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Paper Title Other Keywords Page
MOPC003 Benchmarking of Simulation Codes Based on the Montague Resonance in the CERN Proton Synchrotron simulation, lattice, emittance, resonance 330
  • I. Hofmann, G. Franchetti
    GSI, Darmstadt
  • J.F. Amundson, P. Spentzouris
    Fermilab, Batavia, Illinois
  • S.M. Cousineau, J.A. Holmes
    ORNL, Oak Ridge, Tennessee
  • M. Giovannozzi, E. Métral
    CERN, Geneva
  • F.W. Jones
    TRIUMF, Vancouver
  • A.U. Luccio
    BNL, Upton, Long Island, New York
  • S. Machida
    KEK, Ibaraki
  • J. Qiang, R.D. Ryne
    LBNL, Berkeley, California
  Experimental data on emittance exchange by the space charge driven ‘‘Montague resonance'' have been obtained at the CERN Proton Synchrotron in 2002-04 as a function of the working point. These data are used to advance the benchmarking of major simulation codes (ACCSIM, IMPACT, MICROMAP, ORBIT, SIMBAD, SIMPSONS, SYNERGIA) currently employed world-wide in the design or performance improvement of high intensity circular accelerators. In this paper we summarize the experimental findings and compare them with the first three steps of simulation results of the still progressing work.  
MOPC007 Anisotropy-Driven Instability in Intense Charged Particle Beams betatron, plasma, simulation, dipole 558
  • E. Startsev, R.C. Davidson, H. Qin
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

In electrically neutral plasmas with strongly anisotropic distribution functions, free energy is available to drive different collective instabilities such as the electrostatic Harris instability and the transverse electromagnetic Weibel instability. Such anisotropies develop naturally in particle accelerators and may lead to a detoriation of beam quality. We have generalized the analysis of the classical Harris and Weibel instabilities to the case of a one-component intense charged particle beam with anisotropic temperature including the important effects of finite transverse geometry and beam space-charge. For a long costing beam, the delta-f particle-in-cell code BEST and the eighenmode code bEASt have been used to determine detailed 3D stability properties over a wide range of temperature anisotropy and beam intensity. A theoretical model is developed which describes the essential features of the linear stage of these instabilities. Both, the simulations and analytical theory, clearly show that moderately intense beams are linearly unstable to short-wavelength perturbations, provided the ratio of the longitudinal temperature to the transverse temperature is smaller than some threshold value.

MOPC010 Longitudinal Dynamics in the University of Maryland Electron Ring electron, cathode, gun, longitudinal-dynamics 713
  • J.R. Harris, D.W. Feldman, R. Feldman, Y. Huo, J.G. Neumann, P.G. O'Shea, B. Quinn
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: Work supported by the Department of Energy, the Office of Naval Research, the Joint Technology Office, and the Directed Energy Professional Society.

The University of Maryland Electron Ring (UMER) is a low energy electron recirculator for the study of space charge dominated beam transport. The system’s pulse length (100 ns) and large number of diagnostics make it ideal for investigating the longitudinal evolution of intense beams. Pulse shape flexibility is provided by the pulser system and the gridded gun, which has the ability to produce thermionic and photoemission beams simultaneously. In this paper, we report on the generation and evolution of novel line charge distributions in UMER.

MPPE006 Particle Distribution Function Forming in Nonlinear Systems octupole, quadrupole, target, lattice 985
  • S.N. Andrianov, S. Edamenko
    St. Petersburg State University, Applied Mathematics & Control Processes Faculty, St. Petersburg
  Modern ion-optical systems are used in different fields of beam physics both independent facilities as consisting of largemachines. One of these destination is to create beams with a desired distribution of beams particles. Often there is a need to ensure a homogeneous distribution for a terminal beam phase portrait in a transverse configuration space. This is one of problems of nonlinear aberrations management. It is known that nonlinearity properties inhere to any beam lines. Such these nonlinearities have unremovable character, and their influence can be remove using only special nonlinear lattice elements, which are introduced artificially into the beam line. In this paper we suggest a procedure to find necessary nonlinear correcting control elements for purposive forming of beam particle distribution functions.  
MPPE008 Synthesis of Beam Lines with Necessary Properties quadrupole, target, simulation, octupole 1096
  • S.N. Andrianov
    St. Petersburg State University, Applied Mathematics & Control Processes Faculty, St. Petersburg
  In this paper a new approach to the problem of synthesis of beam lines is discussed. Usually this problem can be overcome by the use of numerical simulation and optimal control theory methods. But this results in sufficiently great number of variable parameters and functions. Obviously, that this degrades quality of a modeling procedure. The suggested approach is demonstrated on a problem of a microprobe design problem. Essence of the problem is that necessary to design a high precision focusing system which satisfies some additional conditions. For solution of this problem we use an algebraic treatment based on Lie algebraic methods and computer algebra techniques. Using the symmetry ideology this approach allows rewriting beam properties to enough simple conditions for control parameters and functions. This leads a set of desired solutions and show results in some most suitable form. Moreover, this approach decreases the number of variable parameters.  
MPPE016 Hamiltonian Analysis of Transverse Dynamics in Axisymmetric RF Photoinjector emittance, space-charge, acceleration, 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.  
MPPE023 Improvement of the Longitudinal Beam Dynamics Tuning Procedure for the MSU RIA Driver Linac linac, emittance, lattice, ion 1826
  • M. Doleans
    MSU, East Lansing, Michigan
  • D. Gorelov, T.L. Grimm, F. Marti, X. Wu, R.C. York
    NSCL, East Lansing, Michigan
  The Rare Isotope Accelerator (RIA) driver linac will use a superconducting, cw linac with independently phased superconducting radio frequency cavities for acceleration and, for the heavier ions, utilize beams of multiple-charge-states (multi-q). Given the acceleration of multi-q beams and a stringent beam loss requirement in the RIA driver linac, a new beam envelope code capable of simulating nonlinearities of the multi-q beam envelopes in the longitudinal phase space was developed. Using optimization routines, the code is able to maximize the linearity of the longitudinal phase space motion and thereby minimizing beam loss by finding values for the amplitude and phase of the cavities for a given accelerating lattice. Relative motion of the multi-q beams is also taken into account so that superposition of the beam centroids and matching of their Twiss parameters are automatically controlled. As a result, the linac tuning procedure has been simplified and the longitudinal lattice performance has been improved. In this paper, the general architecture of the code and the results of using it to determine tuning parameters for the RIA driver linac are presented.  
MPPE024 Failure Modes Analysis for the MSU-RIA Driver Linac linac, lattice, emittance, simulation 1868
  • X. Wu, M. Doleans, D. Gorelov, T.L. Grimm, F. Marti, R.C. York
    NSCL, East Lansing, Michigan
  Previous end-to-end beam dynamics simulation studies* using experimentally-based input beams including alignment and rf errors and variation in charge-stripping foil thickness have indicated that the Rare Isotope Accelerator (RIA) driver linac proposed by MSU has adequate transverse and longitudinal acceptances to accelerate light and heavy ions to final energies of at least 400 MeV/u with beam powers of 100 to 400 kW. During linac operation, equipment loss due to, for example, cavity contamination, availability of cryogens, or failure of rf or power supply systems, will lead to at least a temporary loss of some of the cavities and focusing elements. To achieve high facility availability, each segment of the linac should be capable of adequate performance even with failed elements. Beam dynamics studies were performed to evaluate the linac performance under various scenarios of failed cavities and focusing elements with proper correction schemes, in order to prove the flexibility and robustness of the driver linac lattice design. The result of these beam dynamics studies will be presented.

*X. Wu, "End-to-End Beam Simulations for the MSU RIA Driver Linac," Proceedings of the XXII Linac Conference, Lubeck, Germany, August 2004.

MPPE034 Symmetries and Invariants of the Time-dependent Oscillator Equation and the Envelope Equation lattice, plasma 2315
  • H. Qin, R.C. Davidson
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

Single-particle dynamics in a time-dependent focusing field is examined. The existence of the Courant-Snyder invariant* is fundamentally the result of the corresponding symmetry admitted by the oscillator equation with time-dependent frequency.** A careful analysis of the admitted symmetries reveals a deeper connection between the nonlinear envelope equation and the oscillator equation. A general theorem regarding the symmetries and invariants of the envelope equation, which includes the existence of the Courant-Snyder invariant as a special case, is demonstrated. The symmetries of the envelope equation enable a fast algorithm for finding matched solutions without using the conventional iterative shooting method.

*E.D. Courant and H.S. Snyder, Ann. Phys. 3, 1 (1958). **R.C. Davidson and H. Qin, Physics of Intense Charged Particle Beams in High Energy Accelerators (World Scientific, 2001).

MPPE055 Fitting the Fully Coupled ORM for the Fermilab Booster booster, lattice, quadrupole, simulation 3322
  • X. Huang, S.-Y. Lee
    IUCF, Bloomington, Indiana
  • C.M. Ankenbrandt, E. Prebys
    Fermilab, Batavia, Illinois
  Funding: This work is supported in part by grants from DE-AC02-76CH03000, DOE DE-FG02-92ER40747 and NSF PHY-0244793.

The orbit response matrix (ORM) method* is applied to model the Fermilab Booster with parameters such as the BPM gains and rolls, and parameters in the lattice model, including the gradient errors and magnets rolls. We found that the gradients and rolls of the adjacent combined-function magnets were deeply correlated, preventing full determination of the model parameters. Suitable constraints of the parameters were introduced to guarantee an unique, equivalent solution. Simulations show that such solution preserves proper combinations of the adjacent parameters. The result shows that the gradient errors of combined-function magnets are within design limits.

*J. Safranek, Nucl. Instr and Meth. A, {\bf 388}, 27 (1997).

MPPE063 Optimization of Steering Elements in the RIA Driver Linac linac, simulation, lattice, quadrupole 3600
  • E.S. Lessner, V.S. Assev, P.N. Ostroumov
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Department of Energy under contract W-31-109-ENG-38.

The driver linac of the projected RIA facility is a versatile accelerator, a 1.4-GV, CW superconducting linac designed to simultaneously accelerate several heavy-ion charge states, providing beams from protons at about 1 GeV to uranium at 400 MeV/u at power levels at a minimum of 100 kW and up to 400 kW for most beams. Acceleration of multiple-charge-state uranium beams places stringent requirements on the linac design. A steering algorithm was derived that fulfilled the driver’s real estate requirements, such as placement of steering dipole coils on SC solenoids and of beam position monitors outside cryostats, and beam-dynamics requirements, such as coupling effects induced by the focusing solenoids.* The algorithm has been fully integrated in the tracking code TRACK** and is used to study and optimize the number and position of steering elements that minimize the multiple-beam centroid oscillations and preserve the beam emittance under misalignments of accelerating and transverse focusing elements in the driver linac.

