A   B   C   D   E   F   G   H   I   K   L   M   O   P   Q   R   S   T   U   V    

focusing

  
Paper Title Other Keywords Page
MOP01 Beam Intensity Adjustment in the RIA Driver Linac target, ion, linac, impedance 33
 
  • P.N. Ostroumov, J.A. Nolen, I. Sharamentov
    ANL/Phys, Argonne, Illinois
  • A.V. Novikov-Borodin
    RAS/INR, Moscow
  The Rare Isotope Accelerator Facility currently being designed in the U.S. will use both heavy ion and light ion beams to produce radionuclides via the fragmentation and spallation reactions, respectively. Driver beam power of up to 400 kW will be available so that beam sharing between target stations is a viable option to increase the number of simultaneous users. Using a combination of rf-sweepers and DC magnets the driver beams can be delivered to up to four targets simultaneously. With simultaneous beam delivery to more than one target independent adjustment of the relative beam intensities is essential. To enable such intensity adjustment we propose to use a fast chopper in the Medium Energy Beam Transport (MEBT) section. Several options of fast chopper design are discussed. The MEBT beam optics is being designed to accommodate and match the chopper technical specifications. Possible solutions and performance with the fast chopper are proposed.  
 
MOP15 TRASCO-RFQ as Injector for the SPES-1 Project target, linac, rfq, beam-losses 66
 
  • P. Posocco, M. Comunian, A. Pisent
    INFN/LNL, Legnaro, Padova
  • E. Fagotti
    INFN Milano, Milano
  The funded first phase of SPES foresees the realization at LNL of a facility able, on one hand, to accelerate a 10 mA protons beam up to 20 MeV for nuclear studies and, on the other hand, to accelerate a 30 mA protons beam up to 5 MeV for BNCT and preliminary ADS studies. In this two-way facility, the TRASCO RFQ will operate in two different current regimes. Moreover a specific MEBT has to be designed able to match the beam to the following superconducting linac and to deliver a beam with the correct characteristics to the neutron production target for the BNCT studies.  
 
MOP35 The Research of a Novel SW Accelerating Structure with Small Beam Spot electron, coupling, photon, target 114
 
  • X. Yang, H. Chen, Y. Chen, X. Jin, M. Li, H. Lu, Z. Xu
    CAEP/IAP, Mianyang, Sichuan
  A new kind of on-axis coupled biperiodic standing-wave (SW) accelerating structure has been built for a 9 MeV accelerator. The research progress was introduced in this paper, it includes the choice of the accelerating structure, the analysis of electron beam dynamics, the tuning of the cavity, the measurement of the accelerating tube and the powered test. The small beam spot is the most interesting feature of this accelerating structure, the diameter of the beam spot is 1.4 mm. This accelerator has been used for the x photons generation and the x-ray dose rate is about 3400 rad/min/m.  
 
MOP39 Positron Transmission and Polarization in E-166 Experiment positron, polarization, target, photon 126
 
  • Y.K. Batygin
    SLAC, Stanford
  The proposed experiment E-166 at SLAC is designed to demonstrate the possibility of producing longitudinally polarized positrons from circularly polarized photons. Experimental set-up utilizes a low emittance 50 GeV electron beam passing through a helical undulator in the Final Focus Test Beam line of SLAC accelerator. Circularly polarized photons generated by the electron beam in undulator hit a target and produce electron-positron pairs. The purpose of post-target optics is to select the positron beam and to deliver it to a polarimeter keeping positron beam polarization as high as possible. Paper analyzes the positron transmission and polarization both numerically and analytically. The value of positron transmission has a maximum of 3% for positron energy of 7 MeV while positron polarization is around 80%.  
 
MOP68 Ribbon Ion Beam Dynamics in Undulator Linear Accelerator undulator, acceleration, ion, linac 177
 
  • E.S. Masunov, S.M. Polozov
    MEPhI, Moscow
  The possibility to use radio frequency undulator fields for ion beam focusing and acceleration in linac (UNDULAC-RF) is discussed. In periodical resonator structure the accelerating force is produced by the combination of two or more space harmonics of a longitudinal or a transverse undulator field*. The particle motion equations in Hamilton form are carried out by means of smooth approximation. The analysis of 3D effective potential permits to find the conditions under which focusing and acceleration of the particles occur simultaneously. The analytical results are verified with a numerical simulation. Examples illustrating the efficiency of the proposed method of acceleration are given for longitudinal and transverse undulators. The results are compared with a conventional linac and the other possibility of ion beam acceleration in UNDULAC-E(M) where electrostatic and magnetic fields are used.

