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Paper Title Other Keywords Page
MOP013 Focusing Solenoids for the HINS Linac Front End solenoid, linac, dipole, alignment 82
  • I. Terechkine, G. Apollinari, J. DiMarco, Y. Huang, D.F. Orris, T.M. Page, R. Rabehl, M.A. Tartaglia, J.C. Tompkins
    Fermilab, Batavia

Low energy part of the linac for the HINS project at Fermilab will use superconducting solenoids as beam focusing elements (lenses). While lenses for the conventional, DTL-type accelerating section of the front end require individual cryostats, in the superconducting accelerating sections solenoids will be installed inside rf cryomodules. Some of the lenses in the conventional and in the superconducting sections are equipped with horizontal and vertical dipole correctors. Lenses for the conventional DTL section are in the stage of production with certification activities ongoing at Fermilab. For the superconducting sections of the linac, several prototypes of focusing lenses were built and tested. Solenoid magnetic axis is used for alignment of the lenses in the transport channel of the accelerator. Corresponding technique has been developed at Fermilab and is used during certification of the production lenses for the DTL section. This report will summarize main design features, parameters, and test results of the focusing lenses of the linac. Magnetic axis alignment technique will also be described.

MOP025 An Intermediate Structure SFRFQ Between RFQ and DTL rfq, cavity, DTL, ion 118
  • Y.R. Lu, J.E. Chen, J.X. Fang, S.L. Gao, Z.Y. Guo, M. Kang, S.X. Peng, Z. Wang, X.Q. Yan, M. Zhang, J. Zhao, K. Zhu
    PKU/IHIP, Beijing

Funding: supported by NSFC 10455001
Longer the RFQ length is, lower kinetic energy gain per unit length is; lower the injection energy DTL is, much higher accelerating efficiency is; more accelerating gaps at DTL entrance means stronger transverse focusing is needed for the beam. SFRFQ is such an intermediate structure, which combines RFQ and DTL together, it can increase the accelerating efficiency at RFQ high energy end by inserting gap acceleration between RFQ electrodes while provide strong focusing by RFQ focusing field. One prototype cavity has been manufactured and will be used as a post accelerator of ISR RFQ to accelerate O+ from 1 MeV to 1.6 MeV in 1meter. A code SFRFQCODEV1.0 was developed for the beam dynamics design. The rf conditioning and full rf power test has been carried out. The intervane or gap voltage have reached 86 kV at 29 kW with 1/6 duty cycle and repetition frequency 166 Hz. The initial beam test results will also be presented in this paper.

MOP032 Upgrade of the Unilac High Current Injector RFQ rfq, emittance, simulation, ion 136
  • A. Kolomiets, S. Minaev
    ITEP, Moscow
  • W. Barth, L.A. Dahl, H. Vormann, S. Yaramyshev
    GSI, Darmstadt

Funding: Work supported by the European Community INTAS Project Ref. no. 06-1000012-8782.
For the operation of the GSI-accelerator chain as an injector for the future FAIR facility a considerable increase of the heavy ion beam intensity by a factor 3-5 at the end of the UNILAC is required. The bottleneck of the whole UNILAC, is the front-end system of the High Current Injector. It is shown that the transverse RFQ-acceptance can be significantly increased while the emittance growth can be reduced. Both goals are achieved with only a moderate change of the RFQ electrode geometry; the intervane voltage raised from 125 kV to 155 kV keeping the design limit of the maximum field at the electrode surface. The changed resonant frequency can be compensated with a relatively small correction of the carrying rings. The beam parameters in the final focusing elements of the LEBT were improved together with the input radial matcher design; the length of the gentle buncher section was considerably increased to provide slow and smooth bunching resulting in a reduce influence of space charge forces. DYNAMION-simulation with the modified electrode design resulted in an increase of U4+-beam current of up to 20 emA. It is planned to start the upgrade measure in spring 2009.

