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acceleration

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MPPE016 Hamiltonian Analysis of Transverse Dynamics in Axisymmetric RF Photoinjector focusing, emittance, space-charge, transverse-dynamics 1476
 
  • C.-X. Wang
    ANL, Argonne, Illinois
  A general Hamiltonian that governs the beam dynamics in an rf photoinjector is derived from first principles. With proper choice of coordinates, the resulting Hamiltonian has a simple and familiar form, while taking into account the rapid acceleration, rf focusing, magnetic focusing, and space-charge forces. From the linear Hamiltonian, beam-envelope evolution is readily obtained, which better illuminates the theory of emittance compensation. Preliminary results on the third-order nonlinear Hamiltonian will be given as well.  
 
MPPE017 Longitudinal Acceptance in Linear Non-Scaling FFAGs emittance, longitudinal-dynamics, extraction, injection 1532
 
  • J.S. Berg
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-98CH10886.

Linear Non-Scaling FFAGs have, particularly for muon acceleration, a unique type of longitudinal motion. This longitudinal motion can be approximated by a parabolic dependence time-of-flight on energy. This motion can be described in dimensionless variables with two parameters. I describe the relationship between the parameters and the distortion of ellipses in longitudinal space. I discuss the relationship between the longitudinal acceptance and the time spent in the FFAG, the latter being especially relevant for decays in muon accelerators. I discuss what improvement one can expect to achieve by adding higher-harmonic RF systems to the accelerator.

 
 
MPPE035 Transfers from High Power Hadron Linacs to Synchrotrons linac, proton, SNS, injection 2375
 
  • G.P. Jackson
    Hbar Technologies, LLC, West Chicago, Illinois
  The Fermilab Proton Driver is an example of a high power H- linear accelerator proposed as a new source of high brightness protons for the Main Injector synchrotron. Because of the elevated radioactive activation of accelerator components associated with beam losses during injection and acceleration, extra attention must be paid to RF manipulations wherein small losses were once deemed acceptable. Especially when injecting into existing synchrotrons from upgraded injectors, instabilities and beam loading make loss free manipulations especially problematic. This paper discusses some options for reducing the losses associated with common longitudinal beam manipulations.  
 
MPPE042 6-D BEAM DYNAMICS IN AN ISOCHRONOUS FFAG RING factory, closed-orbit, injection, resonance 2693
 
  • F. Meot
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • F. Lemuet
    CERN, Geneva
  • G. Rees
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  Funding: CEA/DAPNIA and CERN.

Numerical ray-tracing tools for 6-D tracking in FFAG accelerators have been developed. They are applied to the simulation of muon acceleration in the newly introduced isochronous type of FFAG ring designed for 16-turn, 8 to 20~GeV muon acceleration in the Neutrino Factory.

 
 
MPPE081 The Comparison of a New Beam-Tracking Code to the Acceleration Test linac, simulation, dipole, injection 4072
 
  • K. Yamamoto, S. Yamada, K. Yamamoto
    NIRS, Chiba-shi
  • T. Hattori
    RLNR, Tokyo
  • M. Okamura
    RIKEN, Saitama
  A new beam-tracking code using a 3D electro-magnetic field map of a linac is being developed. In this code, beam dynamics including non-linear and dipole effects can be easily estimated based on simulated field maps provided by commercial 3D analysis software. To verify the code, we manufactured an IH-linac and acceleration test of the linac was carried out with proton beam. The simulated results were compared with the tested acceleration performances.  
 
MPPP039 Impedance of Finite Length Resistor impedance, electromagnetic-fields 2595
 
  • S. Krinsky, B. Podobedov
    BNL, Upton, Long Island, New York
  • R.L. Gluckstern
    University of Maryland, College Park, Maryland
  Funding: Department of Energy contract DE-AC02-98CH10886.

We determine the impedance of a cylindrical metal tube (resistor) of radius a and length g, attached at each end to perfect conductors of semi-infinite length. Our main interest is in the behavior of the impedance at high frequency (k>>1/a). In the equilibrium regime, ka2<<g, the impedance per unit length is accurately described by the well-known result for an infinite length resistive tube. In the transient regime, ka2>>g, we derive an analytic expression for the impedance and compute the short-range wakefield.

 
 
MPPT023 A New Magnetic Field Integral Measurement System photon, insertion, insertion-device, multipole 1808
 
  • J.Z. Xu, I. Vasserman
    ANL, Argonne, Illinois
  Funding: Work supported by U.S. Department of Energy Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

In order to characterize the insertion devices at the Advanced Photon Source (APS) more efficiently, a new stretched-coil magnetic field integral measurement system has been developed. The system uses the latest state-of-the-art field programmable gate array (FPGA) technology to compensate the speed variations of the coil motions. Initial results demonstrate that the system achieves the system measurement accuracy of 0.15 Gauss centimeter (G-cm) in a field integral measurement of 600 G-cm, probably the world’s best accuracy of its kind.

 
 
MPPT046 Superconducting Helical Snake Magnet for the AGS dipole, resonance, magnet-design, proton 2935
 
  • E. Willen, M. Anerella, J. Escallier, G. Ganetis, A. Ghosh, R.C. Gupta, M. Harrison, A.K. Jain, A.U. Luccio, W.W. MacKay, A. Marone, J.F. Muratore, S.R. Plate, T. Roser, N. Tsoupas, P. Wanderer
    BNL, Upton, Long Island, New York
  • M. Okamura
    RIKEN, Saitama
  Funding: DOE

A superconducting helical magnet has been built for polarized proton acceleration in the Brookhaven AGS. This "partial Snake" magnet will help to reduce the loss of polarization of the beam due to machine resonances. It is a 3 T magnet some 1940 mm in magnetic length in which the dipole field rotates with a pitch of 0.2053 degrees/mm for 1154 mm in the center and a pitch of 0.3920 degrees/mm for 393 mm in each end. The coil cross-section is made of two slotted cylinders containing superconductor. In order to minimize residual offsets and deflections of the beam on its orbit through the Snake, a careful balancing of the coil parameters was necessary. In addition to the main helical coils, a solenoid winding was built on the cold bore tube inside the main coils to compensate for the axial component of the field that is experienced by the beam when it is off-axis in this helical magnet. Also, two dipole corrector magnets were placed on the same tube with the solenoid. A low heat leak cryostat was built so that the magnet can operate in the AGS cooled by several cryocoolers. The design, construction and performance of this unique magnet will be summarized.

 
 
MPPT069 A Pulsed Solenoid for Intense Ion Beam Transport ion, quadrupole, heavy-ion, beam-transport 3798
 
  • D. Shuman, E. Henestroza, G. Ritchie, D.L. Vanecek, W. Waldron, S. Yu
    LBNL, Berkeley, California
  Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

A design for a pulsed solenoid magnet is presented. Some simple design formulas are given that are useful for initial design scoping. Design features to simplify fabrication and improve reliability are presented. Fabrication, assembly, and test results are presented.

 
 
TPAE001 Experiments on Wake Field Acceleration in Plasma and the Program of the Further Works in YerPhI electron, plasma, laser, vacuum 752
 
  • M.L. Petrosyan, M. Akopov, Y.A. Garibyan, E.M. Laziev, R.A. Melikian, Y. Nazaryan, M.K. Oganesyan, G.M. Petrosyan, L.M. Petrosyan, V.S. Pogosyan, G.K. Tovmasyan
    YerPhI, Yerevan
  Funding: ISTC, Project A-405.

The use of wake field acceleration basically is aimed to obtaining of high acceleration rate in comparison with traditional methods of acceleration. Meantime in the last years in YerPhI it was offered to use wake field acceleration for acceleration of high-current electron bunches on energy about 100 MeV. Experimental installation for research of formation of high-current electron bunches of the given configuration, necessary for wake field acceleration and acceleration of these bunches in plasma is created. The installation is intended for acceleration of electron bunches with a current of few tens amperes and up to energy 1-2 MeV. For excitation of wake waves in plasma the electron accelerator of direct action with use of high-voltage pulse transformer is used. Results of researches have revealed some properties of formation of high-current bunches, especially restrictions of a electron current because of space charge effects at sub-picoseconds duration of bunches. The basic parameters of the wake field acceleration project on energy about 100 MeV are given, taking into account results of researches on experimental installation.

 
 
TPAE002 The Project PLASMONX for Plasma Acceleration Experiments and a Thomson X-Ray Source at SPARC laser, plasma, electron, simulation 820
 
  • L. Serafini, F. Alessandria, A. Bacci, I. Boscolo, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, M. Mauri, V. Petrillo, R. Pozzoli, M. Rome
    INFN-Milano, Milano
  • D. Alesini, M. Bellaveglia, S. Bertolucci, M.E. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, M.  Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M.A. Preger, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
    INFN/LNF, Frascati (Roma)
  • W. Baldeschi, A. Barbini, M. Galimberti, A. Giulietti, A. Gizzi, P. Koester, L. Labate, A. Rossi, P. Tommasini
    CNR/IPP, Pisa
  • R. Bonifacio, N. Piovella
    Universita' degli Studi di Milano, MILANO
  • U. Bottigli, B. Golosio, P.N. Oliva, A. Poggiu, S. Stumbo
    INFN-Cagliari, Monserrato (Cagliari)
  • F. Broggi
    INFN/LASA, Segrate (MI)
  • C.A. Cecchetti, D. Giulietti
    UNIPI, Pisa
  We present the status of the activity on the project PLASMONX, which foresees the installation of a multi-TW Ti:Sa laser system at the CNR-ILIL laboratory to conduct plasma acceleration experiments and the construction of an additional beam line at SPARC to develop a Thomson X-ray source at INFN-LNF. After pursuing self-injection experiments at ILIL, when the electron beam at SPARC will be available the SPARC laser system will be upgraded to TW power level in order to conduct either external injection plasma acceleration experiments and ultra-bright X-ray pulse generation with the Thomson source. Results of numerical simulations modeling the interaction of the SPARC electron beam and the counter-propagating laser beam are presented with detailed discussion of the monochromatic X-ray beam spectra generated by Compton backscattering: X-ray energies are tunable in the range 20 to 1000 keV, with pulse duration from 30 fs to 20 ps. Preliminary simulations of plasma acceleration with self-injection are illustrated, as well as external injection of the SPARC electron beam. The proposed time schedule for this initiative is finally shown, which is tightly correlated with the progress of the SPARC project.  
 
TPAE003 Numerical Study of Injection Mechanisms for Generation of Mono-Energetic Femtosecond Electron Bunch from the Plasma Cathode electron, plasma, laser, injection 859
 
  • T. Ohkubo, M. Uesaka, G. Zhidkov
    UTNL, Ibaraki
  Acceleration gradients of up to the order of 100GV/m and mono-energetic electron bunch up to 200MeV have recently been observed in several plasma cathode experiments. However, mechanisms of self-injection in plasma are not sufficiently clarified, presently. In this study, we carried out 2D PIC simulation to reveal the mechanisms of mono-energetic femtosecond electron bunch generation. We found two remarkable conditions for the generation: electron density gradient at vacuum-plasma interface and channel formation in plasma. Steep electron density gradient (~ plasma wave length) causes rapid injection and produces an electron bunch with rather high charge and less than 100fs duration. The channel formation guides an injected laser pulse and decreases the threshold of laser self-focusing, which leads to high electric field necessary for wave-breaking injection.  
 
TPAE011 Fast Sweeping Device for Laser Bunch laser, radiation, focusing, electron 1219
 
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  Electro-optical laser sweeping device deflects the head and tail of laser bunch into different frontal directions, so at some distance, the laser bunch becomes tilted with respect to forward direction. For sweeping of laser bunch having 300 ps duration up to 10 mrad, the voltage drop along the laser bunch must be ~10kV. Repetition rate desirable for this type of device used in laser acceleration or generation of secondary back-scattered electrons is up to 1 MHz. Details of the scheme described here.  
 
TPAE012 Rectangular Diamond-Lined Accelerator Structure impedance, vacuum, quadrupole, linear-collider 1282
 
  • C. Wang, V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  Funding: Work supported by U.S. DOE.

For high frequency accelerators with normal-conducting structures studied by the NLC/GLC collaboration and the CLIC group, rf breakdown is the main gradient limitation. In this paper, a Ka-band rectangular dielectric-lined structure is described as an attempt to increase accelerating gradient beyond the limits suitable for metallic structures. The structure is based on amorphous dielectrics that are known to exhibit high breakdown limits (~ GV/m). An example is artificial diamond that has already been successfully used on an industrial basis for large-diameter output windows of high power gyrotrons, and is produced industrially in increasing quantities. Artificial diamond has low loss tangent, moderate dielectric constant and high breakdown limit of ~2 GV/m. In the proposed structure diamond-slabs are employed to support high-gradient acceleration fields. Interposition of vacuum gaps between the dielectric slabs and the side walls is shown to reduce Ohmic losses substantially, leading to an increase in shunt impedance and reduced susceptibility to rf breakdown and fatigue on metal surfaces.

 
 
TPAE013 Rectangular Dielectric-Lined Two-Beam Wakefield Accelerator Structure radiation, vacuum, extraction, coupling 1333
 
  • C. Wang, V.P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT
  • T.C. Marshall
    Columbia University, New York
  Funding: Work supported by U.S. DOE.

A novel dielectric structure is described for a two-beam wake field accelerator (WFA), which consists of three or four rectangular dielectric slabs positioned within a rectangular conducting pipe. This structure can be thought of as equivalent to two symmetric dielectric-lined three-zone rectangular waveguides, joined side-by-side. The design mode in the two-beam structure is the LSM-31 mode, a combination of two symmetric LSM-11 modes of the two three-zone waveguides. This two-channel mode can be employed to decelerate drive particles in one channel and accelerate test particles in the other. It is possible to find structure parameters that give a high ratio of acceleration gradient for the test beam, to deceleration gradient for the drive beam, of the order of 100.

 
 
TPAE014 Optical Phase Locking of Modelocked Lasers for Particle Accelerators laser, vacuum, electron, controls 1389
 
  • T. Plettner, S. Sinha, J. Wisdom
    Stanford University, Stanford, Califormia
  • E.R. Colby
    SLAC, Menlo Park, California
  Funding: Department of Energy DE-FG03-97ER41043, DARPA DAAD19-02-1-0184.

Particle accelerators require precise phase control of the electric field through the entire accelerator structure. Thus a future laser driven particle accelerator will require optical synchronism between the high-peak power laser sources that power the accelerator. The precise laser architecture for a laser driven particle accelerator is not determined yet, however it is clear that the ability to phase-lock independent modelocked oscillators will be of crucial importance. We report the present status on our work to demonstrate long term phaselocking between two modelocked lasers to within one dregee of optical phase and describe the optical synchronization techniques that we employ.