*E.S. Masunov, Technical Physics, Vol. 46, No.11, 2001, pp. 1433-1436.

 
 
TUP01 RFQ Drift-Tube Proton Linacs in IHEP rfq, linac, quadrupole, emittance 285
 
  • Yu. Budanov, O.K. Belyaev, S.V. Ivanov, A.P. Maltsev, I.G. Maltsev, V.B. Stepanov, S.A. Strekalovskyh, V.A. Teplyakov, V. Zenin
    IHEP Protvino, Protvino, Moscow Region
  A linac with drift tubes and RF quadrupoles (alias, an RFQ DTL) constitutes a natural extension of the RFQ concept towards higher beam energies. Complementing an RFQ with drift tubes intermitted by spacer electrodes separates functions of focusing and acceleration. Such a structure allows for an increased accelerating rate and upgrades shunt impedance to values competitive against those inherent in the other common accelerator types. Various accelerating/focusing structures for the RFQ DTLs were implemented in IHEP. Their succession is marked by a progress in performance, which is due to efforts in design, manufacturing technology and calculation technique advances that facilitated R&D of such the structures. A sound practical expertise in the field is accumulated. The 30 MeV RFQ DTL is in service as an injector for a 1.5 GeV PS of IHEP since 1985. An upgraded successor – the RFQ DTL, employing a cavity loaded by a novel accelerating/focusing structure with an increased accelerating rate, is now being assembled and tested. Its pre-commissioning results will be outlined. Prospects in R&D of a structure suitable for a front-end part of the CERN SPL will be evaluated.  
Transparencies
 
TUP02 Development of a 352 MHz Cell-Coupled Drift Tube Linac Prototype coupling, linac, quadrupole, alignment 288
 
  • M. Vretenar, Y. Cuvet, J. Genest, C. Völlinger
    CERN, Geneva
  • F. Gerigk
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  At linac energies above 40 MeV, alternative structures to the conventional Drift Tube Linac can be used to increase efficiency and to simplify construction and alignment. In the frame of the R&D activities for the CERN SPL and Linac4, a prototype of Cell-Coupled Drift Tube Linac (CCDTL) at 352 MHz has been designed and built. This particular CCDTL concept is intended to cover the energy range from 40 to 90 MeV and consists of modules of ~5 m length made of 3 or 4-gap DTL tanks linked by coupling cells. The focusing quadrupoles are placed between tanks, and are aligned independently from the RF structure. The CCDTL prototype consists of two half tanks connected by a coupling cell and requires an RF power of 120 kW to achieve the design gradient. RF tests will be made at low and high power, the latter up to a 20% duty cycle. This paper introduces the main features of this CCDTL design, describes the RF and mechanical design of the prototype and presents the first measurement results.  
 
TUP07 A Linac-to-Booster Injection Line for Transverse Matching and Correlated Injection Painting booster, injection, linac, simulation 303
 
  • R. Garnett, L. Rybarcyk
    LANL, Los Alamos, New Mexico
  In this paper we discuss a compact linac-to-booster ring transfer line originally proposed for the Los Alamos Advanced Hydrotest Facility design to vertically inject a 157 MeV H- beam from the linac into a 10 GeV booster. TRACE 3-D and PARMILA simulations were used to demonstrate the performance of the transfer line to deliver the required transverse beam to the foil while also allowing correlated longitudinal injection painting. Schemes for both transverse and longitudinal matching are important for high-intensity ring applications where low beam loss operation is desirable. The main features of the beam line layout, a proposed longitudinal painting scheme, and the simulation results will be discussed.  
 