MOP036 The IFMIF-EVEDA RFQ: Beam Dynamics Design rfq, emittance, space-charge, beam-losses 145
  • M. Comunian, A. Pisent
    INFN/LNL, Legnaro, Padova
  • E. Fagotti
    Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova

The IFMIF-EVEDA (Engineering Validation and Engineering Design Activities) project foresees the construction of a high intensity deuteron accelerator up to 9 MeV, with the characteristics required for the actual IFMIF facility. The linac will be installed in Rokkasho, and INFN is in charge of the construction of a 5 MeV, 125 mA, deuteron RFQ operating at 175 MHz. In this article the beam dynamics design of this challenging RFQ is described, namely the design, the main outcomes in terms of beam particles physics, and finally the study of mechanical and rf field error tolerances. The RFQ design method has been aimed to the optimization of the voltage and R0 law along the RFQ, the accurate tuning of the maximum surface field and the enlargement of the acceptance in the final part of the structure. As a result this RFQ is characterized by a length shorter than in all previous design, very low losses (especially at higher energy) and small rf power dissipation.

MOP054 Experience with Stripping Carbon Foils in ALPI Super-Conducting Accelerator cavity, ion, target, linac 199
  • P.A. Posocco
    Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova
  • D. Carlucci, A. Pisent, M. Poggi, P.A. Posocco
    INFN/LNL, Legnaro, Padova

The superconducting linac ALPI, injected either by a XTU tandem or by the superconducting RFQ of PIAVE, is composed by 3 cryostats of bulk Nb cavities (β=0.056) and 13 cryostats of Nb sputtered on Cu cavities (β=0.11 and β=0.13), for a total of 64 cavities and an equivalent voltage of 35MV. The linac is build up in two branches connected by an achromatic and isochronous U-bend. In January 2007 a stripping station equipped with carbon foils of different thickness was placed after 6 cryostats, before the U-bend, to test the feasibility of acceleration and transport of a charge enhanced beam. The study was performed with 4 different beams (Ca, Ar, Zr and Xe) and a complete data analysis has been carried out.

MOP060 Quality Improvement of Laser-produced Protons by Phase Rotation and its Possible Extension to High Energies laser, proton, ion, cavity 214
  • A. Noda, Y. Iwashita, H. Souda, H. Tongu, A. Wakita
    Kyoto ICR, Uji, Kyoto
  • H. Daido, M. Ikegami, H. Kiriyama, M. Mori, M. Nishiuchi, K. Ogura, S. Orimo, A. Sagisaka, A. Yogo
    JAEA/Kansai, Kizu-machi Souraku-gun Kyoto-fu
  • A. Pirozhkov
    JAEA, Ibaraki-ken
  • T. Shirai
    NIRS, Chiba-shi

Funding: This work is supported by Advanced Compact Accelerator project by MEXT of Japanese Government and 21COE of Kyoto University, Center for Diversity and Universality in Physics.
By the phase rotation with the use of rf electric fields created by two gap resonator synchronous to a pulse laser, the energy spread of the laser-produced ions can be reduced*. In addition, owing to the curved structure of the electric field line in the gaps of the phase rotator, radial focusing effect is found also to exist. In order to extend the applicable energy of the phase rotation to the region where such laser produced protons can be directly applied for cancer therapy, multi-gap resonator with higher frequency has been proposed. By controlling the relative phases between the pulse laser and the electric fields in the gaps of phase rotator, we can create peaks in the energy spectrum simultaneously focusing in the radial direction.

* Japanese Journal of Applied Physics (Express Letter), 46 (2007) L717-L720

MOP069 Beam Dynamics Simulations for a 15 MeV Superconducting Electron Linac Coupled to a DC Photo-Injector cathode, simulation, target, solenoid 236
  • D. Guilhem, J.-L. Lemaire, S.J. Pichon
    CEA, Bruyeres-le-Chatel

A 15 MeV accelerator scheme based on a dc photo-injector and a rf superconducting linac as been proposed as a new facility for radiography applications. The overall beam dynamics simulation process based on SUPERFISH and PARMELA codes will be reviewed. We present the results for the following beam operating conditions; acceleration of limited number of bunches, up to twenty electron micro-pulses of 100 ps time duration and 200 nC bunch charge, at 352 MHz repetition rate.

