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Title |
Page |
| MOP21 |
The Pre-Injector Linac for the Diamond Light Source
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84 |
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- C. Christou, V. Kempson
DIAMOND, Chilton, Didcot, Oxon
- K. Dunkel, C. Piel
ACCEL, Bergisch Gladbach
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The Diamond Light Source is a new medium-energy high brightness synchrotron light facility which is under construction on the Rutherford Appleton Laboratory site in the U.K. The accelerator facility can be divided into three major components; a 3 GeV 561 m circumference storage ring, a full-energy booster synchrotron and a 100 MeV pre-injector linac. This paper describes the linac design and plans for operation. The linac is supplied by ACCEL Instruments GmbH under a turn-key contract, with Diamond Light Source Ltd. providing linac beam diagnostics, control system hardware and standard vacuum components. Commissioning of the linac will take place in early 2005 and user operation of the facility will commence in 2007.
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| MOP24 |
Using a Solid State Switch for a 60kV Bouncer to Control Energy Spread during the Beam Pulse*
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87 |
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- L. Donley, J.C. Dooling, G.E. McMichael, V. F. Stipp
ANL, Argonne, Illinois
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The beam injected into the IPNS Linac is from a column utilizing a Cockcroft-Walton voltage source. The accelerating column consists of a single high gradient gap. To lessen the likelihood of gap voltage breakdown, we pulse (“bounce”) the column voltage up during the beam pulse allowing the column DC voltage to be lower. The accelerating voltage is supplied through a 5 MΩ resistor and has only small capacitance to hold the voltage constant during the beam pulse. A capacitor is connected between the high voltage end of the column and the bouncer pulse generator. The bouncer pulse increases the column voltage to the proper level just microseconds before the beam pulse. A slope on the top of the bouncer pulse allows for correction to be added, compensating for the voltage droop that results from beam loading. The bouncer that has served this purpose in the past utilized a tube amplifier. In searching for a suitable replacement system it was decided that the system should be able to deliver a 60 kV pulse and the slope on the top of the pulse could be controlled by an RC rise. A solid state switch was purchased for this application. Switch protection and other design decisions will be discussed.
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| MOP25 |
The LEBRA 125 MeV Electron Linac for FEL And PXR Generation
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90 |
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- K. Hayakawa, Y. Hayakawa, K. Ishiwata, K. Kanno, K. Nakao, T. Sakai, I. Sato, T. Tanaka
LEBRA, Funabashi
- K. Yokoyama
KEK, Ibaraki
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A 125 MeV electron linac has been constructed at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University for Free Electron Laser (FEL) and Parametric X-ray (PXR) generation. Two klystrons feed rf power of approximately 20 MW peak and 20 μsec pulse duration each to an injector and three 4 m accelerating structures. Phase of the rf fed to each component is controlled independently. Two accelerating structures connected with the second klystron and a ninety degrees bending system as a momentum analyzer constitute a magnetic bunching system. Electron bunches of 3 to 4 psec width formed at the injector are compressed to within 1 psec during passing through the magnetic bunching system. Peak current of the electron beam injected to the FEL system installed downstream of the momentum analyzer is expected to be about 50 A. FEL lasing has been achieved at the wavelength range from 1 to 6 mm. Estimated peak power of the extracted FEL light pulse is about 2 MW. Applied researches using the FEL started last autumn. Preliminary experiment for the PXR generation has been continued.
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| MOP26 |
ERLP Gun Commissioning Beamline Design
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93 |
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- D.J. Holder, C.K.M. Gerth, F.E. Hannon
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- R.J. Smith
CLRC, Daresbury, Warrington, Cheshire
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The 4GLS project is a novel next-generation solution for a UK national light source. It is based on an energy recovery linac (ERL) operating at high average beam currents up to 100 mA and with compression schemes producing pulses in the 10 - 100 fs range. This challenging accelerator technology, new to Europe, necessitates a significant R&D programme and a major part of this is a low-energy prototype, the ERLP, which is currently under construction at Daresbury Laboratory, in the north-west of England. The first components of ERLP to be built will be the DC photocathode gun and low-energy beam transport and diagnostics. The gun will initially be operated with a diagnostic beamline in order to measure the properties of the high-brightness beams generated as fully as possible. This will allow comparison of its performance with the results of multi-particle tracking codes, prior to its integration into the ERLP machine. The diagnostic beamline will include diagnostics for measuring the transverse and longitudinal properties of the electron beam. This paper will describe the design of this diagnostic beamline and demonstrate through simulation, the expected characteristics and performance achievable from this system.
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| MOP27 |
Commissioning of a 6 MeV X-Band SW Accelerating Guide
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96 |
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- Q. Jin, Y. Lin, X. Sun, X. Tao, D. Tong
TSINGHUA, Beijing
- B. Chen, B. Sun, Y. Zou
BIEVT, Beijing 100016
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A 6 MeV, X-band on-axis SW electron linear accelerating guide is being developed in Accelerator laboratory of Tsinghua University. It can be suitable for portable radiation therapy and radiography. The design, manufacture and high power test of the guide are given in this paper. The guide is 38 cm long and contains 25 accelerating cells with 24 coupling cells, operated in the π/2 mode. The RF power source is a pulsed magnetron at 9300 MHz with 1.5 MW peak power. The results of beam tests are following: the electron energy is more than 6 MeV at 50 mA and focal spot size is less than φ 1.5 mm without any focusing solenoid.