 
 
TPAE017 Progress on High Power Tests of Dielectric-Loaded Accelerating Structures vacuum, impedance, simulation, plasma 1566
 
  • C.-J. Jing, W. Gai, R. Konecny, J.G. Power
    ANL, Argonne, Illinois
  • S.H. Gold
    NRL, Washington, DC
  • A.K. Kinkead
    ,
  Funding: This work was supported by the U.S. Dept of Energy, High Energy Physics Division and Office of Naval Research.

This paper presents a progress report on a series of high-power rf experiments that were carried out to evaluate the potential of the Dielectric-Loaded Accelerating (DLA) structure for high-gradient accelerator operation. Since the last PAC meeting in 2003, we have tested DLA structures loaded with two different ceramic materials: Alumina (Al2O3) and MCT (MgxCa1-xTiO3). The alumina-based DLA experiments have concentrated on the effects of multipactor in the structures under high-power operation, and its suppression using TiN coatings, while the MCT experiments have investigated the dielectric joint breakdown observed in the structures due to local field enhancement. In both cases, physical models have been set up, and the potential engineering solutions are being investigated.

 
 
TPAE018 34.272 GHz Multilayered Dielectric-Loaded Accelerating Structure impedance, vacuum 1592
 
  • C.-J. Jing, W. Gai, W. Liu, J.G. Power
    ANL, Argonne, Illinois
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  A scheme of multilayered structure design of 34.272 GHz with alternating dielectric of 38 and 9.7 is presented. The multilayer structure employs the Bragg Fiber concepts where the dielectric layers are used to create multiple reflections in order to confine the accelerating fields, thus greatly reducing the power loss of from external metal wall. The structure will operate at TM03 mode instead of normal TM01 mode. Numerical examples for the 2- and 4-layers 34.272 GHz multilayered structures are presented with detailed analysis of TM (acceleration) modes and HEM (parasitic) modes. We found that the power attenuation of the proposed structure can be lowered from ~ 20 dB/m for a single layer structure to ~ 6 dB/m for 2 -4 layered structure in at 34.272 GHz. We will also present a coupler design for the multilayered dielectric-loaded accelerating structure, which has capability of mode selection and high efficient RF transmission.  
 
TPAE022 Analytical and Numerical Calculations of Two-Dimensional Dielectric Photonic Band Gap Structures and Cavities for Laser Acceleration simulation, lattice, laser, plasma 1793
 
  • K.R. Samokhvalova, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
  • B.L. Qian
    National University of Defense Technology, Hunan
  Funding: Research supported in part by Department of Energy, Office of High Energy Physics, Grant No. DE-FG02-95ER40919 and in part by Department of Defense, Joint Technology Office, under a subcontract with University of Arizona.

Dielectric photonic band gap (PBG) structures have many promising applications in laser acceleration. For these applications, accurate determination of fundamental and high order band gaps is critical. We present the results of our recent work on analytical calculations of two-dimensional (2D) PBG structures in rectangular geometry. We compare the analytical results with computer simulation results from the MIT Photonic Band Gap Structure Simulator (PBGSS) code, and discuss the convergence of the computer simulation results to the analytical results. Using the accurate analytical results, we design a mode-selective 2D dielectric cylindrical PBG cavity with the first global band gap in the frequency range of 8.8812 THz to 9.2654 THz. In this frequency range, the TM01-like mode is shown to be well confined.

 
 
TPAE024 Determination of Longitudinal Phase Space in SLAC Main Accelerator Beams simulation, plasma, electron, radiation 1856
 
  • C.D. Barnes, F.-J. Decker, P. Emma, M.J. Hogan, R.H. Iverson, P. Krejcik, C.L. O'Connell, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, D.K. Johnson, C. Joshi, W. Lu, K.A. Marsh
    UCLA, Los Angeles, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  In the E164 Experiment at that Stanford Linear Accelerator Center (SLAC), we seek to drive plasma wakes for electron acceleration using 28.5 GeV bunches from the main accelerator. These bunches can now be made with an RMS length of less than 20 microns, and direct measurement is not feasible. Instead, we use an indirect technique, measuring the energy spectrum at the end of the linac and comparing with detailed simulations of the entire machine. We simulate with LiTrack, a 2D code developed at SLAC which includes wakefields, synchrotron radiation and all second order optical aberrations. Understanding the longitudinal profile allows a better understanding of acceleration in the plasma wake, as well as investigation of possible destructive transverse effects. We present results from the July 2004 experimental run and show how this technique aids in data analysis. We also discuss accuracy and validation of phase space determinations.  
 
TPAE025 Field Ionization of Neutral Lithium Vapor using a 28.5 GeV Electron Beam plasma, electron, diagnostics, radiation 1904
 
  • C.L. O'Connell, C.D. Barnes, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, D.K. Johnson, C. Joshi, W. Lu, K.A. Marsh, W.B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  The E164/E164X plasma wakefield experiment studies beam-plasma interactions at the Stanford Linear Acceleration Center (SLAC). Due to SLAC recent ability to variably compress bunches longitudinally from 650 microns down to 20 microns, the incoming beam is sufficiently dense to field ionize the neutral Lithium vapor. The field ionization effects are characterized by the beam’s energy loss through the Lithium vapor column. Experimental results are presented.  
 
TPAE033 Experimental and Numerical Studies of Particle Acceleration by an Active Microwave Medium laser, simulation, resonance, radiation 2275
 
  • P. Schoessow
    Tech-X, Boulder, Colorado
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  There has been considerable theoretical work on the so-called PASER concept, in which a particle beam is accelerated directly by absorbing energy from an active medium, analogous to the amplification of an optical signal in a laser. Use of an active microwave (maser) medium would have the advantage of requiring relaxed beam quality (mm vs. nm characteristic beam dimensions). Recent work using electron paramagnetic resonance (EPR) techniques has demonstrated activity in the microwave regime (i.e. negative imaginary part of the magnetic susceptibility) for a class of organic compounds. A solution of fullerene (C60) in a liquid crystal solvent has been reported in the literature to possess a maser transition in the X-band region. An external DC magnetic field is required to obtain the effect; the frequency of the maser transition is adjustable by varying the magnetic field strength. We will report on the development of numerical and laboratory tools to evaluate the use of this material for accelerator applications, and evaluate the feasibility of an accelerating structure based on an active microwave medium.  
 
TPAE037 Simulation of the Laser Acceleration Experiment at the Femilab/NICADD Photoinjector Laboratory laser, electron, vacuum, interaction-region 2503
 
  • P. Piot
    Fermilab, Batavia, Illinois
  • A.C. Melissinos, R. Tikhoplav
    Rochester University, Rochester, New York
  The possibility of using a laser to accelerate electrons in a waveguide structure with dimension much larger than the laser wavelength was first proposed by Pantell [NIM A 393 pg 1-5 (1997)] and investigated analytically by M. Xie [reports LBNL-40558 (1997) and LBNL-42055 (1998) available from LBNL Berkeley]. In the present paper we present the status of our experimental plan to demonstrate the laser interaction on an electron beam with initial momentum of 40-50 MeV/c. A laser (λ=1.06 micron) operating on the TM*01 mode has been developed. The large wavenumber (k~6x106 m-1) together with the initial low electron momentum poses a serious problem for efficient acceleration. In the present paper, we present start-to-end simulations of the laser acceleration experiment as foreseen to be installed in the upgraded Femilab/NICADD photoinjector laboratory.  
 
TPAE041 Modeling TeV Class Plasma Afterburners simulation, plasma, collider, emittance 2666
 
  • C. Huang, C.E. Clayton, D.K. Johnson, C. Joshi, W. Lu, W.B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • C.D. Barnes, F.-J. Decker, M.J. Hogan, R.H. Iverson
    SLAC, Menlo Park, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  Funding: Work supported by DOE and NSF.

Plasma wakefield acceleration can sustain acceleration gradients three orders of magnitude larger than conventional RF accelerator. In the recent E164X experiment, substantial energy gain of about 3Gev has been observed. Thus, a plasma afterburner, which has been proposed to double the incoming beam energy for a future linear collider, is now of great interest. In an afterburner, a particle beam drives a plasma wave and generates a strong wakefield which has a phase velocity equal to the velocity of the beam. This wakefield can then be used to accelerate part of the drive beam or a trailing beam. Several issues such as the efficient transfer of energy and the stable propagation of both the drive and trailing beams in the plasma are critical to the afterburner concept. We investigate the nonlinear beam-plasma interaction in such scenario using the 3D computer modeling code QuickPIC. We will report the latest simulation results of both 50 GeV and 1 TeV plasma afterburner stages for electrons including the beam-loading of a trailing beam. Analytic analysis of hosing instability in this regime will be presented.

 
 
TPAE046 Modeling Self-Ionized Plasma Wakefield Acceleration for Afterburner Parameters Using QuickPIC simulation, plasma, electron, betatron 2905
 
  • M. Zhou, C.E. Clayton, V.K. Decyk, C. Huang, D.K. Johnson, C. Joshi, W. Lu, W.B. Mori, F.S. Tsung
    UCLA, Los Angeles, California
  • F.-J. Decker, R.H. Iverson, C.L. O'Connell, D.R. Walz
    SLAC, Menlo Park, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  Funding: DOE

A plasma wakefield accelerator (PWFA) has been proposed as a way to double the energy of a future linear collider. This afterburner concept will require meter long uniform plasmas. For the parameters envisaged in possible afterburner stages, the self-fields of the particle beam are intense enough to tunnel ionize some neutral gases such as lithium. Tunnel ionization has been investigated as a way for the beam itself to create the plasma.* Furthermore, tunnel ionization in a neutral or partially pre-ionized gas may create new plasma electrons and alter the plasma wake.*,** Unfortunately, it is not possible to model a PWFA with afterburner parameters using the models described in Bruhwiler et al. and Deng et al. Here we describe the addition of a tunnel ionization package using the ADK model into QuickPIC, a highly efficient quasi-static particle in cell (PIC) code which can model a PWFA with afterburner parameters. There is excellent agreement between QuickPIC and OSIRIS(a full PIC code) for pre-ionized plasmas. Effects of self-ionization on hosing instability –one of the most critical issues to overcome to make an afterburner a reality – for a bunch propagating in a plasma hundreds of betatron oscillations long will be discussed.

*D. L. Bruhwiler et al., Phys. Plasmas 10 (2003), p. 2022. **S. Deng et al., Phys. Rev. E, 68, 047401 (2003).

 
 
TPAE047 Parameters Optimization for a Novel Vacuum Laser Acceleration Test at BNL-ATF laser, electron, vacuum, simulation 2959
 
  • L.H. Shao, D. Cline, F. Zhou
    UCLA, Los Angeles, California
  Funding: U.S. DOE.

This paper presents a new VLA theory model which has revealed that the injection electrons with low energy and small incident angle relative to the laser beam are captured and significantly accelerated in a strong laser field. For the further step for verifying the novel-VLA mechanics, we propose to use the BNL-ATF Terawatt CO2 laser and a high-brightness electron beam to carry out a proof-of-principle beam experiment. Experiment setup including the laser injection optics and electron extraction system and beam diagnostics is presented. Extensive optimized simulation results with ATF practical parameters are also presented, which shows that even when the laser intensity is not very high, the net energy gain still can be seen obviously. This could be prospect for a new revolution of vacuum laser acceleration.

 
 
TPAE056 Acceleration of Charged Particles by High Intensity Few-Cycle Laser Pulses electron, laser, plasma, undulator 3337
 
  • U. Schramm, F. Gruener, D. Habs, J. Schreiber
    LMU, München
  • S. Becker, M. Geissler, S. Karsch, F. Krausz, J. Meyer-ter-Vehn, K. Schmid, G. Tsakiris, L. Veisz, K. Witte
    MPQ, Garching, Munich
  Funding: Funded by the german DFG (TR18) and BMBF (06ML184).

Only recently a breakthrough in laser plasma acceleration has been achieved with the observation of intense (nC) mono-energetic (10% relative width) electron beams in the 100MeV energy range.* Above the wave-breaking threshold the electrons are trapped and accelerated in a single wake of the laser pulse, called bubble, according to PIC simulations.** However, pulse energis varied from shot-to-shot in the experiments. At the MPQ Garching we prepare the stable acceleration of electrons by this bubble regime by the use of 10TW few-cycle laser pulse. As the pulse lenght of 5-10fs remains below the plasma period also at higher plama densities, we expect the scheme to be more stable and efficient. The status of the experiment will be reported. Further, we exploit a colliding beam setup existing at the Jena multi TW laser system for the investigation of the positron generation in the electron-electron collision or in the collision of hard X-rays resulting from Thomson backscattering. The presentation of results on heavy ion acceleration from laser-irradiated thin foils will round up this summary of the Munich activities.

*See ‘dream beams' in Nature 431 (2004).**A. Pukhov, J. Meyer-ter-Vehn, Appl. Phys. B 74, 355 (2002).

 
 
TPAE061 Experimental Investigation of an X-Band Tunable Dielectric Accelerating Structure resonance, vacuum, polarization, electron 3529
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • W. Gai, J.G. Power
    ANL, Argonne, Illinois
  • S.F. Karmanenko, A. Semenov
    Eltech University, St. Petersburg
  • E. Nenasheva
    Ceramics Ltd., St. Petersburg
  • P. Schoessow
    Tech-X, Boulder, Colorado
  Funding: U.S. Department of Energy.

Experimental study of a new scheme to tune the resonant frequency for dielectric based accelerating structure (driven either by the wakefield of a beam or an external rf source) is underway. The structure consists of a single layer of conventional dielectric surrounded by a very thin layer of ferroelectric material situated on the outside. Carefully designed electrodes are attached to a thin layer of ferroelectric material. A DC bias can be applied to the electrodes to change the permittivity of the ferroelectric layer and therefore, the dielectric overall resonant frequency can be tuned. In this paper, we present the test results for an 11.424 GHz rectangular DLA prototype structure that the ferroelectric material's dielectric constant of 500 and show that a frequency tuning range of 2% can be achieved. If successful, this scheme would compensate for structure errors caused by ceramic waveguide machining tolerances and dielectric constant heterogeneity.