MOP076 Integration of Fringe Field Alpha Magnets into the V-Code Beam Dynamics Simulation Tool simulation, multipole, dipole, electron 254
  • S. Franke, W. Ackermann, B. Steiner, T. Weiland
    TEMF, TU Darmstadt, Darmstadt
  • J. Enders, C. Heßler, Y. Poltoratska
    TU Darmstadt, Darmstadt

Funding: This work was partially funded by DESY Hamburg and DFG (SFB 634).
At the Superconducting DArmstadter LINear Accelerator (S-DALINAC) a new 100 keV polarized electron source is currently being installed. Therefore, a new low energy injection concept has to be designed. One of the main components of the injector are a polarized electron source, an alpha magnet and a Wien filter used for spin rotation as well as various beam forming elements. Fast beam dynamics simulations can advantageously assist the design process because of the flexible parameter variations combined with nearly simultaneous solution responses. Based on the moment approach a fast tracking code named V-Code has been implemented at TEMF. In order to simulate the entire injector an alpha magnet model was added to the V-Code database of beam line elements. In this paper a summary of issues regarding the implementation complemented with simulation results will be provided.

MOP079 Development of Modulating Permanent Magnet Sextupole Lens for Focusing of Pulsed Cold Neutrons neutron, sextupole, dipole, permanent-magnet 263
  • M. Yamada, H. Fujisawa, M. Ichikawa, Y. Iwashita, H. Tongu
    Kyoto ICR, Uji, Kyoto
  • P. Geltenbort
    ILL, Grenoble
  • K. Hirota, Y. Otake, H. Sato
    RIKEN, Wako, Saitama
  • T. Ino, K. Mishima, T. Morishima, S. Mutou, H.M. Shimizu, K. Taketani
    KEK, Ibaraki
  • Y. Kamiya, S. Kawasaki, S. Komamiya, H. Otono, S. Yamashita
    University of Tokyo, Tokyo
  • T. Oku, K. Sakai, T. Shinohara, J. Suzuki
    JAEA, Ibaraki-ken
  • Y. Seki
    Kyoto University, Kyoto
  • T. Yoshioka
    ICEPP, Tokyo

We are developing a modulating permanent magnet sextupole lens to focus pulsed cold neutrons. 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 nested co-axial rings, where the inner ring is fixed and the outer ring can be rotated. Synchronizing the modulation with neutron beam pulse suppresses the chromatic aberration. These devices largely improve the utilization efficiency of neutrons, which makes even small linac based neutron sources practical. We have fabricated a half-scale model and studied its strength, torque and temperature rise during the operation. The main causes of the temperature rise are eddy-current loss in the poles made of soft magnetic material in inner ring and hysteresis loss. A laminated structure reduced the eddy-current loss. The temperature rise was suppressed to about half of the former model. We now study their B-H curve to optimize the thickness of the sheet. Annealing of the material is supposed to reduce the hysteresis loss, which will be tested soon. The experimental results of very-cold neutrons focusing with the half-scale model are also described.


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MOP102 Electron Beam Dynamics in the DARHT-II Linear Induction Accelerator electron, induction, dipole, impedance 311
  • C. Ekdahl, E.O. Abeyta, P. Aragon, R.D. Archuleta, G.V. Cook, D. Dalmas, K. Esquibel, R.J. Gallegos, R.W. Garnett, J.F. Harrison, E.B. Jacquez, J.B. Johnson, B.T. McCuistian, N. Montoya, S. Nath, K. Nielsen, D. Oro, L.J. Rowton, M. Sanchez, R.D. Scarpetti, M. Schauer, G.J. Seitz, H.V. Smith, R. Temple
    LANL, Los Alamos, New Mexico
  • H. Bender, W. Broste, C. Carlson, D. Frayer, D. Johnson, C.-Y. Tom, C.P. Trainham, J.T. Williams
    NSTec, Los Alamos, New Mexico
  • T.C. Genoni, T.P. Hughes, C.H. Thoma
    Voss Scientific, Albuquerque, New Mexico
  • B.A. Prichard, M.E. Schulze
    SAIC, Los Alamos, New Mexico

