Keyword: cavity
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MOCO02 Development of a Passive Cavity Beam Intensity Monitor for Pulsed Proton Beams for Medical Applications proton, linac, booster, simulation 40
 
  • P. Nenzi, A. Ampollini, G. Bazzano, F. Cardelli, L. Picardi, L. Piersanti, C. Ronsivalle, V. Surrenti, E. Trinca
    ENEA C.R. Frascati, Frascati (Roma), Italy
 
  Funding: This work has been funded by the Innovation Department of Regione Lazio Government, Italy.
In this work the design of a passive cavity beam intensity monitor to be used in the TOP-IMPLART medical proton linac for the on-line measurement of beam current is presented. It will be used to monitor the beam between modules and at the linac exit. TOP-IMPLART produces a pulsed proton beam with 3 us duration at 200 Hz repetition rate with a current between 0.1 uA and 50 uA. The current required for medical applications is less than 1 uA and has to be known with an accuracy better than 5%. Large dynamic range and space constraints make the use of usual non-interceptive beam diagnostics unfeasible. The proposed system consists of a resonant cavity working in the TM010 mode, generating an electromagnetic field when the beam enters the cavity; a magnetic pickup senses an RF pulse whose amplitude is proportional to the current. The RF pulse is amplified and subsequently detected with zero-biased Schottky diodes. The cavity operates in vacuum when used in the inter-module space. The work reports also the results of preliminary measurements done on an copper prototype in air at the exit of the TOP-IMPLART linac to test the sensitivity of the system on the actual 35 MeV proton beam.
 
slides icon Slides MOCO02 [3.269 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOCO02  
About • paper received ※ 03 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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MOPP010 Design and Properties of a New DCCT Chamber for the PF-Ring at KEK simulation, impedance, operation, HOM 90
 
  • R. Takai, T. Honda, T. Nogami, T. Obina, Y. Tanimoto
    KEK, Ibaraki, Japan
 
  A DC current transformer (DCCT) for the PF-ring was renewed during the 2018 summer shutdown. A vacuum chamber for the new DCCT was designed based on a circular duct with an inner diameter of 100 mm and has a structure housing a toroidal core inside of electromagnetic shields. The geometry of the ceramic break for interrupting the wall current flow was optimized using a three-dimensional electromagnetic field simulator, and the break was fabricated considering some technical limitations. Both ends of the ceramic break were short-circuited in a high-frequency manner by a sheet-like capacitive structure to suppress the radiation of unneeded higher-order modes (HOMs) into the core housing. The ceramic break is also equipped with water-cooling pipes on metal sleeves brazed to the both ends to efficiently remove the heat generated by HOMs. The new DCCT chamber has been used already in user operation without any problems. A temperature rise near the ceramic break is still approximately six degrees Celsius, even when a 50-mA isolated bunch is stored.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP010  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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MOPP025 Enhancements to the SNS* Differential Current Monitor to Minimize Errant Beam ion-source, linac, controls, real-time 145
 
  • W. Blokland
    ORNL, Oak Ridge, Tennessee, USA
  • C.C. Peters, T.B. Southern
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
The existing Differential Beam Current Monitor (DBCM) has been modified to not only compare beam current waveforms between upstream and downstream locations, but also to compare the previous beam current waveform with the incoming beam current waveform. When there is an unintended change in the beam current, the DBCM now aborts the beam to prevent beam loss on the next pulse. This addition has proved to be crucial to allow beam during specific front-end problems. All data is saved when an abort is issued for post-mortem analy-sis. This paper describes the additions to the implementa-tion, our operational experience, and future plans for the differential beam current monitor.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP025  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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MOPP026 A Longitudinal Kicker Cavity for the BESSY II Booster kicker, booster, feedback, injection 149
 
  • T. Atkinson, M. Dirsat, A.N. Matveenko, A. Schälicke, B. Schriefer, Y. Tamashevich
    HZB, Berlin, Germany
  • T. Flisgen
    FBH, Berlin, Germany
 