*E.S. Lessner and P.N. Ostroumov, Proceedings of the 9-th European Particle Accelerator Conference, July 2005, pp.1476-1478. **V.N. Aseev, P.N. Ostroumov, E.S. Lessner, and B. Mustapha, these proceedings.

MPPE076 Design Study on a New Separator for PEEM3 electron, quadrupole, optics, dipole 3985
  • W. Wan, J. Feng, H.A. Padmore
    LBNL, Berkeley, California
  Funding: Work supported by the Director, Office of Energy Research, Office of Basic Energy Science, Material Sciences Division, U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.

A new aberration-corrected Photoemission Electron Microscope, called PEEM3, is under development at the Advanced Light Source. The resolution and transmission improvement is realized by correcting the lowest order spherical and chromatic aberrations using an electron mirror. A separator is required to separate the incoming uncorrected electron beam to the mirror from the corrected outgoing electron beam to the projector column. In this paper, we present a design study of a new separator for PEEM3. The layout, the Gaussian optics, the analysis of aberrations and the tolerance on power supply stability and alignment errors are reported.

MPPT027 Three-Dimensional Design of a Non-Axisymmetric Periodic Permanent Magnet Focusing System beam-transport, permanent-magnet, simulation, electron 1964
  • C. Chen, R. Bhatt, A. Radovinsky, J.Z. Zhou
    MIT/PSFC, Cambridge, Massachusetts
  Funding: Work supported by the MIT Deshpande Center for Technological Innovation, the U.S. Department of Energy, High-Energy Physics Division, Grant No. DE-FG02-95ER40919, and the Air Force Office of Scientific Research, Grant No. F49620-03-1-0230.

A three-dimensional (3D) design is presented of a non-axisymmetric periodic permanent magnet focusing system which will be used to focus a large-aspect-ratio, ellipse-shaped, space-charge-dominated electron beam. In this design, an analytic theory is used to specify the magnetic profile for beam transport. The OPERA3D code is used to compute and optimize a realizable magnet system. Results of the magnetic design are verified by two-dimensional particle-in-cell and three-dimensional trajectory simulations of beam propagation using PFB2D and OMNITRAK, respectively. Results of fabrication tolerance studies are discussed.

MPPT058 Progress on the Focus Coils for the MICE Channel vacuum, emittance, coupling, power-supply 3417
  • M.A. Green
    LBNL, Berkeley, California
  • Y. Ivanyushenkov
    CCLRC/RAL, Chilton, Didcot, Oxon
  • W. Lau, R. Senanayake, S.Q. Yang
    OXFORDphysics, Oxford, Oxon
  Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC03-76SF00098.

This report describes the progress on the magnet part of the absorber focus coil module for the international Muon Ionization Cooling Experiment (MICE). MICE consists of two cells of a SFOFO cooling channel that is similar to that studied in the level 2 study of a neutrino factory. The MICE absorber focus coil module consists of a pair of superconducting solenoids, mounted on an aluminum mandrel. The coil package that is in its own vacuum vessel surrounds an absorber, which does the ionization cooling of the muons. Either a liquid or solid absorber is within a separate vacuum vessel that is within the warm bore of the superconducting magnet. The superconducting focus coils may either be run in the solenoid mode (with the two coils at the same polarity) or in the flip mode (with the coil at opposite polarity causing the field direction to flip within the magnet bore). The superconducting coils will be cooled using a pair of small 4 K coolers. This report discusses the progress on the MICE focusing magnets, the magnet cooling system and the magnet current supply system.

MPPT059 Progress on the Coupling Coil for the MICE Channel coupling, vacuum, power-supply, superconductivity 3468
  • M.A. Green, D. Li, S.P. Virostek, M.S. Zisman
    LBNL, Berkeley, California
  • Y. Ivanyushenkov
    CCLRC/RAL, Chilton, Didcot, Oxon
  • W. Lau, A. E. White, H. Witte, S.Q. Yang
    OXFORDphysics, Oxford, Oxon
  Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC03-76SF00098.

This report describes the progress on the coupling coil module for the international Muon Ionization Cooling Experiment (MICE). MICE consists of two cells of a SFOFO cooling channel that is similar to that studied in the level 2 study of a neutrino factory. The MICE RF coupling coil module consists of a superconducting solenoid, mounted around four cells of conventional 201.25 MHz closed RF cavities. This report discusses the progress that has been made on the superconducting coupling coil that is around the center of the RF coupling module. This report also describes the process one would use to cool the coupling coil using a single small 4 K cooler. The coupling magnet power system and quench protections system is also described.

MPPT061 Ideal Wiggler wiggler, quadrupole, emittance, dipole 3511
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  Described is the wiggler with reduced nonlinear components for usage in damping ring of Linear Collider. Zigzag field dependence on longitudinal coordinate made by profiling of poles.  
MPPT064 Elements of Magneto-Optics Acting in One Direction octupole, wiggler, multipole, quadrupole 3618
  • A.A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  We describe here the way to use quadrupole, octupole lenses so they are acting in one direction only. The beam is running across the lens in contrast with usual axis running.  
MPPT080 Design, Fabrication and Characterization of a Large-Aperture Quadrupole Magnet for CESR-c quadrupole, luminosity, photon, alignment 4063
  • M.A. Palmer, J.A. Crittenden, J. Kandaswamy, A. Temnykh
    Cornell University, Department of Physics, Ithaca, New York
  • T.I. O'Connell
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  Funding: National Science Foundation.

Installation of a radiative Bhabha luminosity monitor for CESR-c operation in 2004 required replacing a 40-mm aperture steel quadrupole magnet with one of aperture 75 mm, while maintaining field-quality tolerances at the level of a few parts in $104. We present the design methodology using 2D- and 3D-finite-element field calculations, compare the calculated 3D integrals to flip-coil measurements, and discuss related mechanical tolerances.

MOPB007 Future Directions in Electron Sources cathode, electron, emittance, gun 563
  • J.W. Lewellen
    ANL, Argonne, Illinois
  Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The emittance-compensated rf photoinjector is in the process of evolving from an experiment in and of itself, to a laboratory instrument, to a workhorse component of large user facilities such as next-generation light sources. In recent years the performance achieved by the standard p-mode design has approached the levels predicted by theory and experiment. The basic design has been scaled from X-band down to less than 1 GHz in terms of operating frequency, and superconducting designs are presently undergoing initial testing at various locations. The requirements for linac-based light sources will require at least one order of magnitude improvement in beam quality; other applications, such as electron microscopes or high-energy electron lithography, require still greater improvements. The migration towards fully superconducting accelerators provides some additional design challenges. This paper briefly presents requirements for some future applications, and presents four new approaches to extending injector performance: the diamond-emitter photocathode, the planar focusing cathode, the magnetic-mode emittance compensation technique, and the field-emission-gated cathode.

TPAE011 Fast Sweeping Device for Laser Bunch laser, radiation, acceleration, 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.  
TPAE015 Laser and Particle Guiding Micro-Elements for Particle Accelerators laser, undulator, radiation, vacuum 1434
  • T. Plettner, R.M. Gaume, J. Wisdom
    Stanford University, Stanford, Califormia
  • J.E. Spencer
    SLAC, Menlo Park, California
  Funding: Department of Energy contract DE-AC02-76SF00515, DARPA contract DAAD19-02-1-0184.

Laser driven particle accelerators based on the current generation of lasers will require sub-micron control of the laser field as well as precise beam guiding. Hence the fabrication techniques that allow integrating both elements into an accelerator-on-chip format become critical for the success of such particle accelerators. Micromachining technology for silicon has been shown to be one such feasible technology in PAC2003 but with a variety of complications on the laser side. Fortunately, in recent years the fabrication of transparent ceramics has become an interesting technology that could be applied for laser-particle accelerators in several ways. We discuss this area, its advantages such as the range of materials it provides and various ways to implement it followed by some different test examples that have been considered. One important goal of this approach is an integrated system that could avoid the necessity of having to inject either laser or particle pulses into these structures.

TPAE042 Beam Matching to a Plasma Wake Field Accelerator Using a Ramped Density Profile at the Plasma Boundary plasma, synchrotron, emittance, ion 2702
  • K.A. Marsh, C.E. Clayton, C. Huang, 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, P. Krejcik, C.L. O'Connell, R. Siemann, D.R. Walz
    SLAC, Menlo Park, California
  • S. Deng, T.C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  Funding: DOE Grant No. DE-FG03-92ER40727.

An important aspect of plasma wake field accelerators (PWFA) is stable propagation of the drive beam. In the under dense regime, the drive beam creates an ion channel which acts on the beam as a strong thick focusing lens. The ion channel causes the beam to undergo multiple betatron oscillations along the length of the plasma. There are several advantages if the beam size can be matched to a constant radius. First, simulations have shown that instabilities such as hosing are reduced when the beam is matched. Second, synchrotron radiation losses are minimized when the beam is matched. Third, an initially matched beam will propagate with no significant change in beam size in spite of large energy loss or gain. Coupling to the plasma with a matched radius can be difficult in some cases. This paper shows how an appropriate density ramp at the plasma entrance can be useful for achieving a matched beam. Additionally, the density ramp is helpful in bringing a misaligned trailing beam onto the drive beam axis. A plasma source with boundary profiles useful for matching has been created for the PWFA experiments at SLAC.

TPAE048 The UCLA/FNPL Time Resolved Underdense Plasma Lens Experiment plasma, electron, quadrupole, space-charge 3013
  • M.C. Thompson, H. Badakov, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • H. Edwards, R.P. Fliller, G.M. Kazakevich, P. Piot, J.K. Santucci
    Fermilab, Batavia, Illinois
  • J.L. Li, R. Tikhoplav
    Rochester University, Rochester, New York
  Funding: Work Supported by U.S. Dept. of Energy grant DE-FG03-92ER40693.

An underdense plasma lens experiment is planned as a collaboration between UCLA and the Fermilab NICADD Photoinjector Laboratory (FNPL). The experiment will focus on measuring the variation of the plasma focusing along the longitudinal beam axis and comparing these results with theory and simulation. The experiment will utilize a thin gaussian underdense plasma lens with peak density 6 x 1012 cm-3 and a FWHM length of 1.6 cm. This plasma lens will have a focusing strength equivalent to a quadrupole magnet with a 180 T/m field gradient. A 15 MeV, 8nC electron beam with nominal dimensions sr = 400 μm and sz = 2.1 mm will be focused by this plasma lens onto an OTR screen approximately 2 cm downstream of the lens. The light from the OTR screen will be imaged into a streak camera in order to directly measure the correlation between z and sr within the beam. Status and progress on the experiment are reported.

TPAT002 Three-Dimensional Simulation of Large-Aspect-Ratio Ellipse-Shaped Charged-Particle Beam Propagation simulation, space-charge, vacuum, permanent-magnet 823
  • R. Bhatt, C. Chen, J.Z. Zhou
    MIT/PSFC, Cambridge, Massachusetts
  Funding: U.S. Department of Energy: Grant No. DE-FG02-95ER40919, Grant No. DE-FG02-01ER54662, Air Force Office of Scientific Research: Grant No. F49620-03-1-0230, and the MIT Deshpande Center for Technological Innovation.