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| MOP28 |
A Study of Higher-Band Dipole Wakefields in X-Band Accelerating Structures for the G/NLC
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99 |
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- R.M. Jones
SLAC/ARDA, Menlo Park, California
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The X-band linacs for the GLC/NLC (Global Linear Collider/Next Linear Collider) have evolved from the DDS (Damped Detuned Structure) series [1,2]. The present series of accelerating structures are each 60 cm in length and incorporate both damping and detuning of the dipole modes which comprise the wakefield. In order to adequately damp the wakefield the dipole frequencies of adjacent structures are interleaved. The properties of the first dipole band have been extensively studied. However, limited analysis has been done on the higher order dipole bands. Here, we calculate the contribution of the higher order bands of the interleaved structures to the wakefield using a mode matching computer code [3]. Beam dynamics issues are also studied by tracking the beam through the complete linac using the particle beam tracking code LIAR [4].
[1] R.M Jones et al,1996,Proc. EPAC96 (also SLAC-PUB-7187) [2] J.W. Wang et al, 2000, Proc. LINAC2000 (also SLAC-PUB-8583) [3] V.A. Dolgashev, Ph.D. thesis, Budker INP, Novosibirsk, 2002.[4] R. Assman et al, LIAR, SLAC-PUB AP-103
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| MOP29 |
RHIC Electron Cooler
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102 |
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- J. Kewisch, I. Ben-Zvi, R. Calaga, X.Y. Chang, A. Jain, V. Litvinenko, C. Montag, V. Yakimenko
BNL, Upton, Long Island, New York
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Electron cooling has been applied in many accelerators with low energies where cooling times are short. Electron cooling is now considered for RHIC, where gold ions are stored at 100 GeV/u. For a cooling time of one hour an electron beam with 55 MeV and 10 nC/bunch is necessary. The transverse normalized emittance must be 50 mm·mrad, the energy spread 10-4. Only a Photo-cathode Energy Recovery LINAC (PERL) promises such quality. For a minimum electron temperature inside the 1 Tesla cooling solenoid it is necessary to have a "magnetized beam", i.e. a beam from a cathode immersed in a longitudinal magnetic field. The emittance compensation scheme used in RF guns was adapted so that the magnetization does not lead to strong emittance growth. A super-conducting cavity was developed for the RHIC electron cooler, optimized for high current operation. Simulations with the TBBU computer code show a multi-bunch beam breakup threshold of 3 Amperes. After acceleration the bunches are lengthened and the energy spread is reduced by rotation in the longitudinal phase space. The original bunch length must be restored by a second rotation before deceleration and energy recovery.
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| MOP30 |
Linear Accelerator LINAC-800 of the DELSY Project
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105 |
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- V.V. Kobets, N. Balalykin, I.N. Meshkov, I.A. Seleznev, G. Shirkov
JINR, Dubna, Moscow Region
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In the report the modernization of electron linear accelerator MEA (Medium Energy Accelerator) is discussed. The goal of the work is to create on the base of MEA a complex of free electron lasers overlaying a range of radiation waves from infrared to ultraviolet. Status of the work is reported.
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| MOP31 |
Development of a C-band Accelerating Module for SUPERKEKB
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108 |
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- S. Ohsawa, M. Ikeda, K. Kakihara, T. Kamitani, T. Oogoe, T. Sugimura, S. Yamaguchi, K. Yokoyama
KEK, Ibaraki
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High power rf processing of 1 m C-band accelerating section for Super KEKB was successfully performed and power corresponding to 42 MV/m was achieved. Processing data were accumulated including acoustic sensor to find the arcing position. No structural damage was observed from the phase shift measurement performed after the processing. Processed accelerator was installed in the beam line of KEKB linac and being re-processed. The beam acceleration of 40 MV/m was successfully achieved in October 2003. Present status of C-band accelerator development is reported.
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| MOP34 |
Injector Linac Upgrade for the BEPCII Project
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111 |
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- S.H. Wang
IHEP Beijing, Beijing
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BEPCII- an upgrade project of Beijing Electron Positron Collider (BEPC) is a factory type of e+e- collider. It requests its injector linac to have the higher beam energy (1.89 GeV) for on-energy injection and the higher beam current (40 mA e+ beam) for higher injection rate (≥50 mA/min). The low beam emittance (1.6 π·mm·mrad for e+ beam, and 0.2 π·mm·mrad for 300 mA e- beam) and low beam energy spread (±0.5%) are also requested to meet the storage ring acceptance. Hence the original BEPC injector linac must be upgraded to have a new electron gun with its complete tuning system, a new positron source with a flux concentrator, a new RF power system with its phasing loops and a new beam tuning system with orbit correction and optics tuning devices. These new components have been designed, fabricated, tested and now being installed in their final positions, which are described in this paper. The beam commissioning is expected to start from the October of 2004.
