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resonance

 
Paper Title Other Keywords Page
MOPCH024 Future Seeding Experiments at SPARC FEL, undulator, laser, radiation 95
 
  • L. Giannessi, S. Ambrogio, F. Ciocci, G. Dattoli, A. Doria, G.P. Gallerano, E. Giovenale, M. Quattromini, A. Renieri, C. Ronsivalle, I.P. Spassovsky
    ENEA C.R. Frascati, Frascati (Roma)
  • D. Alesini, M.E. Biagini, R. Boni, M. Castellano, A. Clozza, A. Drago, M. Ferrario, V. Fusco, A. Gallo, A. Ghigo, M. Migliorati, L. Palumbo, C. Sanelli, F. Sgamma, B. Spataro, S. Tomassini, C. Vaccarezza, C. Vicario
    INFN/LNF, Frascati (Roma)
  • M. Bougeard, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Salieres, O. Tcherbakoff
    CEA, Gif-sur-Yvette
  • M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • A. Dipace, E. Sabia
    ENEA Portici, Portici (Napoli)
  • M. Mattioli, P. Musumeci, M. Petrarca
    Università di Roma I La Sapienza, Roma
  • M. Nisoli, G. Sansone, S. Stagira, S. de Silvestri
    Politecnico/Milano, Milano
  • L. P. Poletto, G. T. Tondello
    Univ. degli Studi di Padova, Padova
  • L. Serafini
    INFN-Milano, Milano
  Sources based on High order Harmonics Generated in gases (HHG) with high power Ti:Sa lasers pulses represent promising candidates as seed for FEL amplifiers for several reasons, as spatial and temporal coherence, wavelength tunability and spectral range, which extends down to the nm wavelength scale. This communication describes the research work plan that is under implementation at the SPARC FEL facility in the framework of the EUROFEL programme. The main goal of the collaboration is to study and test the amplification and the FEL harmonic generation process of an input seed signal obtained as higher order harmonics generated both in crystals (400 nm and 266 nm) and in gases (266 nm, 160 nm, 114 nm). The SPARC FEL can be configured to test several cascaded FEL layouts that will be analysed in this contribution.  
 
MOPCH089 Basic Aspects of the SIS100 Correction System Design dipole, quadrupole, lattice, sextupole 240
 
  • V.A. Mikhaylov, A.V. Alfeev, A.V. Butenko, A.V. Eliseev, H.G. Khodzhibagiyan, A.D. Kovalenko, O.S. Kozlov, V.V. Seleznev, A.Y. Starikov, V. Volkov
    JINR, Dubna, Moscow Region
  • E. Fischer, P.J. Spiller, J. Stadlmann
    GSI, Darmstadt
  The basic concept and the main design features of the superconducting SIS100 correction system are presented. The system comprises 84 steerer magnets consisting of two orthogonal dipole windings each for correction of the beam close orbit in vertical and horizontal planes, 48 normal sextupole windings connected in two families with opposite polarities for chromaticity correction and 12 units containing skew quadrupoles, normal and skew sextupoles and octupoles as well. The correction system should operate in a pulse mode corresponding to the accelerator cycle, i.e., up to 1 Hz. The main magnetic, geometrical and electrical parameters of the corrector magnets were specified. They are based on the beam dynamic analysis within the frames of the DF-type SIS100 lattice at different betatron tune numbers and tolerable alignment and manufacturing errors of the main lattice dipole and quadrupole magnets. The problem of reasonable unification of the corrector modules is discussed also, including their geometrical sizes, maximum supply current and cooling at 4.5 K. The concept of the SIS100 corrector magnets is based on the pulsed correctors designed for the Nuclotron.  
 
MOPCH100 Polarized Proton Acceleration in the AGS with Two Helical Partial Snakes polarization, AGS, injection, extraction 273
 
  • H. Huang, L. Ahrens, M. Bai, A. Bravar, K.A. Brown, E.D. Courant, C.J. Gardner, J. Glenn, A.U. Luccio, W.W. MacKay, V. Ptitsyn, T. Roser, S. Tepikian, N. Tsoupas, J. Wood, K. Yip, A. Zelenski, K. Zeno
    BNL, Upton, Long Island, New York
  • F. Lin
    IUCF, Bloomington, Indiana
  • M. Okamura, J. Takano
    RIKEN, Saitama
  Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and it is not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results. The effect of horizontal intrinsic resonances in the presence of two partial snakes are also discussed.  
 
MOPCH115 Transverse Space Charge Studies for the ISIS Synchrotron space-charge, synchrotron, simulation, focusing 312
 
  • C.M. Warsop
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. It is based on a 50 Hz proton synchrotron which, once the commissioning of a new dual harmonic RF system is complete, will accelerate about 3.5·1013 protons per pulse from 70 to 800 MeV, corresponding to mean beam powers of 0.2 MW. Following this upgrade, transverse space charge is expected to be one of the main intensity limitations, and is also a key factor for further machine upgrades. A programme of R&D on transverse space charge is now under way, aiming not only to improve the ISIS ring but also to exploit it as an experimental tool for testing theory and codes. This paper summarises work so far, outlining calculations for coherent envelope modes on ISIS, using numerical solutions of the envelope equation to show the expected behaviour near half integer resonance. Progress on work linking these predictions with more realistic beam models in space charge codes, and extending calculations to images, coupling and non linear resonances will be described. Plans and preparations for experiments, along with initial results, will also be presented.  
 
MOPCH140 Compensation of Lorentz Force Detuning of a TTF 9-cell Cavity with a New Integrated Piezo Tuner TTF, klystron, controls, feedback 378
 
  • G. Devanz, P. Bosland, M. Desmons, E. Jacques, M. Luong, B. Visentin
    CEA, Gif-sur-Yvette
  The high gradient operation of superconducting elliptical multicells in pulsed mode is required for linear colliders or free-electron lasers based on the superconducting technology. Such an operation is limited by dynamic Lorentz force detuning if no compensation for this effect is attempted. The RF power headroom required for accelerating field amplitude and phase stabilisation by low-level RF control techniques solely would be too costly. A new active tuner with integrated piezo actuators has been developped in the framework of the european CARE/SRF program solve this issue. The design is based on the lever-arm concept of the Saclay tuner already installed on running TTF cavities. We have carried out integrated tests of the 9-cell cavity equipped with the piezo tuner and power coupler in the CryHoLab horizontal test cryostat. Characterisation of the electromechanical system consisting of the cavity and piezo-tuner assembly and full power pulsed tests will be presented.  
 
MOPCH149 Microphonics Measurements in a CW-driven TESLA-type Cavity cryogenics, klystron, pick-up, linac 405
 
  • O. Kugeler, W. Anders, J. Knobloch, A. Neumann
    BESSY GmbH, Berlin
  Superconducting cavities with a high quality factor exhibit a very low bandwidth in their resonant frequency, which makes their operation very sensitive to mechanical oscillations. In CW mode of operation, as is intended for the BESSY-FEL Linac, microphonics are therefore the dominant error source for field stability. In order to compensate the detuning, it is necessary to properly characterize amplitude and frequency with respect to all involved mechanical and electrical components. Such measurements have been performed at the HoBiCaT test facility at BESSY and will be described in detail.  
 
MOPCH150 Characterization of a Piezo-based Microphonics Compensation System at HoBiCaT controls, TESLA, FEL, linac 408
 
  • A. Neumann, W. Anders, S. Klauke, J. Knobloch, O. Kugeler, M. Schuster
    BESSY GmbH, Berlin
  In the superconducting driver linac for the BESSY FEL, piezo actuators will be utilized to rapidly counteract the detuning of the cavity resonance caused by nm mechanical oscillations (microphonics). This is of importance to guarantee field stability and lower the power consumption of the RF system for the superconducting cavities. To design a suitable compensator, mechanical and electro-mechanical transfer functions, as well as the tuning range of the system under operating conditions have been measured and will be presented.  
 
