• 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

• E. Startsev, R.C. Davidson, H. Qin
  PPPL, Princeton, New Jersey

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.

• 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

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.

• S.N. Andrianov, S. Edamenko
  St. Petersburg State University, Applied Mathematics & Control Processes Faculty, St. Petersburg

• S.N. Andrianov
  St. Petersburg State University, Applied Mathematics & Control Processes Faculty, St. Petersburg

• C.-X. Wang
  ANL, Argonne, Illinois

• M. Doleans
  MSU, East Lansing, Michigan
• D. Gorelov, T.L. Grimm, F. Marti, X. Wu, R.C. York
  NSCL, East Lansing, Michigan

• X. Wu, M. Doleans, D. Gorelov, T.L. Grimm, F. Marti, R.C. York
  NSCL, East Lansing, Michigan

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

• H. Qin, R.C. Davidson
  PPPL, Princeton, New Jersey

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).

• X. Huang, S.-Y. Lee
  IUCF, Bloomington, Indiana
• C.M. Ankenbrandt, E. Prebys
  Fermilab, Batavia, Illinois

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).

• E.S. Lessner, V.S. Assev, P.N. Ostroumov
  ANL, Argonne, Illinois

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.

• W. Wan, J. Feng, H.A. Padmore
  LBNL, Berkeley, California

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.

• C. Chen, R. Bhatt, A. Radovinsky, J.Z. Zhou
  MIT/PSFC, Cambridge, Massachusetts

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.

• M.A. Green
  LBNL, Berkeley, California
• Y. Ivanyushenkov
  CCLRC/RAL, Chilton, Didcot, Oxon
• W. Lau, R. Senanayake, S.Q. Yang
  OXFORDphysics, Oxford, Oxon

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.

• 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

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.

• A.A. Mikhailichenko
  Cornell University, Department of Physics, Ithaca, New York

• A.A. Mikhailichenko
  Cornell University, Department of Physics, Ithaca, New York

• 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

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.

• J.W. Lewellen
  ANL, Argonne, Illinois

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.

• A.A. Mikhailichenko
  Cornell University, Department of Physics, Ithaca, New York

• T. Plettner, R.M. Gaume, J. Wisdom
  Stanford University, Stanford, Califormia
• J.E. Spencer
  SLAC, Menlo Park, California

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.

• 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

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.

• 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

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.

• R. Bhatt, C. Chen, J.Z. Zhou
  MIT/PSFC, Cambridge, Massachusetts

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.

• J.Z. Zhou, R. Bhatt, C. Chen
  MIT/PSFC, Cambridge, Massachusetts

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.

• S. Bernal, R.A. Kishek, P.G. O'Shea, B. Quinn, M. Walter
  IREAP, College Park, Maryland
• M. Reiser
  University Maryland, College Park, Maryland

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.

• Y. Senichev, R. Maier, N.E. Vasyukhin
  FZJ, Jülich

• E.P. Pozdeyev
  Jefferson Lab, Newport News, Virginia
• F. Marti, R.C. York
  NSCL, East Lansing, Michigan
• J.A. Rodriguez
  CERN, Geneva

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.

• 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

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.

• P. Efthimion, R.C. Davidson, E.P. Gilson, L. Grisham
  PPPL, Princeton, New Jersey
• B. G. Logan, W. Waldron, S. Yu
  LBNL, Berkeley, California

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.

• E.P. Gilson, M. Chung, R.C. Davidson, P. Efthimion, R. M. Majeski, E. Startsev
  PPPL, Princeton, New Jersey

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.

• V. Zadorozhny
  NASU/IOC, Kiev
• Z.P. Parsa
  BNL, Upton, Long Island, New York

• R. Pakter, F.B. Rizzato, W. Simeoni
  IF-UFRGS, Porto Alegre

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.

• N.E. Vasyukhin, Y. Senichev, R. Tölle
  FZJ, Jülich

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.

• N.E. Vasyukhin, Y. Senichev, R. Tölle
  FZJ, Jülich

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.

• O.A. Anderson
  LBNL, Berkeley, California

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.

• E. Startsev, R.C. Davidson, W.L. Lee
  PPPL, Princeton, New Jersey

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.

• 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

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).

• Q. Zhao, A.I. Balabin, M. Doleans, F. Marti, J.W. Stetson, X. Wu
  NSCL, East Lansing, Michigan

• J.W. Stetson, G. Machicoane, F. Marti, P. Miller, M. Steiner, P.A. Zavodszky
  NSCL, East Lansing, Michigan
• Yu. Kazarinov
  JINR, Dubna, Moscow Region

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.

• Yu. Kazarinov
  JINR, Dubna, Moscow Region
• J.W. Stetson, P.A. Zavodszky
  NSCL, East Lansing, Michigan

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.

• 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

*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.

• 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

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.

• Y.S. Derbenev
  Jefferson Lab, Newport News, Virginia
• R.P. Johnson
  Muons, Inc, Batavia

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.

• 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

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.

• A. Klier, G.G. Hanson
  UCR, Riverside, California

• R.C. Fernow
  BNL, Upton, Long Island, New York

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.

• 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

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.