  As part of the global refurbishment of the injector systems at BESSY II, a new longitudinal kicker cavity and suitable feedback will be installed in the booster. Both a flexible bunch charge and spacing is essential for efficient injection. Such a cavity is needed to mitigate the unwanted couple bunch instabilities associated with these elaborate filling patterns and the HOMs of additional accelerating structures. This paper covers the conceptual design, simulation strategy, manufacture and bench tests of the longitudinal kicker cavity before it is installed in the ring.  
poster icon Poster MOPP026 [4.756 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP026  
About • paper received ※ 02 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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MOPP035 Electron Beam Diagnostics Concept for the LWFA Driven FEL at ELI-Beamlines electron, diagnostics, FEL, plasma 185
 
  • K.O. Kruchinin, D. Kocon, A.Y. Molodozhentsev
    ELI-BEAMS, Prague, Czech Republic
  • A. Lyapin
    JAI, Egham, Surrey, United Kingdom
 
  Uniquely short high energy electron bunches produced by compact Laser Wakefield Accelerators (LWFA) are attractive for the development of new generation Free Electron Lasers (FEL). Although the beam quality of LWFA is still significantly lower than provided by conventional accelerators, with persistent progress seen in the area of laser plasma acceleration, they have a great potential to be considered the new generation drivers for FELs and even colliders. A new LWFA based FEL project called "LUIS" is currently being commissioned at ELI-beamlines in Czech Republic. LUIS aims to demonstrate a stable generation of X-ray photons with a wavelengths of 6 nm and lower, suitable for user applications. Electron beam diagnostics are absolutely crucial for achieving LUIS’s aims. Low charge, poor beam stability and other beam properties inherent for a LWFA require rethinking and adaptation of the conventional diagnostic tools and, in some cases, development of new ones. In this paper we provide an overview of the electron beam instrumentation in LUIS with a focus on the current challenges and some discussion of the foreseen future developments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP035  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUCO04 Longitudinal Phase Space Reconstruction for the Heavy Ion Accelerator HELIAC heavy-ion, linac, emittance, proton 261
 
  • S. Lauber, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, J. List, M. Miski-Oglu
    HIM, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, P. Forck, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Rubin, T. Sieber, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    KPH, Mainz, Germany
  • F.D. Dziuba, S. Lauber, J. List
    IKP, Mainz, Germany
  • H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  At the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany, a prototype cryomodule (Advanced Demonstrator) for the superconducting (SC) continuous wave (CW) Helmholtz Linear Accelerator (HELIAC) is under construction. A transport line, comprising quadrupole lenses, rebuncher cavities, beam correctors and sufficient beam instrumentation has been built to deliver the beam from the GSI 1.4 MeV/u High Charge Injector (HLI) to the Advanced Demonstrator, which offers a test environment for SC CW multigap cavities. In order to achieve proper phase space matching, the beam from the HLI must be characterized in detail. In a dedicated machine experiment the bunch shape has been measured with a non destructive bunch shape monitor (BSM). The BSM offers a sufficient spatial resolution to use it for reconstruction of the energy spread. Therefore, different bunch projections were obtained by altering the voltage of two rebunchers. These measurements were combined with dedicated beam dynamics simulations using the particle tracking code Dynamion. The longitudinal bunch shape and density distribution at the beginning of the matching line could be fully characterized.  
slides icon Slides TUCO04 [1.810 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUCO04  
About • paper received ※ 30 August 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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TUPP003 A Common Diagnostic Platform for Elettra 2.0 and FERMI controls, FPGA, diagnostics, Ethernet 275
 
  • G. Brajnik, S. Cleva, R. De Monte, D. Giuressi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  Elettra 2.0 is the project of upgrading the current synchrotron light source to a low emittance machine. In this framework, various components of diagnostics have to be refurbished due to the obsolescence of the same or due to the tight requirements of the new accelerator. In this paper we present a high performance FPGA-based (Altera/Intel Arria 10) digital board developed internally, capable of hosting two FMC modules, equipped with DDR3 ram and 10 Gb/s Ethernet links. The presence of the FMC connectors allows a flexible use of the board: various configurations of A/D and D/A converters (different number of channels, resolution, sampling rate) can be obtained, also with various I/O ports for trigger and synchronisation. These features make it applicable as a base platform for various applications not only for Elettra (electron and photon BPMs, DLLRF systems, etc.) but also for Fermi (cavity BPMs, bunch arrival monitor, link stabiliser). The peripherals on board have been fully debugged, and probably a new version with a SoC (System on Chip) will be released in the next future.  
poster icon Poster TUPP003 [1.586 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP003  
About • paper received ※ 02 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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TUPP004 High-Speed Beam Signal Processor for SHINE timing, FPGA, SRF, interface 278
 