MOPCH152 A Pulsed-RF High-power Processing Effect of Superconducting Niobium Cavities observed at the ELBE Linear Accelerator controls, ELBE, radiation, linac 413
 
  • U. Lehnert, H. Buettig, P. Michel, Ch. Schneider, R. Schurig
    FZR, Dresden
  • A. Buechner, F.G. Gabriel
    FZR/FWFE, Dresden
  The driver LINAC of the ELBE radiation source is built for cw operation. However, in some cases a pulsed-mode operation was desired to extend the otherwise stringent gradient limits. The main restriction results from field emission that decreases the Q of the cavities which was evaluated from measurements of the liquid helium consumption. After pulsed-mode operation with gradients exceeding the maximum cw accelerating gradients by 30–40\% a significant reduction in the field emission was observed. This in turn allows higher accelerating gradients to be used in cw as well. We attribute this behaviour to an rf-processing of the cavity surface which burns off field emitters.  
 
MOPCH158 HIPPI Triple-spoke Cavity Design simulation, electron, gun, vacuum 427
 
  • E. Zaplatin, M. Pap, R. Tölle
    FZJ, Jülich
  In the frames of the European project of High Intensity Pulsed Proton Injector (HIPPI) the 352 MHz, beta=0.48 triple-spoke cavity is under development and will be built at the research center FZJ in Juelich. The criteria and results of the cavity RF and structural analyses are presented.  
 
MOPLS022 On the Feasibility of Polarized Heavy Ions in RHIC ion, RHIC, proton, heavy-ion 586
 
  • W.W. MacKay
    BNL, Upton, Long Island, New York
  Heavy nonspherical ions such as uranium have been proposed for collisions in RHIC. When two such ions collide with their long axes aligned, then the plasma density might be as much as 60% higher. Since the collisions might have any orientation of the two nuclei, the alignment of the nuclei must be inferred from a complicated unfolding of multiplicity distributions. Instead, if it is possible to polarize the ions and control the orientation in RHIC, then a much better sensitivity could be obtained. This paper investigates the manipulation of such polarized ions with highly distorted shapes in RHIC. Several ion species are considered as possibilities with either full or partial Siberian snakes in RHIC.  
 
MOPLS038 Beam Energy Calibration in Experiment on Precise Tau Lepton Mass Measurement at VEPP-4M with KEDR Detector energy-calibration, lepton, polarization, electron 625
 
  • A. Bogomyagkov, V.E. Blinov, S. Karnaev, V. Kiselev, E.V. Kremyanskaya, E. Levichev, O.I. Meshkov, S.I. Mishnev, I. Morozov, N.Yu. Muchnoi, S.A. Nikitin, I.B. Nikolaev, A.G. Shamov, D.N. Shatilov, E.A. Simonov, A.N. Skrinsky, V.V. Smaluk, Yu.A. Tikhonov, G.M. Tumaikin, V.N. Zhilich
    BINP SB RAS, Novosibirsk
  Experiment on mass measurement of tau lepton requires an absolute energy calibration. The resonant depolarization technique is used for most accurate (1 keV) but once at a time energy calibration. The measured energy is used for calibration of the germanium detector for Compton backscattering energy monitoring. The developed Compton backscattering facility allows continuous energy monitoring with accuracy of 50 keV for 10 minutes of data acquisition. The tau lepton threshold is in the vicinity of integer spin resonance, which minimizes polarization lifetime in the presence of vertical orbit distortions. Therefore, spin matching of the VEPP-4M is required. The achieved lifetime is sufficient for absolute energy calibration.  
 
MOPLS063 Accelerator Component Vibration Studies and Tools quadrupole, TESLA, DESY, vacuum 688
 
  • R. Amirikas, A. Bertolini, W. Bialowons
    DESY, Hamburg
  This talk will cover a research program on accelerator component vibrations. Ground motion and technical noise, such as vacuum and refrigeration systems, couple to the beam, mainly via quadrupoles, making the design of their supports, especially, in the case of the superconducting magnets, critical. This program includes investigation of cold mass vibration of the superconducting quadrupoles inside an accelerating module and sensor performance in the main or fringe field of a linear collider detector. Seismometer accuracy limitations in correlated ground motion measurements are also being investigated.  
 
MOPLS076 The Stimulated Breit-Wheeler Process as a Source of Background e+e- Pairs at the ILC photon, electron, background, electromagnetic-fields 727
 
  • A.F. Hartin, A.F. Hartin
    OXFORDphysics, Oxford, Oxon
  Passage of beamstrahlung photons through the bunch fields at the interaction point of the ILC determines background pair production. The number of background pairs per bunch crossing due to the Breit-Wheeler, Bethe-Heitler and Landau-Lifshitz processes is well known. However the Breit-Wheeler process also takes place in and is modified by the bunch fields. A full QED calculation of this Stimulated Breit-Wheeler process reveals cross section resonances due to the virtual particle reaching the mass shell. The one loop Electron Self energy in the bunch field is also calculated and included as a radiative correction. The bunch field is considered to be a contant crossed electromagnetic field with associated bunch field photons. Resonance is found to occur whenever the energy of contributed bunch field photons is equal to the beamstrahlung photon energy. The Stimulated Breit-Wheeler cross section exceeds the ordinary Breit-Wheeler cross section by several orders of magnitude and a significantly different pair background may result.  
 
TUPCH032 Precise Measurements of the Vertical Beam Size in the ANKA Storage Ring with an In-air X-ray Detector synchrotron, electron, radiation, photon 1073
 
  • A.-S. Müller, I. Birkel, E. Huttel, P. Wesolowski
    FZK, Karlsruhe
  • K.B. Scheidt
    ESRF, Grenoble
  A major part of the X-rays generated in the ANKA dipole magnets is unused by the experimental beamlines and is, on a number of dipoles, absorbed in a conical shaped Copper absorber. The 8 mm thickness that it presents lets a tiny fraction of the hard X-rays above 70KeV enter the free air space behind it. The transmitted power of only a few uW/mrad hor. is sufficient to be detected, with sub-second measurement time, by a novel In-Air X-ray detector. This extremely compact and low-cost device is situated just behind the absorber. The design, developed and in use at the ESRF, is based on a Cadmium Tungstenate (CdWO4) scintillator converting X-rays into visible light that is collected and focused onto a commercial CCD camera. Since the small vertical divergence of the high energy photons and the distance of the detector from the source point are known, it is possible to derive the vertical electron beam size with a high intrinsic precision. This paper presents results of beam size measurements as a function of various ANKA machine parameters, that illustrates the great diagnostic potential of this type of detector for a 2.5GeV medium energy light source like ANKA.  
 
TUPCH082 The EuroTeV Confocal Resonator Monitor Task coupling, CTF3, pick-up, vacuum 1202
 
  • V.G. Ziemann, T. J. C. Ekelof, A. Ferrari, M. A. Johnson, E. A. Ojefors, A. B. Rydberg
    UU/ISV, Uppsala
  • F. Caspers
    CERN, Geneva
  We describe the progress in the analysis of the confocal resonator monitor task which is part of the diagnostics workpackage of EuroTeV. The initial design was analyzed both numerically and experimentally and found limitations. We therefore digressed from strict confocality and report the numerical analysis and S-parameter measurements of a modified design. Furthermore, we discuss the mechanical design needed for planned tests with beam in CTF3 which requires integration of the monitor into the beam pipe, damping of trapped modes, and frequency tunability.  
 
TUPCH118 Manufacturing and Testing of 2.45 GHz and 4.90 GHz Biperiodic Accelerating Structures for MAMI C coupling, MAMI, vacuum, SLAC 1292
 
  • A. Jankowiak, O. Chubarov, H. Euteneuer
    IKP, Mainz
  • K. Dunkel, C. Piel, H. Vogel, P. vom Stein
    ACCEL, Bergisch Gladbach
  At the Institut fur Kernphysik (IKPH) of Mainz University the fourth stage of the Mainz Microtron (MAMI), a 855MeV to 1500MeV Harmonic Double Sided Microtron*, is now on the verge of first operation. For this project ACCEL Instruments GmbH manufactured biperiodic, on axis coupled, standing wave accelerating structures at the frequencies of 2.45GHz and 4.90GHz. Four resp. eleven multicell sections were manufactured, low power characterized and after delivery tested at the high power test stand of IKPH. This paper describes the production and characterization of these structures, presents results of the high power tests, and compares these data with results gained at IKPH for an in house built 4.90GHz prototype and the 2.45GHz structures built in the 1980s.

*A. Jankowiak et al. "Design and Status of the 1.5 GeV-Harmonic Double Sided Microtron for MAMI", Proceedings EPAC2002, Paris, p. 1085.