The three-dimensional trajectory code, OMNITRAK, is used to simulate a space-charge-dominated beam of large-aspect-ratio elliptic cross-section propagating in a non-axisymmetric periodic permanent magnet focusing field. The simulation results confirm theoretical predictions in the paraxial limit. A realistic magnetic field profile is applied, and the beam sensitivity to magnet nonlinearities and misalignments is studied. The image-charge effect of conductor walls is examined for a variety of beam tunnel sizes and geometries.

TPAT003 Cold-Fluid Equilibrium of a Large-Aspect-Ratio Ellipse-Shaped Charged-Particle Beam in a Non-Axisymmetric Periodic Permanent Magnet Focusing Field simulation, vacuum, emittance, permanent-magnet 853
  • J.Z. Zhou, R. Bhatt, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
  Funding: U.S. DOE, Grant: No. DE-FG02-95ER40919,Grant No. DE-FG02-01ER54662, Air Force Office of Scientific Research, Grant No. F49620-03-1-0230, and the MIT Deshpande Center for Technological Innovation.

A new class of equilibrium is discovered for a large-aspect-ratio ellipse-shaped charged-particle beam in a non-axisymmetric periodic permanent magnet focusing field. A paraxial cold-fluid model is employed to derive the equilibrium flow properties and generalized envelope equations with negligibly small emittance. A periodic beam equilibrium solution is obtained numerically from the generalized envelope equations. It is shown that the beam edges are well confined in both transverse directions, and that the equilibrium beam exhibits a small-angle periodic wobble as it propagates. A two-dimensional particle-in-cell (PIC) code, PFB2D, is used to verify the theoretical predictions in the paraxial limit, and to establish validity under non-paraxial situations and the influence of the conductor walls of the beam tunnel.

TPAT004 Strongly Asymmetric Beams at the University of Maryland Electron Ring (UMER) electron, quadrupole, diagnostics, emittance 892
  • S. Bernal, R.A. Kishek, P.G. O'Shea, B. Quinn, M. Walter
    IREAP, College Park, Maryland
  • M. Reiser
    University Maryland, College Park, Maryland
  Funding: This work is funded by U.S. Dept. of Energy under grants DE-FG02-94ER40855 and DE-FG02-92ER54178.

The standard operation of the University of Maryland electron ring employs symmetric strong focusing with magnetic quadrupoles, i.e., a FODO scheme whereby the zero-current betatron phase advances per period in the two transverse planes are equal or nearly so. Asymmetric focusing, on the other hand, employs quadrupoles with different strengths in a FODO cell. Typically, a small focusing asymmetry is implemented in most accelerators to set the operating point (horizontal and vertical zero-current tunes) in order to avoid resonances and/or compensate for edge focusing of bend magnets. Extreme asymmetry, however, is rarely, if at all, used. We review the motivation and theory of beam transport with general focusing asymmetry. We also present results of preliminary experiments and simulations with highly asymmetric focusing of a space-charge dominated electron beam in UMER.

TPAT007 RF Defocusing in Super-Conducting Structure with Constant Geometry quadrupole, space-charge 1042
  • Y. Senichev, R. Maier, N.E. Vasyukhin
    FZJ, Jülich
  Due to higher accelerating gradient in the super-conducting linac the RF defocusing factor plays significant role in the beam dynamics. Together with the space charge it is a main reason for the stability loss. Usually it is estimated in frame of the travelling wave formalism with synchronous motion. However, the super-conducting cavity is desirable to have the constant geometry, when synchronous motion is absent. In this case the quasi-synchronous phase velocity is adjusted by RF phasing. In this paper we investigate RF defocusing factor in absent of synchronism between the beam and the accelerating structure.  
TPAT022 Future Plans for the Small Isochronous Ring space-charge, quadrupole, betatron, dipole 1778
  • E.P. Pozdeyev
    Jefferson Lab, Newport News, Virginia
  • F. Marti, R.C. York
    NSCL, East Lansing, Michigan
  • J.A. Rodriguez
    CERN, Geneva
  Funding: Work supported by NSF Grant #PHY-0110253 and DOE Contract DE-AC05-84ER40150.

The Small Isochronous Ring has been operational at Michigan State University since December 2003. It is used for experimental studies of the beam dynamics in high-intensity isochronous cyclotrons and synchrotrons at the transition energy. The operational experience with SIR has proven that the ring can be successfully used to study space charge effects in accelerators. The low velocity of beam particles in the ring allowed us to achieve a high accuracy of longitudinal profile measurements that is difficult to achieve in full-size accelerators. The experimental data obtained in the ring was used for validation of multi-particle, space-charge codes CYCO and WARP3D. Inspired by the solid performance of SIR in the isochronous regime, we consider options for expanding the scope of the beam physics studied in the ring. In this paper, we outline possible future experiments and discuss required modifications of the ring optics and hardware.

TPAT033 Experimental Characterizations of 4-D Transverse Phase-Space of a Compressed Beam emittance, linac, electron, space-charge 2263
  • F. Zhou, R.B. Agustsson, G. Andonian, D. Cline, A.Y. Murokh, J.B. Rosenzweig
    UCLA, Los Angeles, California
  • I. Ben-Zvi, V. Yakimenko
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. DOE.

Coherent synchrotron radiation can significantly distort beam phase spaces in longitudinal direction and bending plane through a bunch compressor. A tomography technique is used to reconstruct transverse phase space of electron beam. Transverse 4-D phase spaces are systematically measured at UCLA/ATF compressor and their characteristics with different bunch compression conditions are analyzed.

TPAT036 Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization plasma, ion, electron, heavy-ion 2452
  • P. Efthimion, R.C. Davidson, E.P. Gilson, L. Grisham
    PPPL, Princeton, New Jersey
  • B. G. Logan, W. Waldron, S. Yu
    LBNL, Berkeley, California
  Funding: Research supported by the U.S. Department of Energy.

Plasmas are employed as a medium for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ~ 0.1-1 m would be suitable. To produce 1 meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic. High voltage (~ 1-5 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long produced plasma densities ~ 5x1011 cm-3. The source was integrated into the experiment and successfully charge neutralized the K ion beam. Presently, the 1 meter source is being fabricated. It will be characterized and integrated into NDCX for charge neutralization experiments. Experimental results will be presented.

TPAT037 Simulating the Long-Distance Propagation of Intense Beams in the Paul Trap Simulator Experiment plasma, ion, simulation, lattice 2491
  • E.P. Gilson, M. Chung, R.C. Davidson, P. Efthimion, R. M. Majeski, E. Startsev
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

The Paul Trap Simulator Experiment (PTSX) makes use of a compact Paul trap configuration with quadrupolar oscillating wall voltages to simulate the propagation of intense charged particle beams over distances of many kilometers through magnetic alternating-gradient transport systems. The simulation is possible because of the similarity between the transverse dynamics of particles in the two systems. One-component pure cesium ion plasmas have been trapped that correspond to normalized intensity parameters s < 0.8, where s is the ratio of the square of the plasma frequency to twice the square of the average transverse focusing frequency. The PTSX device confines the plasma for hundreds of milliseconds, which is equivalent to beam propagation over tens of kilometers. Results are presented for experiments in which the amplitude of the oscillating confining voltage waveform has been modified as a function of time. A comparison is made between abrupt changes in amplitude and adiabatic changes in amplitude. The effects of varying the frequency are also discussed. A barium ion source and a laser system have been installed and initial measurements made with this system are presented.

TPAT041 On the Vlasov-Maxwell Equations acceleration, 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.  
TPAT046 Nonlinear Stability of Intense Mismatched Beams in a Uniform Focusing Field space-charge, coupling, emittance, beam-losses 2941
  • R. Pakter, F.B. Rizzato, W. Simeoni
    IF-UFRGS, Porto Alegre
  Funding: Work supported by Brazilian agencies CNPq, CAPES, and FAPERGS.

We investigate the nonlinear coupling between axisymmetric and elliptic oscillations in the dynamics of intense beams propagating in a uniform magnetic focusing field. It is shown that finite amplitude mismatched oscillations of an initially round beam may destabilize elliptic oscillations, heavily affecting stability and the shape of the beam. This is a potential mechanics for beam particle loss in such systems. Self consistent simulations are performed to verify the findings.

TPAT048 The Transverse Nonlinear Tune Shift as Stabilising Factor in Halo Creation in Space Charge Dominated Beam resonance, space-charge, linac, quadrupole 3004
  • N.E. Vasyukhin, Y. Senichev, R. Tölle
    FZJ, Jülich
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395).

One of the most important problems for space charge dominated beam in the low energy part of superconducting linac is halo creation. Many authors show one of the key effects in halo creatiation is parametric resonance due to the mismatched beta-function oscillation (between core and particle). To estimate parametric resonance conditions the nonlinear tune shift for binomial distributed beam is described theoretically in this article. Simultaneously the beam dynamics simulation 3D PIC code was developed. The transverse oscillation frequencies compared with parametric resonance criteria. As a result the recommendation for space charge shift is concluded to minimize halo creation.

TPAT049 Comparison of Beam Dynamic in Different Superconducting Options of Low Energy High Intense Linac quadrupole, linac, simulation, space-charge 3058
  • N.E. Vasyukhin, Y. Senichev, R. Tölle
    FZJ, Jülich
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" program (CARE, contract number RII3-CT-2003-506395).

At present the superconducting proton linacs have obvious applications in energy range ~100-1000 MeV. For the lower energy the comprehensive investigations are required. In this article the various variants of superconducting options from 3MeV up to 100MeV are discussed. The considered variants include both the conventional combination of half-wave and spoke cavity with quadrupoles and new schemes. In conclusion the table of major parameters for different structures is given.

TPAT061 Accurate Iterative Analysis of the K-V Equations quadrupole, lattice, emittance, simulation 3535
  • O.A. Anderson
    LBNL, Berkeley, California
  Funding: Supported in part by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

Previous solutions of the K-V equations have either yielded poor accuracy or have been complex and difficult to follow. We describe a new approach, simple in concept, easy to use, with accuracy substantially improved over previous treatments. The results are given in the same form as the smooth approximation but include a few correction terms obtained from the field gradient integrated along the axis of a quadrupole cell. The input quantities–quadrupole field, beam current, and emittance–yield the average beam radius, the maximum envelope excursion, and the depressed and undepressed tunes. For all values of the input parameters, the results are much closer to the exact values from simulations than are results from the smooth approximation. For example, with the parameters adjusted for an exact phase advance of 83.4 degrees and 50% tune depression, both tunes are in error by less than 0.5%–over 22 times better than the smooth approximation. The error in maximum radius is 0.04%, improved by a factor of 80. The new method and its application to a wide range of cases will be presented.