 
 
TPAE063 Observation of Superposition of Wake Fields Generated by Electron Bunches in a Dielectric-Lined Waveguide electron, gun, vacuum, laser 3609
 
  • S.V. Shchelkunov, T.C. Marshall
    Columbia University, New York
  • M. Babzien
    BNL, Upton, Long Island, New York
  • J.L. Hirshfield, M.A. LaPointe
    Yale University, Physics Department, New Haven, CT
  Funding: Research supported by the Department of Energy, Division of High Energy Physics.

We report results from an experiment, done at the Accelerator Test Facility, Brookhaven National Laboratory, which demonstrates the successful superposition of wake fields excited by 50MeV bunches which travel ~50cm along the axis of a cylindrical waveguide which is lined with alumina. Wake fields from two short (5-6psec) 0.15-0.35nC bunches are superimposed and the energy losses of each bunch are measured as the separation between the bunches is varied so as to encompass approximately one wake field period (~21cm). A spectrum of 40 TM0m eigenmodes is excited by the bunch. A substantial retarding wake field (2.65MV/m×nC for just the first bunch) is developed because of the short bunches and the narrow vacuum channel diameter (3mm) through which they move. The energy loss of the second bunch exhibits a narrow resonance with a 4mm (13.5psec) footprint. This experiment may be compared with a related experiment reported by a group at the Argonne National Laboratory where a much weaker wake field (~0.1MV/m×nC for the first bunch) having ~10 eigenmodes was excited by a train of much longer bunches,* and the bunch spacing was not varied.

*J. G. Power, M. E. Conde, W. Gai, R. Konecny, and P. Schoessow, Phys. Rev. ST Accel. Beams 3, 101302 (2000).

 
 
TPAE065 Development of a 20-MeV Dielectric-Loaded Accelerator Test Facility electron, shielding, injection, controls 3673
 
  • S.H. Gold
    NRL, Washington, DC
  • H. Chen, Y. Hu, Y. Lin, C. Tang
    TUB, Beijing
  • W. Gai, C.-J. Jing, R. Konecny, J.G. Power
    ANL, Argonne, Illinois
  • A.K. Kinkead
    ,
  • C.D. Nantista, S.G. Tantawi
    SLAC, Menlo Park, California
  Funding: Work supported by DOE and ONR.

This paper will describe a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded accelerator (DLA) test facility powered by the high-power 11.424-GHz magnicon that was developed by NRL and Omega-P, Inc. The magnicon can presently produce 25 MW of output power in a 250-ns pulse at 10 Hz, and efforts are in progress to increase this to 50 MW.* The facility will include a 5-MeV electron injector being developed by the Accelerator Laboratory of Tsinghua University in Beijing, China. The DLA test structures are being developed by ANL, and some have undergone testing at NRL at gradients up to ~8 MV/m.** SLAC is developing a means to combine the two magnicon output arms, and to drive an injector and accelerator with separate control of the power ratio and relative phase. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA structure, and spectrometer, should take place within the next year. The initial goal is to produce a compact 20-MeV dielectric-loaded test accelerator.

*O. A. Nezhevenko et al., Proc. PAC 2003, p. 1128.**S. H. Gold et al., AIP Conf. Proc. 691, p. 282.

 
 
TPAP006 Detecting Impacts of Proton Beams on the LHC Collimators with Vibration and Sound Measurements proton, radiation, collimation, beam-losses 1018
 
  • S. Redaelli, O. Aberle, R.W. Assmann, A.M. Masi, G. Spiezia
    CERN, Geneva
  The 350 MJ stored energy of the 7 TeV LHC beams can seriously damage the beam line elements in case of accidental beam losses. Notably, the LHC collimators, which sit at 6 to 7 σs from the beam centre (1.2-1.4 mm), might be hit and possibly damaged in case of failures, with a consequent degradation of their cleaning performance. The experience from operating machines shows that an a-posteriori identification of the damaged collimators from the observed performance degradation is extremely challenging. Collimator tests with beam at the SPS have proven that the impact of 450 GeV proton beams at intensities from 1010 to 3x1013 can be detected by measuring the collimator vibrations. This was achieved by using high-resolution, radiation hard accelerometers and a microphone to record mechanical and sound vibrations of a LHC-like prototype collimator with impacting beams at different intensities and depth. A similar system could be also used in the LHC to detect collimators damaged by the beam.  
 
TPAP022 Mixed pbar Source Operation at the Fermilab Tevatron injection, collider, luminosity, simulation 1763
 
  • C.M. Bhat, D. Capista, B. Chase, J.E. Dey, I. Kourbanis, K. Seiya, V. Wu
    Fermilab, Batavia, Illinois
  Funding: Work supported by the Universities Research Association, Inc., under contract DE-AC02-76CH03000 with the U.S. Department of Energy.

Recently, we have adopted a scheme called "Mixed pbar Source Operation" to transfer 2.5 MHz pbar bunches from the Recycler and the Accumulator to the Fermilab Main Injector (MI). In this scheme, 2.5MHz pbar bunches are captured adiabatically in 53 MHz buckets at 8 GeV in the MI and accelerated to 150 GeV before bunch coalescing and transfer to the Tevatron collider stores. A special magnet ramp was needed in the MI to allow for pbar beam of slightly different 8 GeV energies from the Recycler and the Accumulator. Here we present the details of the scheme and its advantage over the method used for past several years.

 
 
TPAP031 Simulations of an Acceleration Scheme for Producing High Intensity and Low Emittance Antiproton Beam for Fermilab Collider Operation emittance, beam-loading, simulation, antiproton 2164
 
  • V. Wu, C.M. Bhat, J.A. MacLachlan
    Fermilab, Batavia, Illinois
  Funding: Operated by Universities Research Association, Inc. for the U.S. Department of Energy under contract DE-AC02-76CH03000.

During Fermilab collider operation, the Main Injector (MI) provides high intensity and low emittance proton and antiproton beams for the Tevatron. The present coalescing scheme for antiprotons in the Main Injector yields about a factor of two increase in the longitudinal emittance and a factor of 5% to 20% decrease in intensity before injection to the Tevatron. In order to maximize the integrated luminosity delivered to the collider experiments, it is important to minimize the emittance growth and maximize the intensity of the MI beam. To this end, a new scheme* using a combination of 2.5 MHz and 53 MHz accelerations has been developed and tested. This paper describes the full simulation of the new acceleration scheme, taking account of space charge, 2.5 MHz and 53 MHz beam loading, and the effect of residual 53 MHz rf voltage during 2.5 MHz acceleration and rf manipulations. The simulations show the longitudinal emittance growth at the 10% level with no beam loss. The experimental test of the new scheme is reported in another PAC'05 paper.

*G.P. Jackson, The Fermilab Recycler Ring Technical Design Report, FERMILAB-TM-1991, November 1996.

 
 
TPAT040 Actual Stationary State for Plasma Lens plasma, electron, ion, heavy-ion 2619
 
  • V. Zadorozhny
    NASU/IOC, Kiev
  • A. Goncharov
    NSC/KIPT, Kharkov
  • Z.P. Parsa
    BNL, Upton, Long Island, New York
  The electrostatic plasma lens (PL) provides an attractive and unique tool for manipulating high-current heavy ion beams. The fundamental concept of the PL is based on the use of magnetically insulated electrons and equipotentialization of magnetic field lines. Rigorous application of PL is, however, limited. The reason is the estimation behaviour of electrons for complicated magnetic fields runs into severe difficults.We show that there are specific conditions that admit steady-state of a longitudinal motion, and consider a question of it stability. These results are needed to develop an optimized PL with minimal spherical aberation, in party by optimization of the magnetic field conficuration in the low-magnetic-field range.  
 
TPAT041 On the Vlasov-Maxwell Equations focusing, simulation 2654
 
  • V. Zadorozhny
    NASU/IOC, Kiev
  • Z.P. Parsa
    BNL, Upton, Long Island, New York
  There are many interesting physical question which based on of the solution Vlasov-Maxwell Equation (VME). However, the procedure of solve is very difficult and hard. But it is often preferable, on physical grounds, to a common point of view. Such point of view maybe a structure of some solution. We define and discuss the notaion of structure for the distribution function and prove, the structure of the Lorentz force represent the structure of the one. At the time of the discovery of the integrable systems the question of VME integrability had been considered. Moreover, as example, we consider, by means of this approach, the relation integrability and dispersion with a spectra of Vlasov's operat.  
 
TPAT057 Observations of UHF Oscillations in the IPNS RCS Proton Bunch quadrupole, synchrotron, proton, extraction 3375
 
  • J.C. Dooling, F.R. Brumwell, G.E. McMichael, S. Wang
    ANL, Argonne, Illinois
  Funding: This work is supported by the U.S. Department of Energy under contract no. W-31-109-ENG-38.

The Intense Pulsed Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS) accelerates 3.2x 1012 protons from 50 MeV to 450 MeV in a single bunch (h=1) at 30 Hz. The rf frequency varies from 2.21 MHz to 5.14 MHz during the 14.2 ms acceleration interval. To maintain stability of the bunch, phase modulation is introduced to the rf at approximately twice the synchrotron frequency (synchrotron tune is 0.0014). This phase modulation causes a parametric quadrupole oscillation to develop in the bunch, and as this occurs, the bunch spectrum shows a significant increase in high frequency content. Without phase modulation, the beam experiences an instability which results in the loss of a large fraction of the charge 2-4 ms prior to extraction. It is unclear if the stability imparted to the beam by phase modulation comes from the quadrupole oscillation or from the high frequency excitation. A longitudinal tracking code is presently being modified to include amplitude and phase modulation of the bunch. The numerical analysis will be used to compare growth rates with those observed in the machine. The results of this analysis will be important as we introduce second harmonic rf with a new third cavity in the RCS later in 2005.

 
 
TPAT058 Calculation of Electron Beam Potential Energy from RF Photocathode Gun simulation, gun, electron, space-charge 3441
 
  • W. Liu
    Illinois Institute of Technology, Chicago, Illinois
  • W. Gai, J.G. Power, H. Wang
    ANL, Argonne, Illinois
  Funding: U.S. Department of Energy.

In this paper, we consider the contribution of potential energy to beam dynamics as simulated by PARMELA at low energies (10 - 30MeV). We have developed a routine to calculate the potential energy of the relativistic electron beam using the static coulomb potential in the rest frame (first order approximation as in PARMELA). We found that the potential energy contribution to the beam dynamics could be very significant, particularly with high charge beams generated by an RF photocathode gun. Our results show that when the potential energy is counted correctly and added to the kinetic energy from PARMELA, the total energy is conserved. Simulation results of potential and kinetic energies for short beams (~1 mm) at various charges (1 - 100 nC) generated by a high current RF photocathode gun are presented.

 
 
TPAT096 Focusing-Free Transition Crossing in RHIC using Induction Acceleration induction, beam-losses, synchrotron, emittance 4314
 
  • K. Takayama, Y. Shimosaki, K. Torikai
    KEK, Ibaraki
  • J. Wei
    BNL, Upton, Long Island, New York
  Focusing-free transition crossing (FFTC) in RHIC is proposed. The original idea of FFTC proposed by J.Griffin was tried in the FNAL 500GeV main ring, where a gradient in the acceleration voltage was smoothed flat by introducing multi higher-harmonic RF. If the longitudinal focusing disappears during a limited time period near TC, various undesired features, such as bunch shortening and elongation in the momentum space, should be mitigated. In present RHIC operation, the slow ramping across transition leads into complications of nonlinear chromatic effects, vacuum pressure rise, instability, and transition-jump related lattice distortions. Recently, induction acceleration of a single RF bunch has been successfully demonstrated in KEK-PS,* where a proton bunch is trapped by the existing RF and accelerated with an induction step-voltage to 8 GeV. The utilized acceleration device is capable of generating a step voltage of 2 kV/cell at most at an arbitrary repetition rate up to 1 MHz. We here propose focusing-free TC in RHIC, introducing similar devices. In this scheme, the RF voltage is tuned off during an optimized time-period of several tens of ms, and the required acceleration voltage is provided as an induction flat-voltage.

*K.Takayama et al., submitted to Phys. Rev. Lett., http://www.arxiv.org/pdf/physics/0412006.

 
 
TPPT005 Dual Harmonic Operation with Broadband MA Cavities in J-PARC RCS impedance, linac, vacuum, injection 931
 
  • M. Yamamoto, M. Nomura, A. Schnase, F. Tamura
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Anami, E. Ezura, K. Hara, Y. Hashimoto, C. Ohmori, A. Takagi, M. Yoshii
    KEK, Ibaraki
  In the J-PARC RCS RF system, the fundamental rf acceleration voltage and the 2nd higher harmonic one are applied to each cavity. This is possible, because the magnetic alloy loaded cavities have a broadband characteristic and require no resonant frequency tuning. The tube amplifier provides both rf components. We calculate the operation of the tube under the condition of the dual harmonic, the non-pure resistive load and the class AB push-pull mode.  
 
TPPT014 Induction System for a Proton Bunch Acceleration in Synchrotron induction, proton, power-supply, synchrotron 1398
 
  • K. Torikai, Y.A. Arakida, J. Kishiro, T. Kono, E. Nakamura, Y. Shimosaki, K. Takayama, T. Toyama, M. Wake
    KEK, Ibaraki
  Funding: The project is officially supported by Grant-In-Aid for Creative Scientific Research (KAKENHI 15GS0217, 5 years term).

An induction cavity capable of operating at a repetition rate of 1MHz with a 50% duty has been built and employed for the first induction acceleration of a proton bunch from 500MeV to 8GeV in the KEK-PS.* In this experiment, an acceleration voltage of 4.7kV and an repetition frequency of 667kHz-882kHz were required. The installed induction device consists of three induction cells, each of which can generate a bipolar induction voltage of a maximum output voltage of 2 kV with a flat-top of 300ns and a 25ns rising/falling time. Electrical characteristics of the cavity itself, such as inductance, capacitance, and resistance, have been evaluated in three independent ways: (1) excitation due to a small signal from a network analyzer, (2) excitation by a proton beam as a primary driver, (3) excitation with a actual pulse modulator in an entire system. This paper will compare these results as well as theoretical design values. A general design procedure for an induction acceleration cavity will be given.

*K.Takayama et al., submitted to Phys. Rev. Lett. http://www.arxiv.org/pdf/physics/0412006.

 
 
TPPT016 Development of Co-Based Amorphous Core for Untuned Broadband RF Cavity impedance, radiation, medical-accelerators 1511
 
  • T. Misu, M. Kanazawa, A. Sugiura, S. Yamada
    NIRS, Chiba-shi
  • K. Katsuki, K. S. Sato
    Toshiba, Yokohama
  We have developed a co-based amorphous core as a new magnetic-alloy (MA) core for the loaded RF cavity. Because of its permeability found to be approximately twice as high as that of FINEMET, this MA core is an excellent candidate for constructing a compact broadband RF cavity with less power consumption. In this report, we present our recent studies of the co-based amorphous core’s physical properties, performance, and development.  
 