 
 
TUPCH121 The IASA Cooling System for the 10 MeV Linac controls, linac, klystron, microtron 1298
 
  • A. Karabarbounis, D. Baltadoros, T. Garetsos, C.N. Papanicolas, E. Stiliaris
    IASA, Athens
  • A. Zolfaghari
    MIT, Middleton, Massachusetts
  A de-ionized water cooling system for the IASA room temperature 10 MeV CW Linac has been constructed and successfully installed. Commissioning is undergoing achieving resistivity larger to 5M?cm with a temperature accuracy of for all three linacs. Three ways mixing valves with a stepping capability of one thousand different mixing steps fulfill independently for each section the required temperature stability and the appropriate resonance frequency to our cavities. The RF requirements for the three linacs is 190kW provided by a single high power klystron tube capable to deliver up to 500 kW CW at 2380 MHz. The klystron is been cooled with a parallel similar cooling system and a third system cools our Aluminum waveguide complex. In this paper we will present the design, specifications and results of our preliminary tests. A sophisticated control and interlock system based on EPICS guarantees the proper functioning of the system.  
 
TUPCH147 High Pressure RF Cavities in Magnetic Fields pick-up, klystron, vacuum, ion 1364
 
  • P.M. Hanlet, M. Alsharo'a, R. E. Hartline, R.P. Johnson, M. Kuchnir, K. Paul
    Muons, Inc, Batavia
  • C.M. Ankenbrandt, A. Moretti, M. Popovic
    Fermilab, Batavia, Illinois
  • D.M. Kaplan, K. Yonehara
    Illinois Institute of Technology, Chicago, Illinois
  A study of RF breakdown in pressurized cavities immersed in strong magnetic fields has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 805 MHz test cell is being used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, and beryllium electrodes as functions of hydrogen and helium gas densities and magnetic field strength. These results will be compared to the predicted or known RF breakdown behavior of these metals in vacuum with and without external magnetic fields.  
 
TUPCH190 Universal Controller for Digital RF Control controls, klystron, beam-loading, feedback 1459
 
  • S. Simrock
    DESY, Hamburg
  • W. Cichalewski, M.K. Grecki, G.W. Jablonski
    TUL-DMCS, Lodz
  • W.J. Jalmuzna
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw
  Digital RF control systems allow to change the type of controller by programming of the algorithms executed in FPGAs and/or DSPs. It is even possible to design a universal controller where the controller mode is selected by change of parameters. The concept of a universal controller includes the self-excited-loop (SEL) and generator driven resonator (GDR) concept, the choice of I/Q and amplitude or phase control, and allows for different filters (including Kalman filter and method of optimal controller synthesis) to be applied. Even time-varying mixtures of these modes are possible. Presented is the implementation of such a controller and the operational results with a superconducting cavity.  
 
TUPCH194 Analogue and Digital Low Level RF for the ALBA Synchrotron controls, synchrotron, shielding, linac 1468
 
  • F. Pérez, H. Hassanzadegan, A. Salom
    ALBA, Bellaterra
  ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. Two LLRF prototypes are being developed in parallel, both following the IQ modulation/demodulation technique. One is fully based on analogue technologies; the other is based on digital FPGA processing. The advantages of the IQ technique will be summarised and the control loop logic described. The hardware implementation in analogue as well as in digital format will be presented and first test results shown. The implementation of the same logic with both technologies will give us a perfect bench to compare, and use the better of them, for the final LLRF of the ALBA synchrotron.  
 
TUPLS024 FFAGs as Muon Accelerators for a Neutrino Factory emittance, acceleration, alignment, beam-losses 1541
 
  • S. Machida
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  The FFAG accelerator is a solution for rapid acceleration of muons because of its large aperture and no need of magnet ramping. Its particle dynamics is, however, peculiar due to high energy gain per turn and large transverse amplitude, which has not been seen in other types of circular accelerators. One variation of FFAG, called non-scaling FFAG, employs quite new scheme, namely, out of bucket acceleration. We studied emittance distortion, coupled motions among 3-D planes, effects of resonance lines, etc., based on a newly developed tracking code. In this paper, we will emphasize new regime of particle dynamics as well as a modeling technique of FFAG.  
 
TUPLS037 The Frankfurt Funneling Experiment rfq, ion, ion-source, simulation 1574
 
  • U. Bartz, D. Ficek, N. Mueller, A. Schempp, J. Thibus, M. Vossberg
    IAP, Frankfurt-am-Main
  The goal of the Frankfurt Funneling Experiment is to multiply beam currents of RFQ accelerators at low energies to avoid problems with space charge. The two beams from the ion sources are injected into two RFQ channels. The last part of the RFQ electrodes have been replaced to achieve a 3d focus at the crossing point of the two beam axis where the funneling deflector as a central peace of the experiment is located. The newly designed multi-cell deflector is adapted to the optimised funneling section. It is mechanically solid, easy to tune in and ready for operation. First measurements will be presented.  
 
TUPLS040 Tuning of a 4-rod CW-mode RFQ Accelerator rfq, acceleration, pick-up, vacuum 1583
 
  • P. Fischer, A. Schempp
    IAP, Frankfurt-am-Main
  A four-rod RFQ accelerator has been built which operates in CW mode with a power consumption of 250 kW. The assembly of a high power RFQ structure requires a precise mechanical alignment and field tuning of the electrode field. The field distribution must be very flat to enable a proper operation with few losses. Adjusting of the field distribution is critical in long structures. Simulations and the status of the tuned structure will be discussed.  
 
TUPLS042 First Cryogenic Tests of the Superconducting CH-structure cryogenics, GSI, pick-up, coupling 1588
 
  • H. Podlech, C. Commenda, H. Klein, H. Liebermann, U. Ratzinger, A.C. Sauer
    IAP, Frankfurt-am-Main
  The CH-structure is a new multi-cell drift tube structure operated in the TE21-mode and is well suited for the acceleration of low and medium beta ion and proton beams. Due to the mechanical stiffness room temperature as well as superconducting CH-cavities can be realised. A 19-cell, beta=0.1 superconducting CH-prototype cavity has been developed and built. First cryogenic tests have been performed at 4.5 K in Frankfurt successfully. An effective accelerating voltage of 3.6 MV has been achieved so far. This corresponds to an electric peak field of 23 MV/m. Actual measurements aim on a localisation of possible field emission centers, afterwards further surface preparation will take place.  
 
TUPLS073 Formulae for Linear-field Non-scaling FFAG Accelerator Orbits lattice, betatron, proton, ion 1666
 
  • M.K. Craddock
    UBC & TRIUMF, Vancouver, British Columbia
  • S.R. Koscielniak
    TRIUMF, Vancouver
  Non-scaling FFAG accelerators using constant-gradient F and D magnets with their fields decreasing outwards can compact ion orbits for a wide range of momentum (e.g., 1:2) into a narrow radial range. Designs to accelerate protons, ions and muons are currently being studied for proton drivers, cancer therapy facilities and neutrino factories. In this paper, analytic formulae are reported for some basic orbit properties, helping to make clear their dependence on the various design parameters and momentum. For the designs tested so far the numerical results are in excellent agreement with those obtained using lattice codes.  
 
TUPLS075 Design of the Flat-top Acceleration Cavity for the LNS Superconducting Cyclotron acceleration, cyclotron, extraction, simulation 1669
 
  • L.A.C. Piazza, D. Battaglia, L. Calabretta, A.C. Caruso, F. Consoli, M.M. Maggiore, D. Rifuggiato, A. Spartà
    INFN/LNS, Catania
  A 3rd harmonic Flat-top acceleration system for the K800 Superconducting Cyclotron of the Laboratori Nazionali del Sud (LNS) was designed to reduce the energy spread of the accelerated particles and to improve the beam quality and the extraction efficiency. The Flat-top effect is realized by the superposition of the 3rd harmonic to the fundamental acceleration frequency. The 3rd harmonic frequency is produced by an additional resonator, capacitively coupled to the K 800 cavities. The Flat-top cavity was designed with the 3D electromagnetic codes Ansoft HFSS and CST MicroWaveStudio.  
 
