Keyword: quadrupole
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MOPG43 Beam Tuning for Longitudinal Profile at J-PARC Linac emittance, linac, resonance, DTL 150
  • A. Miura
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Liu, T. Maruta
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Miyao
    KEK, Ibaraki, Japan
  Using bunch shape monitors (BSMs), we measured the longitudinal bunch lengths of negative hydrogen ion beams in the J-PARC linac. A BSM was installed between two linacs, separate-type drift tube linac (SDTL) and an annular-ring-coupled structure linac (ACS), having acceleration frequencies of 324 and 972 MHz, respectively. We used radio-frequency amplitude modulation of bunches in the beam transport between the SDTL and ACS to minimize emittance growth and beam loss. We conducted amplitude scanning and compared the results with the twiss-parameters obtained from the transverse profiles. In this paper, we discuss the results of amplitude tuning of the buncher cavity at the point of beam loss and emittance. We also discuss the measurement results for various equipartitioning settings of quadrupole magnets.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG43  
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TUPG06 Development Status of a Stable BPM System for the SPring-8 Upgrade electronics, radiation, photon, alignment 322
  • H. Maesaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • H. Dewa, T. Fujita, M. Masaki, S. Takano
    JASRI, Hyogo, Japan
  A stable and precise BPM system is necessary for the low-emittance upgrade of SPring-8. Key requirements for the BPM system are: 1) long-term stability to maintain the photon beam direction of the beamline well within the intrinsic photon divergence, 2) single-pass resolution better than 100 μm rms for a 100 pC injected bunch for first turn steering in the beam commissioning, and 3) accuracy better than 100 μm rms with respect to aligned quadrupole and sextupole magnet centers to achieve the design performance of the upgraded ring. To realize the demanded stability, the BPM drift should be reduced to 1 μm level. Therefore, we have been pursuing designs to suppress the thermal deformation of a BPM head and its support and to minimize the drifts of BPM electronics and coaxial cables. The investigation results on causes of drifts of the present SPring-8 BPM system are reflected to the design of the new BPM system. A button-type BPM head has been developed*, which can generate sufficient signal to satisfy the required single-pass resolution. We have also been studying the strategies of the alignment, position survey and electric center calibration of the BPM head better than 100 μm.
* M. Masaki et al., in this conference.
poster icon Poster TUPG06 [5.250 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG06  
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TUPG09 Novel Electrostatic Beam Position Monitors With Enhanced Sensitivity simulation, instrumentation, linac, monitoring 333
  • M. Ben Abdillah
    IPN, Orsay, France
  Beam Position Monitors (BPM) measure the beam transverse position, the beam phase with respect to the radiofrequency voltage, and give an indication on beam transverse shape. Electrostatic BPMs are composed of four electrodes that transduce the associated electromagnetic field to the beam into electrical signal allowing the calculation of the beam parameters mentioned above. During commissioning and/or experiences phases that needs very low beam current; the precision of the BPM measurements is reduced due to the low sensitivity of electrostatic BPM to beam current. This paper addresses the design, the realization and the testing of a new set of electrostatic BPMs with large electrodes. It emphasizes the strong points of these BPMs in comparison with BPMs present in SPIRAL2 facility  
poster icon Poster TUPG09 [0.770 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG09  
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WEBL01 Beam Diagnostics Challenges for Beam Dynamics Studies optics, emittance, linac, diagnostics 577
  • O.R. Jones
    CERN, Geneva, Switzerland
  This presentation will review the performance and limitations of present beam instrumentation in relation to beam dynamics studies, and give an overview of the main requirements from the accelerator physics community for new or improved measurements that need R&D effort from the beam diagnostics side.  
slides icon Slides WEBL01 [47.201 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEBL01  
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WECL03 Measurement of the Beam Response to Quadrupole Kick by Using Stripline Pickup Monitor at J-PARC Main Ring kicker, resonance, betatron, operation 604
  • Y. Nakanishi, A. Ichikawa, A. Ichikawa, A. Minamino, K.G. Nakamura, T. Nakaya
    Kyoto University, Kyoto, Japan
  • T. Koseki, H. Kuboki, M. Okada, T. Toyama
    KEK, Tokai, Ibaraki, Japan
  Funding: Work supported by MEXT KAKENHI, GA 25105002, Grant-in-Aid for Scientific Research on Innovative Areas titled "Unification and Development of the Neutrino Science Frontier"
In high intensity proton synchrotrons, linear and nonlinear betatron resonances cause beam loss. When the betatron tune spreads over a resonance line, the oscillation amplitude will get larger, causing a large beam loss. Our study aims for a direct measurement of the betatron tune spread by using a quadrupole kicker and a 4-electrode monitor. The monochromatic rf signal is inputted to the kicker and we induce an oscillation by kicking the beam. The amplitude of the quadrupole oscillation will depend on the number of particles having a certain tune. In the beam test at J-PARC MR, the dipole kicker was used as a quadrupole kicker by exciting the two facing electrodes in-phase. We measured the response to the kick at several frequencies. We observed that the amplitude depends on the kicker frequency and the number of particles per bunch. This demonstrates that the quadrupole oscillation can be induced by a kicker and the possibility of measuring the number of a particular tune particle from the response. We will present the result of the beam test and our prospect and the comparison between the experimental result and a numerical calculation.