TUP08 Carbon Ion Injector Linac for a Heavy Ion Medical Synchrotron linac, rfq, ion, vacuum 306
 
  • D.A. Swenson
    LLC, Albuquerque, New Mexico
  The design of a Carbon Ion Injector Linac for a heavy ion medical synchrotron will be presented. The linac is designed to accelerate quadruply-ionized carbon ions (12C4+) with a charge/mass ratio (q/A) of 0.333, and all other ions with the same or higher charge/mass ratios, such as H1+, H21+, D1+, T1+, 3He1+, 4He2+, 6Li2+, 10B4+, and 16O6+ to an output energy of 7 MeV/u. The 200 MHz linac consists of an Radio Frequency Quadrupole (RFQ) linac to accelerate the ions from an input energy of 0.008 MeV/u to an intermediate energy of 0.800 MeV/u, and an Rf-Focused Interdigital (RFI) linac to accelerate these ions to the output energy. The combined linac structures have a total length of 7.8 meters and a total peak rf power requirement of about 600 kW. The RFQ linac employs a radial-strut, four-bar design that is about twice as efficient as the conventional four-bar RFQ design. The RFI linac, which is basically an interdigital drift tube structure with rf quadrupole focusing incorporated into each drift tube, is about 5 times more efficient than the conventional Drift Tube Linac (DTL) structure. Details of the linac structures and their calculated performance will be presented.  
 
TUP16 Investigation on Beam Dynamics Design of High-Intensity RFQs rfq, space-charge, acceleration, emittance 327
 
  • C. Zhang, A. Schempp
    IAP, Frankfurt-am-Main
  • J. Chen, J. Fang, Z.Y. Guo
    PKU/IHIP, Beijing
  Recently various potential uses of high-intensity beams bring new opportunities as well as challenges to RFQ accelerator research because of the new problems arising from the strong space-charge effects. Unconventional concepts of beam dynamics design, which surround the choice of basic parameters and the optimization of main dynamics parameters’ variation along the machine, are illustrated by the designing Peking University (PKU) Deuteron RFQ. An efficient tool of LANL RFQ Design Codes for beam dynamics simulation and analysis, RFQBAT, is introduced. Some quality criterions are also presented for evaluating design results.  
 
TUP26 Alternating Phase Focusing in Low-Velocity Heavy-Ion Superconducting Linac linac, emittance, ion, heavy-ion 348
 
  • P.N. Ostroumov, K.W. Shepard
    ANL/Phys, Argonne, Illinois
  • A. Kolomiets
    ITEP, Moscow
  • E.S. Masunov
    MEPhI, Moscow
  The low-charge-state injector linac of the RIA post-accelerator is based on ~60 independently phased SC resonators providing total ~70 MV accelerating potential. The low charge-state beams, however, require stronger transverse focusing, particularly at low velocities, than is used in existing SC ion linacs. For the charge-to-mass ratios considered here (q/A = 1/66) the proper focusing can be reached by the help of strong SC solenoid lenses with the field up to 15 T. Magnetic field of the solenoids can be reduced to 9 T applying an Alternating Phase Focusing (APF). A method to set the rf field phases has been developed and studied both analytically and by the help of the three-dimensional ray tracing code. The paper discusses the results of these studies.  
 
TUP42 Beam Optics Studies for the TESLA Test Facility Linac undulator, optics, linac, quadrupole 360
 
  • P. Castro, V. Balandin, N. Golubeva
    DESY, Hamburg
  The aim of the TESLA Test Facility Linac is to create electron bunches of small transverse emittance and high peak current with energies up to 1 GeV for the VUV-FEL at DESY. The linac consists of a RF photo-cathode gun, a superconducting linac, two magnetic chicanes (for bunch compression), a long undulator magnet section and a beam line bypassing the undulator (for commissioning purposes). A study of (linear) beam optics of the linac is presented for the case of beam commissioning (and beam measurements), FEL operation and long bunch train operation. The requirements of each part of the linac upon the optics are discussed in detail and an appropriate solution for each case is shown, as well as the matching solution to the rest of the accelerator. The chromatic properties of the linac have been studied also.  
 