TPAT069 Numerical Studies of Electromagnetic Instabilities in Intense Charged Particle Beams with Large Energy Anisotropy plasma, simulation, heavy-ion, vacuum 3780
  • E. Startsev, R.C. Davidson, W.L. Lee
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

In intense charged particle beams with large energy anisotropy, free energy is available to drive transverse electromagnetic Weibel-type instabilities. Such slow-wave transverse electromagnetic instabilities can be described by the so-called Darwin model, which neglects the fast-wave portion of the displacement current. The Weibel instability may also lead to an increase in the longitudinal velocity spread, which would make the focusing of the beam difficult and impose a limit on the minimum spot size achievable in heavy ion fusion experiments. This paper reports the results of recent numerical studies of the Weibel instability using the Beam Eigenmode And Spectra (bEASt) code for space-charge-dominated, low-emittance beams with large tune depression. To study the nonlinear stage of the instability, the Darwin model is being developed and incorporated into the Beam Equilibrium Stability and Transport(BEST) code.

TPAT082 Phonon Modes and the Maintenance Condition of a Crystalline Beam lattice, resonance, coupling, emittance 4111
  • J. Wei
    BNL, Upton, Long Island, New York
  • H. Enokizono, H. Okamoto, Y. Yuri
    HU/AdSM, Higashi-Hiroshima
  • X.-P. Li
    Skyworks Solutions, Inc., Newbury Park. California
  • A. Sessler
    LBNL, Berkeley, California
  Funding: * Work performed under the auspices of the U.S. Department of Energy.

Previously it has been shown that the maintenance condition for a crystalline beam requires that there not be a resonance between the crystal phonon frequencies and the frequency associated with a beam moving through a lattice of N periods. This resonance can be avoided provided the phonon frequencies are all below half of the lattice frequency. Here we make a detailed study of the phonon modes of a crystalline beam. Analytic results obtained in a “smooth approximation” using the ground-state crystalline beam structure is compared with numerical evaluation employing Fourier transform of Molecular Dynamic (MD) modes. The MD also determines when a crystalline beam is stable. The maintenance condition, when combined with either the simple analytic theory or the numerical evaluation of phonon modes, is shown to be in excellent agreement with the MD calculations of crystal stability.

[1] X-P. Li, A. M. Sessler, J. Wei, EPAC (1994) p. 1379 - 1381. ‘Necessary Conditions for Attaining a Crystalline Beam''}[2] J. Wei, H. Okamoto, A.M. Sessler, Phys. Rev. Lett., Vol. 80, p. 2606-2609 (1998).

TPPE013 Simulations of Solenoid and Electrostatic Quadrupole Focusing of High Intensity Beams from ECR Ion Source at NSCL quadrupole, space-charge, emittance, simulation 1336
  • Q. Zhao, A.I. Balabin, M. Doleans, F. Marti, J.W. Stetson, X. Wu
    NSCL, East Lansing, Michigan
  Solenoidal focusing has been widely used to focus beams at various injectors for its axisymmetric focusing with reasonable effectiveness. Experiments and simulations have shown that space charge effects can significantly deteriorate the beam quality when solenoidal focusing is used in a multi-component beam. This is due to the magnetic focusing strength dependence on the beam charge-to-mass ratio. Electrostatic quadrupole focusing has been explored as an alternate option at NSCL for the injection line of the superconducting cyclotron. We present in this paper the results of simulations for both systems. The electrostatic quadrupoles have been optimized to reduce the radial dependent aberrations and to increase the transmission efficiency.  
TPPE033 A Comparison of Electrostatic and Magnetic Focusing of Mixed Species Heavy Ion Beams at NSCL/MSU sextupole, cyclotron, ion, quadrupole 2281
  • J.W. Stetson, G. Machicoane, F. Marti, P. Miller, M. Steiner, P.A. Zavodszky
    NSCL, East Lansing, Michigan
  • Yu. Kazarinov
    JINR, Dubna, Moscow Region
  Funding: This work has been supported by National Science Foundation under grant PHY-0110253.

Experience at the National Superconducting Cyclotron Laboratory has shown the first focusing element after the electron cyclotron resonance ion source (ECRIS), before the beam is analyzed by a magnetic dipole, to be critical to subsequent beam transport and matching. Until 2004, both ion sources at the NSCL used a solenoid as this first focusing element. Observation of hollow beam formation led to further analysis and the decision to replace the solenoid with an electrostatic quadrupole triplet on a test basis [1]. Substantial increases in net cyclotron output were achieved, leading us to adopt electrostatic quadrupole focusing as the permanent configuration. In addition, a sextupole magnet was installed in this beam line. Motivations for these changes and results of operating experience are discussed.

TPPE034 Possible Scheme of the Analyzing Part of a Cyclotron Injection Beamline with Higher Energy ion, emittance, injection, vacuum 2345
  • Yu. Kazarinov
    JINR, Dubna, Moscow Region
  • J.W. Stetson, P.A. Zavodszky
    NSCL, East Lansing, Michigan
  Funding: This work was supported in part by the National Science Foundation under grant PHY-0110253.

The ion beam produced with an ECR ion source (ECRIS) with an extraction voltage of 30 kV may be additionally accelerated using a negative voltage of -30 kV applied to the last electrode of the extraction system, connected to the beamline biased to the same -30 kV potential. In this way the kinetic energy of the beam is increased to 60 keV/q, decreasing to half the space charge effect on the beam emittance. Using a large gap analyzing magnet placed right after the ECRIS and no focusing element, the transmission is still close to 100%. The voltage on the beamline must be kept constant from the ECRIS till the image focal plane of the analyzing magnet where the full separation of the beam charge states is achieved. An insulator break separates the biased beamline from the downstream section, which is at zero potential. Passing through this section of the beamline, the ion beam is decelerated to 30 keV/q, the energy necessary for the injection in the cyclotron. In order to prevent the increase of the beam divergence, a focusing solenoid is installed behind the break point. This work will present the results of a simulation of the transport of an argon beam in the proposed beamline.

TPPE050 Beam Injection in Recirculator SALO injection, electron, quadrupole, gun 3109
  • I.S. Guk, A. Dovbnya, S.G. Kononenko, F.A. Peev, A.S. Tarasenko
    NSC/KIPT, Kharkov
  • J.I.M. Botman, M.J. Van der Wiel
    TUE, Eindhoven
  Possible antetypes of injectors for electron recirculator SALO,* intended for nuclear-physical research, are analyzed. The plan injection of beams in recirculator is offered. Expected parameters of beams are designed.

*I.S. Guk, A.N. Dovbnya, S.G. Kononenko, A.S. Tarasenko, M. van der Wiel, J.I.M. Botman, NSC KIPT accelerator on nuclear and high energy physics, Proceedings of EPAC 2004, Lucerne, Switzerland, p. 761-764.

TPPP013 Simulations of Parametric Resonance Ionization Cooling of Muon Beams synchrotron, simulation, resonance, lattice 1321
  • K. Beard, S.A. Bogacz, Y.S. Derbenev
    Jefferson Lab, Newport News, Virginia
  • R.P. Johnson, K. Paul, T.J. Roberts
    Muons, Inc, Batavia
  • K. Yonehara
    Illinois Institute of Technology, Chicago, Illinois
  Funding: This work was supported in part by DOE SBIR grants DE-FG02-03ER83722, and 04ER84016.

The technique of using a parametric resonance to allow better ionization cooling is being developed to create small beams so that high collider luminosity can be achieved with fewer muons. In the linear channel that is studied in this effort, a half integer resonance is induced such that the normal elliptical motion of particles in x-x' phase space becomes hyperbolic, with particles moving to smaller x and larger x' as they pass down the channel. Thin absorbers placed at the focal points of the channel then cool the angular divergence of the beam by the usual ionization cooling mechanism where each absorber is followed by RF cavities. Thus the phase space of the beam is compressed in transverse position by the dynamics of the resonance and its angular divergence is compressed by the ionization cooling mechanism. We report the first results of simulations of this process, including comparisons to theoretical cooling rates and studies of sensitivity to variations in absorber thickness and initial beam conditions.

TPPP014 Ionization Cooling Using a Parametric Resonance emittance, resonance, betatron, luminosity 1374
  • Y.S. Derbenev
    Jefferson Lab, Newport News, Virginia
  • R.P. Johnson
    Muons, Inc, Batavia
  Funding: This work was supported in part by DOE SBIR grant DE-FG02-04ER84016.

Muon collider luminosity depends on the number of muons in the storage ring and on the transverse size of the beams in collision. Ionization cooling as it is presently envisioned will not cool the beam sizes sufficiently well to provide adequate luminosity without large muon intensities. A new idea to combine ionization cooling with parametric resonances has been developed that will lead to beams with much smaller sizes so that high luminosity in a muon collider can be achieved with fewer muons. In the linear channel described here, a half integer resonance is induced such that the normal elliptical motion of particles in x-x' phase space becomes hyperbolic, with particles moving to smaller x and larger x' as they pass down the channel. Thin absorbers placed at the focal points of the channel then cool the angular divergence of the beam by the usual ionization cooling mechanism where each absorber is followed by RF cavities. We discuss the theory of Parametric-resonance Ionization Cooling, including the sensitivity to aberrations and the need to start with a beam that has already been cooled adequately.

TPPP018 Progress on the MICE Liquid Absorber Cooling and Cryogenic Distribution System vacuum, emittance, factory, scattering 1601
  • M.A. Green
    LBNL, Berkeley, California
  • E. Baynham, T.W. Bradshaw, P. Drumm, Y. Ivanyushenkov
    CCLRC/RAL, Chilton, Didcot, Oxon
  • M.A.C. Cummings
    Northern Illinois University, DeKalb, Illinois
  • S. Ishimoto
    KEK, Ibaraki
  • W. Lau, S.Q. Yang
    OXFORDphysics, Oxford, Oxon
  Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC03-76SF00098.

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. Because the muon beam in MICE is of low intensity, there is no beam heating in the absorber. As a result, the absorber can be cooled using a single 4 K cooler. This report describes progress on the MICE liquid absorber and its cryogenic cooling system.

TPPP039 Geant Simulation of Six-Dimensional Cooling of a Muon Beams in a Ring Coolers simulation, emittance, dipole, beam-losses 2580
  • A. Klier, G.G. Hanson
    UCR, Riverside, California
  The reduction of the phase-space volume of the beam (cooling) is essential for both muon colliders and neutrino factories. In a muon collider, in particular, the six-dimensional (6D) emittance must be reduced by six orders of magnitude. Cooling the beam in all phase space dimensions can be done through emittance exchange, where the beam loses energy passing through wedge-shaped absorbers in a dispersive magnetic field, designed in a way that fast muons go through more absorber material than slow ones and lose more energy. The longitudinal momentum is then regained using RF cavities. We simulate ring coolers, in which the beam undergoes 6-dimensional cooling through emittance exchange while rotating several times in the ring. The simulation software is a Geant3-based package, specially designed this purpose, with changing electric fields in RF cavities treated correctly. Magnetic fields are read from external maps. Some ring cooler designs and cooling simulation results are presented.  
TPPP041 Recent Developments on the Muon-Facility Design Code ICOOL simulation, multipole, emittance, factory 2651
  • R.C. Fernow
    BNL, Upton, Long Island, New York
  Funding: Work supported by U.S. Department of Energy.