TUPLS079 Hadron Cancer Therapy Complex Employing Non-scaling FFAG Accelerator and Fixed Field Gantry Design acceleration, extraction, kicker, proton 1681
 
  • E. Keil
    CERN, Geneva
  • A. Sessler
    LBNL, Berkeley, California
  • D. Trbojevic
    BNL, Upton, Long Island, New York
  Non-scaling FFAG rings for cancer hadron therapy offer reduced physical aperture and large dynamic aperture as compared with scaling FFAGs. The variation of tune with energy implies the crossing of resonances during acceleration. Our design avoids intrinsic resonances, although imperfection resonances must still be crossed. We consider a system of three non-scaling FFAG rings for cancer therapy with 250 MeV protons and 400 MeV/u carbon ions. Hadrons are accelerated in a common RFQ and linear accelerator, and injected into the FFAG rings at v/c=0.1128. The H+/C6+ ions are accelerated in the two smaller/larger rings to 31 and 250 MeV/52.5 and 400 MeV/u kinetic energy, respectively. The lattices consist of symmetrical triplet cells with a straight section for RF cavities. The gantry with similar triplet cells accepts the whole required momentum range at fixed field. This unique design uses either High Temperature super-conductors or super-conducting magnets reducing gantry size and weight. Elements with a variable field at the beginning and at the end set the extracted beam at the correct position for the specific energy and adapt the beam to specific requirements during treatment.  
 
TUPLS099 The New 14 GHz Ion Source for the U-400 Heavy Ion Cyclotron ion, ion-source, plasma, cyclotron 1732
 
  • M. Leporis, V.B. Bekhterev, S.L. Bogomolov, A. Efremov, G. Gulbekyan, Yu.K. Kostyukhov, N. Lebedev, V.N. Loginov, Yu. Yazvitsky
    JINR, Dubna, Moscow Region
  The new 14 GHz ion source DECRIS-4, to be used as a second injector of heavy multiply charged ions for the U-400 cyclotron and, in the future, also as a "charge breeder" (the "1+ -> n+" method) for the second phase of the DRIBs project, has been designed and constructed at the FLNR. The main feature of the ion source design is the creation of the extended resonance zone in a comparatively compact ECRIS. For this purpose the axial magnetic field is formed with a flat minimum by mounting only one additional solenoid coil to the classical CAPRICE magnetic structure. In this case the superposition of the axial magnetic field and the radial field of the permanent magnet hexapole, made from NdFeB, allows one to create a larger resonance volume. First results of the ion source tests show that in this resonance volume electrons are heated very efficiently which allows to produce intense beams of medium charge state ions with comparatively low level of input microwave power. The basic design features, construction issues and the first results of ion source tests are presented.  
 
WEOFI01 Beam Dynamics Measurements in the Vicinity of a Half-integer Resonance betatron, emittance, beam-beam-effects, radiation 1902
 
  • T. Ieiri, J.W. Flanagan, H. Fukuma, H. Ikeda, Y. Ohnishi, K. Oide, M. Tobiyama
    KEK, Ibaraki
  The operating point of the betatron tune set near a half-integer is a crucial parameter to make high luminosity in electron/positron ring colliders. Dynamic beam-beam effects would change the optics parameters of the colliders, depending on the betatron tune and the beam-beam parameter. On the other hand, existence of the half-integer stopband makes the beam unstable. Therefore, beam behavior near a half-integer might provide interesting issues from the viewpoint of beam dynamics. We measured a frequency response of the beam across a half-integer for measuring the betatron tune at KEKB. A sharp spike just at a half-integer was observed in the tune spectrum. We believe that the spectrum would be a nonlinear resonance caused by some off-momentum particles in a bunch, not by a coherent motion of a whole bunch. The horizontal beam size measured using a synchrotron radiation monitor indicated a slight increase when the tune approached a half-integer. The variations in the beam size are discussed, considering both dynamic beam-beam effects and a beta beat due to the half-integer stopband.  
slides icon Transparencies
 
WEPCH004 Estimation of Transverse Coupling From Pinhole Images coupling, emittance, radiation, wiggler 1921
 
  • X.R. Resende, P.F. Tavares
    LNLS, Campinas
  The Brazilian Synchrotron Light Laboratory (LNLS) has recently started filling its storage ring straight sections with insertion devices. Last year a 2-Tesla Wiggler was successfully installed and integrated in the control system. An elliptically polarizing undulator is now under construction and scheduled to be installed in the next shutdown, by the end of the current year. The VUV beamline for the undulator is very demanding with respect to orbit stability and other beam parameters. Considerable reduction of the vertical emittance via reduction of the transverse coupling is a must in order for the undulator beamline to achieve its promised outstanding performance. In this paper we report on recent efforts to better understand the residual coupling in the machine and we describe preliminary proposals of viable solutions that aim at controlling the linear coupling within beamline specifications.  
 
WEPCH008 The Beta-beam Decay Ring Design injection, lattice, insertion, ion 1933
 
  • A. Chancé, J. Payet
    CEA, Gif-sur-Yvette
  The aim of the beta-beams is to produce highly energetic beams of pure electron neutrino and anti-neutrino, coming from beta radioactive decays of the 18Ne10+ and 6He2+, both at gamma = 100, directed towards experimental halls situated in the Frejus tunnel. The high intensity ion beams are stored in a ring until the ions decay. Consequently, all the injected particles will be lost anywhere in the ring, generating a high level of losses. The ring circumference has to be a multiple of the SPS circumference. The straight sections must be as long as possible in order to maximize the useful neutrino flux. The straight section length is chosen to be about 35% of the circumference length, which gives 1-km-long arcs. The bend field in the arcs is then reasonable. The arc has been chosen as a 2Pi phase advance insertion, which improves the optical properties (dynamic aperture and momentum acceptance) and allows the easy determination of the working point by the optics of the straight sections.  
 
WEPCH011 Optimisation of a New Lattice for the ESRF Storage Ring optics, quadrupole, lattice, ESRF 1942
 
  • A. Ropert, L. Farvacque
    ESRF, Grenoble
  The installation of canted undulators in some of the straight sections of the ESRF storage ring is envisaged in the future. In order to free maximum space in the straight sections and minimise the reduction in length of the undulators, a new lattice, in which the straight section quadrupole triplets are replaced by doublets, is being studied. The paper describes the main features of the lattice and presents the experimental results achieved so far.  
 
WEPCH024 Matrix Formulation for Hamilton Perturbation Theory of Linearly Coupled Betatron Motion betatron, coupling, lattice, storage-ring 1975
 
  • M. Takao
    JASRI/SPring-8, Hyogo-ken
  Linear coupled motion in a circular accelerator was successfully parametrized through the transfer matrix approach, where normal mode Twiss and coupling parameters are defined as an extension of Courand and Snyder formulation. However it is not straightforward to assign analytical expressions to the coupling parameters. On the other hand the coupled motion was analytically solved by the Hamilton perturbation theory, which ingeniously describes the resonance phenomena. In the perturbation theory, however, the symplectic structure of the coupled motion is obscure in turn. Hence, for the purpose of combining both the theories with each other with keeping the respective virtues, we develop the matrix formulation based on the Hamilton perturbation theory. Since we have already known the solution of equation of motion, we can construct the transfer matrix in terms of the solution. Thus we formulate the betatron motion with linear coupling resonance in analytic and symplectic manner. As an application of the formulation, we investigate the two-dimensional beam ellipse in an electron storage ring.  
 
WEPCH028 Position Shuffling of the J-PARC Main Ring Magnets sextupole, quadrupole, lattice, betatron 1984
 
  • M. Tomizawa, K. Fan, S. Igarashi, K. Ishii, H. Kobayashi, A.Y. Molodozhentsev, K. Niki, E. Yanaoka
    KEK, Ibaraki
  • Y. Irie
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Machida
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  The J-PARC 50GeV main ring has 96 dipole, 216 quadrupole with 11 families and 72 sextupole magnets with 3 families. Magnets installation in the tunnel started last year and will be planed to finish by the end of next fiscal year. Field measurements of all magnets will soon finish by this March. Deviations for BL, B'L, B"L in dipole, quadrupole and sextupole magnets make COD, beta beat and third integer stopband, respectively. They can be reduced by choosing a pair of magnets with similar field deviation and by positioning them so as to cancel each other considering betatron phase (shuffling). In this paper, we will report our shufflling scheme chosen under the given schedule for installation and field measurements and also will show performances expected by the shufflings.  
 