  • L.W. Lai, Y.B. Leng
    SSRF, Shanghai, People’s Republic of China
 
  A CW hard X-ray FEL is under construction in SSRF, which pulse rate is designed to 1MHz. A new high-speed sampling BPM signal processor is under development to meet the high performance requirements of beam position measurement system. The processor’s sampling rate can be up to 500MHz, and beam position information of each bunch (1MHz rate) can be retrieved with the power of FPGA. Time stamp is aligned with the position data for offline analysis. The processor is designed to be a common signal processing platform for beam diagnostics. The first application is cavity BPM, and other applications, including button BPM, stripline BPM, and even wire scanner processor will be developed based on this platform. At the same time, a RF direct sampling processor is designed for cavity BPM signal processing. This novel technology will greatly simplify the cavity BPM electronic system, and make the system design more efficient and more flexible.  
poster icon Poster TUPP004 [0.983 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP004  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUPP041 Observations of Long-Range and Short-Range Wakefield Effects on Electron-Beam Dynamics in TESLA-type Superconducting RF Cavities HOM, wakefield, detector, FEL 423
 
  • A.H. Lumpkin, N. Eddy, D.R. Edstrom, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Fermilab Accelerator Science and Technology (FAST) facility has a unique configuration of a photocathode rf gun beam injecting two TESLA-type single cavities (CC1 and CC2) in series prior to the cryomodule. Beam propagation off axis in these cavities can result in both long-range and short-range transverse wakefields which can lead to emittance dilution within the macropulses and micropulses, respectively. Two configurations of a Hamamatsu C5680 streak camera viewing a downstream OTR screen were utilized to track centroid shifts during the macropulse (framing mode) for the long-range case and during the micropulse for the short-range case (~10-micron spatial resolution and 2-ps temporal resolution). Steering off axis before CC1, resulted in a 100-kHz bunch centroid oscillation within the macropulse that was detected by the downstream rf BPMs and the streak camera*. At 500 pC/b, 50b, and 4-mrad off-axis vertical steering into CC2, we observed an ~ 100-micron head-tail centroid shift in the streak camera image y(t) profiles which we attributed to a short-range wakefield effect. Additional results for kick-angle compensations and model results will be presented.
*A.H. Lumpkin et al., Phys. Rev. Accel. and Beams 21,064401 (2018).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP041  
About • paper received ※ 10 September 2019       paper accepted ※ 11 September 2019       issue date ※ 10 November 2019  
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WEAO02 Pile-Up Effect of Cold Button BPMs in the European XFEL Accelerator resonance, FEL, electron, electronics 450
 
  • D. Lipka, B. Lorbeer
    DESY, Hamburg, Germany
 
  The European XFEL facility is in operation with a maximum of 2700 bunches in one train. The highest bunch repetition rate is 4.5 MHz; this corresponds to a minimum time separation of 222 ns. The measurement of the beam properties for each bunch in a train is required. Therefore the beam position monitor (BPM) system needs to separate the signals from each bunch. All BPM types (button, re-entrant and cavity) fulfill this requirement except a few button BPMs installed inside of the cold accelerator module, where Pile-Up from the train can be observed. To identify the cause of this effect we measured the S-parameters during a shutdown of the accelerator, compared it with a similar BPM at the FLASH accelerator but located in a warm section and finally measured the spectrum of the button signal during beam operation. As a result, resonances were found at about 2.46 GHz with relatively high quality factor that remains within the frequency range accepted by the electronics.  
slides icon Slides WEAO02 [5.621 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEAO02  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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WEPP004 Concept of a Beam Diagnostics System for the Multi-Turn ERL Operation at the S-DALINAC linac, operation, recirculation, impedance 505
 