TPPT022 The Structure of the High Frequency Focusing Cells in Linear Ion Accelerators focusing, quadrupole, ion, proton 1796
 
  • V.A. Bomko, O.F. Dyachenko, A.P. Kobets, E.D. Marynina, Z.O. Ptukhina, S.S. Tishkin, B.V. Zajtsev
    NSC/KIPT, Kharkov
  The versions of the high frequency quadrupole doublets (RFQD) for proton and heavy ion linear accelerators are discussed. Advantages of focusing of this type over magnetic quadrupoles lie in the simplicity of the structure and high efficiency and reliability of focusing. In the multi-gap structures, focusing periods contain a sequence of focusing and accelerating cells. The elaborated technique of the local cell adjustment provides the high acceleration rate. Various RFQD versions for the specific peculiarities of accelerating structures are discussed. Application of the RF-quadrupole doublets in the spoke cavity, CCDTL and Crossbar structures will allow the application of superconductive cavities for proton acceleration in the range of intermediate energies of 5-100 MeV. In the interdigital H-structures, the application of RFQDs will allow to increase the efficiency of ion beam focusing and to expand the energy range of the ions being accelerated over 10 MeV/u.  
 
TPPT028 Design of a New Main Injector Cavity for the Fermilab Proton Driver Era proton, simulation, coupling, impedance 2015
 
  • V. Wu, A.Z. Chen, Z. Qian, D. Wildman
    Fermilab, Batavia, Illinois
  Funding: Operated by Universities Research Association, Inc. for the U.S. Department of Energy under contract DE-AC02-76CH03000.

In the design report of the Fermilab Proton Driver [1],* the Main Injector (MI) needs to be upgraded to a 2 MW machine. For the Main Injector radiofrequency (rf) upgrade, R&D efforts are launched to design and build a new rf system. This paper presents the new cavity design study for the rf system. The cavity is simulated with the design code Mafia [2].**

**Proton Driver Study II, FERMILAB-TM-2169, May 2002, edited by G.W. Foster, W. Chou and E. Malamud. **Computer Simulation Technology, MAFIA 4, December 1996.

 
 
TPPT038 Development of C-Band Accelerator Structure with Smooth Shape Couplers simulation, target, linac, positron 2530
 
  • T. Sugimura, M. Ikeda, K. Kakihara, T. Kamitani, S. Ohsawa, T. T. Takatomi, K. Yokoyama
    KEK, Ibaraki
  The first C-band accelerator structure for the SuperKEKB injector linac has been operated in the beam line of e+/e- injector linac for KEKB/PF/PF-AR since September, 2003. A new accelerator structure will locate upstream of the first structure. The upstream structure is exposed to higher RF field than that of downstream structure. For the case of first structure, most of an RF breakdown occurs in an input coupler. In order to reduce a frequency of the breakdown, improvement of a coupler is required. In order to suppress a thermionic emission around the coupler iris, thick and smooth iris is adopted for the upstream structure. The development status of this type of upstream structure is described.  
 
TPPT042 The Simulation Calculations and Dielectric Characteristics Investigation of an X-Band Hybrid Dielectric-Iris-Loaded Traveling Accelerating Structure simulation, resonance, synchrotron, synchrotron-radiation 2720
 
  • C.-F. Wu, S. Dong, S. Hongbing, D. Jia, H. Lin, L. Wang
    USTC/NSRL, Hefei, Anhui
  Funding: This work is supported by the National Natural Science Foundation of China(No.10375060,10205014)and the Project of Knowledge Innovation Program of the Chinese Academy of Sciences.

Mafia code has been used to calculate the RF properties versus the geometric parameters and dielectric permittivity for the X-band (f=9.37GHz) hybrid dielectric-iris-loaded traveling accelerating structure. The simulation results show that when the range of the permittivity is about 5-9, the new structure may have lower ratio (about 1) of peak surface electric field at the iris to axial accelerating electric field by optimizing the geometric parameters, while r, Q, r/Q of the new structure being comparable to iris-loaded accelerating structure. The experimental investigations of the permittivity of the ceramics have been made at the X-band by using the cavity perturbation technique. The measured results are in good agreement with the simulation results of Microwave Studio. Furthermore, the stability of the ceramics is examined. A number of experimental results show that the certain ceramic with permittivity of 5.78 is applied to the design of the new accelerating structure.

 
 
TPPT043 The Studies of Hybrid Dielectric-Iris-Loaded Accelerating Structure synchrotron, synchrotron-radiation, simulation, impedance 2747
 
  • C.-F. Wu, S. Dong, H. Lin
    USTC/NSRL, Hefei, Anhui
  Funding: This work is supported by the National Natural Science Foundation of China(No.10375060,10205014) and the Project of Knowledge Innovation Program of the Chinese Academy of Sciences.

The dispersion property and the propagation characteristics of the accelerating mode (TM01 mode) and higher-order-modes about a new hybrid dielectric-iris-loaded accelerating structure have been analysed and discussed by the field matching method. Mafia code has been used to calculate the RF properties versus the geometric parameters and dielectric permittivity for the X-band (f=9.37GHz) hybrid dielectric-iris-loaded traveling accelerating structure. Some model cavities have been developed, and experimental investigations have been carried on. The above results will provided some beneficial datum for the design and manufacture of X-band hybrid dielectric-iris-loaded traveling-wave accelerating structure.

 
 
TPPT052 Cryogenic, Magnetic and RF Performance of the ISAC-II Medium Beta Cryomodule at TRIUMF alignment, target, coupling, ion 3191
 
  • R.E. Laxdal, K. Fong, A.K. Mitra, T.C. Ries, I. Sekachev, G. Stanford, V. Zviagintsev
    TRIUMF, Vancouver
  The medium beta section of the ISAC-II Heavy Ion Accelerator consists of five cryomodules each containing four quarter wave resonators and one superconducting solenoid. The first cryomodule has been designed, assembled and cold tested at TRIUMF. The cryomodule vacuum space shares the cavity vacuum and contains a mu-metal shield, an LN2 cooled, copper thermal shield, plus the cold mass and support system. The bulk niobium cavities are fitted with an LN2 cooled coupling loop fed in series from the side thermal shield and a tuner plate coupled to an out-of-vacuum linear servo motor. All cavities have been locked at the ISAC-II frequency and gradient for extended periods. This paper will report the cryogenic and rf test results from the three cold tests. Of note are measurements of the magnetic field in the cryomodule and estimations of changes in the magnetic field during the test due to trapped flux in the solenoid and magnetization of the environment.  
 
TPPT055 Electro-Polishing Surface Preparation for High Gradient Cavities at DESY superconductivity, radio-frequency, feedback, linac 3304
 
  • A. Matheisen, h. Morales Zimmermann, B. Petersen, ms. Schmoekel, N. Steinhau-Kuehl
    DESY, Hamburg
  Improvement of acceleration gradients in super conducting accelerator structures was reached by applying electro polishing of the niobium surfaces. This technology is actually foreseen to serve as major surface preparation step for projects like the XFEL at DESY and the proposed ILC linear accelerator. At DESY an electro polishing apparatus was build up in 2003. After commissioning the apparatus operates regular for cavity surface treatment. We report on experiences with the electro-polishing set up, polishing parameters and results on the preparation of S.C. resonators for a high gradient module to be tested in the TTF2 accelerator at DESY.  
 
TPPT068 Optimized Shape of Cavity Cells for Apertures Smaller than in TESLA Geometry coupling, linear-collider, collider, superconductivity 3748
 
  • V.D. Shemelin
    Cornell University, Ithaca, New York
  The accelerating rate (Eacc) of TESLA cavities can be increased for the same iris aperture if 1) some increase of Epk/Eacc is permitted so that the value of Hpk/Eacc can be lowered in comparison with the original cells (Epk and Hpk are maximal surface electric and magnetic fields); 2) shape of the cells is described by two elliptic arcs; 3) the reentrant cells obtained as a result of consecutive optimization with this geometry are treated as a possible version of cells in spite of some complications for fabrication. Not only the value of Hpk/Eacc can be improved but also values of cell-to-cell coupling and the geometry constants R/Q and G grow with the transition to the reentrant shapes. And these are not all benefits of this shape. The increased coupling prompts that the aperture of the original cell is big enough to be decreased without loss of field flatness in comparison with the original design. This decrease will lead to further increase of the Eacc for the same Hpk also as to improvement of others important parameters. Here, results of calculations for the original and for smaller apertures are presented and proposals for a better choice of TESLA cavity cells are derived.

Cornell University

 
 
TOPA006 High Energy Gain IFEL at UCLA Neptune Laboratory laser, undulator, electron, simulation 500
 
  • P. Musumeci, S. Boucher, C.E. Clayton, A. Doyuran, R.J. England, C. Joshi, C. Pellegrini, J.E. Ralph, J.B. Rosenzweig, C. Sung, S. Tochitsky, G. Travish, R.B. Yoder
    UCLA, Los Angeles, California
  • S.V. Tolmachev, A. Varfolomeev, A. Varfolomeev, T.V. Yarovoi
    RRC Kurchatov Institute, Moscow
  We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 mkm laser with power larger than 400 GW. The Rayleigh range of the laser, ~ 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the first half of the undulator at a gradient of 70 MeV/m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator.  
 
TOPA007 Proton Acceleration and High-Energy Density Physics from Laser Foil Interactions proton, target, ion, electron 573
 
  • P.A. Norreys
    CCLRC/RAL, Chilton, Didcot, Oxon
  • F.N. Beg
    UCSD, La Jolla, California
  • A.E. Dangor, K.M. Krushelnick, M. Wei
    Imperial College of Science and Technology, Department of Physics, London
  • M. Tatarakis
    ,
  • M. Zepf
    Queen's University of Belfast, Belfast, Northern Ireland
  Intense laser plasma interactions have long been shown to be a source of very energetic ions - from the first experiments in the 1970's. However, there has been a recent revival of interest in the production of protons and ions from the such plasmas - primarily from the observation of collimated beams of protons and heavier ions which were observed at the rear thin foil targets irradiated by ultra-high intensity laser pulses (such that I > 1018 W/cm2). These ion beams have unique properties which may make them suitable for a variety of applications such as for probing high density plasmas, for fast ignition in inertial confinement fusion, as an ion source for subsequent acceleration stages in a particle accelerator or potentially for medical applications. Recent experimental results will be reviewed and the potential for such future applications will be highlighted.  
 
TOPA008 First Observation of Laser-Driven Acceleration of Relativistic Electrons in a Semi-Infinite Vacuum Space laser, electron, polarization, vacuum 650
 
  • T. Plettner, R.L. Byer, T.I. Smith
    Stanford University, Stanford, Califormia
  • E.R. Colby, B.M. Cowan, C.M.S. Sears, R. Siemann, J.E. Spencer
    SLAC, Menlo Park, California
  Funding: Department of Energy DE-FG03-97ER41043.

We have observed acceleration of relativistic electrons in vacuum driven by a linearly polarized laser beam incident on a thin gold-coated reflective boundary. The observed energy modulation effect follows all the characteristics expected for linear acceleration caused by a longitudinal electric field. As predicted by the Lawson-Woodward theorem the laser driven modulation only appears in the presence of the boundary. It shows a linear dependence with the strength of the electric field of the laser beam and also it is critically dependent on the laser polarization. Finally, it appears to follow the expected angular dependence of the inverse transition radiation process.

 
 
TOPA009 Photonic Band Gap Accelerator Demonstration at Ku-Band. linac, electron, klystron, lattice 656
 
  • E.I. Smirnova, L.M. Earley, R.L. Edwards
    LANL, Los Alamos, New Mexico
  • A.S. Kesar, I. Mastovsky, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts
  Funding: The research is supported by DOE High Energy Physics, Contract No. DE-FG02-91ER40648.

We report progress on the design and cold test of a metal Ku-band PBG accelerator structure. The 17.140 GHz 6-cell PBG accelerator structure with reduced long-range wakefields was designed for the experiment. The copper structure was electroformed and cold-tested. Tuning was performed through chemical etching of the rods. Final cold test measurements were found to be in very good agreement with the design. The structure will be installed on the beam line at the accelerator laboratory at Massachusetts Institute of Technology and will be powered with 3 MW of peak power from the Haimson 17.14 GHz klystron. Results of the design, fabrication, cold test and hot test on the Haimson accelerator will be presented.

 
 
TOPA011 Self Consistent Scheme for Obtaining Electron-Positron Collisions with Multi-TeV Energy laser, radiation, photon, damping 740
 
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  We describe here a self-consistent scheme for arrangement of multi-TeV collisions of electrons and positrons by using laser burst swept along microstructures with stable rate of acceleration ~10GeV/m. Shown that all component of the scheme are within present day technology. For energy ~1TeV luminosity could reach 1035 /cm2/s with wall-plug power of few tens of kW only.  
 
WPAE022 Progress on the Liquid Hydrogen Absorber for the MICE Cooling Channel vacuum, scattering, focusing, target 1772
 
  • M.A.C. Cummings
    Northern Illinois University, DeKalb, Illinois
  • S. Ishimoto
    KEK, Ibaraki
  This report describes the progress made on the design of the liquid hydrogen absorber for the international Muon Ionization Cooling Experiment (MICE). The absorber consists of a 21-liter vessel that contains liquid hydrogen (1.5 kg) or liquid helium (2.63 kg). The cryogen vessel is within the warm bore of the superconducting focusing magnet for the MICE. The purpose of the magnet is to provide a low beam beta region within the absorber. For safety reasons, the vacuum vessel for the hydrogen absorber is separated from the vacuum vessel for the superconducting magnet and the vacuum that surrounds the RF cavities or the detector. The absorber has two 300 mm-diameter thin aluminum windows. The vacuum vessel around the absorber has a pair of thin aluminum windows that separate the absorber vacuum space from adjacent vacuum spaces. The absorber will be cooled down using a heat exchanger that is built into the absorber walls. Liquid nitrogen is used to cool the absorber to 80 K. Liquid helium completes the absorber cool down and condenses hydrogen in the absorber. The absorber may also be filled with liquid helium to measure muon cooling in helium.  
 