WEPCH038 Nonlinear Characteristics of the TME Cell emittance, betatron, sextupole, lattice 2002
 
  • V.A. Kvardakov, E. Levichev
    BINP SB RAS, Novosibirsk
  The TME (Theoretical Minimum Emittance) cell is being used now for designing the lattice of different storage rings (SR sources, damping rings, FFAG accelerators, etc.). Strong sextupoles required to correct the natural chromaticity of the lattice reduce the dynamic aperture. In the paper we consider the main features of the nonlinear perturbation strength and its connection with the essential lattice parameters: horizontal emittance, betatron tunes, and natural chromaticity. The analytical results are compared with the computer simulation.  
 
WEPCH045 Sorting Strategies for the Arc Quadrupoles of the LHC LHC, quadrupole, optics, simulation 2017
 
  • Y. Papaphilippou, A.M. Lombardi
    CERN, Geneva
  The variation in the field gradient of the LHC arc quadrupoles can not be corrected independently by the dedicated trim quadrupole circuits. This may result to a beta function beating larger than the one accepted by the machine budget. In this respect, sorting strategies for the installation of these magnets were implemented in order to eliminate this effect, as locally as possible. Special care was taken for quadrupoles whose warm measurements showed large gradient errors due to an excessive magnetic permeability. The figures of merit used in the sorting and the results obtained for all 8 sectors of the LHC are detailed. The global optics function beating foreseen, as computed by both analytical estimates and simulations with MAD-X are finally presented.  
 
WEPCH058 Progress with Collision Optics of the Fermilab Tevatron Collider optics, quadrupole, luminosity, lattice 2053
 
  • A. Valishev, Y. Alexahin, G. Annala, V.A. Lebedev, V.P. Nagaslaev
    Fermilab, Batavia, Illinois
  • V. Sajaev
    ANL, Argonne, Illinois
  Recent advances in the measurement and modeling of the machine parameters and lattice functions at the Tevatron allowed modifications of the collision optics to be performed in order to increase the collider luminosity. As the result, beta functions in the two collision points were decreased from 35cm to 29cm which resulted in ~10% increase of the peak luminosity. In this report we describe the results of optics measurements and corrections. We also discuss planned improvements, including the new betatron tune working point and correction of the beta function chromaticity.  
 
WEPCH064 Fast Compensation of Global Linear Coupling in RHIC using AC Dipoles coupling, quadrupole, RHIC, injection 2071
 
  • F. Franchi
    GSI, Darmstadt
  • R. Calaga
    BNL, Upton, Long Island, New York
  • R. Tomas
    CERN, Geneva
  Global linear coupling has been extensively studied in accelerators and several methods have been developed to compensate the coupling vector C using skew quadrupole families scans. However, scanning techniques can become very time consuming especially during the commissioning of an energy ramp. In this paper we illustrate a new technique to measure and compensate, in a single machine cycle, global linear coupling from turn-by-turn BPM data without the need of a skew quadrupole scan. The algorithm is applied to RHIC BPM data using AC dipoles and compared with traditional methods.  
 
WEPCH072 The High Order Non-linear Beam Dynamics in High Energy Storage Ring of FAIR multipole, sextupole, lattice, octupole 2083
 
  • A.N. Chechenin, R. Maier, Y. Senichev, E. Senicheva
    FZJ, Jülich
  The High Energy Storage Ring (HESR) is part of the international project FAIR for antiproton physics with beam in the momentum range from 1.5 to 15 GeV/c to explore the research areas of hadron structure and quark-gluon dynamics. An important feature of the project is the combination of phase space cooled beams with thick internal targets. Therefore there are two obvious reasons of beam heating: the target-beam interaction and the intra-beam scattering. Another source of the beam size growth is the higher order resonances. In the paper we investigate the non-linear beam dynamics together with different correction schemes minimizing this effect and compare with other sources of beam heating. Since the tune working point has a spread dependent on the chromaticity correction scheme and space charge, we include in our consideration both effects as well. All beam dynamics calculations are carried out with the SIMBAD code from the Unified Accelerator Library (UAL). We use 10000 macro particles, grid sizes 64x64 and 1000 turns per run.  
 
WEPCH075 Effect of Insertion Devices on Beam Dynamics of the Diamond Storage Ring Using Kick Maps injection, lattice, coupling, storage-ring 2092
 
  • B. Singh, A.I. Baldwin, R. Bartolini, I.P.S. Martin
    Diamond, Oxfordshire
  The effect of the all Phase-I Insertion Devices (IDs) on the beam dynamic of the Diamond storage ring has been investigated using the kick map modelisation of the IDs. Kick maps have been produced with high accuracy using the computer code RADIA, considering many longitudinal harmonics. The effect of IDs on the dynamic aperture, Touschek lifetime and injection efficiency in the low emittance lattice, was investigated considering both coupling errors and physical engineering apertures. Harmful resonances have been identified using Frequency Map Analysis (FMA) and full 6D tracking was performed to estimate the Touschek lifetime and the injection efficiency. Additionally, the kick maps have been used to generate feed-forward tables for compensation of linear optics distortion.  
 
WEPCH076 Renormalization Group Reduction of the Frobenius-Perron Operator betatron, sextupole, lattice, storage-ring 2095
 
  • S.I. Tzenov
    Universita' degli Studi di Salerno, Dipartimento di Fisica E.R. Caianiello, Baronissi
  The Renormalization Group (RG) method is adopted as a tool for a constructive analysis of the properties of the Frobenius-Perron Operator. The renormalization group reduction of a generic symplectic map in the case, where the unperturbed rotation frequency of the map is far from structural resonances driven by the kick perturbation has been performed in detail. It is further shown that if the unperturbed rotation frequency is close to a resonance, the reduced RG map of the Frobenius-Perron operator (or phase-space density propagator) is equivalent to a discrete Fokker-Planck equation for the renormalized distribution function. The RG method has been also applied to study the stochastic properties of the standard Chirikov-Taylor map.  
 
WEPCH079 Effects of Intrinsic Nonlinear Fields in the J-PARC RCS sextupole, simulation, space-charge, injection 2104
 
  • H. Hotchi, Y. Irie, F. Noda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Machida
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A.Y. Molodozhentsev
    KEK, Ibaraki
  In order to accelerate a high intense proton beam with small particle losses, the J-PARC RCS, which is being constructed at JAEA, has a large acceptance. In such synchrotrons, the nonlinear motion of the beam particles, especially moving away from the axis of the elements, is a common issue, and it becomes essential to consider intrinsic field nonlinearities. The main sources of nonlinear magnetic fields in the RCS are as follows: fringes of the main dipole and quadrupole magnets, sextupole fields used for the chromatic correction, leak fields from the injection and extraction beam lines, etc. In this paper, we will discuss influences of the intrinsic field nonlinearities and a cure for the induced betatron resonances, based on single-particle and multi-particle tracking simulations.  
 
WEPCH082 Simulation of Ions Acceleration and Extraction in Cyclotron C400 ion, cyclotron, acceleration, extraction 2113
 
  • Y. Jongen, W.J.G.M. Kleeven
    IBA, Louvain-la-Neuve
  • G.A. Karamysheva, S.A. Kostromin, N.A. Morozov, E. Samsonov
    JINR, Dubna, Moscow Region
  The Belgian company IBA, together with scientists of the JINR in Dubna is designing a superconducting isochronous cyclotron for therapy by Carbon beams. The new cyclotron C400 has to deliver carbon ions with energy 400 MeV/amu and protons with energy close to 250 MeV. The cyclotron has a compact type superconducting magnet, with a pole radius of 187 cm. The axial focusing is provided by four sectors, with a spiral angle increasing to a maximum value close to 70° at maximum energy. With this design, an axial betatron frequency is maintained during most of the acceleration. The beam acceleration is provided by two spiral dees located in opposite valleys. The dee voltage increases from 100 kV at the center to 200 kV at extraction. The paper presents the analysis of the beam acceleration in the proposed new cyclotron. During the acceleration, several resonance lines are crossed, but the paper demonstrates that this resonance crossing is done without damaging the beam properties. Extraction of the Carbon ions is done by an electrostatic deflector, followed by magnetic correctors. Protons are extracted at lower energy by stripping 2H+1 ions.  
 
