator ring is a high intensity ring and must have low uncontrolled losses for hands on maintenance. To achieve these low losses one needs very tight tolerance. These tight tolerances have been achieved through shimming the magnets and sorting. Dipoles are solid core magnets and had very good field quality but magnet to magnet variation were sorted out according to ITF, since all the dipole are powered with one power supply. Typically, sorting is done to minimize linear effects in beam dynamics. Here, sorting of quadrupoles was done according to a scheme which allows to reduce unwanted strength of nonlinear resonances. As a result, the strength of sextupole resonances for our base line tune-box was strongly reduced which was confirmed by a subsequent beam dynamics simulation.  
 
WEOALH03 Installation Strategy for the LHC Main Dipoles dipole, injection, dynamic-aperture, resonance 176
 
  • S.D. Fartoukh
    CERN, Geneva
  All positions in the LHC machine are not equivalent in terms of beam requirements on the geometry and the field quality of the main dipoles. In the presence of slightly or strongly out-of tolerance magnets, a well-defined installation strategy will therefore contribute to preserve or even optimize the performance of the machine. In view of present state of the production, we have anticipated a list of potential issues (geometry, transfer function, field direction and random b3) which, combined by order of priority, have been taken into account to define a robust installation algorithm for the LHC main dipoles. Among the different possible strategies, the proposed one has been optimised in terms of simplicity and flexibility in order not to slow down and complicate the installation process. Its output is a prescription for installing the available dipoles in sequence while reducing to an absolute minimum the number of holes required by geometry or field quality issues.  
Video of talk
Transparencies
 
WEPKF006 Field Quality and Hysteresis of LHC Superconducting Corrector Magnets dipole, injection, quadrupole, target 1600
 
  • A. Santrich Badal, M. Allitt, C. Giloux, M. Karppinen, A.M. Lombardi, V. Remondino, W.  Venturini Delsolaro, R. Wolf
    CERN, Geneva
  • M. Bagre, P. Khare, T. Maurya, A. Puntambekar
    CAT, Indore (M.P.)
  The Large Hadron Collider (LHC) will use some 6400 superconducting corrector magnets. There are 19 corrector types. These are assembled 14 different types of magnets of which 4 are nested. They are being manufactured by 4 firms in Europe and 3 in India. The magnetic field quality is measured at room temperature by 12 magnetic measurement benches employed by the corrector manufacturers. CERN performs magnetic measurement at 4.2K and at 1.9K on a small subset of corrector magnets. The paper discusses the correlation between the warm and cold field measurements. The field quality is compared to the magnet design expectations and to the target field quality for LHC. Many corrector circuits will be powered in a way which cannot be predicted before LHC will start operation and which even then may change between physics runs. The measured magnetic hysteresis and its influence on possible setting errors during operation is discussed, in particular for the orbit correctors and the tuning/trim quadrupole magnet circuits.  
 
WEPKF008 A Strategy for Sampling of the Field Quality of the LHC Dipoles dipole, target, injection, dynamic-aperture 1606
 
  • L. Bottura, S.D. Fartoukh, V. Granata, E. Todesco
    CERN, Geneva
  We have measured the magnetic field of a considerable fraction of the superconducting LHC main dipoles, of the order of 300 in warm conditions and 100 in cold conditions. All LHC dipoles will be measured in warm conditions at the manufacturers to steer the production inside the acceptance limits imposed by beam dynamics. Using the available data we analysed the distributions of the main field and higher order field errors in warm and cold conditions, as well as the distribution of the warm-to-cold correlation. Based on this analysis we predict the minimum number of magnets that should be measured in cold conditions in order to guarantee that (1) the production is controlled within the specified limits (2) the field is known to a sufficient level for a sound installation and (3) the uncertainty on the knowledge of the magnetic field of the LHC dipoles is small enough for the commissioning of the accelerator and to insure operation of the machine in any condition, including higher energy. The main outcome of this analysis is that cold measurements on a fraction of the order of one third of the total production, i.e. approximately 400 dipoles, will be sufficient to achieve the above objectives.  
 