Current ideas for designing neutrino factories and muon colliders require unique configurations of fields and materials to prepare the muon beam for acceleration. We have continued the development of the 3D tracking code ICOOL for examining possible system configurations. Development of the ICOOL code began in 1996 in order to simulate the process of ionization cooling. This required tracking in magnetic focusing lattices, together with interactions in shaped materials that must be placed in the beam path.* The most important particle interactions that had to be simulated were energy loss and straggling. Since the optimum way of designing a cooling channel was not known, the code had to have a flexible procedure for specifying field and material geometries. Eventually the early linear cooling channels evolved into cooling rings. In addition the designs require many other novel beam manipulations besides ionization cooling, such as pion collection in a high field solenoid, rf phase rotation, and acceleration in FFAG rings. We describe new features that have been incorporated in ICOOL for handling these new requirements. A suite of auxilliary codes have also been developed for pre-processing, post-processing, and optimization.

*R.C. Fernow, ICOOL: a simulation code for ionization cooling of muon beams, Proc. 1999 Part. Accel. Conf., New York, p. 3020.

TPPP052 Simulations of a Gas-Filled Helical Muon Beam Cooling Channel simulation, emittance, quadrupole, beam-cooling 3215
  • K. Yonehara, D.M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois
  • K. Beard, S.A. Bogacz, Y.S. Derbenev
    Jefferson Lab, Newport News, Virginia
  • R.P. Johnson, K. Paul, T.J. Roberts
    Muons, Inc, Batavia
  Funding: This work was supported in part by DOE STTR/SBIR grants DE-FG02-02ER86145 and 03ER83722.

A helical cooling channel (HCC) has been proposed to quickly reduce the six-dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of a series of RF cavities filled with dense hydrogen gas that acts as the energy absorber for ionization cooling and suppresses RF breakdown in the cavities. Magnetic solenoidal, helical dipole, and helical quadrupole coils outside of the RF cavities provide the focusing and dispersion needed for the emittance exchange for the beam as it follows a helical equilibrium orbit down the HCC. In the work presented here, two Monte Carlo programs have been developed to simulate a HCC to compare with the analytic predictions and to begin the process of optimizing practical designs that could be built in the near future. We discuss the programs, the comparisons with the analytical theory, and the prospects for a HCC design with the capability to reduce the six-dimensional phase space emittance of a muon beam by a factor of over five orders of magnitude in a linear channel less than 100 meters long.

TPPT022 The Structure of the High Frequency Focusing Cells in Linear Ion Accelerators quadrupole, ion, acceleration, 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.  
TPPT060 Design of a Multi-Cell, HOM Damped Superconducting Cavity for the Strong RF Focusing Experiment at DAFNE coupling, synchrotron, factory, feedback 3505
  • A. Gallo, D. Alesini, C. Biscari, R. Boni, F. Marcellini, M. Zobov
    INFN/LNF, Frascati (Roma)
  • C. Pagani
    DESY, Hamburg
  A strong RF focusing experiment to be performed at the DAFNE Phi-factory has been proposed to create and observe a bunch length modulation along the ring. The very large RF gradient required to reach the strong focusing regime can only be obtained by using a multi-cell superconducting cavity. Moreover, in order to demonstrate the feasibility of a high luminosity collider based on this principle, a total multibunch current of the order of 1A has to be stored under stable conditions in this regime. A 1.3 GHz 7-cells cavity has been designed for this purpose, based on the TESLA geometry with small modifications of the basic cell to comply with the DAFNE revolution frequency. The number of cells has been changed from 9 to 7 to reduce the number of the cavity HOMs, while the beam tubes have been enlarged to let most of the HOMs propagate and be damped by room-temperature ferrite rings. The modes of the first longitudinal band, which include the accelerating TM010_pi, do not propagate in the beam tubes and have been studied with special care to prevent the overlap with the bunch revolution harmonics and to cure the effects of coupling to the synchrotron tune sidebands.  
TPPT071 Preliminary Results on the Simultaneous Excitation of the TM010 and TE011 Modes in a Single Cell Niobium Cavity coupling, emittance, superconducting-RF, pick-up 3844
  • G. Ciovati, P. Kneisel
    Jefferson Lab, Newport News, Virginia
  Funding: Work supported by the U.S. DOE Contract No DE-AC05-84ER40150.

Simultaneous excitation of both TM010 and TE011 modes has been proposed recently for superconducting photoinjector applications to take advantage of the accelerating field of the TM mode, combined with the focusing magnetic field of the TE mode. Simultaneous excitation of both modes has been carried out on a CEBAF single cell cavity. The cavity has two beam pipe side-ports for each mode for input and pick-up couplers. Coupling to the TE011 mode is done by magnetic loop couplers while for the TM010 mode coaxial antennas are used. The TE011 mode has the property of having zero surface electric field, surface magnetic field orthogonal to the one in the TM010 mode and concentrated in the iris/wall regions of the cavity. The presence of both modes in the cavity at the same time can also be used to investigate the so-called high field Q-drop in the TM010 mode. This paper will present some preliminary result on the test of the single cell cavity at 2K.

TPPT096 Cryomodule Design for a Superconducting Linac with Quarter-Wave, Half-Wave, and Focusing Elements quadrupole, vacuum, alignment, linac 4317
  • M. J. Johnson, J. Bierwagen, S. Bricker, C. Compton, P. Glennon, T.L. Grimm, W. Hartung, D. Harvell, A. Moblo, J. Popielarski, L. Saxton, R.C. York, A. Zeller
    NSCL, East Lansing, Michigan
  The low-energy section of the driver linac for the proposed Rare Isotope Accelerator (RIA) incorporates the following superconducting elements: quarter-wave resonators, half-wave resonators, and 9 T solenoids. A prototype cryomodule has been designed to house all of these elements. A 31 T/m superferric quadrupole is also included as an alternative focusing element, since its stray magnetic field is more easily shielded. The cryomodule design is based on the RIA v/c=0.47 prototype cryomodule that was successfully tested in 2004.* The design uses a titanium rail structure to support the beam line elements. The beam line assembly is done in a class 100 clean room to maintain resonator cleanliness for optimal high-field performance. The cavities will be equipped with RF input couplers, tuners, and magnetic shields. High Tc current leads are used for both magnets. The cryomodule design takes into account static heat leak requirements and alignment tolerances for the beam line elements. A heat exchanger and J-T throttle valve will be used to provide a continuous supply of liquid helium for 2 K operation.

*T.L. Grimm et al., "Experimental Study of an 805 MHz Cryomodule for the Rare Isotope Accelerator", in Proceedings of the XXII International Linear Accelerator Conference, Lubeck, Germany (2004).

TOPA010 Photonic Crystal Laser-Driven Accelerator Structures lattice, laser, dynamic-aperture, simulation 731
  • B.M. Cowan
    SLAC, Menlo Park, California
  Funding: Work supported by Department of Energy contract DE-AC03-76SF00515 (SLAC).

We discuss simulated photonic crystal structure designs, including two- and three-dimensional planar structures and fibers. The discussion of 2D structures demonstrates guiding of a speed-of-light accelerating mode by a defect in a photonic crystal lattice and reveals design considerations and trade-offs. With a three-dimensional lattice, we introduce a candidate geometry and discuss beam dynamics, coupling, and manufacturing techniques for that structure. In addition we discuss W-band scale tests of photonic crystal structures. The computational methods are also discussed.

WPAE022 Progress on the Liquid Hydrogen Absorber for the MICE Cooling Channel vacuum, scattering, acceleration, 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.  
WPAE036 Harmonic Analysis of Linac Alignment alignment, linac, lattice, laser 2431
  • R.C. McCrady
    LANL, Los Alamos, New Mexico
  Funding: Work conducted at Los Alamos National Laboratory, which is operated by the University of California for the United States Department of Energy under contract W-7405-ENG-36.

We have analyzed the requirements on alignment of the focusing elements (quadrupole doublets) in the Los Alamos Neutron Science Center (LANSCE) side coupled linac. The analysis is performed in terms of harmonics of the quardrupole spacing. This allows us to determine the effect of intentional deviations from a straight line, such as following the curvature of the Earth, and of unintentional deviations introduced by measurement and alignment errors. Results are compared to measured positions of the doublets.

WPAE042 Beam Loss and Residual Activation Trending beam-losses, survey, linac, SNS 2726
  • G.W. Dodson, M. Giannella, A.T. Ruffin, T.L. Williams
    ORNL, Oak Ridge, Tennessee
  Funding: This work was supported by SNS through UT-Batelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The SNS Front End, Drift Tube Linac and most of the Coupled Cavity Linac have been operated during commissioning. Beam loss data were taken with differential Beam Current Monitors, and Beam loss Monitors during commissioning. Residual activation data were taken at various times during and after the run. An analysis of beam loss trending, beam loss monitor data and residual activation will be shown.

WPAP016 High Brightness Electron Gun for X-Ray Source target, electron, injection, brightness 1488
  • S. Ohsawa, M. Ikeda, T. Sugimura, M. Tawada
    KEK, Ibaraki
  • Y. Hozumi
    GUAS/AS, Ibaraki
  • K. Kanno
    AET Japan, Inc., Kawasaki-City
  A new electron-gun system is under development in order to increase X-ray from a rotating target. In commercial X-ray sources electron beams usually hit targets at the outer part. Owing to deformation by centrifugal force, there has been a limit on electron beam intensities. In order to overcome this difficulty, we adopted a new injection system which strikes inside of a ring-shape projection on a rotating target. It has an advantage in that heated-up points have supports back side against centrifugal force. This merit allows us to raise electron beam to give stronger X-rays.  
WPAP023 Compact Source of Electron Beam with Energy of 200 kEv and Average Power of 2 kW electron, ion, power-supply, radiation 1832
  • I.V. Kazarezov, V. Auslender, V.E. Balakin, A.A. Bryazgin, A.V. Bulatov, I.I. Glazkov, I.V. Kazarezov, E.N. Kokin, G.S. Krainov, G.I. Kuznetsov, A.M. Molokoedov, A.F.A. Tuvik
    BINP SB RAS, Novosibirsk
  The paper describes a compact electron beam source with average electron energy of 200 keV. The source operates with pulse power up to 2 MW under average power not higher than 2 kW, pulsed beam current up to 10 A, pulse duration up to 2 mks, and repetition rate up to 5 kHz. The electron beam is extracted through aluminium-beryllium alloy foil. The pulse duration and repetition rate can be changed from control desk. High-voltage generator for the source with output voltage up to 220 kV is realized using the voltage-doubling circuit which consists of 30 sections. The insulation type - gas, SF6 under pressure of 8 atm. The cooling of the foil supporting tubes is provided by a water–alcohol mixture from an independent source. The beam output window dimensions are 180?75 mm, the energy spread in the beam +10/-30%, the source weight is 80 kg.  
WPAP057 Three-Dimensional Theory and Simulation of an Ellipse-Shaped Charged-Particle Beam Gun simulation, emittance, electron, vacuum 3372
  • R. Bhatt, T. Bemis, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
  Funding: U.S. DOE: Grant No. DE-FG02-95ER40919, Grant No. DE-FG02-01ER54662, Air Force Office of Scientific Research: Grant No. F49620-03-1-0230, and the MIT Deshpande Center for Technological Innovation.