Funding: Work supported by USDOE under contract DE-AC52-06NA25396
The DARHT-II linear induction accelerator (LIA) accelerates a 2 kA electron beam to more than 17 MeV. The beam pulse has a greater than 1.5-microsecond flattop region over which the electron kinetic energy is constant to within 1%. The beam dynamics are diagnosed with 21 beam-position monitors located throughout the injector, accelerator, and after the accelerator exit, where we also have beam imaging diagnostics. I will discuss the tuning of the injector and accelerator, and I will present data for the resulting beam dynamics. Beam motion at the accelerator exit is undesirable for its application as a bremsstrahlung source for multi-pulse radiography of explosively driven hydrodynamic experiments. I will discuss the tuning procedures and other methods we use to minimize beam motion, and to suppress the beam-breakup (BBU) and ion-hose instabilities*.

*"Long-pulse beam stability experiments on the DARHT-II linear induction accelerator", Carl Ekdahl, et al., IEEE Trans. Plasma. Sci. Vol. 34, 2006, pp. 460-466.

MOP108 Phase Law of a High Intensity Superconducting Linac cavity, optics, linac, beam-losses 328
  • D. Jeon, J. Galambos
    ORNL, Oak Ridge, Tennessee

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The importance of a proper phase law is recognized to tune the synchronous phase of each superconducting cavities of a high intensity proton linac such as the SNS linac. The factors to be optimized are:

  1. maximizing the longitudinal acceptance
  2. better matching throughout the linac and
  3. achieving maximum beam energy.
The driving force behind this study is how to effectively control the large voltage fluctuation from cavity to cavity, achieving low beam loss and high beam quality.

TUP077 Development of Screen Monitor with a Spatial Resolution of Ten Micro-meters for XFEL/SPring-8 electron, target, vacuum, undulator 573
  • K. Yanagida, H. Tomizawa, A. Yamashita
    JASRI/SPring-8, Hyogo-ken
  • S.I. Inoue, Y. Otake
    RIKEN/SPring-8, Hyogo

At SPring-8, the 8 GeV linac for an X-ray free electron laser (XFEL) is now under construction. In order to realize the XFEL, highly qualified electron beams are required. A measurement of spatial structure of such beam is very important for the beam tuning of XFEL. The spatial structure is measured with a screen monitor, which we now develop. The resolution of the measurement is required within 10 um. The screen monitor comprises a vacuum chamber with a thin metal (100 um, SUS) foil to emit OTR, lenses for focusing and a CCD camera system. The main feature of the monitor is a bright and high-resolution optical system. In order to realize this system, the lenses are placed close to the foil, the distance between the lenses and the foil is 100 mm, and the lenses have a large diameter (2 in.). This optical-geometrical structure also contributes much to reduce the airy radius of a near field image. Although the range of an observation wavelength is wide as which is form 400 to 800 nm, the resolution of the measurement on the foil is calculated as 2.5 um. The experimental data of the developed screen monitor also suggested the same resolution.

TH203 Beam Compression in Heavy-Ion Induction Linacs plasma, target, ion, solenoid 754
  • P.A. Seidl, A. Anders, F.M. Bieniosek, A.X. Chen, J.E. Coleman, J.-Y. Jung, M. Leitner, S.M. Lidia, B.G. Logan, P.N. Ni, P.K. Roy, K. Van den Bogert, W.L. Waldron
    LBNL, Berkeley, California
  • J.J. Barnard, R.H. Cohen, D.P. Grote
    LLNL, Livermore, California
  • J.A. Calanog
    UCB, Berkeley, California
  • M. Dorf, E.P. Gilson
    PPPL, Princeton, New Jersey
  • D.R. Welch
    Voss Scientific, Albuquerque, New Mexico

Funding: This work was supported by the Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, DE-AC52-07NA27344, DE-AC02-76CH3073.
The Heavy-Ion Fusion Sciences Virtual National Laboratory is pursuing an approach to target heating experiments in the Warm Dense Matter regime, using space-charge-dominated ion beams that are simultaneously longitudinally bunched and transversely focused. Longitudinal beam compression by large factors has been demonstrated in the LBNL Neutralized Drift Compression Experiment (NDCX) experiment with controlled ramps and forced neutralization. The achieved peak beam current and energy can be used in experiments that generate plasmas of warm dense matter. Using an injected 30 mA K+ ion beam with initial kinetic energy 0.3 MeV, axial compression leading to ~100X current amplification and simultaneous radial focusing to beam radii of a few mm have led to encouraging energy deposition approaching the intensities required for eV-range target heating experiments. We discuss the status of several improvements to the experiment and associated beam diagnostics that are under development to reach the necessary higher beam intensities.