WEPKF009 A Scaling Law for Predicting Snap-back in Superconducting Accelerator Magnets sextupole, dipole, injection, magnet-design 1609
 
  • T. Pieloni, L. Bottura, S. Sanfilippo
    CERN, Geneva
  • G. Ambrosio, P. Bauer
    Fermilab, Batavia, Illinois
  • M. Haverkamp
    METROLAB, Plan-les-Ouates
  The decay of the sextupole component in the bending dipoles during injection and the subsequent snap-back at particle acceleration are issues of common concern, albeit at different levels of criticality, for all superconducting colliders built (Tevatron, HERA, RHIC) or in construction (LHC) to date. The main difficulty is the correction of the relatively large and fast sextupole change during snap-back. Motivated by the above considerations, we have conducted an extended study of sextupole snap-back on two different magnet families, the Tevatron and the LHC bending dipoles, using the same measurement method. We show in this paper that it is possible to generalise all the results obtained by using a simple, exponential scaling law. Furthermore, we show that for magnets of the same family the parameters of the scaling law correlate linearly. This finding could be exploited during accelerator operation to produce accurate forecast of the snap-back correction based solely on beam-based measurements.  
 
WEPKF011 Performance of the Superconducting Matching Quadrupoles for the LHC Insertions quadrupole, insertion, alignment, target 1615
 
  • N. Catalan-Lasheras, G. Kirby, R. Ostojic, J.C. Perez, H. Prin, W.  Venturini Delsolaro
    CERN, Geneva
  The optics flexibility of the LHC insertions is provided by the individually powered quadrupoles in the dispersion suppressors and matching sections. These units comprise special quadrupole magnets of the MQM and MQY type and range in length from 5.4 m to 11.4 m. In total, 82 insertion quadrupoles will be assembled at CERN. In this paper we present the advance in construction and report on the performance of the first series built quadrupoles. In particular, we present the quench performance of the individual magnets and alignment measurements of the cold masses, and discuss the field quality trends and possible implications.  
 
WEPKF049 Stretched Wire Flip Coil System for Magnetic Field Measurements quadrupole, insertion, insertion-device, target 1714
 
  • D.E. Kim, C.W. Chung, H.S. Han, Y.G. Jung, H.G. Lee, W.W. Lee, K.-H. Park, H.S. Suh
    PAL, Pohang
  A flip-coil system using a stretched wire measuring the magnetic field properties of accelerator magnets is described. This system is similar to the conventional rotating coil system except that the stretched wires are used instead of wires wound on the machined surface. This system has advantage of simple fabrication and flexible operation so that different length and bore magnets can be easily measured using the same system. The system also has two loop coils to buck the dominant fundamental field so as to increase the measurement accuracy. This kind of system has issues related to the reproducibility, accuracy of the measured results. The system is evaluated to verify its performances and its results were discussed. The analyzing methods and various efforts to keep the system in high accuracy are presented. Measurement results with this loop coil system were compared with that of the other system.  
 
WEPKF060 Bending Magnets for the SAGA Storage Ring: Manufacturing and Magnetic Measurements dipole, storage-ring, focusing, electron 1738
 
  • S.V. Sinyatkin, I.N. Churkin, O.B. Kiselev, V. Korchuganov, A.B. Ogurtsov, A.V. Philipchenko, L.M. Schegolev, K.K. Schreiner, A.G. Steshov, V. Ushakov
    BINP SB RAS, Novosibirsk
  • M. Kuroda, Y. Tsuchida
    Saga Synchrotron Light Source, Industry Promotion Division, Saga City
  The paper describes the design, the manufacture and the magnetic measurement of the dipole bending magnets (BM) for SR Source storage ring (prefecture SAGA, Japan) carried out in BINP, Novosibirsk, Russia. The requirement was to create the laminated C-shape BMs with the 3.2 m radius and parallel edges. The magnetic field homogeneity must be not worth than ±2? 10-4 inside the working area: H = 30+40mm and V = ±20mm at 0.26T (250 MeV), and H = ± 28mm and V = ±20mm at 1.46 T (1.4GeV). The BMs were designed on the basis of the 2-D 3-D modeling taking into account the laminated core. The BMs yokes were produced with the help of the technology of the high temperature gluing. The computer simulations are in a good agreement with the magnetic measurements. The main parameters of the magnetic fields satisfy to the requirements and are presented. The features of the design, manufacturing and precise magnetic measurements of SAGA BMs are discussed.  
 