WPAE063 CERN-PS Main Power Converter Renovation: How To Provide and Control the Large Flow of Energy for a Rapid Cycling Machine? synchrotron, pulsed-power, superconductivity, superconducting-magnet 3612
 
  • F. Bordry, J.-P. Burnet, F. Voelker
    CERN, Geneva
  The PS (Proton-Synchrotron) at CERN, which is part of the LHC injector chain, is composed of 101 main magnets connected in series. During a cycle (about 1 second), the active power at the magnet terminals varies from plus to minus 40 MW. Forty years ago, the solution was to insert a motor-generator (M-G) set between the AC supply network and the load. The M-G set acts as a fly-wheel with a stored kinetic energy of 233 MJ. The power converter is composed of two 12-pulse rectifiers connected in series. A renovation or replacement of the installation is planned in the near future as part of the consolidation of the LHC injectors. This paper presents a first comparison of technical solutions: - a direct connection to the 400 kV mains; - a kinetic energy storage system either by the existing or by a new “state of the art” M-G set; - a new local inductive or capacitive energy storage system. All these solutions need new power electronics equipment, which should be based on proven industrial topologies, techniques and components. The related studies will address the challenge of controlling by a modern power converter with local energy storage the positive and negative flow of energy to a rapid cycling accelerator load.  
 
WPAE071 Power Supply for Magnet of Compact Proton and/or Heavy Ion Synchrotron for Radiotherapy power-supply, dipole, injection, synchrotron 3859
 
  • S. Yamanaka
    NIRS, Chiba-shi
  • K. Egawa, K. Endo, Z. Fang
    KEK, Ibaraki
  A resonant type pulse power supply, for an application to a compact proton and/or heavy ion synchrotron with a several Hz repetition rate, is attractive from the view point of attaining an average beam current that is enough for the radiation therapy. Maximum ampere-turn of the dipole magnet is as large as 200 kAT to make the bending radius as small as possible. Pulse current is generated by discharging the stored energy in a capacitor bank through a pulse transformer. Moreover, the auxiliary power supply for the dipole magnets which adds the flat magnetic field (10-20μs) for the multi-turn beam-injection is being developed. The power supply for the quadrupole magnets is the high switching frequency (20 kHz × 5) switching-mode Power Supply for the adjusting tune and the tracking between the quadrupole and the dipole fields.Detailed analyses on these pulse power supplies will be presented.  
 
WPAP014 Development of Electron Gun of Carbon Nanotube Cathode cathode, electron, gun, vacuum 1392
 
  • Y. Hozumi
    GUAS/AS, Ibaraki
  • M. Ikeda, S. Ohsawa, T. Sugimura
    KEK, Ibaraki
  We are developing high brightness electron guns utilizing carbon nanotube (CNT) cathodes. Recently, we succeeded to achieved field emission currents to 0.2 A (3 A/cm2) from a triode type CNT cathode of 3 mm diameter. The emission tests were performed at DC100kV acceleration voltage in pulse operations of 50 Hz using 6 nsec pulses. The emission currents were very stable for long term periods of 3 weeks. Photo emission tests from CNT cathode by 266nm laser pulses is also due to be reported simultaneously.  
 
WPAP044 Advanced Electromagnetic Analysis for Electron Source Geometries cathode, electron, gun, space-charge 2815
 
  • M. Hess, C.S. Park
    IUCF, Bloomington, Indiana
  One of the challenging issues for analytically modeling electron sources, such as rf photoinjectors, is how to incorporate fully electromagnetic effects which are generated by the electron beam. The main difficulties that arise in finding an analytical solution of the electromagnetic fields are due to the complex shape of the conductor boundary, as well as the complicated structure of the beam density and current. Both of these problems can be handled self-consistently by using an electromagnetic Green’s function method. In this paper, we present a solution to the exact electromagnetic fields, which were derived from the Green’s function, for a simplified electron source conductor geometry, namely a semi-infinite circular pipe with an endcap. We assume that the beam currents are in the axial direction and satisfy the continuity equation in conjunction with the beam charge density, but may have arbitrary spatial and time dependency. We discuss how these analytical methods may be extended to include in the effect of one or multiple irises, which are found in rf photoinjector systems.  
 
WPAT007 Control Loops for the J-PARC RCS Digital Low-Level RF Control synchrotron, feedback, controls, damping 1063
 
  • A. Schnase, M. Nomura, F. Tamura, M. Yamamoto
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Yoshii
    KEK, Ibaraki
  The low-level radiofrequency control for the Rapic Cycling Syncrotron of J-PARC is based on digital signal processing. This system controls the acceleration voltages of 12 magnetic alloy loaded cavities. To achive a short overall delay, mandatory for stable loop operation, the data-processing is based on distributed arithmetics in FPGA. Due to the broadband characteristic of the acceleration cavities, no tuning loop is needed. To handle the large beam current, the RF system operates simultaneously with dual harmonics (h=2) and (h=4). The stability of the amplitude loops is limited by the delay of the FIR filters used after downconversion. The phase loop offers several operation modes to define the phase relation of (h=2) and (h=4) between the longitudinal beam signal and the vector-sum of the cavity voltages. Besides the FIR filters, we provide cascaded CIC filters with smoothly varying coefficients. Such a filter tracks the revolution frequency and has a substantially shorter delay, thereby increasing the stable operating region of the phase loops. The adaptive radial loop accumulates the orbit variation over several machine cycles to reduce the effects of measurement errors on the effective acceleration frequency program.  
 
WPAT018 The LEIR RF System impedance, ion, resonance, coupling 1619
 
  • M.M. Paoluzzi, R. Garoby, M. Haase, P. Maesen, C. Rossi
    CERN, Geneva
  • C. Ohmori
    KEK, Ibaraki
  The lead-lead physics program of LHC relies on major changes of the CERN ion injector chain. In this framework, the conversion of LEAR (low energy antiproton ring) into the Low Energy Ion Ring (LEIR) is central and implies a new accelerating system covering a wide frequency range (0.35 - 5 MHz,) with a moderate voltage (4 kV). For this purpose two new wide-bandwidth cavities, loaded with FinemetŪ magnetic alloy cores, have been built in collaboration with KEK. Two 60 kW RF power amplifiers have also been built and the RF systems are now installed in the LEIR ring. They individually cover the whole frequency range without tuning and allow multi-harmonic operation. The design has been guided by need of safety margins, reliability and ease of maintenance. Some design aspects are presented as well as the performance achieved.  
 
WPAT019 Beam Tests of a New Digital Beam Control System for the CERN LEIR Accelerator pick-up, booster, injection, proton 1649
 
  • M.-E. Angoletta, J. Bento, A. Blas, A. Findlay, P. Matuszkiewicz, F. Pedersen, A. Salom.Sarasqueta
    CERN, Geneva
  • J. DeLong
    BNL, Upton, Long Island, New York
  We are developing a digital beam control and cavity servo system for controlling the RF acceleration in CERN’s Low Energy Ion Ring (LEIR), a major component in the LHC lead ion injector chain. As the LEIR ring will only start during summer 2005, we have tested a simplified prototype of the system with low intensity beams on the CERN PS Booster (PSB). The hardware and software have been developed within the framework of a CERN-BNL collaboration. This fully digital beam control system is contained in VME mother boards which can accommodate several daughter boards. The fast signal processing is implemented in Field Programmable Gate Arrays (FPGAs), while the slower signal processing and communication with the software layer above is implemented in programmable Digital Signal Processors (DSPs). The objectives of the tests with beam in the PSB are to verify the multiple DSP and FPGA architecture, the sampling rates and data flows and the feedback loop dynamics. An additional goal is to integrate a number of highly complex intelligent VME modules with many sub-functions in the CERN controls environment to provide adequate signal acquisition, control and diagnostics to operate the system.  
 
WPAT024 First Results from the Use of Dual Harmonic Acceleration on the ISIS Synchrotron synchrotron, proton, beam-losses, injection 1871
 
  • A. Seville, D. Bayley, R.G. Bendall, M.G. Glover, A. Morris, J.W.G. Thomason
    CCLRC/RAL/ISIS, Chilton, Didcot, Oxon
  • D.J. Adams, I.S.K. Gardner, C.M. Warsop
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  The ISIS facility at the Rutherford Appleton Laboratory in the UK is currently the most intense pulsed, spallation, neutron source. The accelerator consists of a 70 MeV H- Linac and an 800 MeV, 50 Hz, rapid cycling, proton Synchrotron. The synchrotron beam intensity is 2.5x1013 protons per pulse, corresponding to a mean current of 200 μA. The synchrotron beam is accelerated using six, ferrite loaded, RF cavities with harmonic number 2. Four additional, harmonic number 4, cavities have been installed to increase the beam bunching factor with the potential of raising the operating current to 300 μA. This paper reports on the hardware commissioning and the first beam tests.  
 
WPAT035 The LANSCE 805 MHZ RF System History and Status klystron, focusing, power-supply 2402
 
  • M.T. Lynch, G. Bolme, P.J. Tallerico
    LANL, Los Alamos, New Mexico
  The Los Alamos Neutron Science Center (LANSCE) linear accelerator runs at 201.25 MHz for acceleration to 100 MeV. The remainder of the acceleration to 800 MeV is at 805 MHz. This is done with 44 accelerator cavity stages driven by 805 MHz klystrons. Each klystron has a peak power capability of 1.25 MeV. Originally, 97 klystrons were purchased, which was 70 from Varian/CPI and 27 from Litton. The 44 RF systems are laid out in sectors with either 6 or 7 klystrons per sector. The klystrons in each sector are powered from a common HV sytem. The current arrangement uses the Varian/CPI klystrons in 6 of the 7 sectors and Litton klystrons in the remaining sector. With that arrangement there are 38 CPI klystrons installed and 1 spare klystron per sector and 6 Litton klystrons installed in the final sector with 2 spares. The current average life of all of the operating and spare klystrons (52 total) is >112,000 filament hours and >93,000 HV hours. That is three times the typical klystron lifetime today for other similar klystrons. This paper summarizes the details of the LANSCE klystron history and status and a summary of the predicted failure rate.  
 
WPAT052 Present Status of RF System for Medical Proton Synchrotron synchrotron, proton, feedback, impedance 3185
 
  • Z. Fang, K. Egawa, K. Endo, S. Yamanaka
    KEK, Ibaraki
  • Y. Cho, T. Fusato, T. Hirashima
    DKK, Kanagawa
  The 200MeV proton synchrotron of circumference of 9.54m is being developed for medical radiotherapy. The rf system has been carried out with a wide bandwidth of frequency sweeping from 2.0MHz to 17.8MHz. The rf cavity is designed of a compact dimension and a high acceleration gradient. The high power test of the rf system has been successfully performed and maximal acceleration gradient of 60kV/m has been achieved. The experiments with feedback control system are being studied by using a dummy beam signal. In this paper, the recent progress of the rf system and test results will be presented in detail.  
 
WPAT094 Traveling Wave Accelerating Structure for a Superconducting Accelerator feedback, superconductivity, linear-collider, simulation 4296
 
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio
  • P.A. Avrakhov
    LPI, Moscow
  • N. Solyak
    Fermilab, Batavia, Illinois
  We are presenting a superconducting traveling wave accelerating structure (STWA) concept, which may prove to be of crucial importance to the International Linear Collider. Compared to the existing design of a TESLA cavity, the traveling wave structure can provide ~20-40% higher accelerating gradient for the same aperture and the same peak surface magnetic RF field. The recently achieved SC structure gradient of 35 MV/m can be increased up to ~50 MV/m with the new STWA structure design. The STWA structure is supposed to be installed into the superconducting resonance ring and is fed by the two couplers with appropriate phase advance to excite a traveling wave inside the structure. The system requires two independent tuners to be able to adjust the cavity and feedback waveguide frequencies and hence to reduce the unwanted backward wave. In this presentation we discuss the structure design, optimization of the parameters, tuning requirements and plans for further development.  
 
WOAC001 Aberration Correction in Electron Microscopy electron, quadrupole, sextupole, multipole 44
 
  • H.H. Rose, W. Wan
    LBNL, Berkeley, California
  The resolution of conventional electron microscopes is limited by spherical and chromatic aberrations. Both defects are unavoidable in the case of static rotationally symmetric electromagnetic fields (Scherzer theorem). Multipole correctors and electron mirrros have been designed and built, which compensate for these aberrations. The principles of correction will be demonstrated for the tetrode mirror, the quadrupole-octopole corrector and the hexapole corrector. Electron mirrors require a magnetic beam separator free of second-order aberrations. The multipole correctors are highly symmetric telescopic systems compensating for the defects of the objective lens. The hexapole corrector has the most simple structure yet eliminates only the spherical aberration, whereas the mirror and the quadrupole-octopole corrector are able to correct for both aberrations. Chromatic correction is achieved in the latter corrector by cossed electric and magnetic quadrupoles acting as first-order Wien filters. Micrographs obtained with aberration-corrected electron microscopes will be shown demonstrating the improvement in resolution to better than 1 Angstroem.  
 
RPAP020 Fixed Field Alternating Gradient Accelerators (FFAG) for Fast Hadron Cancer Therapy proton, resonance, ion, cyclotron 1667
 
  • E. Keil
    CERN, Geneva
  • A. Sessler
    LBNL, Berkeley, California
  • D. Trbojevic
    BNL, Upton, Long Island, New York
  Funding: * AMS supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF0009

Cancer accelerator therapy continues to be ever more prevalent with new facilities being constructed at a rapid rate. Some of these facilities are synchrotrons, but many are cyclotrons and, of these, a number are FFAG cyclotrons. The therapy method of "spot scanning” requires many pulses per second (typically 200 Hz), which can be accomplished with a cyclotron (in contrast with a synchrotron). We briefly review commercial scaling FFAG machines and then discuss recent work on non-scaling FFAGs, which may offer the possibility of reduced physical aperture and a large dynamic aperture. However, a variation of tune with energy implies the crossing of resonances during the acceleration process. A design can be developed such as to avoid intrinsic resonances, although imperfection resonances must still be crossed. Parameters of two machines are presented; a 250 MeV proton therapy accelerator and a 400 MeV carbon therapy machine.

 
 
RPAP032 Hardware Tracking Related to Compact Medical Pulse Synchrotron dipole, synchrotron, quadrupole, proton 2260
 
  • K. Endo, K. Egawa, Z. Fang
    KEK, Ibaraki
  • S. Yamanaka
    NIRS, Chiba-shi
  A compact 200 MeV proton synchrotron for the radiotherapy is being developed. Dipole and quadrupole magnets were already manufactured and are ready to measure their field properties under the pulse excitation. Preliminary field measurement was already done on the prototype dipole. Small RF cavity with a wide bandwidth (2~18 MHz) was successfully developed. Concerning to the simultaneous pulse operation of these components, there are some issues to be solved beforehand. These are the tracking between dipole field and the quadruple field gradient, the RF frequency generation sensing the dipole current (or field), the sextupole field correction of the dipole and etc. These issues studied experimentally using the dipole current will be presented in conjunction with the progress of the development.  
 