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Transparencies
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| MOP35 |
The Research of a Novel SW Accelerating Structure with Small Beam Spot
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114 |
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- X. Yang, H. Chen, Y. Chen, X. Jin, M. Li, H. Lu, Z. Xu
CAEP/IAP, Mianyang, Sichuan
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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.
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| MOP46 |
Experimental Investigation of the Longitudinal Beam Dynamics in a Photo-Injector using a Two-Macroparticle Bunch
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147 |
| |
- R. Tikhoplav, A.C. Melissinos
Rochester University, Rochester, New York
- N. Barov, D. Mihalcea
Northern Illinois University, DeKalb, Illinois
- P. Piot
FNAL, Batavia, Illinois
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We have developed a two-macroparticle bunch to explore the longitudinal beam dynamics through various component of the Fermilab/NICADD photoinjector laboratory. Such a two-macroparticle bunch is generated by splitting the photocathode drive laser impinging the photocathode. The presented method allows the exploration of rf-induced compression in the 1+1/2 cell rf-gun and in the 9-cell TESLA cavity. It also allows a direct measurement of the magnetic chicane bunch compressor parameters such as its momentum compaction. The measurements are compared with analytical and numerical models. Finally we present possible extension of the technique to investigate the transverse beam dynamics.
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| MOP47 |
Limiting Effects in the Round-To-Flat Beam Transformation
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150 |
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- Y.-E. Sun, K.-J. Kim
Chicago University, Chicago, Illinois
- P. Piot
FNAL, Batavia, Illinois
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The transformation of an angular-momentum-dominated beam into a flat beam was analyzed in Ref. [K.-J. Kim, Phys. rev. ST A&B, vol 6, 104002 (2003)]. The analysis was performed assuming that the beam and the transport channel upstream of the flat beam transformer are cylindrically symmetric and that the particle dynamics is symplectic. We extend the analysis to include chromatic and space-charge effects as well as asymmetries in the four dimensional transverse phase space distribution.
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| WE104 |
State of the Art Electron Bunch Compression
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528 |
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- P. Piot
FNAL, Batavia, Illinois
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Many accelerator applications such as advanced accelerator R&D, free-electron laser drivers and linear colliders, require high peak current electron bunches. The bunch is generally shortened via magnetic compression. In the present paper we review various bunch compression schemes and discuss their limitations. We present experimental results, achieved at various facilities, along with on-going theoretical work on promising novel compression techniques.
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Transparencies
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| WE204 |
PAL Linac Upgrade for a 1-3 Å XFEL
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544 |
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- J-O. Oh, W. Namkung
POSTECH, Pohang
- Y. Kim
DESY, Hamburg
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With the successful SASE FEL saturation at 80 nm wavelength at TTF1, TTF2 will begin re-commissioning in the fall of 2004 as an FEL user facility to 6 nm with 1 GeV beams. The high gain harmonic generation is also confirmed by the DUV-FEL experiments at 266 nm with seeding wavelength at 800 nm. In order to realize a hard X-ray SASE FEL (SASE XFEL) with a lower energy beams, we need a long in-vacuum mini-gap undulator and a GeV-scale FEL driving linac that can supply an extremely low slice emittance, a high peak current, and an extremely low slice energy spread. PAL is operating a 2.5 GeV electron linac as a full-energy injector to the PLS storage ring. By adding an RF photo-cathode gun, two bunch compressors, and a 0.5 GeV S-band injector linac to the existing PLS linac, and by installing a 60 m long in-vacuum undulator, the PLS linac can be converted to a SASE XFEL facility (PAL XFEL) which supplies coherent X-ray down to 0.3 nm wavelength. The third harmonic enhancement technique can supply coherent hard X-ray beams to 0.1 nm. The technical parameters related to these goals are examined, and preliminary design details are reviewed for the PAL linac upgrade idea for a 1-3 Å PAL XFEL.
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Transparencies
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| WE205 |
KEKB Injector Linac and Upgrade for SuperKEKB
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549 |
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- S. Michizono
KEK, Ibaraki
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KEKB Injector linac has provided the 8 GeV electrons and 3.5 GeV positrons to the KEKB asymmetric collider rings designed for the B-physics study. The KEKB has recorded the highest luminosity records to which the linac contributes with an advanced operational stability. The dualbunch injection and continuous injection schemes have been adopted. The operational status of the KEKB injector linac is summarized here. The Super KEKB project aiming for the ten-times higher luminosity is under consideration as the upgrade of KEKB. In this upgrade, the injector linac has to increase the positron acceleration energy from 3.5 GeV to 8 GeV. In order to double the acceleration field (from 20 to 40 MV/m), the C-band rf system has been tested. The newly developed components, such as an acceleration structure and an rf window, are summarized. A C-band acceleration structure is installed in KEKB linac after the rf conditioning of more than 40 MW. The energy gain of more than 40 MV/m is confirmed by the beam analysis. The C-band acceleration unit has been operated continuously for the stability test. The recent operational status of the c-band acceleration unit will be also reported.
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Transparencies
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