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permanent-magnet

 
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MOPLS134 Minimizing Emittance for the CLIC Damping Ring wiggler, damping, emittance, CLIC 870
 
  • H.-H. Braun, M. Korostelev, D. Schulte, F. Zimmermann
    CERN, Geneva
  • E.B. Levitchev, P.A. Piminov, S.V. Sinyatkin, P. Vobly, K. Zolotarev
    BINP SB RAS, Novosibirsk
  The CLIC damping rings aim at unprecedented small normalized equilibrium emittances of 3.3 nm vertical and 550 nm horizontal, for a bunch charge of 2.6 109 particles and an energy of 2.4 GeV. In this parameter regime the dominant emittance growth mechanism is intra-beam scattering. Intense synchrotron radiation damping from wigglers is required to counteract its effect. Here the overall optimization of the wiggler parameters is described, taking into account state-of-the-art wiggler technologies, wiggler effects on dynamic aperture, and problems of wiggler radiation absorption. Two technical solutions, one based on superconducting magnet technology and the other on permanent magnets, are presented. Although dynamic aperture and tolerances of this ring design remain challenging, benefits are obtained from the strong damping. Only bunches for a single machine pulse need to be stored, making injection/extraction particularly simple and limiting the synchrotron-radiation power. With a 360 m circumference, the ring remains comparatively small.  
 
TUYFI02 Latest Developments on Insertion Devices undulator, wiggler, electron, ESRF 969
 
  • P. Elleaume, J. Chavanne
    ESRF, Grenoble
  A review will be carried out of the developments on Insertion Devices that have taken place world wide in the last few years. These include the development of long period electro-magnet undulators, the operational results of a number of Apple-II undulators, the development of superconducting short period multipole wigglers, as well as the construction and operation of several in-vacuum undulators. The construction of a large number of competitive middle energy synchrotron sources in the hard X-ray range means that the need to increase the photon energy in the fundamental peak of an undulator is becoming a very important issue. Two main development strategies are currently being investigated. One consists of using superconducting undulator technology, the other of a further refinement of the in-vacuum undulator permanent magnet technology with cryogenic cooling of the magnetic assembly. The issues and challenges that are part of each approach will be presented, together with the latest results.  
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TUPLS094 Development of a Permanent Magnet Microwave Ion Source for Medical Accelerators ion, ion-source, proton, linac 1723
 
  • S. Hara, T. Iga, M. Tanaka
    Hitachi, Ltd., Power & Industrial Systems R&D Laboratory, Ibaraki-ken
  A permanent magnet microwave ion source was developed to improve availability of proton accelerator application systems based on industrial microwave ion source technologies. The ion source needs no filament in the discharge chamber, which leads to reliability improvement and less maintenance time. Because the ion source uses a permanent magnet, the ion source needs no coils, no coil power and no coil coolant. The hydrogen beam of over 60 mA has been extracted from a single 5mm diameter aperture with a proton fraction of 85% at a microwave power of 1.3kW. Rise times of the microwave power and beam current to 90 % of the final value were about 30 and 100μseconds respectively at a pulse operation mode with 400μseconds pulse width and 20 Hz repetition rate. These performance parameters are equal to the solenoid coil ion source parameters, making the ion source desirable for accelerator applications like proton therapy systems.  
 
WEPLS073 A Super Strong Adjustable Permanent Magnet Quadrupole for the Final Focus in a Linear Collider quadrupole, linear-collider, collider, CERN 2550
 
  • Y. Iwashita, T. Mihara
    Kyoto ICR, Uji, Kyoto
  • M. Kumada
    NIRS, Chiba-shi
  • C.M. Spencer
    SLAC, Menlo Park, California
  An adjustable permanent magnet quadrupole has been fabricated to demonstrate its feasibility for use in the final focus of a linear collider. The supposed requirements for such a final focus lens are the tight stabilities of its integrated field gradient and magnetic center, plus it must have adjustable strength. The high temperature coefficient of the permanent magnet material NEOMAX is compensated by use of the MS-1 Fe-Ni alloy. The magnet has two concentric rings of NEOMAX. The replacement of the inner ring with a smaller diameter one is planned in order to reach the highest gradient with the current configuration of the quadrupole system; the system has to be scaled down in size to fit in a real linear collider final focus system. A precise magnetic field measurement system is also under fabrication that will be able to measure the magnetic center to a fraction of a micron.  
 
WEPLS089 Feasibility Study of a Permanent Magnet Made from High-Tc Bulk Superconductor dipole, LEFT, superconductivity, shielding 2580
 
  • M. Masuzawa, K. Egawa, K. Tsuchiya
    KEK, Ibaraki
  A field trapping experiment using a magnetic field up to ~1.5 T was performed using high-Tc bulk superconductors. Applications of bulk high-Tc superconductors have been investigated in various fields. High-Tc superconductors are attractive since they can trap higher magnetic fields than conventional permanent magnets. The trapping experiment was done with a field of above 1 T, which can be easily produced by conventional magnets. However, achieving the desired field distribution and understanding the characteristics of the trapped field and its decay process would open up the possibility of high-Tc bulk superconductor applications in the design of magnets for particle accelerators The distribution of the trapped field and its decay process was monitored by an array of Hall sensors for different shapes of the bulk superconductors. The observations are reported on in this paper.  
 