A three-dimensional (3D) theory of non-relativistic, laminar, space-charge-limited, ellipse-shaped, charged-particle beam formation has been developed recently (Bhatt and Chen, PR:ST-AB, submitted Dec. 2004), whereby charged particles (electrons or ions) are accelerated across a diode by a static voltage differential and focused transversely by Pierce-type external electrodes placed along analytically specified surfaces. The treatment is extended to consider the perturbative effects of anode hole lensing, thermal isolation of the emitter, finiteness and nonuniformities of beam-forming electrodes, and an initial thermal spread. Analytic and semi-analytic results are presented along with 3D simulations utilizing the 3D trajectory code, OMNITRAK. Considerations with regard to beam matching into a periodic magnetic focusing lattice are discussed.

WPAT031 Design and Operation of a High Power L-Band Multiple Beam Klystron klystron, electron, cathode, higher-order-mode 2170
  • A. Balkcum, H.P. Bohlen, M. Cattelino, L. Cox, M. Cusick, S. Forrest, F. Friedlander, A. Staprans, E.L. Wright, L. Zitelli
    CPI, Palo Alto, California
  • K. Eppley
    SAIC, Burlington, Massachusetts
  A 1.3 GHz, 10 MW, higher-order-mode multiple beam klystron (MBK) has been developed for the TESLA program. The relative advantages of such a device are many-fold. Multiple beams generate higher beam currents and thereby require much lower operating voltages which allows for the use of smaller, less expensive modulators. A lower perveance per cathode can also be used which leads to higher operating efficiencies. Higher-order-mode cavities allow for the use of much larger cathodes which leads to lower cathode current density loadings and subsequently longer cathode lifetimes. This requires that the cathodes be located far off the geometric axis of the device. The compromise is an increase in the complexity of the magnetic focusing circuit required to transport the off-axis electron beams. Such a device has been successfully built and tested. Excellent beam transmission has been achieved (99.5% DC and 98% at RF saturation). A peak power of 10 MW with 150 kW of average power and 60% efficiency, 49 dB gain have also been measured. The achieved low cathode loading of 2.1 A/cm2 corresponds to an expected cathode life of over 140,000 operational hours.  
WPAT035 The LANSCE 805 MHZ RF System History and Status klystron, acceleration, 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.  
WPAT083 Steering and Focusing Effects in TESLA Cavity Due to High Order Mode and Input Couplers coupling, simulation, electromagnetic-fields, linac 4135
  • P. Piot
    Fermilab, Batavia, Illinois
  • M. Dohlus, K. Floettmann, M. Marx, S.G. Wipf
    DESY, Hamburg
  Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. Department of Energy, and by NICADD.

Many state-of-art electron accelerator proposals incorporate TESLA-type superconducting standing wave cavities. These cavities include input coupler (to feed the RF power into the cavity) and a pairs of high order mode couplers (HOM) to absorb the energy associated to HOM field excited as the bunch passes through the cavity. In the present paper we investigate, using numerical simulations, the impact of the input and HOM couplers on the beam dynamics. We show the overall effects are: a dipole kick (zeroth order) and normal and skew quadrupole-type focusing (first order). We present parametric studies of the strength of these effect for various operating gradients and incoming beam energies. We finally study the impact of this non-asymmetric field on the beam dynamics, taking as an example the low energy section of the European X-FEL injector.

WOPA002 Experimental Results from the Small Isochronous Ring space-charge, cyclotron, simulation, electron 159
  • E.P. Pozdeyev
    Jefferson Lab, Newport News, Virginia
  • F. Marti, R.C. York
    NSCL, East Lansing, Michigan
  • J.A. Rodriguez
    CERN, Geneva
  Funding: Work supported by NSF Grant # PHY-0110253 and DOE Contract DE-AC05-84ER40150.

The Small Isochronous Ring (SIR) is a compact, low-energy storage ring designed to investigate the beam dynamics of high-intensity isochronous cyclotrons and synchrotrons at the transition energy. The ring was developed at Michigan State University and has been operational since December 2003. It stores 20 keV hydrogen beams with a peak current of 10-20 microamps for up to 200 turns. The transverse and longitudinal profiles of extracted bunches are measured with an accuracy of approximately 1 mm. The high accuracy of the measurements makes the experimental data attractive for validation of multi-particle space charge codes. The results obtained in the ring show a fast growth of the energy spread induced by the space charge forces. The energy spread growth is accompanied by a breakup of the beam bunches into separated clusters that are involved in the vortex motion specific to the isochronous regime. The experimental results presented in the paper show a remarkable agreement with simulations performed with the code CYCO. In this paper, we discuss specifics of space charge effects in the isochronous regime, present results of experiments in SIR, and conduct a detailed comparison of the experimental data with results of simulations.

WOPB002 Symmetries and Einstein vacuum, background, coupling, survey 217
  • M. Kobayashi
    KEK, Ibaraki
  After brief survey of influence of Einstein on current particle physics, fundamental symmetry between particles and antipaticles will be discussed. Existence of antiparticles is an important outcome of special relativity and quantum mechanics and disappearance of antiparticles from the present universe is one of the mysteries in Big Bang cosmology based on the Einstein equation. Remarkable progress has been made recently in the studies on the violation of symmetry between particles and antiparticles with the use of a new type of accelerator. Some of their achievements will be reported.  
RPAE020 Production of High Harmonic X-Ray Radiation from Non-linear Thomson at LLNL PLEIADES laser, electron, scattering, radiation 1673
  • J. Lim, A. Doyuran, P. Frigola, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • S.G. Anderson, M. Betts, K. Crane, D.J. Gibson, F.V. Hartemann, A.M. Tremaine
    LLNL, Livermore, California
  Funding: US-DOE under contract no. DE-FG-98ER45693 and DE-FG03-92ER40693, and by LLNL under contract no. W-7405-Eng-48 and the LLNL ILSA program under contract LS04-001-B.

We describe an experiment for production of high harmonic x-ray radiation from Thomson backscattering of an ultra-short high power density laser by a relativistic electron beam at the PLEIADES facility at LLNL. In this scenario, electrons execute a “figure-8” motion under the influence of the high-intensity laser field, where the constant characterizing the field strength is expected to exceed unity: $aL=e*EL/m*c*ωL ≥ 1$. With large $aL$ this motion produces high harmonic x-ray radiation and significant broadening of the spectral peaks. This paper is intended to give a layout of the PLEIADES experiment, along with progress towards experimental goals.

RPAE043 Beam Position Monitor for Undulator by Using SR Monitor Technique undulator, radiation, monitoring, photon 2789
  • T. Mitsuhashi, M.T. Tadano
    KEK, Ibaraki
  A beam position monitor for the undulator by using the optical SR monitor technique has been tested in the Photon Factory. A visible SR in far tail of the undurater spectrum is extracted by a water-cooled beryllium mirror. The extraction mirror has a hole in the center for passing through the central peak of the undulator radiation which has an opening angle of 1/gamma. Extracted visible light in large opening angle has exactly same optical axis of the undulator radiation, because of it’s a far tail of the spectrum of same radiation. We applied focusing system to observe the beam position in the undulator through the optical image of beam. The results show us this method is applicable to monitor a position of beam in the undulator, and gap change of undulator has no effect of beam position monitoring. We can easily measure the angle of visible ray, this method is applicable not only beam position monitor but also monitoring the angular deviation of undulator radiation.  
RPAP015 Modeling of Internal Injection and Beam Dynamics for High Power RF Accelerator electron, simulation, cathode, injection 1419
  • M.A. Tiunov, V. Auslender, M.M. Karliner, G.I. Kuznetsov, I. Makarov, A.D. Panfilov, V.V. Tarnetsky
    BINP SB RAS, Novosibirsk
  Funding: The work is supported by ISTC grant #2550.

A new high power electron accelerator for industrial applications is developed in Novosibirsk. Main parameters of the accelerator are: operating frequency of 176 MHz, energy of electrons of 5 MeV, average beam power up to 300 kW. The accelerator consists of a chain of accelerating cavities, connected by the on-axis coupling cavities with coupling slots in the walls. A triode RF gun on the base of grid-cathode unit placed on the wall of the first accelerating cavity is used for internal injection of electrons. The paper presents the results of modeling and optimization of the accelerating structure, internal injection, and beam dynamics.

RPAP023 RF-Based Accelerators for HEDP Research ion, linac, extraction, target 1829
  • J.W.  Staples, R. Keller, A. Sessler
    LBNL, Berkeley, California
  • W. Chou
    Fermilab, Batavia, Illinois
  • P.N. Ostroumov
    ANL, Argonne, Illinois
  Funding: This work sponsored by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.

Accelerator-driven High-Energy Density Physics experiments require typically 1 nanosecond, 1 microcoulomb pulses of mass 20 ions accelerated to several MeV to produce eV-level excitations in thin targets, the "warm dense matter" regime. Traditionally the province of induction linacs, RF-based acceleration may be a viable alternative with recent breakthroughs in accelerating structures and high-field superconducting solenoids. A reference design for an RF-based accelerator for HEDP research is presented using 15 T solenoids and multiple-gap RF structures configured with either multiple parallel beams (combined at the target) or a single beam and a small stacking ring that accumulates 1 microcoulomb of charge. In either case, the beam is ballistically compressed with an induction linac core providing the necessary energy sweep and injected into a plasma-neutralized drift compression channel resulting in a 1 mm radius beam spot 1 nanosecond long at a thin foil or low-density target.

RPAT069 Electron Beam Size Measurements in a Cooling Solenoid electron, antiproton, optics, radiation 3801
  • T.K. Kroc, T.B. Bolshakov, A.V. Burov, A.V. Shemyakin
    Fermilab, Batavia, Illinois
  • S. Seletsky
    Rochester University, Rochester, New York
  Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy.

The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide effective cooling of the antiprotons in the Recycler. A measurement system was developed using movable appertures and steering bumps to measure the beam size in a 20 m long, nearly continuous, solenoid. This paper discusses the required beam parameters, the implimentation of the measurement system and results for our application.