TUP50 Cumulative Beam Breakup with Time-Dependent Parameters coupling, injection, linear-collider, dipole 384
 
  • J. R. Delayen
    Jefferson Lab, Newport News, Virginia
  A general analytical formalism developed recently for cumulative beam breakup (BBU) in linear accelerators with arbitrary beam current profile and misalignments [1] is extended to include time-dependent parameters such as energy chirp or rf focusing in order to reduce BBU-induced instabilities and emittance growth. Analytical results are presented and applied to practical accelerator configurations.

[1] J. R. Delayen, Phys. Rev. ST Accel. Beams 6, 084402 (2003)

 
 
TUP54 Resistive-Wall Wake Effect in the Beam Delivery System single-bunch, impedance, vacuum, linear-collider 393
 
  • J. Wu
    SLAC, Menlo Park, California
  • J. R. Delayen
    Jefferson Lab, Newport News, Virginia
  • T.O. Raubenheimer
    SLAC/NLC, Menlo Park, California
  • J.-M. Wang
    BNL/NSLS, Upton, Long Island, New York
  The resistive wall instability is investigated in the context of the final beam delivery system of linear colliders. The emittance growth is calculated analytically and compared against the results of full numerical simulations. Criteria for the design of final beam delivery systems are developed.  
 
TUP67 Beam-Based Alignment Measurements of the LANSCE Linac injection, quadrupole, lattice, linac 420
 
  • R.C. McCrady, L. Rybarcyk
    LANL, Los Alamos, New Mexico
  We have made measurements of the alignment of the LANSCE Drift Tube linac (DTL) and Side Coupled linac (SCL) using beam position measurements and analyzing them with linear models. In the DTL, we varied the injection steering, measured the beam position after each DTL tank, and analyzed the data with a linear model using R-matrices that were computed by the Trace-3D computer program. The analysis model allowed for tank-to-tank misalignments. The measurements were made similarly in the SCL, where the analysis model allowed for misalignments of each quadrupole doublet lens. We present here the analysis techniques, the resulting alignment measurements and comparisons to measurements made with optical instruments.  
 
TUP82 Low Energy Beam Transport using Space Charge Lenses space-charge, rfq, ion, emittance 465
 
  • O. Meusel, A. Bechtold, H. Klein, J. Pozimski, U. Ratzinger, A. Schempp
    IAP, Frankfurt-am-Main
  Gabor lenses provide strong cylinder symmetric electric focusing using a confined nonneutral plasma. The density distribution of the enclosed space charge is defined by the enclosure conditions in transverse and longitudinal direction. For a homogeneous charge density distribution the resulting electrostatic field and therefrom the focusing forces inside the space charge cloud are linear. Additionally in case of a positive ion beam the space charge of the confined electrons causes compensation of the ion beam space charge forces. To study the capabilities of a Gabor double lens system to match an ion beam into a RFQ a testinjector was installed at the IAP and put into operation successfully. First beam profiles and emittance measurements as well as measurements of the beam energy and energy spread have already been performed and show satisfactory results and no significant deviation from the theoretical predictions. To verify the beam focusing of bunched beams using this lens type at beam energies up to 500 keV a new high field Gabor lens was build and will be installed behind of the RFQ.  
 
TUP90 Improvements of RF Characteristics in the SDTL of the J-PARC Proton LINAC simulation, insertion, linac, proton 489
 
  • S. Wang
    IHEP Beijing, Beijing
  • T. Kato
    KEK, Ibaraki
  • V.V. Paramonov
    RAS/INR, Moscow
  A separated drift tube linac (SDTL)* was selected as an accelerator structure of Japan Proton Accelerator Complex (J-PARC), which follows DTL. The SDTL of J-PARC consists of 32 short tanks, ranging from 1.5 to 2.5 m in length. A design of frequency tuners of the SDTL was performed by taking account of 3-D field distribution calculated with MAFIA. The effects of stems on the resonant frequency and field distribution were also analyzed. An easy and effective compensation method for perturbation by stems of both end cells was proposed and applied to the SDTL tanks.