WEPCH086 Adiabatic Theory of Slow Extraction of Particles from a Synchrotron synchrotron, extraction, betatron, heavy-ion 2119
 
  • S.A. Nikitin
    BINP SB RAS, Novosibirsk
  An analytical approach is developed to describe the process of slow extraction of particles from a synchrotron based on adiabatic crossing of the betatron resonance of the third order. An exact expression for the phase integral is found to analyze the conditions of oscillation amplitude growth near the resonance band. It allows one to directly define the interval of adiabatic motion from the start of decreasing the resonant tune to the beginning of fast increase of the oscillation amplitude. The interval distribution function is constructed for the cases of zero momentum spread and zero machine chromaticity as well as for the general case, taking into account non-zero momentum spread, non-zero chromaticity and synchrotron oscillations. Some numeric calculations of the time dependence of the extracted particle current are presented. It is shown that the momentum spread in the extracted beam can be minimized with the use of additional RF acceleration of particles during the slow extraction procedure.  
 
WEPCH096 Measurement and Correction of the 3rd Order Resonance in the Tevatron sextupole, coupling, CERN, dipole 2140
 
  • F. Schmidt
    CERN, Geneva
  • Y. Alexahin, V.A. Lebedev, D. Still, A. Valishev
    Fermilab, Batavia, Illinois
  At Fermilab Tevatron BPM system has been recently upgraded resulting much better accuracy of beam position measurements and improvements of data acquisition for turn-by-turn measurements. That allows one to record the beam position at each turn for 8000 turns for all BPMs (118 in each plane) with accuracy of about 10-20 μm. In the last decade a harmonic analysis tool has been developed at CERN that allows relating each FFT line derived from the BPM data with a particular non-linear resonance in the machine. In fact, one can even detect the longitudinal position of the sources of these resonances. Experiments have been performed at the Tevatron in which beams have been kicked to various amplitudes to analyze the 3rd order resonance. It was possible to address this rather large resonance to some purposely powered sextupoles. An alternative sextupole scheme allowed the suppression of this resonance by a good factor of 2. Lastly, the experimental data are compared with model calculations.  
 
WEPCH100 Application of the Lie-transform Perturbation Theory for the Turn-by-turn Data Analysis coupling, optics, lattice, betatron 2146
 
  • Y. Alexahin
    Fermilab, Batavia, Illinois
  Harmonic analysis of turn-by-turn BPM data is a rich source of information on linear and nonlinear optics in circular machines. In the present report the normal form approach first introduced by R. Bartolini and F. Schmidt is extended on the basis of the Lie-transform perturbation theory to provide direct relation between the sources of perturbation and observable spectra of betatron oscillations. The goal is to localize strong perturbing elements, find the resonance driving terms - both absolute value and phase - that are necessary for calculation of the required adjustments in correction magnet circuits: e.g. skew-quadrupoles for linear coupling correction. The theory is nonlinear and permits to analyze higher order effects, such as coupling contribution to beta-beating and nonlinear sum resonances.  
 
WEPCH153 Symplectic Interpolation coupling, AGS, BNL, dipole 2284
 
  • W.W. MacKay, A.U. Luccio
    BNL, Upton, Long Island, New York
  It is important to have symplectic maps for the various electromagnetic elements in an accelerator ring. For some tracking problems we must consider elements which evolve during a ramp. Rather than performing a complicated numerical integration for every turn, it should be possible to integrate the trajectory for a few sets of parameters, and then interpolate the transport map as a function of one or more parameters, such as energy. We present two methods for interpolation of symplectic matrices as a function of parameters: one method is based on the logarithm of the matrix, and the other is based on the related but simpler Healy symplectification method.  
 
WEPLS018 Optics for Phase Ionization Cooling of Muon Beams emittance, focusing, collider, space-charge 2430
 
  • R.P. Johnson
    Muons, Inc, Batavia
  • S.A. Bogacz, Y.S. Derbenev
    Jefferson Lab, Newport News, Virginia
  The realization of a muon collider requires a reduction of the 6D normalized emittance of an initially generated muon beam by a factor of more than 106. Analytical and simulation studies of 6D muon beam ionization cooling in a helical channel filled with pressurized gas or liquid hydrogen absorber indicate that a factor of 106 is possible. Further reduction of the normalized 4D transverse emittance by an additional two orders of magnitude is envisioned using Parametric-resonance Ionization Cooling (PIC). To realize the phase shrinkage effect in the parametric resonance method, one needs to design a focusing channel free of chromatic and spherical aberrations. We report results of our study of a concept of an aberration-free wiggler transport line with an alternating dispersion function. Resonant beam focusing at thin beryllium wedge absorber plates positioned near zero dispersion points then provides the predicted PIC effect.  
 
WEPLS040 Progress towards an Experimental Test of an Active Microwave Medium Based Accelerator electron, laser, controls, acceleration 2463
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • P. Schoessow
    Tech-X, Boulder, Colorado
  • L. Schächter
    Technion, Haifa
  We have been working on an experimental test of the PASER concept, where an active medium is used to provide the energy for accelerating charged particles. Initial theoretical work in this area focused on acceleration at optical frequencies; however we have identified a candidate active material operating in the X-band: a solution of fullerene (C60) in a nematic liquid crystal has been found to exhibit a maser transition* in this frequency range. The ability to employ a microwave frequency material simplifies the construction of test structures and allows beam experiments to be performed with relatively large beam emittances. We will report results on synthesis and testing of the active material using EPR spectroscopy, design and numerical simulations of bench test structures and plans for future beam experiments.

*A. Blank et al. IEEE Trans. Microwave Theory and Techniques 46 (2137) 1998.

 
 
WEPLS068 The IASA Magnetic Field Mapping (MFM) Project electron, controls, dipole, TESLA 2538
 
  • E.P. Pournaras, A. Karabarbounis, C.N. Papanicolas, E. Stiliaris
    IASA, Athens
  The design and development of an automatic magnetic field mapping device as supporting equipment for the 10 MeV CW-Linac and its transport system at the Institute of Accelerating Systems and Applications (IASA) is presented. The MFM project aims to totally automate the operation of mapping room temperature magnetic field sources, reconstruct the 3D-field shape and reveal nonlinearities in the fridge field regions. The positioning system covers an area of 50x50 cm2 with an accuracy of less than 20 ?m in both axes; magnetic field measurements, mainly based on a Hall probe, can reach in precision the 1x 10-4 value. Several software tools for the visualization of the measured fields and for a direct comparison with theoretical estimates are also presented.  
 
THPCH004 Space Charge Induced Resonance Trapping in High-intensity Synchrotrons beam-losses, synchrotron, space-charge, scattering 2790
 
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt
  With the recent development of high-intensity circular accelerators, the simultaneous presence of space charge and lattice nonlinearities has gained special attention as possible source of beam loss. In this paper we present our understanding of the role of space charge and synchrotron motion as well as chromaticity for trapping of particles into the islands of nonlinear reonances. We show that the three effects combined can lead to significant beam loss, where each individual effect leads to small or negligible loss. We apply our findings to the SIS100 of the FAIR project, where the main source of field nonlinearities stems from the pulsed super-conducting dipoles, and the beam dynamics challenge is an extended storage at the injection flat-bottom, over almost one second, together with a relatively large space charge tune shift.  
 
THPCH005 Considerations for the High-intensity Working Point of the SIS100 beam-losses, LEFT, dipole, synchrotron 2793
 
  • G. Franchetti, O. Boine-Frankenheim, I. Hofmann, V. Kornilov, P.J. Spiller, J. Stadlmann
    GSI, Darmstadt
  In the FAIR project the SIS100 synchrotron is foreseen to provide high-intensity beams of U 28+, including slow extraction to the radioactive beam experimental area, as well as high-intensity p beams for the production of antiprotons. In this paper we discuss the proposal of three different working points, which should serve the different needs: (1) a high intensity working point for U28+; (2) a slow extraction working point (also U28+); (3) a proton operation working point to avoid transition crossing. The challenging beam loss control for all three applications requires a careful account of the effects of space charge, lattice nonlinearities and chromaticity, which will be discussed in detail in this paper. Since tunes are not split by an integer and the injected emittances are different, the Montague stop-band needs to be avoided. Moreover, final bunch compression for the U beam requires a sufficiently small momentum spread, and the risk of transverse resisitive wall instabilities poses further limitations on our choice of working points.  
 