ROPB008 Halo Mitigation Using Nonlinear Lattices collimation, simulation, damping, space-charge 620
  • K.G. Sonnad, J.R. Cary
    CIPS, Boulder, Colorado
  This work shows that halos in beams with space charge effects can be controlled by combining nonlinear focusing and collimation. The study relies on Particle-in-Cell (PIC) simulations for a one dimensional, continuous focusing model. The PIC simulation results show that nonlinear focusing leads to damping of the beam oscillations thereby reducing the mismatch. It is well established that reduced mismatch leads to reduced halo formation. However, the nonlinear damping is accompanied by emittance growth causing the beam to spread in phase space. As a result, inducing nonlinear damping alone cannot help mitigate the halo. To compensate for this expansion in phase space, the beam is collimated in the simulation and further evolution of the beam shows that the halo is not regenerated. The focusing model used in the PIC is analysed using the Lie Transform perturbation theory showing that by averaging over a lattice period, one can reuduce the focusing force to a form that is identical to that used in the PIC simulation.  
RPPE027 High Intensity High Energy E-Beam Interacting with a Thin Solid State Target: First Results at AIRIX electron, target, scattering, emittance 1982
  • M. Caron, F. Cartier, D.C. Collignon, L.H. Hourdin, E. Merle, M. Mouillet, C. Noel, D.P. Paradis, O.P. Pierret
    CEA, Pontfaverger-Moronvilliers
  • O. Mouton, N. Pichoff
    CEA/DAM, Bruyères-le-Châtel
  Funding: CEA, Polygone d’Expérimentation de Morronvilliers, LEXA F-51 475 Pontfaverger (France).

AIRIX is a 2 kA, 20 MeV, 60 ns linear accelerator dedicated to X-ray flash radiography. During a regular running phase, the primary electron beam is accelerated to and focused on a high atomic number target in order to generate X-rays by brembtrahlung mainly. The huge energy density deposited into the material is such that temperature rises up to 15000°K and that clusters and particles are violently ejected from the surface. In that mechanism, the backward emission speed can reach 5 km.s-1 and the debris can gradually accumulate and subsequently contaminate some sensitive parts of the machine. In order to protect the whole accelerating line from the detrimental effect of back-ejected particles, we have investigated the technical feasibility of a thin foil implementation upstream the X-ray converter.

RPPE031 Target and Horn Cooling for the Very Long Baseline Neutrino Experiment target, proton, radiation, simulation 2209
  • S. Bellavia, S.A. Kahn, H.G. Kirk, H. Ludewig, D. Raparia, N. Simos
    BNL, Upton, Long Island, New York
  Funding: This work is performed under the auspices of the US DOE.

Thermodynamic studies have been performed for the beam target and focusing horn system to be used in a very long baseline neutrino oscillation experiment. A 2mm rms beam spot with power deposition of over 18 KW presents challenging material and engineering solutions to this project. Given that the amount of heat transferred by radiation alone from the target to the horn is quite small, the primary mechanism is heat removal by forced convection in the annular space between the target and the horn. The key elements are the operating temperature of the target, the temperature of the cooling fluid and the heat generation rate in the volume of the target that needs to be removed. These working parameters establish the mass flow rate and velocity of the coolant necessary to remove the generated heat. Several cooling options were explored using a carbon-carbon target and aluminum horn. Detailed analysis, trade studies and simulations were performed for cooling the horn and target with gaseous helium as well as water.

RPPP038 Electron-Cloud Effects in Transport Lines of a Normal Conducting Linear Collider positron, electron, vacuum, resonance 2527
  • J. Wu, M.T.F. Pivi, T.O. Raubenheimer, A. Seryi
    SLAC, Menlo Park, California
  Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.

In the transport lines of a normal conducting linear collider, the long positron bunch train can generate an electron cloud which can then amplify intra-train offsets. This is a transient effect which is similar to but different from the electron-cloud driven coupled bunch instabilities in a positron storage ring. In this paper, we study this phenomenon both analytically and via numerical simulation. Some criterion on the critical cloud density with respect to given collider parameters is discussed.

RPPT049 Linear Optics Compensation of the Superconducting Wiggler in HLS wiggler, quadrupole, storage-ring, optics 3037
  • L. Wang, G. Feng, W. Li, H. Xu, H. Zhang
    USTC/NSRL, Hefei, Anhui
  Hefei Light Source is a dedicated VUV light source. A superconducting wiggler magnet with 6 Tesla magnetic field was installed on the storage ring to generate hard X-ray radiation. With the compensation of tune shift due to insertion device, beam was successfully stored, but the beam lifetime was decreased much. In order to cure the lifetime, a simple hard-edge model of the wiggler was constructed in lattice simulation code and the compensation scheme was extensively studied again. Calculation showed that it is difficulty to localize the strong focusing effects from wiggler magnet. Then, a new scheme was brought forward and experimental result showed that it can restore the beam lifetime largely. As the application of LOCO method in HLS, a new compensation scheme was calculated by response matrix fitting, and the experimental result also presented in this paper.  
RPPT068 Pion-Muon Concentrating System for Detectors of Highly Enriched Uranium target, antiproton, simulation, shielding 3757
  • S.S. Kurennoy, D.B. Barlow, B. Blind, A.J. Jason, N. Neri
    LANL, Los Alamos, New Mexico
  One of many possible applications of low-energy antiprotons collected in a Penning trap can be a portable muon source. Released antiprotons annihilate on impact with normal matter producing on average about 3 charged pions per antiproton, which in turn decay into muons. Existence of such negative-muon sources of sufficient intensity would bring into play, for example, detectors of highly enriched uranium based on muonic X-rays. We explore options of collecting and focusing pions and resulting muons to enhance the muon flux toward the detector. Simulations with MARS and MAFIA are used to choose the target material and parameters of the magnetic system consisting of a few solenoids.  
RPPT072 Ion Chamber Arrays for the NuMI Beam at Fermilab target, hadron, ion, proton 3892
  • D. Indurthy, R. Keisler, S.E. Kopp, S. Mendoza, Z. Pavlovich, M. Proga, R.M. Zwaska
    The University of Texas at Austin, Austin, Texas
  • M.B. Bishai, M. Diwan, B. Viren
    BNL, Upton, Long Island, New York
  • A.R. Erwin, H.P. Ping, C.V. Velissaris
    UW-Madison/PD, Madison, Wisconsin
  • D. Harris, A. Marchionni, G. Morfin
    Fermilab, Batavia, Illinois
  • J. McDonald, D. Naples, D. Northacker
    University of Pittsburgh, Pittsburgh, Pennsylvania
  The NuMI beamline and the MINOS experiment will study at a long baseline the possible oscillation of muon neutrinos and provide a precision measurement of the oscillation parameters. Neutrinos are produced from charged pion decays, where the pions are produced from interaction of the 120 GeV FNAL Main Injector proton beam with a graphite target. Ion chamber arrays have been built to monitor the resulting muons from pion decays, as well as remnant hadrons at the end of the NuMI decay pipe. The arrays of ion chambers measure both the intensity and lateral profile of the muon and hadron beams, allowing studies of sytematics of the neutrino beam. We will describe the design, construction, and precise calibration of the ion chamber arrays. Initial data from commissioning of the beam line and experience from long-term operations will be presented.  
ROPA007 Vlasov Simulations of Beams and Halo simulation, lattice, hadron, brightness 581
  • E. Sonnendrucker, M. Gutnic, M. Haefele, G. Latu
    IRMA, Strasbourg
  • J.-L. Lemaire
    CEA/DIF/DPTA/SP2A, Bruyeres-le-Chatel
  Even though PIC simulations have proven an efficient tool for beam simulations for many years, they are subject to numerical noise which only decreases slowly when the number of particles is increased. Therefore other methods might be preferable, when one is interested in accurate simulations of high intensity beams especially in the low density part of phase space. We have been developing new methods based on the direct resolution of the Vlasov equation on a grid of phase space. In order for these methods to be efficient special care needs to be taken to optimize the number of necessary grid points. We shall describe two different approaches that are used to this aim: moving grid methods and wavelet based automatic grid refinement. Beam simulations in different configurations using direct Vlasov methods will be presented.  
FPAE020 Induction Acceleration of a Single RF Bunch in the KEK PS induction, acceleration, synchrotron, 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.

FPAE054 Front End Design of a Multi-GeV H-minus Linac rfq, linac, lattice, emittance 3286
  • P.N. Ostroumov, K.W. Shepard
    ANL, Argonne, Illinois
  • G.W. Foster, I.G. Gonin, G. Romanov
    Fermilab, Batavia, Illinois
  Funding: This work was supported by the U.S. Department of Energy under Contracts No. W-31-109-ENG-38 and DE-AC02-76CH03000.

The proposed 8-GeV driver at FNAL is based on ~480 independently phased SC resonators. Significant cost saving is expected by using an rf power fan out from high-power klystrons to multiple cavities. Successful development of superconducting (SC) multi-spoke resonators operating at ~345-350 MHz provides a strong basis for their application in the front end of multi-GeV linear accelerators. Such a front-end operating at 325 MHz would enable direct transition to high-gradient 1300 MHz SC TESLA-style cavities at ~400 MeV. The proposed front end consists of 5 sections: a conventional RFQ, room-temperature (RT) cross-bar H-type (CH) cavities, single-, double- and triple-spoke superconducting resonators. For several reasons which are discussed in this paper there is a large advantage in using independently phased RT CH-cavities between the RFQ and SC sections in the energy range 3-15 MeV.

FPAE055 Heavy-Ion Beam Dynamics in the RIA Post-Accelerator linac, rfq, emittance, ion 3301
  • P.N. Ostroumov, V.N. Aseev
    ANL, Argonne, Illinois
  • A. Kolomiets
    ITEP, Moscow
  Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. W-31-109-ENG-38.

The RIB linac includes two strippers for the heaviest ions and three main sections: a room temperature injector up to an energy of ~100 keV/u, a superconducting (SC) linac for ions with charge-to-mass ratio 1/66 or more up to an energy of ~1 MeV and a higher energy SC linac to produce 10 MeV/u beams up to the mass of uranium. The RIA post-accelerator is a complex system designed for acceleration singly-charged ions before the stripper and includes many different accelerating and focusing structures operating both at room and cryogenic temperatures. Extensive accelerator design studies and end-to-end beam dynamics simulations have been performed to minimize the cost of the linac while providing high-quality and high-intensity radioactive beams. Specifically, we have found that cost-effective acceleration can be provided by several hybrid RFQs in the front end. The hybrid RFQs have been proposed and developed for acceleration of low-velocity heavy ions.* For the beam focusing in the second section it is appropriate to use electrostatic lenses and SC quadrupoles inside common cryostats with the resonators. The electrostatic lenses are most effective in the first cryostat of the SC linac.