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WECL03  
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WEPG05 Design of Stripline Beam Position Monitors for the ESS MEBT impedance, electronics, simulation, coupling 620
  • S. Varnasseri, I. Bustinduy, A. Ortega, I. Rueda, A. Zugazaga
    ESS Bilbao, Zamudio, Spain
  • R.A. Baron, H. Hassanzadegan, A. Jansson, T.J. Shea
    ESS, Lund, Sweden
  There will be overall 8 Beam Position Monitors (BPM) installed in MEBT of ESS. Seven of them will be used for the measurement of beam position, phase and intensity. One BPM will be used for the fast timing characterization of the chopped beam. The design is based on shortened stripline to accommodate the signal level for low velocity proton beam within MEBT read by electronics. Due to mechanical space limits, all the BPMs are embedded inside quadrupoles; which requires special care on the magnetic properties of the materials within BPM sets and in particular the feedthroughs. The prototype electromagnetic and mechanical design is finished and its fabrication is underway. This paper gives an overview of the electromagnetic and mechanical design and related analysis including position signal sensitivity of the BPMs.  
poster icon Poster WEPG05 [1.107 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG05  
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WEPG35 Design of an Electron Cloud Detector in a Quadrupole Magnet at CesrTA detector, electron, simulation, vacuum 704
  • J.P. Sikora, S.T. Barrett, M.G. Billing, J.A. Crittenden, K.A. Jones, Y. Li, T.I. O'Connell
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
We have designed a detector that measures the electron cloud density in a quadrupole magnet using two independent techniques. Stripline electrodes collect electrons that would otherwise impact the beam-pipe surface. The striplines are placed behind an array of small holes in the beam-pipe wall in order to shield them from the beam-induced electromagnetic pulse. There are three striplines placed near one of the pole tips so that they cover a roughly 0.43 radian azimuth. The beam-pipe chamber has also been designed so that microwave measurements of the electron cloud density can be performed. Beam position monitor buttons have been included for excitation and reception of microwaves and the chamber has been designed so that the resonant microwaves are confined to be within the 56 cm length of the quadrupole field. This paper provides some details of the design including CST Microwave Studio time domain simulation of the stripline detectors and eigenmode simulation of the resonant chamber. The detector is installed in the Cornell Electron Storage Ring and is part of the test accelerator program for the study of electron cloud using electron and positron beams from 2 to 5 GeV.
poster icon Poster WEPG35 [2.166 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG35  
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WEPG51 A Transverse Deflecting Structure for the Plasma Wakefield Accelerator Experiment, FLASHForward plasma, emittance, optics, cavity 759
  • R.T.P. D'Arcy, V. Libov, J. Osterhoff
    DESY, Hamburg, Germany
  The FLASHForward project at DESY is an innovative plasma-wakefield acceleration experiment, aiming to accelerate electron beams to GeV energies over a few centimeters of ionized gas. These accelerated beams must be of sufficient quality to be used in a free-electron laser; achievable only through rigorous analysis of both the drive- and accelerated-beam's longitudinal phase space. The pulse duration of these accelerated beams is typically in the few femtosecond range, and thus difficult to resolve with traditional diagnostic methods. In order to longitudinally resolve these very short bunch-lengths, it is necessary to utilize the properties of a transverse RF deflector (operating in the hybrid electromagnetic mode, HEM11), which provides a relation between longitudinal and transverse co-ordinates. It is proposed that this type of device, commonly known as a Transverse Deflecting Structure (TDS) due to its 'streaking' in the transverse plane, will be introduced to the FLASHForward beamline in order to perform these single-shot longitudinal phase space measurements. The initial investigations into the realization of this diagnostic tool are outlined.  
poster icon Poster WEPG51 [10.726 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG51  
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WEPG55 Synchronization of ps Electron Bunches and fs Laser Pulses Using a Plasmonics-Enhanced Large-Area Photoconductive Detector electron, laser, detector, vacuum 774
  • E.J. Curry, M. Jarrahi, P. Musumeci, N.T. Yardimci
    UCLA, Los Angeles, California, USA
  • B.T. Jacobson
    RadiaBeam, Santa Monica, California, USA
  Temporal synchronization between short relativistic electron bunches and laser pulses at the ps and sub-ps level is required for accelerator applications like inverse Compton light sources. Photoconductive antennas with THz and sub-THz bandwidth which are gated by fs lasers provide this level of timing resolution. This paper describes the operating principals of the diagnostic along with bench-top experimental results with recently developed plasmonics-enhanced large-area devices. A vacuum chamber with robust electronic noise reduction has been designed for upcoming beam-based experiments.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG55  
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WEPG79 Time-Resolved Measurement of Quadrupole Wakefields in Corrugated Structures wakefield, emittance, electron, focusing 840
  • C. Lu, T. Jiang, L.B. Shi, L. Zhao
    LLP, Shanghai, People's Republic of China
  • F. Fu, S. Liu, D. Xiang, P.F. Zhu
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
  • R. Wang
    SINAP, Shanghai, People's Republic of China
  • Z. Zhang
    TUB, Beijing, People's Republic of China
  Corrugated structures have recently been widely used for manipulating electron beam longitudinal phase space and for producing THz radiation. Here we report on time-resolved measurements of the quadrupole wakefields in planar corrugated structures. It is shown that while the time-dependent quadrupole wakefield produced by a planar corrugated structure causes significant growth in beam transverse emittance, it can be effectively canceled with a second corrugated structure with orthogonal orientation. The strengths of the time-dependent quadrupole wakefields for various corrugated structure gaps are also measured and found to be in good agreement with theories. Our work should forward the applications of corrugated structures in many accelerator based scientific facilities.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG79  
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