• V.A. Bomko, O.F. Dyachenko, A.P. Kobets, E.D. Marynina, Z.O. Ptukhina, S.S. Tishkin, B.V. Zajtsev
  NSC/KIPT, Kharkov

• A. Gallo, D. Alesini, C. Biscari, R. Boni, F. Marcellini, M. Zobov
  INFN/LNF, Frascati (Roma)
• C. Pagani
  DESY, Hamburg

• G. Ciovati, P. Kneisel
  Jefferson Lab, Newport News, Virginia

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.

• 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

*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).

• B.M. Cowan
  SLAC, Menlo Park, California

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.

• M.A.C. Cummings
  Northern Illinois University, DeKalb, Illinois
• S. Ishimoto
  KEK, Ibaraki

• R.C. McCrady
  LANL, Los Alamos, New Mexico

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.

• G.W. Dodson, M. Giannella, A.T. Ruffin, T.L. Williams
  ORNL, Oak Ridge, Tennessee

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.

• S. Ohsawa, M. Ikeda, T. Sugimura, M. Tawada
  KEK, Ibaraki
• Y. Hozumi
  GUAS/AS, Ibaraki
• K. Kanno
  AET Japan, Inc., Kawasaki-City

• 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

• R. Bhatt, T. Bemis, C. Chen
  MIT/PSFC, Cambridge, Massachusetts

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.

• 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

• M.T. Lynch, G. Bolme, P.J. Tallerico
  LANL, Los Alamos, New Mexico

• P. Piot
  Fermilab, Batavia, Illinois
• M. Dohlus, K. Floettmann, M. Marx, S.G. Wipf
  DESY, Hamburg

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.

• E.P. Pozdeyev
  Jefferson Lab, Newport News, Virginia
• F. Marti, R.C. York
  NSCL, East Lansing, Michigan
• J.A. Rodriguez
  CERN, Geneva

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.

• M. Kobayashi
  KEK, Ibaraki

• 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

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.

• T. Mitsuhashi, M.T. Tadano
  KEK, Ibaraki

• M.A. Tiunov, V. Auslender, M.M. Karliner, G.I. Kuznetsov, I. Makarov, A.D. Panfilov, V.V. Tarnetsky
  BINP SB RAS, Novosibirsk

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.

• J.W.  Staples, R. Keller, A. Sessler
  LBNL, Berkeley, California
• W. Chou
  Fermilab, Batavia, Illinois
• P.N. Ostroumov
  ANL, Argonne, Illinois

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.

• T.K. Kroc, T.B. Bolshakov, A.V. Burov, A.V. Shemyakin
  Fermilab, Batavia, Illinois
• S. Seletsky
  Rochester University, Rochester, New York

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.

• K.G. Sonnad, J.R. Cary
  CIPS, Boulder, Colorado

• 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

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.

• S. Bellavia, S.A. Kahn, H.G. Kirk, H. Ludewig, D. Raparia, N. Simos
  BNL, Upton, Long Island, New York

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.

• J. Wu, M.T.F. Pivi, T.O. Raubenheimer, A. Seryi
  SLAC, Menlo Park, California

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.

• L. Wang, G. Feng, W. Li, H. Xu, H. Zhang
  USTC/NSRL, Hefei, Anhui

• S.S. Kurennoy, D.B. Barlow, B. Blind, A.J. Jason, N. Neri
  LANL, Los Alamos, New Mexico

• 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

• E. Sonnendrucker, M. Gutnic, M. Haefele, G. Latu
  IRMA, Strasbourg
• J.-L. Lemaire
  CEA/DIF/DPTA/SP2A, Bruyeres-le-Chatel

• 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

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

• P.N. Ostroumov, K.W. Shepard
  ANL, Argonne, Illinois
• G.W. Foster, I.G. Gonin, G. Romanov
  Fermilab, Batavia, Illinois

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.

• P.N. Ostroumov, V.N. Aseev
  ANL, Argonne, Illinois
• A. Kolomiets
  ITEP, Moscow

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.

• P. Junphong, Mr. Ano, Mr. Lekprasert, Dr. Suwannakachorn, N. Thongnopparat, T. Vilaithong
  FNRF, Chiang Mai
• H. Wiedemann
  SLAC, Menlo Park, California

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.

• 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

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.

• H. Qin, R.C. Davidson, S.R. Hudson, E. Startsev
  PPPL, Princeton, New Jersey

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).

• S.M. Lund
  LLNL, Livermore, California
• S. R. Chawla
  UCB, Berkeley, California

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.

• R.D. Lifshitz
  Technion, Haifa
• D. Schulte
  CERN, Geneva

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.

• 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

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.

• J.Z. Zhou, C. Chen
  MIT/PSFC, Cambridge, Massachusetts

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).

• T. Kikuchi, S. Kawata, T. Someya
  Utsunomiya University, Utsunomiya
• K. Horioka, M. Nakajima
  TIT, Yokohama
• T. Katayama
  CNS, Saitama

• P. Emma, K.L.F. Bane
  SLAC, Menlo Park, California

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.

• E. Schuster
  Lehigh University, Bethlehem, Pennsylvania
• C.K. Allen
  LANL, Los Alamos, New Mexico
• M. Krstic
  UCSD, La Jolla, California

• 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

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.