* T. Kato. Proposal of a Separated-type Proton Drift Tube Linac for a Medium-Energy Structure. KEK Report 92-10, (1992)

 
 
THP18 The Acceleration Test of the APF-IH-LINAC linac, acceleration, ion, proton 636
 
  • K. Yamamoto, M. Okamura
    RIKEN, Saitama
  • T. Hattori
    TIT, Tokyo
  • S. Yamada
    NIRS, Chiba-shi
  We manufactured an IH linac with Alternating Phase Focusing as a test machine for medical accelerator injection. It will accelerate C4+ ions from 40 keV/u up to 2 MeV/u. The tank length is around 1.5 m, operation frequency is 100 MHz. We have succeeded to accelerate protons with a simple acceleration system, consisting of a PIG ion source, bending magnets and focus lenses, less than 5m long. This IH linac was calculated using a simple thin lens approximation. Now we are making a beam-tracking program using the results of the electro-magnetic simulation soft (Micro-Wave-Studio, OPERA-3D); it has the merit of easily calculating the 3D-beam dynamics including non-linear effects. We will report the test, the beam simulations and comparisons of the test to the simulations.  
 
THP21 Calculation of Electron Beam Dynamics of the LUE-200 Accelerator electron, target, quadrupole, simulation 639
 
  • A.P. Sumbaev, V. Alexandrov, N.Y. Kazarinov, V.F. Shevtsov
    JINR, Dubna, Moscow Region
  The results of calculations of the focusing and transportation systems of the electron beam of LUE-200 accelerator – the driver of a pulse source of resonant neutrons IREN, JINR (Dubna), are presented. Simulations of the beam dynamics in the traveling wave accelerator were carried out by means of PARMELA code. The calculations have been fulfilled for various parameters of the focusing magnetic fields in the accelerator and the channel, various currents of the beam and various initial distributions of electrons.  
 
THP26 Comparison of 2 Cathode Geometries for High Current (2 kA) Diodes cathode, simulation, electron, emittance 654
 
  • N. Pichoff
    CEA/DAM, Bruyères-le-Châtel
  • F. Bombardier, M. Caron, E. Merle, C. Noël, O. Pierret, R. Rosol, C. Vermare
    CEA, Pontfaverger-Moronvilliers
  • D.C. Moir
    LANL, Los Alamos, New Mexico
  • A. Piquemal
    CEA/PTN, Bruyères-le-Châtel
  AIRIX (FRANCE) and DARHT axis-1 (USA) are two high current accelerators designed for flash X-ray radiography. The electron beam produced (2 kA, 3.5 to 3.8 MV, 60 ns) is extracted from a velvet cold cathode. Specific calculations have demonstrated the influence of the cathode geometry on the emitted beam profile [1]. To check this assumption we have made two different experiments (DARHT March 2003 – AIRIX March 2004). We have compared the beam characteristics with two different geometries both theoretically and experimentally. The beam simulations have been done with 3 codes: a home-made code (M2V) and 2 commercial codes (PBGUNS and MAGIC). The extracted beam current and transverse profiles, for the first experiment, have been measured and compared to simulations results. In the second one, we have compared the beam’s extracted current and the energy spread.

[1] E. Merle et al., "Efforts to Improve Intense Linear Induction Accelerator (LIA) Sources for Flash Radiography",Proceedings of the LINAC2002 conference. August 19-23, 2002 Gyeongju, Korea.

 
 
FR102 Muon Ionization Cooling Experiment (MICE) emittance, factory, simulation, collider 832
 
  • M.S. Zisman
    LBNL, Berkeley, California
  There is presently considerable activity worldwide on developing the technical capability for a “neutrino factory” based on a muon storage ring and, a muon collider. Muons are obtained from the decay of pions produced when an intense proton beam hits a high-Z target, so the initial muon beam has a large 6-dimensional phase space. To increase the muons’ phase-space density, we use ionization cooling, which is based on energy loss in an absorber, followed by re-acceleration with high-gradient, normal-conducting RF cavities. The absorber of choice is liquid hydrogen to minimize multiple scattering. A superimposed solenoidal focusing channel contains the muons. Although the physics is straightforward, the technology and its implementation are not. The international MICE collaboration will demonstrate ionization cooling of a muon beam in a short section of a typical cooling channel. The experiment is approved for operation at Rutherford Appleton Lab. We will measure the cooling effects of various absorber materials at various initial emittance values using single-particle counting techniques. The experiment layout and goals will be discussed, along with the status of component R&D.  
Transparencies