THPCH006 Scaling Laws for the Montague Resonance emittance, simulation, synchrotron, coupling 2796
 
  • I. Hofmann, G. Franchetti
    GSI, Darmstadt
  The space-charge-driven Montague resonance is a source of emittance coupling in high-intensity accelerators with un-split tunes. Here we present scaling laws for the stop-band widths, growth rates and crossing behavior of this fourth order resonance. Our results on the coupling can be applied to circular machines as well as to linear accelerators. Based on self-consistent coasting beam simulation we show that for slow crossing of the stop-bands a strong directional dependence exists: in one direction the exchange is smooth and reversible, in the other direction it is discontinuous. We also discuss the combined effect of the Montague resonance and linear coupling by skew quadrupoles.  
 
THPCH008 The Non-linear Space Charge Field Compensation of the Electron Beam in the High Energy Storage Ring of FAIR electron, antiproton, space-charge, multipole 2802
 
  • A.N. Chechenin, R. Maier, Y. Senichev
    FZJ, Jülich
  In the High Energy Storage Ring, a part of the FAIR project at GSI in Darmstadt, the internal target is used. To compensate the interaction of the beam with the target, the electron beam cooling is needed. However, together with the cooling, the non-linear space charge field of electron beam modifies the dynamic aperture. We investigate the possible schemes of this effect compensation using the multi-pole correctors on the HESR.  
 
THPCH013 Study of Particle Losses Mechanism for J-PARC Main Ring injection, space-charge, sextupole, emittance 2811
 
  • A.Y. Molodozhentsev, M. Tomizawa
    KEK, Ibaraki
  Detailed understanding as well as confidence in simulation modeling of long-term effects (~ 100'000 turns) of high intensity proton beam is crucial for Main Ring (MR) of the J-PARC project, where it is necessary to hold the high-intensity beam over typically ~ 2 sec with a loss level less than 1%. The major focus of such study is the combined effect of space charge and nonlinear resonances and its impact on halo formation and/or beam loss. In frame of this report, the tracking results for the injection process including realistic representation of the ring's focusing structure are discussed. Optimization of the working point during the injection process is presented. The halo formation and particle losses during the injection and acceleration for MR have been estimated for realistic magnetic field errors.  
 
THPCH015 Matched and Equipartitioned Method for High-intensity RFQ Accelerators rfq, emittance, linac, space-charge 2814
 
  • X.Q. Yan, J.-E. Chen, J.X. Fang, Z.Y. Guo, Y.R. Lu
    PKU/IHIP, Beijing
  • R.A. Jameson
    LANL, Los Alamos, New Mexico
  Maintaining beam envelope match, avoiding structure resonances, and using an equilibrium (equipartitioned) energy balance within the beam are the primary methods for preventing emittance growth and halo formation in high current linacs. A design strategy that requires the RFQ accelerator to be matched and equipartitioned over most of its length will produces very robust designs under a wide variety of conditions, the beam with proper energy balance is also inherently stable against resonances near the operation point. Based on this strategy, a new dynamics method is proposed to avoid the envelope mismatch and energy imbalance between different degrees of freedom. The beam sizes are well confined to match the accelerating channel in this method, to minimize the emittance growth and the related beam loss. Following the method, a RFQ design code named MATCHDESIGN has been written at Peking University. A test design of 50mA proton RFQ operating at 350 MHz was given to prove this method and it resulted in a good dynamics design.  
 
THPCH018 Resonance Trapping, Halo Formation and Incoherent Emittance Growth due to Electron Cloud electron, emittance, simulation, LHC 2820
 
  • E. Benedetto, E. Benedetto
    Politecnico di Torino, Torino
  • G. Franchetti
    GSI, Darmstadt
  • G. Rumolo, F. Zimmermann
    CERN, Geneva
  The pinched electron cloud introduces a tune shift along the bunch, which together with synchrotron motion, leads to a periodic crossing of resonances. The resonances are excited by the longitudinal distribution of the electron cloud around the storage ring. We benchmark the PIC code HEADTAIL against a simplified weak-strong tracking code based on an analytical field model, obtaining an excellent agreement. The simplified code is then used for exploring the long term evolution of the beam emittance, and for studying more realistic lattice models. Results are presented for the CERN SPS and the LHC.  
 
THPCH031 Impedance and Beam Stability Study at the Australian Synchrotron impedance, synchrotron, storage-ring, higher-order-mode 2844
 
  • R.T. Dowd, M.J. Boland, G. LeBlanc, M.J. Spencer, Y.E. Tan
    ASP, Clayton, Victoria
  We present the preliminary results of an impedance study of the Australian Synchrotron storage ring. Beam stability thresholds have been determined and an overall impedance budget set. Broad-band impedance has been evaluted for various components of the vacuum chamber, using both analytical formulae and results from MAFIA simulations. Narrow band resonances have also been investigated, with particular attention paid to higher order modes in the RF cavities and their effect on multi-bunch instabilities.  
 
THPCH059 Kicker Impedance Measurements for the Future Multi-turn Extraction of the CERN Proton Synchrotron kicker, impedance, extraction, LEFT 2919
 
  • E. Métral, F. Caspers, M. Giovannozzi, A. Grudiev, T. Kroyer, L. Sermeus
    CERN, Geneva
  In the context of the novel multi-turn extraction, where charged particles are trapped into stable islands in transverse phase space, the ejection of five beamlets will be performed by means of a set of three new kickers. Before installing them into the machine, a measurement campaign has been launched to evaluate the impedance of such devices. Two measurement techniques were used to try to disentangle the driving and detuning impedances. The first consists in measuring the longitudinal impedance for different transverse offsets using a single displaced wire. The sum of the transverse driving and detuning impedances is then deduced applying Panofsky-Wenzel theorem. The second uses two wires excited in opposite phase and yields the driving transverse impedance only. Finally, the consequences on the beam dynamics are also analyzed.  
 
THPCH087 Design and Operation of a Ferrite Loaded Kicker Cavity for the Longitudinal Coupled Bunch Feedback for HERA-p kicker, damping, impedance, feedback 2991
 
  • J. Randhahn, S. Choroba, M. Dohlus, M. Ebert, F.E. Eints, M.G. Hoffmann, R. Wagner
    DESY, Hamburg
  A longitudinal broadband damper system to control coupled bunch instabilities has recently been constructed and installed in the 920 GeV proton accelereator HERA-p at the Deutsches Elektronen-Synchrotron DESY. The goal of this system is to reduce the bunch length and thus increase specific luminosity at HERA-p. Within the control system a kicker cavity is used as an actuator. The original aspect of this cavity lies in the simple geometry with no need for vacuum inside the cavity and high shunt impedance despite an internal ferrite load. The ferrite load is succesfully used to dampen higher order modes down to Q < 50 while the fundamental mode is damped by less than 2 dB. While nominal input power is rated at 60 dBm the cavity is prepared to handle beam loading. In spite of power requirements and ferrite load the cavity needs no active cooling. It can be tuned in center frequency and bandwidth over a range of 96..105 MHz and 4..7 MHz respectively and in consequence provides an optimal actuator for the particle beam control system. Presented will be the design details, all relevant parameters, the design of the internal ferrite load and operational experience.  
 
THPCH106 ISAC II RF Controls - Status and Commissioning controls, CERN, target, damping 3047
 
  • M.P. Laverty, S.F. Fang, K. Fong, Q. Zheng
    TRIUMF, Vancouver
  The rf control system for the 20 ISAC II superconducting cavities is a hybrid analogue/digital design which has undergone several iterations in the course of its development. In the current design, the cavity operates in a self-excited feedback loop, while phase locked loops are used to achieve frequency and phase stability. One digital signal processor provides amplitude and phase regulation, while a second is used for mechanical cavity tuning control. The most recent version has been updated to incorporate newer hardware and software technology, as well as to allow for improved manufacturability and diagnostics. Operating firmware and software can be updated remotely, if the need arises and system security permits. This paper describes the RF control system, outlines the status of the system, and details the commissioning experience gained in operating this system with the first four-cavity cryomodule.  
 
THPCH159 Analysis of Microphonic Disturbances and Simulation for Feedback Compensation feedback, simulation, FEL, linac 3167
 
  • M. Luong, P. Bosland, G. Devanz, E. Jacques
    CEA, Gif-sur-Yvette
  For FEL projects based on a superconducting linac operating in CW mode, the RF power optimization finally comes up against the microphonics disturbances, which result in an unpredictable detuning of the cavities. A new piezoelectric tuner was developed and mounted on a TTF 9-cell cavity with an appropriate instrumentation. This system enables a full characterization of the disturbances and the tuner behavior. First measurements were made in a horizontal cryomodule at 4.2 K. They set a basis for simulations to assess the possibility of a feedback compensation, which is usually credited as impracticable. The outcome of such a compensation is also shown in terms of acceleration voltage amplitude and phase residual errors.  
 