RPAT017 Using Time Separation of Signals to Obtain Independent Proton and Antiproton Beam Position Measurements Around the Tevatron antiproton, proton, injection, closed-orbit 1557
 
  • R.C. Webber
    Fermilab, Batavia, Illinois
  Funding: Fermilab is operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

Independent position measurement of the counter-circulating proton and antiproton beams in the Tevatron presents a challenge to upgrading the Tevatron Beam Position Monitor (BPM) system. The inherent directionality of the Tevatron BPM pickup design provides 26dB isolation between signals from the two beams. At the present typical 10:1 proton-to-antiproton bunch intensity ratio, this isolation alone is insufficient to support millimeter accuracy antiproton beam position measurements due to interfering proton signals. An accurate and manageable solution to the interfering signal problem is required for antiproton measurements now and, as machine improvements lead to increased antiproton intensity, will facilitate future elimination of antiproton bias on proton beam position measurements. This paper discusses the possibilities and complications of using time separation of the two beam signals at the numerous Tevatron BPM locations and given the dynamic longitudinal conditions of Tevatron operation. Results of measurements results using one such method are presented.

 
 
RPAT045 Beam Phase Detection for Proton Therapy Accelerators cyclotron, proton, pick-up, feedback
 
  • B. A. Aminov, M. G. Getta, S. K. Kolesov, N. Pupeter
    CRE, Wuppertal
  • A. Geisler, T. Stephani, J. H. Timmer
    ACCEL, Bergisch Gladbach
  The industrial application of proton cyclotrons for medical applications has become one of the important contributions of accelerator physics during the last years. This paper describes an advanced vector demodulating technique used for non-destructive measurements of beam intensity and beam phase over 360°. A computer controlled I/Q-based phase detector with a very large dynamic range of 70 dB permits the monitoring of beam intensity, phase and eventually energy for wide range of beam currents down to –130 dBm. In order to avoid interference from the fundamental cyclotron frequency the phase detection is performed at the second harmonic frequency. A digital low pass filter with adjustable bandwidth and steepness is implemented to improve accuracy. With a sensitivity of the capacitive pickup in the beam line of 30 nV per nA of proton beam current at 250 MeV, accurate phase and intensity measurements can be performed with beam currents down to 3.3 nA.  
 
RPAT078 Bunch Length Measurements Using Coherent Radiation radiation, electron, plasma, vacuum 4027
 
  • R. Ischebeck, C.D. Barnes, I. Blumenfeld, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, D.K. Johnson, W. Lu, K.A. Marsh
    UCLA, Los Angeles, California
  • S. Deng, E. Oz
    USC, Los Angeles, California
  • N.A. Kirby
    Stanford University, Stanford, Califormia
  Funding: Work supported by Department of Energy contracts DE-AC02-76SF00515 (SLAC), DE-FG03-92ER40745, DE-FG03-98DP00211, DE-FG03-92ER40727, DE-AC-0376SF0098, and National Science Foundation grants No. ECS-9632735, DMS-9722121 and PHY-0078715.

The accelerating field that can be obtained in a beam-driven plasma wakefield accelerator depends on the current of the electron beam that excites the wake. In the E-167 experiment, a peak current above 10kA will be delivered at a particle energy of 28GeV. The bunch has a length of a few ten micrometers and several methods are used to measure its longitudinal profile. Among these, autocorrelation of coherent transition radiation (CTR) is employed. The beam passes a thin metallic foil, where it emits transition radiation. For wavelengths greater than the bunch length, this transition radiation is emitted coherently. This amplifies the long-wavelength part of the spectrum. A scanning Michelson interferometer is used to autocorrelate the CTR. However, this method requires the contribution of many bunches to build an autocorrelation trace. The measurement is influenced by the transmission characteristics of the vacuum window and beam splitter. We present here an analysis of materials, as well as possible layouts for a single shot CTR autocorrelator.

 
 
RPAT079 Resolution of Transverse Electron Beam Measurements Using Optical Transition Radiation radiation, electron, plasma, target 4042
 
  • R. Ischebeck, F.-J. Decker, M.J. Hogan, R.H. Iverson, P. Krejcik, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • C.E. Clayton, C. Huang, W. Lu
    UCLA, Los Angeles, California
  • S. Deng, E. Oz
    USC, Los Angeles, California
  • M. Lincoln
    Stanford University, Stanford, Califormia
  Funding: Work supported by Department of Energy contracts DE-AC02-76SF00515 (SLAC), DE-FG03-92ER40745, DE-FG03-98DP00211, DE-FG03-92ER40727, DE-AC-0376SF0098, and National Science Foundation grants No. ECS-9632735, DMS-9722121 and PHY-0078715.

In the plasma wakefield acceleration experiment E-167, optical transition radiation is used to measure the transverse profile of the electron bunches before and after the plasma acceleration. The distribution of the electric field from a single electron does not give a point-like distribution on the detector, but has a certain extension. Additionally, the resolution of the imaging system is affected by aberrations. The transverse profile of the bunch is thus convolved with a point spread function (PSF). Algorithms that deconvolve the image can help to improve the resolution. Imaged test patterns are used to determine the modulation transfer function of the lens. From this, the PSF can be reconstructed. The Lucy-Richardson algorithm is used to deconvolute this PSF from test images.

 
 
ROAB003 Highly Compressed Ion Beams for High Energy Density Science ion, target, plasma, heavy-ion 339
 
  • A. Friedman, J.J. Barnard, D. A. Callahan, G.J. Caporaso, D.P. Grote, R.W. Lee, S.D. Nelson, M. Tabak
    LLNL, Livermore, California
  • R.J. Briggs
    SAIC, Alamo, California
  • C.M. Celata, A. Faltens, E. Henestroza, E. P. Lee, M. Leitner, B. G. Logan, G. Penn, L. R. Reginato, A. Sessler, J.W.  Staples, W. Waldron, J.S. Wurtele, S. Yu
    LBNL, Berkeley, California
  • R.C. Davidson, L. Grisham, I. Kaganovich
    PPPL, Princeton, New Jersey
  • C. L. Olson, T. Renk
    Sandia National Laboratories, Albuquerque, New Mexico
  • D. Rose, C.H. Thoma, D.R. Welch
    ATK-MR, Albuquerque, New Mexico
  Funding: Work performed under auspices of USDOE by U. of CA LLNL & LBNL, PPPL, and SNL, under Contract Nos. W-7405-Eng-48, DE-AC03-76SF00098, DE-AC02-76CH03073, and DE-AC04-94AL85000, and by MRC and SAIC.

The Heavy Ion Fusion Virtual National Laboratory (HIF-VNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target "foils," which may in fact be foams or "steel wool" with mean densities 1% to 100% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the requirements for warm dense matter experiments, and describe suitable accelerator concepts, including novel broadband traveling wave pulse-line, drift-tube linac, RF, and single-gap approaches. We show how neutralized drift compression and final focus optics tolerant of large velocity spread can generate the necessarily compact focal spots in space and time.

 
 
ROAB005 Helical Pulseline Structures for Ion Acceleration ion, vacuum, coupling, induction 440
 
  • R.J. Briggs
    SAIC, Alamo, California
  • L. R. Reginato, W. Waldron
    LBNL, Berkeley, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Berkeley National Laboratory, Contract DE-AC03-76SF00098.

The basic concept of the "Pulseline Ion Accelerator" involves launching a ramped high voltage pulse on a broad band traveling wave (slow-wave) structure. An applied voltage pulse at the input end with a segment rising linearly in time becomes a linear voltage ramp in space that propagates down the line, corresponding to a (moving) region of constant axial accelerating electric field. The ions can "surf" on this traveling wave, experiencing a total energy gain that can greatly exceed the peak of the applied voltage. The applied voltage waveform can also be shaped to longitudinally confine the beam against its own space charge forces, and (in the final stage) to impart an inward compression to the beam for neutralized drift compression in heavy ion HEDP applications. In the first stages of a heavy ion accelerator, the pulseline velocity needs to be the order of 1% of the speed of light and the line must be sufficiently non-dispersive for the broad band voltage pulse propagating down the line to have minimal distortion. Experimental characterization of the dispersion and pulse propagation at low voltage on several helix models will be presented, and compared with theoretical predictions.*

*Caporaso, et al, "Dispersion Analysis of the Pulseline Accelerator," this conference.

 
 
ROAB010 Development of a Compact Radiography Accelerator Using Dielectric Wall Accelerator Technology laser, cathode, vacuum, pulsed-power 716
 
  • S. Sampayan, G.J. Caporaso, Y.-J. Chen, S.A. Hawkins, L. Holmes, J.F. McCarrick, S.D. Nelson, C. Nunnally, B.R. Poole, A. Rhodes, M. Sanders, S. Sullivan, L. Wang, J.A. Watson
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

We are developing of a compact accelerator system primarily intended for pulsed radiography. Design characteristics are an 8 MeV endpoint energy, 2 kA beam current and a cell gradient of approximately 3 MV/m. Overall length of the device is below 3 m. Such compact designs have been made possible with the development of high specific energy dielectrics (> 10 J/cc), specialized transmission line designs and multi-gap laser-triggered low jitter (<1 ns) gas switches. In this geometry, the pulse forming lines, switches and insulator/beam pipe are fully integrated within each cell to form a compact stand-alone stackable unit. We detail our research and modeling to date, recent high voltage test results, and the integration concept of the cells into a radiographic system.

 
 
RPPE001 The CARE Accelerator R&D Programme in Europe electron, proton, linac, hadron 749
 
  • O. Napoly, R. Aleksan, A. Devred
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • A. Den Ouden
    Twente University, Laser Physics and Non-Linear Optics Group, Enschede
  • R. Garoby, R. Losito, L. Rinolfi, F. Ruggiero, W. Scandale, D. Schulte, M. Vretenar
    CERN, Geneva
  • T. Garvey, F. Richard
    LAL, Orsay
  • A. Ghigo
    INFN/LNF, Frascati (Roma)
  • E. Gschwendtner
    CUI, Geneva
  • H. Mais, D. Proch
    DESY, Hamburg
  • V. Palladino
    INFN-Napoli, Napoli
  Funding: This work is supported by the European Community-Research Infrastructure Activity under the FP6 “Structuring the European Research Area” programme (CARE, contract number RII3-CT-2003-506395).

CARE, an ambitious and coordinated programme of accelerator research and developments oriented towards HEP projects, has been launched in January 2004 by the main European laboratories and the European Commission within the 6th Framework Programme. This programme aims at improving existing infrastructures dedicated to future projects such as linear colliders, upgrades of hadron colliders and high intensity proton drivers. An important part of this programme is devoted to advancing the performance of the superconducting technology, both in the fields of RF cavities for electron and proton acceleration and of high field magnets, as well as to developing high intensity electron and proton injectors. We describe the R&D plans of the four main R&D activities and report on the results and progress obtained so far.

 
 
RPPP044 Studies of Room Temperature Accelerator Structures for the ILC Positron Source positron, impedance, coupling, linear-collider 2827
 
  • J.W. Wang, C. Adolphsen, V. Bharadwaj, G.B. Bowden, V.A. Dolgashev, R.M. Jones, E.N. Jongewaard, J.R. Lewandowski, Z. Li, R.H. Miller
    SLAC, Menlo Park, California
  Funding: Work supported by U.S. Department of Energy, contract DE-AC02-76F00515.

There are many challenges in the design of the normal-conducting portion of ILC positron injector system such as achieving adequate cooling with the high rf and particle loss heating, and sustaining high accelerator gradients during millisecond-long pulses in a strong magnetic field. The proposed design for the positron injector contains both standing-wave and traveling-wave L-band accelerator structures for high RF efficiency, low cost and ease of fabrication. This paper presents results from studies of particle energy deposition for both undulator based and conventional positron sources, cooling system design, accelerator structure optimization, RF pulse heating, cavity frequency stabilization, and RF feed system design.

 
 
RPPT051 Electron Model of Linear-Field FFAG resonance, electron, quadrupole, extraction 3173
 
  • S.R. Koscielniak
    TRIUMF, Vancouver
  • C. Johnstone
    Fermilab, Batavia, Illinois
  Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada.

A fixed-field alternating-gradient accelerator (FFAG) that employs only linear-field elements ushers in a new regime in accelerator design and dynamics. The linear-field machine has the ability to compact an unprecedented range in momenta within a small component aperture. With a tune variation which results from the natural chromaticity, the beam crosses many strong, uncorrec-table, betatron resonances during acceleration. Further, relativistic particles in this machine exhibit a quasi-parabolic time-of-flight that cannot be addressed with a fixed-frequency rf system. This leads to a new concept of bucketless acceleration within a rotation manifold. With a large energy jump per cell, there is possibly strong synchro-betatron coupling. A few-MeV electron model has been proposed to demonstrate the feasibility of these untested acceleration features and to investigate them at length under a wide range of operating conditions. This paper presents a lattice optimized for a 1.3 GHz rf, initial technology choices for the machine, and describes the range of experiments needed to characterize beam dynamics along with proposed instrumentation.

 
 
RPPT052 Analysis of Rapid Betatron Resonance Crossing resonance, betatron, lattice, linac 3206
 
  • S.R. Koscielniak, A. Baartman
    TRIUMF, Vancouver
  Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada.

The reduction of transverse and longitudinal cooling requirements, the increased number of beam circulations, and the reduce cost, as compared to RLAs, are arguments to adopt the linear-field FFAG as the acceleration stage of a Neutrino Factory. Because of the large range of central momenta, pm 50% delta p/p, and negative uncorrected chromaticity, the non-scaling FFAG will cross many integer and half-integer betatron resonances during the 10-20 turns acceleration. There is the expectation that if driving terms are small enough and crossing is fast enough, then there is insufficient time for the betatron amplitudes to grow. The conventional theory of resonance crossing is applied to slow acceleration, over 100s or 1000s of turns. This paper examines whether the rapid parameter changes encountered in the multi-GeV FFAGs, or few-MeV electron model, are compatible with simple theory.

