Keyword: dipole
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MOPA14 Electron Spectrometer for a Low Charge Intermediate Energy LWFA Electron Beam Measurement electron, laser, experiment, vacuum 57
 
  • A.V. Ottmar, Yu.I. Maltseva, T.V. Rybitskaya
    BINP SB RAS, Novosibirsk, Russia
  • V. Gubin
    Institute of Laser Physics, SB RAS, Novosibirsk, Russia
 
  The Laser-driven Compton light source is under development in ILP SB RAS in collaboration with BINP SB RAS. Electron spectrometer for measurement of LWFA electron beam with energy in the range 10-150 MeV and bunch charge 1-10 pC is presented. Spectrometer based on permanent magnet and luminous screen with CCD registrar and this geometry was optimized for best measurements resolution in compromise with size limitations. Preliminary collimation of electron beam allows achieving energy resolution up to 5-10 % of top limit. System has been tested at the VEPP-5 linear electron accelerator and obtained results correspond to design objectives. Sensitivity of beam transverse charge density was experimentally fixed at 0.03 pC/mm2, it is practically sufficient for our LWFA experiments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPA14  
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MOPA16 Design of a Compact Permanent Magnet Spectrometer for CILEX/APOLLON electron, permanent-magnet, laser, induction 61
 
  • M. Khojoyan, A. Cauchois, J. Prudent, A. Specka
    LLR, Palaiseau, France
 
  Laser wakefield acceleration experiments make extensive use of small permanent magnets or magnet assemblies for analyzing and focusing electron beams produced in plasma accelerators. This choice is motivated by the ease of operation inside vacuum chambers, absence of power-supplies and feedthroughs, and potentially lower cost. Indeed, in these experiments space is at premium, and compactness is frequently required. At the same time, these magnets have to have a large angular acceptance for the divergent laser and electron beams which imposes constraint of the gap size. We will present the optimized design and characterization of a 100 mm long, 2.1 Tesla permanent magnet dipole. Furthermore, we will present the implementation of this magnet in a spectrometer that will measure the energy spectrum of electrons of [60-2000] MeV with a few percent resolution in the CILEX/APOLLON 10PW laser facility in France.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPA16  
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MOPB03 High-Energy Scraper System for the S-DALINAC Extraction Beam Line - Commissioning Run* experiment, linac, extraction, quadrupole 75
 
  • L.E. Jürgensen, M. Arnold, T. Bahlo, C. Burandt, R. Grewe, J. Pforr, N. Pietralla, A. Rost, S. Weih, J. Wissmann
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
  • T. Kürzeder
    HIM, Mainz, Germany
 
  Funding: *Funded by Deutsche Forschungsgemeinschaft under grant No. GRK 2128
The S-DALINAC is a thrice recirculating, superconducting linear electron accelerator at TU Darmstadt. It delivers electron beams in cw-mode with energies up to 130 MeV. The high-energy scraper system has been installed in its extraction beam line to reduce the energy spread and improve the energy stability of the beam for the experiments operated downstream. It comprises three scraper slits within a dispersion-conserving chicane consisting of four dipole magnets and eight quadrupole magnets. The primary scraper, located in a dispersive section, allows to improve and stabilize the energy spread. In addition energy fluctuations can be detected. Scraping of x- and y-halo is implemented in two positions enclosing the position of the primary scraper. We will present technical details and results of the first commissioning run of the recently installed system at the S DALINAC. Besides improving on the energy spread, it proved to be a valuable device to observe energy spread and energy fluctuations as well as to reduce background count rates next to the experimental areas.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPB03  
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TUOB02 Optics Measurements in Storage Rings: Simultaneous 3-Dimensional Beam Excitation and Novel Harmonic Analysis optics, betatron, synchrotron, coupling 177
 
  • L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás
    CERN, Geneva, Switzerland
 
  Optics measurements in storage rings employ turn-by-turn data of transversely excited beams. Chromatic parameters need measurements to be repeated at different beam energies, which is time-consuming. We present an optics measurement method based on adiabatic simultaneous 3-dimensional beam excitation, where no repetition at different energies is needed. In the LHC, the method has been successfully demonstrated utilising AC-dipoles combined with RF frequency modulation. It allows measuring the linear optics parameters and chromatic properties at the same time without resolution deterioration. We also present a new accurate harmonic analysis algorithm that exploits the noise cleaning based on singular value decomposition to compress the input data. In the LHC, this sped up harmonic analysis by a factor up to 300. These methods are becoming a "push the button" operational tool to measure the optics.  
slides icon Slides TUOB02 [1.117 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUOB02  
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TUPA14 Beam Loss Monitoring in the ISIS Synchrotron Main Dipole Magnets detector, synchrotron, controls, radiation 236
 