THPCH175 Automatic Resonant Excitation Based System for Lorentz Force Compensation for Flash controls, radio-frequency, DESY, injection 3206
 
  • P.M. Sekalski, A. Napieralski
    TUL-DMCS, Lodz
  • S. Simrock
    DESY, Hamburg
  The cavity is the key element of each linear accelerator used for high-energy physics purpose. The resonant frequency of cavities depends on its shape. Due to the pulse operation, they are deformed by dynamic Lorentz force (LF) caused by accelerating electromechanical field. As a consequence, the cavities are not working on resonance but they are detuned from master oscillator frequency by few hundreds of Hertz depending on accelerating field gradient. The paper presents an automatic control system for LF compensation applied to fast tuning mechanism CTS. The active element is multilayer low-voltage piezoelectric stack (EPCOS). The resonant excitation with adaptive feed forward algorithm is used to drive the actuator. Test performed at FLASH (former name VUV-FEL) on cav5/ACC1 showed that detuning during flat-top period (800us) might remain below 10Hz for accelerating field gradient of 20MV/m.  
 
THPCH194 Investigation of Using Ferroelectric Materials in High Power Fast RF Phase Shifters for RF Vector Modulation klystron, insertion, controls, simulation 3248
 
  • J.L. Wilson, Y.W. Kang
    ORNL, Oak Ridge, Tennessee
  • A.E. Fathy
    University of Tennessee, Knoxville, Tennessee
  A fast ferroelectric phase shifter controlled by an electric field bias is being investigated for high-power RF phase shifters in vector modulation. Such a device could be used in charged particle accelerators, allowing vector control of the RF power delivered to accelerating RF cavities. Bulk ferroelectric materials, particularly those based on barium-strontium titanate (BST) compounds, have shown promise in high-power applications because of their low loss tangent and high dielectric strength. Such materials have already been investigated for use in fast phase shifters at X-Band frequencies*. Several different compositions of BST compounds are investigated in phase shifter prototypes at 402.5 MHz and 805 MHz that could be easily adapted for future large-scale accelerator projects. The ratio of barium versus strontium in the composition is varied from sample to sample. This allows an investigation of the tradeoffs involved between dielectric strength, loss tangent, tunability, and relative permittivity. Since ferroelectrics are by nature nonlinear dielectric compounds, preliminary study on the nonlinear propagation effects is conducted through computer simulation.

*V. P. Yakovlev et al. Fast X-Band Phase Shifter, Advanced Accelerator Concepts: Eleventh Workshop, 2004.

 
 
THPLS015 Spectral Fingerprints of Femtoslicing in the THz Regime electron, laser, radiation, undulator 3302
 
  • K. Holldack, S. Khan, T. Quast
    BESSY GmbH, Berlin
  • R. Mitzner
    Universität Muenster, Physikalisches Institut, Muenster
  Femtosecond (fs) THz pulses are observed as a consequence of laser-induced energy modulation of electrons in the BESSY II storage ring in order to generate fs x-ray pulses via femtoslicing*. The THz pulses are spectrally characterized by step-scan and rapid scan FTIR spectroscopy. The temporal shape of the laser-induced density modulation is reconstructed from the THz spectra. It is studied as a function of laser and storage ring parameters and monitored over several revolutions. The results are compared with numerical simulations. The THz spectra acquired over a few seconds are used to optimize the laser parameters for achieving minimum x-ray pulse lengths in femtoslicing experiments.

*A. Zholents and M. Zoloterev, PRL 76 (1996), 912.

 
 
THPLS024 Controlling the Vertical Emittance Coupling in CAMD coupling, wiggler, quadrupole, TESLA 3329
 
  • V.P. Suller
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • M.G. Fedurin, P. Jines, D.J. Launey, T.A. Miller, Y. Wang
    LSU/CAMD, Baton Rouge, Louisiana
  The vertical beam size in the CAMD Light Source, as measured with an x-ray pinhole camera, indicates an emittance coupling ratio of 3%. This is consistent with the coupling ratio as measured by the betatron tune split when the coupling resonance is fully engaged. It has been shown that the coupling is mainly produced in the 7T wiggler, which is known to produce non-linear fields. To correct this coupling, it is proposed to install up to four skew quadrupoles. The results of testing a prototype skew quadrupole in the lattice are presented. It is shown that the coupling will be substantially corrected by suitably distributing and powering the four skew quadrupoles.  
 
THPLS055 Effects of Phase 1 Insertion Devices at the ALBA Project undulator, lattice, wiggler, electron 3407
 
  • M. Belgroune, M. Muñoz
    CELLS, Bellaterra (Cerdanyola del Vallès)
  The ALBA new third generation light source offers a large number of straight sections to its community of users. Three types of straights will be available, 4 of 8 m, 12 of 4.2 m and 8 of 2.6 m. The compact lattice of a 268 m circumference ring is now mature and its main components are already fixed. We discuss here the beam dynamics studies performed for Phase 1 Insertion Devices (IDs) where two helical devices HU71, two in-vacuum undulators U21 and a multipole wiggler have been modeled using the kick map approach. This allowed defining the suitable compensation scheme in a machine where the vertical focusing is mainly controlled by the gradients in the dipole magnets. In addition, the Touschek lifetime computations and the identification of the limiting resonances using Frequency Map Analysis showed how strong the working point is in the presence of these IDs. Tolerances on the multipolar components due to the fields' roll-off have also been defined and allowed the progress in the IDs design.  
 
THPLS060 Lifetime and Acceptance at the SLS scattering, coupling, SLS, emittance 3421
 
  • A. Streun, Å. Andersson
    PSI, Villigen
  Beam lifetime at the storage ring of the Swiss Light Source (SLS) is limited by Touschek effect and elastic gas scattering. Both mechanism are affected by narrow gaps in the machine, elastic scattering directly by the vertical acceptance limitation, Touschek scattering via a possible restriction of lattice momentum acceptance due to coupling. The particle loss mechanism was explored by evaluations of lifetime as function of scraper position, chromaticity and emittance coupling.  
 
THPLS063 Nonlinear Beam Dynamics of TPS lattice, dynamic-aperture, sextupole, injection 3430
 
  • H.-P. Chang, P.J. Chou, C.-C. Kuo, G.-H. Luo, H.-J. Tsai, M.-H. Wang
    NSRRC, Hsinchu
  A design study of 3.0 GeV high performance low emittance storage ring Taiwan Photon Source has been conducted recently The natural emittance of the storage ring can be as low as 1.7 nm-rad in our design and its lattice structure is a 24-cell double bend achromat type with circumference of 518.4 m, which will be located in the existing NSRRC site in Hsinchu. The strong focusing requires strong aberration correction with nonlinear sextupole magnets. The distribution of the sextupoles and number of families are studied to ensure a good dynamic aperture. The nonlinear effects in both betatron and synchrotron motions are investigated. Nonlinear beam dynamics effects in the presence of magnetic field imperfections as well as the insertion devices are simulated. The physical aperture limitations are included in the study too, and the Touschek lifetime is calculated. The tracking data are analyzed using frequency map analysis method and corresponding beam dynamics behavior can be revealed more precisely.  
 
THPLS112 Electron Multipacting Observation and Simulation in the APS PAR electron, simulation, vacuum, beam-loading 3541
 
  • C. Yao, Y.-C. Chae
    ANL, Argonne, Illinois
  The particle accumulator ring (PAR) has both fundamental and 12th harmonic rf systems. Gap voltage fluctuations were experienced after vacuum work was performed on the PAR during a maintenance period. This has caused intermittent beam instability and prevented us from running the PAR fundamental rf system at normal power level. Our investigation has concluded that the problem was caused by electron multipacting in the center vacuum chamber of the cavity. We were able to suppress the multipacting by applying a solenoid field in the suspected region. Computer simulation is underway in order to find the location and the parameter range of the multipacting. In this paper we report the experimental observations and results of the simulation relevant to the phenomena.