 
 
RPPT061 Linear Quadrupole Cooling Channel for a Neutrino Factory quadrupole, emittance, simulation, factory 3526
 
  • C. Johnstone
    Fermilab, Batavia, Illinois
  • M. Berz, K. Makino
    MSU, East Lansing, Michigan
  Funding: Work supported by the U.S. Dept. of Energy under contract no. DE-AC02-76CH03000.

The staging and optimization in the design of a Neutrino Factory are critically dependent on the choice and format of accelerator. Possibly the simplest, lowest-cost scenario is a nonscaling FFAG machine coupled to a linear (no bending) transverse cooling channel constructed from the simplest quadrupole lens system, a FODO cell. In such a scenario, transverse cooling demands are reduced by a factor of 4 and no longitudinal cooling is required relative to acceleration using a Recirculating Linac (RLA). Detailed simulations further show that a quadrupole-based channel cools efficiently and over a momentum range which is well-matched to FFAG acceleration. Details and cooling performance for a quadrupole channel are summarized in this work.

 
 
RPPT071 Installation of the Spallation Neutron Source (SNS) Superconducting Linac SNS, vacuum, linac, quadrupole 3838
 
  • D. Stout, I.E. Campisi, F. Casagrande, R.I. Cutler, D.R. Hatfield, M.P. Howell, T. Hunter, R. Kersevan, P. Ladd, W.H. Strong
    ORNL, Oak Ridge, Tennessee
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge.

The Spallation Neutron Source (SNS) cold linac consists of 11 medium beta (0.61) and 12 high beta (0.81) superconducting RF cryomodules, 32 intersegment quadrupole magnet/diagnostics stations, 9 spool beampipes for future upgrade cryomodules, and two differential pumping stations on either side of the linac. The cryomodules and spool beampipes were designed and manufactured by Jefferson Laboratory, and the quadrupole magnets and beam position monitors were designed and furnished by Los Alamos National Laboratory. The remaining items were designed by ORNL. At present we are installing and testing the cold linac. Experience gained during installation will be presented. The performance in terms of mechanical and cryogenic systems will be described.

 
 
RPPT074 Beam Characterizations at Femtosecond Electron Beam Facility electron, cathode, linac, radiation 3925
 
  • S. Rimjaem, V. Jinamoon, Mr. Kangrang, K. Kusoljariyakul, J. Saisut, C. Thongbai, T. Vilaithong
    FNRF, Chiang Mai
  • M.W. Rhodes, P. Wichaisirimongkol
    IST, Chiang Mai
  • H. Wiedemann
    SLAC, Menlo Park, California
  Funding: We are grateful to the Thailand Research Fund, the National Research Council of Thailand, the Thai Royal Golden Jubilee Scholarship, the U.S. Department of Energy, and the Hansen Experimental Physics laboratory of Stanford University.

The SURIYA project at the Fast Neutron Research Facility (FNRF) has been established and is being commissioning to generate femtosecond electron pulses. Theses short pulses are produced by a system consisting of an S-band thermionic cathode RF-gun, an alpha magnet as a magnetic bunch compressor, and a linear accelerator. The characteristics of its major components and the beam characterizations as well as the preliminary experimental results will be presented and discussed.

 
 
ROPC003 RIKEN RI Beam Factory Project ion, cyclotron, heavy-ion, extraction 320
 
  • Y. Yano
    RIKEN/RARF/CC, Saitama
  The world-top-class radioactive-isotope-beam (RIB) facility, which is called ?RI beam factory (RIBF)?, is under construction at RIKEN. This facility is based on the so-called ?in-flight RI beam separation? scheme. Late in 2006, a new high-power heavy-ion accelerator system consisting of a cascade of three ring cyclotrons with K=570 MeV (fixed frequency, fRC), 980 MeV (Intermediate stage, IRC) and 2500 MeV (superconducting, SRC), respectively, will be commissioned. This new accelerator system will boost energies of the output beams from the existing K540-MeV ring cyclotron up to 440 MeV/nucleon for light ions and 350 MeV/nucleon for very heavy ions. These energetic heavy-ion beams are converted into intense RI beams via the projectile fragmentation or in-flight fission of uranium ions by the superconducting isotope separator, BigRIPS, under construction. The combination of the SRC and BigRIPS will expand our nuclear world into presently unreachable region. Major experimental installations are under priority discussion as the second phase program. Construction of the second phase is expected to start in 2006.  
 
ROPC004 Recent Intensity Increase in the CERN Accelerator Chain beam-losses, extraction, injection, booster 413
 
  • E.N. Shaposhnikova, G. Arduini, T. Bohl, M. Chanel, R. Garoby, S. Hancock, K. Hanke, T.P.R. Linnecar, E. Métral, R.R. Steerenberg, B. Vandorpe
    CERN, Geneva
  Future requests for protons from the physics community at CERN, especially after the start-up of the CNGS experiments in 2006, can only be satisfied by a substantial increase in the SPS beam intensity per pulse. In September 2004 a three weeks beam run was dedicated to high intensity; all accelerators in the chain were pushed to their limits to study intensity restrictions and find possible solutions. New record intensities were obtained in the accelerators of the PS & SPS Complex with this fixed-target type beam which is different from the nominal LHC beam. The challenges in producing this high-intensity beam are described together with the measures needed to make it fully operational.  
 
ROPC005 RIA Post Accelerator Design ion, linac, rfq, emittance 425
 
  • S.O. Schriber
    NSCL, East Lansing, Michigan
  Overall design of the post accelerator for the RIA project is described with emphasis on performance for different ion beams. Characteristics for beams from A=10 to A=240 will be provided with an estimate of output intensities. The rational for selection of different accelerating structures, both for the normal conducting and for the superconducting types, will be provided for a system design that accelerates beams to at least 10 MeV/u.  
 
ROPC009 First Acceleration with Superconducting RF Cavities at ISAC-II simulation, diagnostics, ion, vacuum 662
 
  • R.E. Laxdal, K. Fong, M. Marchetto, W.R. Rawnsley, V. Verzilov
    TRIUMF, Vancouver
  We have demonstrated the first acceleration of ions with superconducting rf at TRIUMF/ISAC. Alpha particles from a radioactive source were accelerated from 2.8MeV through the ISAC-II medium beta cryomodule to a maximum energy of 9.4 MeV. The four 106 MHz quarter wave cavities (beta_o=7%) were set to the ISAC-II specified gradient of 6 MV/m (Leff=18cm, Ep=30MV/m and Veff=1.08MV) with a cavity power of about 6W per cavity. The final particle energy spectra was measured with a silicon detector. The initial alpha energy corresponds to a velocity of beta=3.9% giving an expected T/To efficiency of 0.48, 0.76, 0.92 and 0.99 for the four cavities respectively and an expected final energy of 9.6MeV. The experimental set-up including details of the source and diagnostic boxes and the detector electronics are described. Beam simulations of the unbunched, uncollimated beam indicate a unique spectral fingerprint that can be used to unambiguously determine each cavity voltage.  
 
FOAC003 New Concepts in FFAG Design for Secondary Beam Facilities and Other Applications proton, cyclotron, ion, resonance 261
 
  • M.K. Craddock
    UBC & TRIUMF, Vancouver, British Columbia
  Fixed Field Alternating Gradient accelerators offer much higher acceptances and repetition rates - and therefore higher beam intensities - than synchrotrons, at the cost of more complicated magnet and rf cavity designs. Perhaps because of the difficulty and expense anticipated, early studies never progressed beyond the stage of successful electron models, but in recent years, with improvements in magnet and rf design technology, FFAGs have become the focus of renewed attention. Two proton machines have now been built, and three more, plus a muon phase rotator, are under construction. In addition, more than 20 designs are under study for the acceleration of protons, heavy ions, electrons and muons, with applications as diverse as treating cancer, irradiating materials, driving subcritical reactors, boosting high-energy proton intensity, and producing neutrinos. Moreover, it has become apparent that FFAG designs need not be restricted to the traditional 'scaling' approach, in which the orbit shape, optics and tunes are kept fixed. Dropping this restriction has revealed a range of interesting new design possibilities. This paper will review the various approaches being taken.  
 
FPAE012 Experimental Test of a New Antiproton Acceleration Scheme in the Fermilab Main Injector emittance, antiproton, injection, collider 1303
 
  • V. Wu, C.M. Bhat, B. Chase, J.E. Dey, K.G. Meisner
    Fermilab, Batavia, Illinois
  Funding: Operated by Universities Research Association, Inc. for the U.S. Department of Energy under contract DE-AC02-76CH03000.

In an effort to provide higher intensity and lower emittance antiproton beam to the Tevatron collider for high luminosity operation, a new Main Injector (MI) antiproton acceleration scheme has been developed [1-4].* In this scheme, beam is accelerated from 8 to 27 GeV using the 2.5 MHz rf system and from 27 to 150 GeV using the 53 MHz rf system. This paper reports the experimental results of beam study. Simulation results are reported in a different PAC'05 paper [5]. Experiments are conducted with proton beam from the Booster. Acceleration efficiency, emittance growth and beam harmonic transfer between 2.5 MHz (h=28) and 53 MHz (h=588) buckets have been studied. Beam study shows that one can achieve an overall acceleration efficiency of about 100%, longitudinal emittance growth less than 20% and negligible transverse emittance growth.

*G. P. Jackson, The Fermilab Recycler Ring Technical Design Report, FERMILAB-TM-1991, November 1996.

 
 
FPAE019 Booster 6-GeV Study booster, proton, beam-losses, linac 1637
 
  • X. Yang, C.M. Ankenbrandt, J.R. Lackey, R.D. Padilla, W. Pellico
    Fermilab, Batavia, Illinois
  • J. Norem
    ANL, Argonne, Illinois
  Funding: Fermi National Accelerator Laboratory, Accelerator Division, Proton Source Department.

Since a wider aperture has been obtained along the Fermilab Booster beam line, this opens the opportunity for Booster running a higher intensity proton beam than ever before. Sooner or later, the available RF accelerating voltage will become a new limit for the beam intensity. Either by increasing the RF accelerating voltage or by reducing the accelerating rate can achieve the similar goal. The motivation for the 6-GeV study is to gain the relative accelerating voltage via a slower acceleration.

 
 
FPAE020 Induction Acceleration of a Single RF Bunch in the KEK PS induction, synchrotron, focusing, booster 1679
 
  • K. Takayama, D.A. Arakawa, Y.A. Arakida, S. Igarashi, T. Iwashita, T. Kono, E. Nakamura, M. Sakuda, H. Sato, Y. Shimosaki, M.J. Shirakata, T. Sueno, K. Torikai, T. Toyama, M. Wake, I. Yamane
    KEK, Ibaraki
  • K. Horioka
    TIT, Yokohama
  • A.K. Kawasaki, A. Tokuchi
    NICHICON, Shiga
  • J. Kishiro
    JAERI/LINAC, Ibaraki-ken
  • K. Koseki
    GUAS/AS, Ibaraki
  • M.S. Shiho
    JAERI/NAKA, Ibaraki-ken
  • M. Watanabe
    JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  A single bunch trapped in an RF bucket was accelerated by induction devices from 500 MeV to 8GeV beyond transition energy in the KEK-PS. This is the first demonstration of induction acceleration in a high energy circular ring. The acceleration was confirmed by measuring a temporal evolution of the RF phase through an entire acceleration.* Key devices in an induction acceleration system are an induction accelerating cavity capable of generating an induced voltage of 2kV/cell, a pulse modulator to drive the cavity (switching driver), and a DSP system to control gate signals for switching. Their remarkable characteristics are its repetition ratio of about 1MHz and duty factor of 50%. All devices have been newly developed at KEK so as to meet this requirement. The pulse modulator employing MOSFETs as switching elements is connected with the accelerating cavity through a long transmission cable in order to avoid a high-dose irradiation in the accelerator tunnel. The induction system has been running beyond more than 24 hours without any troubles. The paper will take an introductive role for related other 6 papers too, which describe more technical aspects and novel beam physics associated with the induction acceleration.

*K.Takayama et al., submitted to Phys. Rev. Lett., http://www.arxiv.org/pdf/physics/0412006.

 
 
FPAE022 Cycle-to-Cycle Extraction Synchronization of the Fermilab Booster for Multiple Batch Injection to the Main Injector booster, feedback, extraction, injection 1802
 
  • R.M. Zwaska, S.E. Kopp
    The University of Texas at Austin, Austin, Texas
  • W. Pellico
    Fermilab, Batavia, Illinois
  We report on a system to ensure cycle-to-cycle synchronization of beam extraction from the Fermilab Booster accelerator to the Main Injector. Such synchronization is necessary for multiple batch operation of the Main Injector for the Run II upgrade of anti-proton production using slip-stacking in the Main Injector, and for the NuMI (Neutrinos at the Main Injector) neutrino beam. To perform this task, a system of fast measurement and feedback is used to control the longitudinal progress of the Booster beam throughout its acceleration period by manipulation of the transverse position maintained by the low-level radio frequency system.  
 
FPAE026 Development of FFAG Accelerator at KEK extraction, injection, septum, synchrotron 1943
 
  • Y. Yonemura, N. Ikeda, M. Matoba
    Kyushu University, Fukuoka
  • M. Aiba, S. Machida, Y. Mori, A. Muto, J. Nakano, C. Ohmori, K.O. Okabe, I. Sakai, Y. Sato, A. Takagi, T. Yokoi, M. Yoshii, Y. Yuasa
    KEK, Ibaraki
  • R. Taki
    GUAS/AS, Ibaraki
  • T. Uesugi
    NIRS, Chiba-shi
  • A. Yamazaki
    LNS, Sendai
  • M. Yoshimoto
    JAERI, Ibaraki-ken
  The 150MeV proton FFAG accelerator is constructed and a beam is extracted at the final energy. This is the prototype FFAG for various applications such as proton beam therapy. We are now in preparation for using an extracted beam in the practical applications.  
 
FPAE027 Status of the ISAC-II Accelerator at TRIUMF linac, vacuum, ion, heavy-ion 2003
 
  • R.E. Laxdal, W. Andersson, P. Bricault, I. Bylinskii, K. Fong, M. Marchetto, A.K. Mitra, R.L. Poirier, W.R. Rawnsley, P. Schmor, I. Sekachev, G. Stanford, G.M. Stinson, V. Zviagintsev
    TRIUMF, Vancouver
  A heavy ion superconducting linac is being installed at TRIUMF to increase the final energy of radioactive beams at ISAC. A first stage of 20MV consisting of five medium beta cryomodules each with four quarter wave bulk niobium cavities and a superconducting solenoid is being installed with initial beam commissioning scheduled for Dec. 2005. The initial cryomodule has met cryogenic and rf performance specifications. In addition we have demonstrated acceleration of alpha particles in an off-line test. A 500W refrigerator system has been installed and commissioned in Jan. 2005 with cold distribution due for commissioning in Sept. 2005. A transfer beamline from the ISAC accelerator and beam transport to a first experimental station are being installed. The status of the project will be presented.  
 