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TH301 Beam Dynamics Studies of the 8 GeV Linac at FNAL linac, cavity, simulation, proton 760
  • P.N. Ostroumov, B. Mustapha
    ANL, Argonne
  • J.-P. Carneiro
    Fermilab, Batavia

Funding: This work was supported by the U.S. Department of Energy, Office of Scince, under contracts number DE-AC02-06CH11357 and No. W-31-109-ENG-38.
The proposed 8 GeV proton driver (PD) linac at FNAL includes a front end up to ~420 MeV and a high energy section operating at 325 MHz and 1300 MHz respectively. A normal conducting RFQ and short H-type resonators are being developed for the initial acceleration of the H-minus or proton beam up to 10 MeV. From 10 MeV to ~420 MeV the voltage gain is provided by SC spoke-loaded cavities. In the high-energy section, the acceleration will be provided by the International Linear Collider (ILC)-style SC elliptical cell cavities. To employ the existing readily available klystrons, an rf power fan out from high-power klystrons to multiple cavities is being developed. The beam dynamics simulation code TRACK available in both serial and parallel versions has been updated to include H-minus stripping due to all known mechanisms to predict the exact location of beam losses. An iterative procedure has been developed to interact with the transient beam loading model taking into account feedback and feedforward systems applied for the rf distribution from one klystron to multiple cavities.


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TH302 Transport Limits in Periodic Focusing Channels simulation, lattice, space-charge, beam-transport 765
  • S.M. Lund
    LLNL, Livermore, California

It has been empirically observed in both experiments and particle-in-cell simulations that space-charge-dominated beams suffer strong growth in emittance and particle losses in alternating gradient quadrupole transport channels when the undepressed phase advance increases beyond about 85 degrees per lattice period. Although this criterion has been used extensively in practical designs of strong focusing intense beam transport lattices, the origin of the limit has not been understood. We propose a mechanism for the transport limit resulting from strongly chaotic classes of halo particle resonances near the core of the beam that allow near-edge particles to rapidly increase in oscillation amplitude when the space-charge intensity and the flutter of the matched beam envelope are both sufficiently large. A core particle model is applied to parametrically analyze this process and the results are compared with extensive particle simulations.


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THP071 Efficient Low-Beta H-Mode Accelerating Structures with PMQ Focusing cavity, linac, beam-losses, quadrupole 954
  • S.S. Kurennoy, J.F. O'Hara, E.R. Olivas, L. Rybarcyk
    LANL, Los Alamos, New Mexico

We are developing high-efficiency room-temperature rf accelerating structures for beam velocities in the range of a few percent of the speed of light by merging two well-known ideas: H-mode cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we have found that the H-mode structures with PMQ focusing provide a very efficient and practical accelerator for light-ion beams of considerable currents. Such accelerating structures following a short RFQ can be used in the front end of ion linacs or in stand-alone applications such as a compact deuteron-beam accelerator up to the energy of a few MeV.


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FR202 Linacs for Future Muon Facilities linac, optics, acceleration, cavity 1119
  • S.A. Bogacz
    JLAB, Newport News, Virginia
  • R.P. Johnson
    Muons, Inc, Batavia

Funding: Supported in part by DOE STTR grant DE-FG02-05ER86253
Neutrino Factories and Muon Colliders require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculated Linear Accelerator (RLA) that uses a single Linac and teardrop return arcs (the so called 'Dogbone' RLA) can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. Since muons are generated as a tertiary beam they occupy large phase-space volume and the accelerator must provide very large transverse and longitudinal acceptances. The above requirements drive the design to low rf frequency. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the rf cavities, leading to greater cost effectiveness. We are developing the optics and technical requirements for RLA designs, using superconducting rf cavities capable of simultaneous acceleration of both μ+ and μ- species, with pulsed Linac quadrupoles to allow the maximum number of passes.


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