*P.N. Ostroumov and A.A. Kolomiets. Proc. of the PAC-2001, Chicago, IL, June 18-22, 2001, p. 4077.

FPAE076 The System of Nanosecond 280-keV-He+ Pulsed Beam ion, ion-source, quadrupole, target 3982
  • P. Junphong, Mr. Ano, Mr. Lekprasert, Dr. Suwannakachorn, N. Thongnopparat, T. Vilaithong
    FNRF, Chiang Mai
  • H. Wiedemann
    SLAC, Menlo Park, California
  Funding: We would like to acknowledge the support of the Thailand Research Fund, the National Research Council of Thailand, the Thai Royal Golden Jubilee Scholarship Program, the Faculty of Science, and the Graduate School of Chiang Mai University.

At Fast Neutron Research Facility,the 150 kV-pulseds neutron generator is being upgraded to produce a 280-keV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45o-double focusing dipole magnet and quadrupole lens. The Multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 μA with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has been found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a target. The calculated distance from a buncher to the target is 4.6 m. Effects of energy spread and phase angle between chopper and buncher have been included in the optimization of the bunch length.

FPAE077 LSP Simulations of the Neutralized Drift Compression Experiment ion, simulation, plasma, emittance 4006
  • C.H. Thoma, D.R. Welch
    ATK-MR, Albuquerque, New Mexico
  • S. Eylon, E. Henestroza, P.K. Roy, S. Yu
    LBNL, Berkeley, California
  • E.P. Gilson
    PPPL, Princeton, New Jersey
  Funding: Work supported by the VNL for HIF through PPPL and LBNL.

The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory involves the longitudinal compression of a singly-stripped K ion beam with a mean energy of 250 keV in a meter long plasma. We present simulation results of compression of the NDCX beam using the PIC code LSP. The NDCX beam encounters an acceleration gap with a time-dependent voltage that decelerates the front and accelerates the tail of a 500 ns pulse which is to be compressed 110 cm downstream. The simulations model both ideal and experimental voltage waveforms. Results show good longitudinal compression without significant emittance growth.

FPAP029 Nonlinear Delta-f Particle Simulations of Collective Effects in High-Intensity Bunched Beams simulation, space-charge, coupling, collective-effects 2107
  • H. Qin, R.C. Davidson, S.R. Hudson, E. Startsev
    PPPL, Princeton, New Jersey
  Funding: Research supported by the U.S. Department of Energy.

The collective effects in high-intensity 3D bunched beams are described self-consistently by the nonlinear Vlasov-Maxwell equations.* The nonlinear delta-f method,** a particle simulation method for solving the nonlinear Vlasov-Maxwell equations, is being used to study the collective effects in high-intensity 3D bunched beams. The delta-f method, as a nonlinear perturbative scheme, splits the distribution function into equilibrium and perturbed parts. The perturbed distribution function is represented as a weighted summation over discrete particles, where the particle orbits are advanced by equations of motion in the focusing field and self-consistent fields, and the particle weights are advanced by the coupling between the perturbed fields and the zero-order distribution function. The nonlinear delta-f method exhibits minimal noise and accuracy problems in comparison with standard particle-in-cell simulations. A self-consistent 3D kinetic equilibrium is first established for high intensity bunched beams. Then, the collective excitations of the equilibrium are systematically investigated using the nonlinear delta-f method implemented in the Beam Equilibrium Stability and Transport (BEST) code.

*R.C. Davidson and H. Qin, Physics of Intense Charged Particle Beams in High Energy Accelerators (World Scientific, 2001). **H. Qin, Physics of Plasmas 10, 2078 (2003).

FPAP034 Space-Charge Transport Limits in Periodic Channels lattice, resonance, space-charge, simulation 2348
  • S.M. Lund
    LLNL, Livermore, California
  • S. R. Chawla
    UCB, Berkeley, California
  Funding: Research performed under the auspices of the US DOE by the University of California at LLNL and LBNL under contract Nos. W-7405-Eng-48 and DE-AC03-76SF00098.

It has been observed in both experiment and particle in cell simulations that space-charge-dominated beams suffer strong emittance growth in alternating gradient quadrupole transport channels when the undepressed phase advance σ0 increases beyond about 80 degrees per lattice period. Transport systems have long been designed to respect this phase advance limit but no theory has been proposed to date to explain the the cause of the limit. Here we propose a mechanism to parametrically explain the transport limit as being due to classes of halo particle orbits moving close to the beam edge in phase-space when σ0 increases beyond 80 degrees. A finite beam edge and/or perturbation acting on an edge particle can then act to move edge particles to large amplitude and lead to large increases in beam phase space area, lost particles, and degraded transport. A core particle model for a uniform density elliptical beam in a periodic focusing lattice was written and is applied to parametrically analyze this process for both periodic alternating gradient quadrupole and solenoidal transport lattices. Self-consistent particle in cell simulations are also carried out to support results.

FPAT002 Automatic Steering for the CTF3 Linear Accelerator simulation, linac, dipole, lattice 814
  • R.D. Lifshitz
    Technion, Haifa
  • D. Schulte
    CERN, Geneva
  Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395)

A system for automatic beam steering has been implemented at the CTF3 linear accelerator. Beam position readings are logged while corrector magnet strengths are scanned over a given range, thus giving a steering response measurement. Assuming linearity, a response matrix is constructed and used to automatically optimize the beam trajectory along the linac. Using a simple BPM-reading minimization for trajectory correction, this system has been tested in the 2004 CTF3 summer run. Although not in routine operation, it has already proved useful as a tool for the machine setup and operation. In this paper, the automatic steering system for the CTF3 linac is introduced, trajectory correction results are presented, and the agreement with a computer model of the machine is discussed.

FPAT026 The Dynamic Aperture of an Electrostatic Quadrupole Lattice simulation, lattice, quadrupole, beam-losses 1946
  • C.M. Celata, F.M. Bieniosek, P.A. Seidl
    LBNL, Berkeley, California
  • A. Friedman, D.P. Grote
    LLNL, Livermore, California
  • L.R. Prost
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U.S. DOE, under contract numbers DE-AC03-76SF00098 and W-7405-Eng-48.

In heavy-ion-driven inertial fusion accelerator concepts, dynamic aperture is important to the cost of the accelerator, most especially for designs which envision multibeam linacs, where extra clearance for each beam greatly enlarges the transverse scale of the machine. In many designs the low-energy end of such an accelerator uses electrostatic quadrupole focusing. The dynamic aperture of such a lattice has been investigated for intense, space-charge-dominated ion beams using the 2-D transverse slice version of the 3-D particle-in-cell simulation code WARP. The representation of the focusing field used is a 3-D solution of the Laplace equation for the biased focusing elements, as opposed to previous calculations which used a less-accurate multipole approximation. 80% radial filling of the aperture is found to be possible. Results from the simulations, as well as corroborating data from the High Current Experiment at LBNL, will be presented.

FPAT030 Parametric Studies of Image-Charge Effects in Small-Aperture Alternating-Gradient Focusing Systems beam-losses, vacuum, simulation, quadrupole 2128
  • J.Z. Zhou, C. Chen
    MIT/PSFC, Cambridge, Massachusetts
  Funding: The U.S. Department of Energy, Office of High-Energy Physics, Grant No. DE-FG02-95ER40919, Office of Fusion Energy Science, Grant No. DE-FG02-01ER54662, and in part by Air Force Office of Scientific Research, Grant No. F49620-03-1-0230.

Image charges have important effects on an intense charged-particle beam propagating through an alternating-gradient (AG) focusing channel with a small circular aperture. This is especially true with regard to chaotic particle motion, halo formation, and beam loss.* In this paper, we examine the dependence of these effects on system parameters such as the filling factor of the AG focusing field, the vacuum phase advance, the beam perveance, and the ratio of the beam size to the aperture. We calculate the percentage of beam loss to the conductor wall as a function of propagating distance and aperture, and compare theoretical results with simulation results from the particle-in-cell (PIC) code PFB2D.

*Zhou, Qian and Chen, Phys. Plasmas 10, 4203 (2003).

FPAT042 Beam Dynamics and Pulse Duration Control During Final Beam Bunching in Driver System for Heavy Ion Inertial Fusion lattice, emittance, beam-transport, bunching 2735
  • T. Kikuchi, S. Kawata, T. Someya
    Utsunomiya University, Utsunomiya
  • K. Horioka, M. Nakajima
    TIT, Yokohama
  • T. Katayama
    CNS, Saitama
  Beam dynamics is investigated by multi-particle simulations during a final beam bunching in a driver system for heavy ion inertial fusion (HIF). The longitudinal bunch compression causes the beam instability induced by the strong space charge effect. The multi-particle simulation can indicate the emittance growth due to the longitudinal bunch compression. Dependence in the beam pulse duration is also investigated for effective pellet implosion in HIF. Not only the spatial nonuniformity of the beam illumination, but also the errors of the beam pulse duration cause changes of implosion dynamics. The allowable regime of the beam pulse duration for the effective fusion output becomes narrow with decreasing the input beam energy. The voltage accuracy requirement at the beam velocity modulator is also estimated for the final beam bunching. It is estimated that the integrated voltage error is allowable as a few percent.  
FPAT091 LiTrack: A Fast Longitudinal Phase Space Tracking Code with Graphical User Interface linac, acceleration, 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.

FPAT092 Optimized Beam Matching Using Extremum Seeking target, simulation, beam-transport, feedback 4269
  • E. Schuster
    Lehigh University, Bethlehem, Pennsylvania
  • C.K. Allen
    LANL, Los Alamos, New Mexico
  • M. Krstic
    UCSD, La Jolla, California
  The transport and matching problem for a low energy transport system is approached from a control theoretical viewpoint. The beam dynamics and transport section is modeled using the KV envelope equations. Principles of optimal control are applied to this model to formulate techniques which aid in the design of the transport and matching section. Multi-Parameter Extremum Seeking, a real-time non-model based optimization technique, is considered in this work for the lens tuning. Numerical simulations illustrate the effectiveness of this approach.  
FOAD002 Ultra-High Density Electron Beams for Beam Radiation and Beam Plasma Interaction electron, emittance, simulation, plasma 145
  • S.G. Anderson, J. Brown, D.J. Gibson, F.V. Hartemann, J.S. Jacob, A.M. Tremaine
    LLNL, Livermore, California
  • P. Frigola, J. Lim, J.B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  • P. Musumeci
    INFN-Roma, Roma
  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.

Current and future applications of high brightness electron beams, which include advanced accelerators such as the plasma wake-field accelerator (PWFA) and beam-radiation interactions such as inverse-Compton scattering (ICS), require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at LLNL’s PLEIADES ICS x-ray source in which the photoinjector-generated beam has been compressed to 300 fsec duration using the velocity bunching technique and focused to 20 μm rms size using an extremely high gradient, permanent magnet quadrupole (PMQ) focusing system.