  • D.M. Harryman, S.A. Fisher, W.A. Frank, B. Jones, A. Pertica, D.W. Posthuma de Boer, C.C. Wilcox
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  Beam loss monitoring at the ISIS Neutron and Muon Source is primarily carried out with the use of gas ionisation chambers filled with argon. These chambers are 3 to 4m long and are positioned around the inside of the synchrotron as well as along the ISIS Linac and Extracted Proton Beamlines (EPBs). To achieve finer spatial resolution a programme has been implemented to install six scintillator Beam Loss Monitors (BLMs), each 300 mm long, inside each of the ten main dipole magnets. Using these scintillator BLMs the accelerator can be fine-tuned during set-up to reduce areas of beam loss that were previously unseen or hard to characterise. As the installation programme comes to an end, this paper will review: the installation of the scintillator BLMs, the electronic hardware and software used to control them, and the initial measurements that have been taken using them.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPA14  
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TUPB05 Design of a Cavity Beam Position Monitor for the ARES Accelerator at DESY resonance, cavity, FEL, simulation 269
 
  • D. Lipka, M. Dohlus, M. Marx, S. Vilcins, M. Werner
    DESY, Hamburg, Germany
 
  The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host various experiments in the field of production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD linac, also called ARES (Accelerator Research Experiment at SINBAD), will be a conventional S-band linear RF accelerator allowing the production of low charge (within a range between 0.5 pC and 1000 pC) ultra-short electron bunches. To detect the low charge bunches a cavity beam position monitor is designed based on the experience from the EU-XFEL. It will consist of a stainless steel body with low Q factor of 70, a resonance frequency of 3.3 GHz and a relative wide gap of 15 mm to reach a high peak position sensitivity of 4.25 V/(nC mm). The design considerations and simulation results will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB05  
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TUPB07 Stability Study of Beam Position Measurement Based on Higher Order Mode Signals at FLASH HOM, cavity, electron, higher-order-mode 273
 
  • J.H. Wei
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • N. Baboi
    DESY, Hamburg, Germany
  • L. Shi
    PSI, Villigen PSI, Switzerland
 
  FLASH is a free-electron laser driven by a supercon-ducting linac at DESY in Hamburg. It generates high-brilliance XUV and soft X-ray pulses by SASE (Self Amplified Spontaneous Emission). Many accelerating cavities are equipped with HOMBPMs (Higher Order Mode based Beam Position Monitors) to align the beam and monitor the transverse beam position. However, these lose their position prediction ability over time. In this paper, we applied an efficient measurement and signal analysis with various data process methods including PLS (Partial Least Square) and SVD (Singular Value Decomposition) to determine the transverse beam position. By fitting the HOM signals with a genetic algorithm, we implemented a new HOMBPM calibration procedure and obtained reliable beam prediction positions over a long time. A stable RMS error of about 0.2 mm by using the spectra of signals and 0.15 mm by using the new method over two months has been observed.  
poster icon Poster TUPB07 [1.816 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB07  
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TUPB10 Design and Simulation of Stripline BPM for HUST Proton Therapy Facility coupling, proton, impedance, electron 281
 
  • J.Q. Li, Q.S. Chen, K. Fan, K. Tang, P. Tian
    HUST, Wuhan, People's Republic of China
 
  Proton beams used in Huazhong University of Science and Technology Proton Therapy Facility(HUST-PTF)have extreme low currents of the order of nanoampere,which is a great challenge to beam diagnostics due to low signal level. Conventional destructive beam diagnostic devices will affect the quality of the beam and cannot work online during the patient treatment, so a non-destructive stripline beam position monitor (BPM) is designed. This study will introduce some analysis and simulation results of the stripline BPM, such as the coupling between the electrodes, impedance matching, signal response, etc. We also discussed how to increase the output signal by geometry optimization.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-TUPB10  
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WEPA17 Development, Fabrication and Laboratory Tests of Bunch Shape Monitors for ESS Linac electron, space-charge, quadrupole, target 407
 
  • S.A. Gavrilov, D.A. Chermoshentsev, A. Feschenko
    RAS/INR, Moscow, Russia
 
  Two Bunch Shape Monitors have been developed and fabricated in INR RAS for European Spallation Source linac. To fulfil the requirements of a 4 ps phase resolution the symmetric λ-type RF-deflector based on the parallel wire line with capacitive plates has been selected. Additional steering magnet to correct incline of the focused electron beam is also used. Limitations due to space charge of the analysed beam and due to external magnetic fields are discussed. The results of the laboratory tests of the monitors are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPA17  
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