THPCH023 Vlasov Equilibrium of a Periodically Twisted Ellipse-shaped Charged-particle Beam in a Non-axisymmetric Periodic Magnetic Focusing Field focusing, emittance, plasma, klystron 2826
 
  • J.Z. Zhou, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
  A new Vlasov equilibrium is obtained for a periodically twisted ellipse-shaped charged-particle beam in a non-axisymmetric periodic permanent magnetic focusing field. The equilibrium distribution function is derived, and the statistical properties of the beam equilibrium are studied. The generalized envelope equations derived from the kinetic theory recovers the generalized envelope equations obtained in the cold-fluid theory when the temperature is taken to be zero*. Examples of periodically twisted elliptic beam equilibrium are presented and applications are explored.

*J. Zhou et al. “Exact Paraxial Cold-Fluid Equilibrium of a High-Intensity Periodically Twisted Ellipse-Shaped Charged-Particle Beam,” Phys. Rev. ST Accel. Beams, submitted for publication (2005).

 
 
THPCH080 Transverse Impedance of Small-gap Undulators for NSLS-II impedance, undulator, vacuum, electron 2970
 
  • A. Blednykh, S. Krinsky, B. Podobedov, J.-M. Wang
    BNL, Upton, Long Island, New York
  We discuss the transverse impedance resulting from the use of small-gap undulators in the proposed NSLS-II storage ring. For superconducting undulators, the impedance arises due to the tapered elliptical vacuum chamber. For in-vacuum permanent magnet devices, the impedance results from a more complex geometry. We consider both cases and report results obtained using the electromagnetic simulation program GdfidL.  
 
THPCH135 65 MEV Neutron Irradiation of ND-FE-B Permanent Magnets radiation, electron, proton, undulator 3116
 
  • X.-M. Maréchal, T. Bizen
    JASRI/SPring-8, Hyogo-ken
  • Y. Asano
    JAEA/SPring-8, Hyogo
  • H. Kitamura
    RIKEN Spring-8 Harima, Hyogo
  Rare-earth permanent magnets are now playing a major role in accelerator technology, from the development of beam transport systems magnets to their extensive use in synchrotron radiation sources and free electron lasers. Unfortunately, operating in a high radiation environment, rare-earth permanent magnets are subject to demagnetization caused by direct and scattered radiation. The lifetime of these components is therefore a major issue: as a result, the number of studies to clarify the demagnetization mechanism or to test materials of interest for a particular application under specific conditions of irradiation has increased in recent years. However, so far, neutron irradiation experiments have been mainly carried out with reactors, were neutrons have a wide, but mainly low, energy spectrum. We present here the results obtained at the TIARA facility of the Japan Atomic Energy Research Institute, a spalliation source of mono highly energetic neutrons. Four types of Nd-Fe-B permanent magnets (Neomax™ 35EH, 32AH, 27VH and 44H) representing a wide range of characteristics (remanence and coervicity) have been studied.  
 
THPLS119 Development of a Cryogenic Permanent Magnet In-vacuum Undulator at the ESRF undulator, ESRF, cryogenics, vacuum 3559
 
  • C.A. Kitegi, J. Chavanne, D. Cognie, P. Elleaume, C. Penel, B. Plan, F. Revol, M. Rossat
    ESRF, Grenoble
  Lowering the temperature of NdFeB materials increases their field remanence and intrinsic coercivity*. This property is potentially interesting for the construction of cryogenic permanent in-vacuum undulators (CPMU)**. Around 150K, the coercivity is increased to such an extent that the NdFeB material is comparable to the Sm2Co17 as far as resistance to radiation damages is concerned. The improvement in field remanence is less remarkable (15% at 150K) and is dominated by a reversible Spin Reorientation Transition (SRT) occurring around 135K. Below this temperature, the remanence decreases. The complete magnetization curves of NdFeB material measured at different cryogenic temperatures are presented. Non-linear models have been constructed and used in the RADIA code in order to compute the field performance of a hybrid NdFeB in-vacuum undulator. A prototype CPMU is presently under construction at the ESRF. It has a period of 18mm and a magnetic length of 2m. The field integral and local field measurements of the cryogenic device require new systems operated in vacuum. A stretched wire bench and a hall probe bench are under construction; their main characteristics will be presented.

*D. Givord et al. Analysis of hysteresis loops in NdFeB sintered magnets, J. Appl. Phys. 60(9) (3263-3265).**T. Hara et al. Cryogenic permanent undulator, Phys.rev. ST AB volume 7 050702 (2004).

 
 
THPLS125 A Concept on Electric Field Error Compensation for the ANKA Superconductive Undulator undulator, electron, photon, simulation 3577
 
  • D. Wollmann, T. Baumbach, A. Bernhard
    University of Karlsruhe, Karlsruhe
  • S. Casalbuoni, MH. Hagelstein, B.K. Kostka, R. Rossmanith
    FZK, Karlsruhe
  • G. Gerlach
    University of Dresden, Institute for Solid-State Electronics, Dresden
  • F. Schoeck, E. Steffens, M. Weisser
    University of Erlangen-Nürnberg, Physikalisches Institut II, Erlangen
  In April 2005 a superconductive undulator test device, the so-called SCU14 (period length 14 mm, 100 periods) was installed at ANKA. Before installation, the magnetic field was measured and documented. This was the first test of a superconductive undulator in a storage ring and the dominating questions to be answered were related to the interaction of the undulator with the beam. The field quality was of lower importance and will be improved by a modified mechanical fabrication technique at the next superconductive undulators. Nevertheless, after finishing the fundamental beam tests the question was discussed how one would improve the field quality (minimize the phase error) of the existing undulator by local correction devices. The concepts could be used later in a weaker form for local field corrections at future undulators, if necessary.