WEPKF082 Radiation Damage Studies with Hadrons on Materials and Electronics radiation, permanent-magnet, radioactivity, hadron 1795
 
  • J.E. Spencer, J. Allan, S. Anderson, R. Wolf
    SLAC, Menlo Park, California
  • M. Boussoufi
    UCD/MNRC, McClellan, California
  • D.E. Pellet
    UCD, Davis
  • J.T. Volk
    Fermilab, Batavia, Illinois
  Many materials and electronic devices need to be tested for the radiation environment expected at the proposed linear colliders (LC) where the accelerator and detectors will be subjected to large fluences of hadrons, electrons and gammas during the life of the facility. Examples are NdFeB permanent magnets which are being considered for the damping rings and final focus, electronic and electro-optical devices which will be utilized in the detector readout and accelerator control systems and CCDs required for the vertex detector. The effects of gammas on a broad range of materials was presented at NSREC2002 and our understanding of the current situation concerning rare earth permanent magnets at PAC2003 where a program was proposed using neutrons from the McClellan Nuclear Reactor Center (MNRC) that has a number of areas for irradiating samples with neutron fluxes up to 4.5·1013 n/cm2s. A specialized area allows irradiation with 1 MeV-equivalent neutrons with fluxes of 4.2·1010 n/cm2s while suppressing thermal neutrons and gammas by large factors. We give our latest results and their interpretation using this facility.  
 
WEPLT017 Numerical Studies of the Impact of the Separation Dipoles and Insertion Quadrupoles Field Quality on the Dynamic Aperture of the CERN LHC quadrupole, dipole, insertion, injection 1858
 
  • M. Giovannozzi, O.S. Brüning, S.D. Fartoukh, T. Risselada, F. Schmidt
    CERN, Geneva
  A wide range of magnets, both warm and superconducting, will be used in the LHC. In addition to main dipoles, quadrupoles are used to focus the beam in regular arcs. Special dipoles separate or merge the two beams in insertion regions. A few very strong superconducting quadrupoles squeeze the beam to achieve the required luminosity, while warm quadrupoles are used in the collimation insertions. At injection the main dipoles largely dominate beam dynamics, but contributions from smaller classes of magnets should not be neglected. Peculiar optical configurations may dramatically enhance beam dynamics effects of few magnetic elements. This paper will focus on the effect of insertion quadrupoles, e.g. wide-aperture, and warm quadrupoles, as well as separation dipoles presenting on the dynamic aperture of the LHC machine.  
 
WEPLT052 A Method to Measure the Skew Quadrupole Strengths in the SIS-18 using Two BPMs quadrupole, resonance, simulation, lattice 1957
 
  • F. Franchi, T. Beier, M. Kirk, M. Moritz, G. Rumolo
    GSI, Darmstadt
  • R. Tomas
    BNL, Upton, Long Island, New York
  In the SIS-18 of GSI a new set of skew quadrupoles has been installed to improve the multi-turn-injection. A new method based on the measurement of the resonance driving terms has been proposed to cross-check the nominal values and polarities of their gradients. Once a beam is transversely kicked, it experiences oscillations whose spectrum contains both the betatron tune line and secondary lines. The amplitude of each line is proportional to the strength of the multipoles, such as skew quadrupoles and sextupoles, present in the lattice. In this paper a recursive algorithm to derive the magnet strength from the spectral lines and the application of this method to the eight skew quadrupoles in the SIS-18 are presented.  
 
WEPLT093 Electromagnetic Fields of an Off-axis Bunch in a Circular Pipe with Finite Conductivity and Thickness - I vacuum, injection, single-bunch, electromagnetic-fields 2068
 
  • S. Petracca, L. Cappetta, T. Demma
    U. Sannio, Benevento
  The electromagnetic field produced by a bunched beam in a circular pipe is usually computed under the assumption that the field penetration(skin depth) is far less than the wall thickness. Chao [*] gave a formula which exploits the wall thickness, but his result is restricted to the monopole term. Piwinski [**] treated the case of a metal coated ceramic wall, when the coating thickness is much smaller than the skin-depth, but his analysis is also limited to the monopole term.In this paper we solve the problem in full generality, by providing an exact (Green's functions) solution for the field of an off-axis point particle running at constant velocity in a circular pipe with finite wall conductivity and thickness.