FPAE037 SPIRAL 2 RFQ Prototype First Tests rfq, vacuum, pick-up, ion 2488
 
  • R. Ferdinand, G. Congretel, A. Curtoni, O. Delferriere, A. France, D. Leboeuf, J. Thinel, J.-C. Toussaint
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  • A.C. Caruso
    INFN/LNS, Catania
  • M. Di Giacomo
    GANIL, Caen
  The SPIRAL2 RFQ is designed to accelerate at 88MHz two kinds of charge-over-mass ratio, Q/A, particles. The proposed injector can accelerate a 5 mA deuteron beam (Q/A=1/2) or a 1 mA particles beam with q/A=1/3 up to 0.75 MeV/A. It is a CW machine which has to show stable operation, provide the request availability, have the minimum losses in order to minimize the activation constraints and show the best quality/cost ratio. The prototype of this 4-vane RFQ has been built and tested. It allowed to verify the mechanical assembly concept (RFQ without any brazing step). The full power was easily injected in the cavity, with no concerns for the RF joints. The paper describes the different achievements.  
 
FPAE040 First Operation of PIAVE, the Heavy Ion Injector Based on Superconducting RFQ's vacuum, ion, linac, ion-source 2621
 
  • G. Bisoffi, G. Bassato, A. Battistella, G.P. Bezzon, l. Boscagli, A. Calore, S. Canella, D. Carlucci, F. Chiurlotto, M. Comunian, M. De Lazzari, A. Facco, E. Fagotti, A. Lombardi, P. Modanese, M.F. Moisio, A. Pisent, M. Poggi, A.M. Porcellato, S. Stark
    INFN/LNL, Legnaro, Padova
  The Positive Ion Accelerator for low-Velocity Ions (PIAVE), based on superconducting RFQ's (SRFQ's), has been completed in fall 2004 with the first acceleration of beams from the ECR ion source. Superconducting RFQ's were used, for the first time, for beam acceleration on a user-oriented accelerator complex. A general status of the injector performances is given: it includes, besides the SRFQ's, eight superconducting (SC) QWR's and three bunchers; the beam is received from an ECR source on a HV platform and is delivered, through the SC accelerator ALPI, to nuclear physics experimental apparatuses. The paper emphasizes, in particular, the technological challenges related to the operation of the SC cavities, the cryogenics, control, diagnostics and vacuum systems.  
 
FPAE056 Review of a Spoke-Cavity Design Option for the RIA Driver Linac linac, beam-losses, simulation, proton 3360
 
  • P.N. Ostroumov, K.W. Shepard
    ANL, Argonne, Illinois
  • J.R. Delayen
    Jefferson Lab, Newport News, Virginia
  Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W-31-109-ENG-38.

A design option for the 1.4 GV, multiple-charge-state driver linac required for the U.S. Rare Isotope Accelerator Project based on 345 MHz, 3-cell spoke-loaded cavities has been previously discussed.* This paper updates consideration of design options for the RIA driver, including recent results from numerically-modeling the multi-charge-state beam dynamics and also cold test results for prototype superconducting niobium 3-cell spoke-loaded cavities.

*"High-energy ion linacs based on superconducting spoke cavities," K.W. Shepard, P.N. Ostroumov, and J.R. Delayen, Phys. Rev. ST Accel. Beams 6, 080101 (2003).

 
 
FPAT008 SDA-Based Diagnostic and Analysis Tools for Collider Run II proton, collider, diagnostics, controls 1099
 
  • V. Papadimitriou, T.B. Bolshakov, P. Lebrun, S. Panacek, A.J. Slaughter, A. Xiao
    Fermilab, Batavia, Illinois
  Funding: Fermilab (Department of Energy).

Operating and improving the understanding of the Fermilab Accelerator Complex for the colliding beam experiments requires advanced software methods and tools. The Shot Data Acquisition and Analysis (SDA) has been developed to fulfill this need. Data is stored in a relational database, and is served to programs and users via Web-based tools. Summary tables are systematically generated during and after a store. These tables, the Supertable, and the Recomputed Emittances and Recomputed Intensity tables are discussed here. This information is also accesible in JAS3 (Java Analysis Studio version 3).

 
 
FPAT028 Extraction Compression and Acceleration of High Line Charge Density Ion Beams ion, space-charge, simulation, heavy-ion 2032
 
  • E. Henestroza, C. Peters, S. Yu
    LBNL, Berkeley, California
  • R.J. Briggs
    SAIC, Alamo, California
  • D.P. Grote
    LLNL, Livermore, California
  Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

HEDP applications require high line charge density ion beams. An efficient method to obtain this type of beams is to extract a long pulse, high current beam from a gun at high energy, and let the beam pass through a decelerating field to compress it. The low energy beam bunch is loaded into a solenoid and matched to a Brillouin flow. The Brillouin equilibrium is independent of the energy if the relationship between the beam size (a), solenoid magnetic field strength (B) and line charge density is such that (Ba)2 is proportional to the line charge density. Thus it is possible to accelerate a matched beam at constant line charge density. An experiment, NDCX-1c is being designed to test the feasibility of this type of injectors, where we will extract a 1 microsecond, 100 mA, potassium beam at 160 keV, decelerate it to 55 keV (density ~0.2 microC/m), and load it into a 2.5 T solenoid where it will be accelerated to 100–150 keV (head to tail) at constant line charge density. The head-to-tail velocity tilt can be used to increase bunch compression and to control longitudinal beam expansion. We will present the physics design and numerical simulations of the proposed experiment

 
 
FPAT029 High Voltage Operation of Helical Pulseline Structures for Ion Acceleration ion, coupling, impedance, vacuum 2092
 
  • W. Waldron, L. R. Reginato
    LBNL, Berkeley, California
  • R.J. Briggs
    SAIC, Alamo, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Berkeley National Laboratory, Contract # DE-AC03-76SF00098.

The basic concept for the acceleration of heavy ions using a helical pulseline requires the launching of a high voltage traveling wave with a waveform determined by the beam transport physics in order to maintain stability and acceleration.* This waveform is applied to the front of the helix, creating over the region of the ion bunch a constant axial acceleration electric field that travels down the line in synchronism with the ions. Several methods of driving the helix have been considered. Presently, the best method of generating the waveform and also maintaining the high voltage integrity appears to be a transformer primary loosely coupled to the front of the helix, generating the desired waveform and achieving a voltage step-up from primary to secondary (the helix). This can reduce the drive voltage that must be brought into the helix enclosure through the feedthroughs by factors of 5 or more. The accelerating gradient is limited by the voltage holding of the vacuum insulator, and the material and helix geometry must be chosen appropriately. The helix must also be terminated into its characteristic impedance, and designs of terminations incorporated into the helix internal enclosure are presented in the paper.

*Briggs, et al, "Helical Pulseline Structures for Ion Acceleration," this conference.

 
 
FPAT034 Dispersion Analysis of the Pulseline Accelerator ion, beam-loading, impedance, vacuum 2330
 
  • G.J. Caporaso, S.D. Nelson, B.R. Poole
    LLNL, Livermore, California
  • R.J. Briggs
    SAIC, Alamo, California
  Funding: This work was perfomed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

We analyze the sheath helix model of the pulseline accelerator.* We find the dispersion relation for a shielded helix with a dielectric material between the shield and the helix and compare it against the results from 3-D electromagnetic simulations. Expressions for the fields near the beam axis are obtained. A scheme to taper the properties of the helix to maintain synchronism with the accelerated ions is described. An approximate circuit model of the system that includes beam loading is derived.

*"Helical Pulseline Structures for Ion Acceleration," Briggs, Reginato, Waldron, this conference.

 
 
FPAT035 Transverse Beam Instability in a Compact Dielectric Wall Induction Accelerator impedance, induction, resonance, simulation 2378
 
  • Y.-J. Chen, J.F. McCarrick, S.D. Nelson
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Using the dielectric wall accelerator technology, we are developing of a compact induction accelerator system primarily intended for pulsed radiography. Unlike the typical induction accelerator cell that is long comparing with its accelerating gap width, the proposed dielectric wall induction accelerator cell is short and its accelerating gap width is comparable with the cell length. In this geometry, the rf modes may be coupled from one cell to the next. We will present recent results of rf modeling of the cells and prediction of transverse beam instability on a 2-kA, 8-MeV beam.

 
 
FPAT038 Electromagnetic Simulations of Dielectric Wall Accelerator Structures for Electron Beam Acceleration simulation, impedance, coupling, monitoring 2550
 
  • S.D. Nelson, B.R. Poole
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

Dielectric Wall Accelerator (DWA) technology incorporates the energy storage mechanism, the switching mechanism, and the acceleration mechanism for electron beams. Electromagnetic simulations of DWA structures includes these effects and also details of the switch configuration and how that switch time affects the electric field pulse which accelerates the particle beam. DWA structures include both bi-linear and bi-spiral configurations with field gradients on the order of 20MV/m and the simulations include the effects of the beampipe, the beampipe walls, the DWA High Gradient Insulator (HGI) insulating stack, wakefield impedance calculations, and test particle trajectories with low emittance gain. Design trade-offs include the transmission line impedance (typically a few ohms), equilibration ring optimization, driving switch inductances, and a layer-to-layer coupling analysis and its affect on the pulse rise time.

 
 
FPAT040 Advanced Electric and Magnetic Material Models for FDTD Electromagnetic Codes induction, simulation 2639
 
  • B.R. Poole, S.D. Nelson
    LLNL, Livermore, California
  • S. Langdon
    REMCOM Incorporated, State College, Pennsylvania
  Funding: This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

The modeling of dielectric and magnetic materials in the time domain is required for pulse power applications, pulsed induction accelerators, and advanced transmission lines. For example, most induction accelerator modules require the use of magnetic materials to provide adequate Volt-sec during the acceleration pulse. These models require hysteresis and saturation to simulate the saturation wavefront in a multipulse environment. In high voltage transmission line applications such as shock or soliton lines the dielectric is operating in a highly nonlinear regime, which requires nonlinear models. Simple 1-D models are developed for fast parameterization of transmission line structures. In the case of nonlinear dielectrics, a simple analytic model describing the permittivity in terms of electric field is used in a 3-D finite difference time domain code (FDTD). In the case of magnetic materials, both rate independent and rate dependent Hodgdon magnetic material models have been implemented into 3-D FDTD codes and 1-D codes.

 
 
FPAT088 Advanced Beam-Dynamics Simulation Tools for RIA linac, simulation, rfq, beam-losses 4218
 
  • R.W. Garnett, J.A. Billen, T.P. Wangler
    LANL, Los Alamos, New Mexico
  • K.R. Crandall
    TechSource, Santa Fe, New Mexico
  • P.N. Ostroumov
    ANL, Argonne, Illinois
  • J. Qiang, R.D. Ryne
    LBNL, Berkeley, California
  • R.C. York, Q. Zhao
    NSCL, East Lansing, Michigan
  Funding: U.S. Department of Energy Contract W-7405-ENG-36.

We are developing multuparticle beam-dynamics simulation codes for RIA driver linac simulations extending from the low-energy beam transport line to the end of the linac. These codes run on the NERSC parallel supercomputing platforms at LBNL, which allow us to run simulations with large numbers of macroparticles. The codes have physics capabilities needed for RIA, including transport and acceleration of multiple-charge-state beams, beam-line elements such as high-voltage platforms within the linac, interdigital accelerating structures, charge-stripper foils, and capabilities for handling the effects of machine errors and other off-normal conditions. In this paper we present the status of the work, describe some recent additions to the codes, and show preliminary end-to-end simulation results for a representative driver-linac design.

 
 
FPAT091 LiTrack: A Fast Longitudinal Phase Space Tracking Code with Graphical User Interface linac, focusing, RF-structure, electron 4266
 
  • P. Emma, K.L.F. Bane
    SLAC, Menlo Park, California
  Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515.

Many linear accelerators, such as linac-based light sources and linear colliders, apply longitudinal phase space manipulations in their design, including electron bunch compression and wakefield-induced energy spread control. Several computer codes handle such issues, but most require detailed information on the transverse focusing lattice. In fact, in most linear accelerators, the transverse distributions do not significantly affect the longitudinal, and can be ignored initially. This allows the use of a fast 2D code to study longitudinal aspects without time-consuming considerations of the transverse focusing. LiTrack is based on a 15-year old code (same name) originally written by one of us (KB), which is now a MATLAB-based code with additional features, such as a graphical user interface and output plotting. The single-bunch tracking includes RF acceleration, bunch compression to 3rd order, geometric and resistive wakefields, aperture limits, synchrotron radiation, and flexible output plotting. The code was used to design both the LCLS and the SPPS projects at SLAC and typically runs in <1 minute. We describe the features, show some examples, and provide access to the code.

 
 
FOAB004 Construction of FFAG Accelerators in KURRI for ADS Study ion, ion-source, proton, booster 350
 
  • M. Tanigaki, K. Mishima, S. Shiroya
    KURRI, Osaka
  • S. Fukumoto, Y. Ishi
    Mitsubishi Electric Corp, Energy & Public Infrastructure Systems Center, Kobe
  • M. Inoue
    SLLS, Shiga
  • S. Machida, Y. Mori
    KEK, Ibaraki
  KART (Kumatori Accelerator driven Reactor Test) project is in progress at Kyoto University Research Reactor Institute (KURRI) from the fiscal year of 2002. The purposes of this project is the feasibility study of ADS, such as studying the effect of incident neutron energy on the effective multiplication factor of the subcritical nuclear fuel system. We are now constructing a proton FFAG accelerator complex as a neutron production driver for this project. Our accelerator complex consists of a 2.5 MeV FFAG with induction acceleration as an injector, 20 MeV and 150 MeV FFAGs with RF acceleration as a booster and a main ring, respectively. Our FFAG injector is a spiral sector type with 32 trim coils to produce a magnetic field of variable field index. Both booster and main rings are the radial sector type in which the field index is determined by the shape of pole-face. The test operations of the injector and the whole FFAG complex are expected around the spring and summer in 2005, respectively. Then this FFAG complex will be combined with our Kyoto University Critical Assembly (KUCA) in KURRI by the end of March 2006 for the feasibility study.