  • M. Dutine, M. Arnold, T. Bahlo, R. Grewe, L.E. Jürgensen, N. Pietralla, F. Schließmann, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by BMBF through grant No. 05H18RDRB2 and DFG through GRK 2128.
The S-DALINAC* is a thrice-recirculating linear electron accelerator operating in cw-mode at a frequency of 3 GHz. A path-length adjustment system in the second recirculation beam line allows to shift the beam phase by 360° and thus to operate in ERL mode. For the multi-turn ERL operation, the beam will be accelerated twice and subsequently decelerated twice again (not demonstrated yet). For this mode, it is necessary to develop a nondestructive beam diagnostics system in order to measure the beam position, phase and beam current of both, the accelerated and the decelerated beam, simultaneously in the same beamline. A particular challenge will be the operation at low beam currents of 100 nA, which corresponds to bunch charges of about 30 aC. The conceptional study of a 6 GHz resonant cavity beam position monitor will be presented together with alternative solutions.
* N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP004  
About • paper received ※ 03 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP010 Design and Simulation of a Cavity BPM for HUST Proton Therapy Facility proton, coupling, simulation, diagnostics 523
 
  • J.Q. Li, Q.S. Chen, K. Tang, P. Tian
    HUST, Wuhan, People’s Republic of China
  • K. Fan
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
 
  In proton therapy facility, non-destructive beam diagnostic devices are essential for on-line measurement during the patient treatment. To meet the clinical requirement, the beam current becomes ultra-low of the order of nano-ampere, which is a great challenge to non-destructive beam diagnostics because of the extremely low signal level. Compared with conventional non-destructive beam diagnostic devices, the cavity beam position monitor (BPM) has a high shunt impedance to get enough power levels, so a cavity BPM system is designed for HUST-PTF. It is made up of two resonant cavities called reference cavity and position cavity, respectively. Both cavities are simulated and optimized by CST Microwave Studio and Particle Studio. Finally, the electronics of cavity BPM we plan to use is shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP010  
About • paper received ※ 03 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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WEPP022 A Method of Correcting the Beam Transverse Offset for the Cavity Bunch Length Monitor simulation, dipole, impedance, laser 565
 
  • Q. Wang, Q. Luo, B.G. Sun
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Supported by National Key R&D Program of China (Grant No. 2016YFA0401900 and No. 2016YFA0401903) and The National Natural Science Foundation of China (Grant No. U1832169 and No. 11575181)
Cavity bunch length monitor uses monopole modes excited by bunches within the cavities to measure the bunch longitudinal root mean square (rms) length. It can provide a very high accuracy and high resolution. However, when the bunch passes through the cavities with transverse offset (that is, the bunch moves off the cavity axis), the amplitude of the monopole modes will change and cannot reflect the bunch length precisely. In this paper, a method of correcting the beam transverse offset is proposed. Simulation results show that the method can reduce the error of the bunch length measurement significantly.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP022  
About • paper received ※ 03 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP033 Position Based Phase Scan MEBT, focusing, alignment, quadrupole 599
 
  • N. Milas, M. Eshraqi, Y. Levinsen, R. Miyamoto, D.C. Plostinar
    ESS, Lund, Sweden
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
 
  Knowledge of the longitudinal beam parameters is important for understanding beam dynamics in linacs. As well as with transverse optics, the settings for the RF cavities have to be established and phase and amplitude seen by the beam must be determined in order to guarantee a stable motion in the longitudinal plane. This work presents an extension of the most widely used phase scan method, relying on time-of-flight, using only transverse positions measured at a few selected BPMs downstream of the cavity being scanned. In principle, the method can be applied both to normal conducting and SC. The suggested method is fast and relatively simple and is capable to provide the values for the cavity transverse misalignment (offsets and tilts) at the same time. It can be a useful part of the initial longitudinal beam tuning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP033  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP043 Time-of-flight Technique for Matching Energies in Electron Cooler electron, hadron, booster, gun 641
 
  • I. Pinayev, R.L. Hulsart, K. Mernick, R.J. Michnoff, Z. Sorrell
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron cooler with bunched electron beam is being commissioned at the Relativistic Heavy Ion Collider at BNL. For the cooler to operate the energies of the hadron and electron beams should be matched with high accuracy. We have developed time-of-flight technique based on the phase measurement of the beam induced signal in the beam position monitors separated by a drift. We present the method description and experimental results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP043  
About • paper received ※ 03 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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