* A.W. Chao, Phys. of Collective Beam Instab. in High En. Accel., Wiley,1993** S. Piwinski, DESY 1972/72

 
 
WEPLT094 Electromagnetic Fields of an Off-axis Bunched Beam in a Circular Pipe with Finite Conductivity and Thickness - II quadrupole, collider, hadron, electromagnetic-fields 2071
 
  • S. Petracca, L. Cappetta, T. Demma
    U. Sannio, Benevento
  • R.P. Croce
    Universita' degli Studi di Salerno, Dipartimento di Fisica E.R. Caianiello, Baronissi
  The general exact solution exploited [*] is applied, introducing suitable dimensionless parameters, and using appropriate asymptotic limiting forms, to compute the wake field multipoles for the different paradigm cases of LHC and DAPHNE.

* R. P. Croce, Th. Demma, S. Petracca "Electromagnetic Fields of an Off-axis Bunch in a Circular Pipe with Finite Conductivity and Thickness", these proceedings

 
 
WEPLT174 Higher Order Hard Edge End Field Effects lattice, chromatic-effects, focusing, dynamic-aperture 2236
 
  • J.S. Berg
    BNL, Upton, Long Island, New York
  In most cases, nonlinearities from magnets must be properly included in tracking and analysis to properly compute quantities of interest, in particular chromatic properties and dynamic aperture. One source of nonlinearities in magnets that is often important and cannot be avoided is the nonlinearity arising at the end of a magnet due to the longitudinal variation of the field at the end of the magnet. Part of this effect is independent of the shape of the end. It is lowest order in the body field of the magnet, and is the result of taking a limit as the length over which the field at the end varies approaches zero. This is referred to as a hard edge" end field. This effect has been computed previously to lowest order in the transverse variables. This paper describes a method to compute this effect to arbitrary order in the transverse variables, under certain constraints. The results of using this hard edge model are compared with performing the computation with finite-length end fields, as well as to the lowest-order hard-edge end field model.  
 
WEPLT181 Measurement of Multipole Strengths from RHIC BPM Data dipole, resonance, lattice, betatron 2242
 
  • R. Tomas, M. Bai, W. Fischer
    BNL, Upton, Long Island, New York
  • F. Franchi, G. Rumolo
    GSI, Darmstadt
  Recently resonance driving terms were successfully measured in the CERN SPS and the BNL RHIC from the Fourier spectrum of BPM data. Based on these measurements a new analysis has been derived to extract multipole strengths.In this paper we present experimental measurements of sextupolar and skew quadrupolar strengths carried out at RHIC. Also discussed is the possibility of a non-destructive measurement using an AC dipole.  
 
WEPLT182 Non-linear Modeling of the RHIC Interaction Regions quadrupole, dipole, interaction-region, lattice 2245
 
  • R. Tomas, W. Fischer, A.K. Jain, Y. Luo, F.C. Pilat
    BNL, Upton, Long Island, New York
  For RHIC's collision lattices the dominant sources of transverse non-linearities are located in the interaction regions. The field quality is available for most of the magnets in the interaction regions from the magnetic measurements, or from extrapolations of these measurements. We discuss the implementation of these measurements on the MADX models of the Blue and the Yellow rings and their impact on beam stability.  
 
THPLT039 SVD Based Orbit Correction Incorporating Corrector Limitations at DELTA dipole, synchrotron, storage-ring, beam-losses 2568
 
  • M. Grewe, P. Hartmann, G. Schmidt, K. Wille
    DELTA, Dortmund
  Singular Value Decompostion (SVD) of the orbit response matrix has become an invaluable tool for orbit correction at storage rings worldwide. SVD based orbit correction has now been realised at DELTA, a 1.5 GeV electron storage ring. However, due to special orbit demands at DELTA and possibly by magnetic imperfections within the storage ring, we frequently have to face corrector limitations during the process of orbit correction. This work focuses on presenting an analytic algorithm on how to treat these limitations when seeking for an optimal SVD based orbit correction. In contrast to previously published methods, this approach is fairly easy to implement and does not afford an numerical solver. Concepts and results will be presented.