Keyword: coupling
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MOPGW003 Collective Instability Studies for Sirius simulation, impedance, storage-ring, radiation 61
 
  • F.H. de Sá
    LNLS, Campinas, Brazil
 
  In this work we will present the estimates of single and multi-bunch instability thresholds and current-dependent effects, such as tune-shifts and potential-well distortion for the Sirius storage ring. The results were obtained by tracking simulations and semi-analytic methods using the updated and detailed impedance budget of the machine, which includes contributions from all the in-vacuum components and the coherent synchrotron radiation (CSR) impedance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW003  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPGW019 Beam-Beam Blowup Issue After Low Emittance Tuning for FCC-ee emittance, lattice, simulation, optics 112
 
  • D. El Khechen, K. Oide, F. Zimmermann
    CERN, Geneva, Switzerland
  • K. Oide
    KEK, Ibaraki, Japan
 
  FCC-ee (Future Circular Collider) is a 100 km electron-positron circular collider with two foreseen experiments, aiming to run at four energies for precision studies of the Z, W, and Higgs boson and the top quark. The FCC-ee is a challenging machine from different points of view. In particular the beam-beam effects are of great importance. For the FCC-ee high-luminosity operation, the beam-beam effects impose profound constraints on the operating point in betatron tune space. In addition, taking into account different sources of machine nonlinearities, a tracking simulation with beam-beam elements revealed a strong beam blowup, especially in the vertical plane. Such a blowup is a potential obstacle to achieving and maintaining a high luminosity; therefore it needs to be carefully studied. In this paper, we present a general overview of simulation results on the FCC-ee beam-beam blowup with realistic machine errors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW019  
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW030 New Analytical Derivation of Group Velocity in TW Accelerating Structures cavity, dipole, simulation, polarization 155
 
  • M. Behtouei, M. Migliorati, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • L. Faillace
    Universita’ degli Studi di Milano & INFN, Milano, Italy
  • B. Spataro
    INFN/LNF, Frascati, Italy
 
  Ultra high-gradient accelerating structures are needed for the next generation of compact light sources. In the framework of the Compact Light XLS project, we are studying a high harmonic traveling-wave accelerating structure operating at a frequency of 35.982 GHz, in order to linearize the longitudinal space phase. In this paper, we propose a new analytical approach for the estimation of the group velocity in the structure and we compare it with numerical electromagnetic simulations that are carried out by using the code HFSS in the frequency domain.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW030  
About • paper received ※ 08 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW031 Analysis and Correction for the Effect of Multipoles with Skewed Errors on IP Beam Dynamics in SuperKEKB luminosity, MMI, betatron, optics 159
 
  • K. Hirosawa
    Sokendai, Ibaraki, Japan
  • Y. Funakoshi, H. Koiso, A. Morita, K. Ohmi, Y. Ohnishi, H. Sugimoto, D. Zhou
    KEK, Ibaraki, Japan
 
  The beam dynamics at the interaction point (IP) in the accelerators which has the nano-beam scheme like as SuperKEKB is extremely sensitive for skewed error of final focusing magnets (QCS). As proceeding the beta squeezing in the interaction region (IR), the effect of optics aberrations at IP is enhanced. In the SuperKEKB Phase-2 commissioning, there was the problem come from skewed quadrupole fields in IR. The dominant skew parameters ‘‘R" for this problem is very hard to see directly by using beam position monitors, thus it was corrected by scanning R parameters. In the next commissioning Phase-3 which is just before the operation with the Belle II experiment, it is planned that the IP beta squeezing is going forward to design parameters which is smaller than it achieved in Phase-2 by the factor of 4 (for horizontal beta) and 10 (for vertical beta). Hence the effect of skew error will be considerable larger and it is estimated that skew sextupoles will emerge as a serious cause for the aberration from the orbit. This report is the study of analysis and correction results for the effect of QCS skewed errors in the SuperKEKB commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW031  
About • paper received ※ 19 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW074 New Spiral Beam Screen Design for the FCC-hh Injection Kicker Magnet kicker, impedance, injection, vacuum 270
 
  • A. Chmielinska, M.J. Barnes
    CERN, Geneva, Switzerland
 
  The injection kicker system for the Future Circular Collider (FCC-hh) must satisfy demanding requirements. To achieve low pulse ripple and fast field rise and fall times, the injection system will use ferrite loaded transmission line type magnets. The beam coupling impedance of the kicker magnets is crucial, as this can be a dominant contribution to beam instabilities. In addition, interaction of the high intensity beam with the real part of the longitudinal beam coupling impedance can result in high power deposition in the ferrite yoke. This gives a significant risk that the ferrite yoke will exceed its Curie temperature: hence, a suitable beam screen will be a critical feature. In this paper, we present a novel concept - a spiral beam screen. The fundamental advantage of the new design is a significant reduction of the maximum voltage induced on the screen conductors, thus decreased probability of electrical breakdown. In addition, the longitudinal beam coupling impedance is optimized to minimize power deposition in the magnet.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW074  
About • paper received ※ 26 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW076 Verification by RF Measurements of New HOM Mitigation Scheme Developed for Future SPS 33-Cell Accelerating Structures HOM, damping, simulation, impedance 274
 
  • P. Kramer, A. Farricker, C. Vollinger
    CERN, Geneva, Switzerland
 
  Longitudinal higher-order modes (HOMs) at a frequency of around 630 MHz in the 200 MHz travelling wave RF structures currently limit the beam intensities in the CERN SPS to less than that required by the High Luminosity (HL-) LHC. In the framework of the LHC Injectors Upgrade (LIU) project, the performance of the already existing HOM damping scheme for these standing wave modes must be improved. This involves improving the existing HOM-couplers as well as the possible use of a new mitigation technique via the insertion of resonant posts in some cells of the multi-cell structures. The development of the new damping scheme has been performed using theoretical analysis of the cavity-coupler interaction in conjunction with full-wave electromagnetic (EM) field simulations. This contribution will show the verification of the improved HOM damping performance by measurements on a single section with 11 cells and on the future 33-cell structures. The parasitic impact of the damping scheme on the travelling wave fundamental passband (FPB) will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW076  
About • paper received ※ 11 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW077 Impedance Reduction in the CERN SPS Through Element Layout Optimisation impedance, extraction, cavity, quadrupole 277
 
  • A. Farricker, C. Vollinger
    CERN, Geneva, Switzerland
 
  The CERN accelerator complex is currently in its long shutdown while the LHC Injector Upgrade is being carried out. The upgrade of the SPS includes but is not limited to: the relocation of the beam dumping system, upgrade of the RF system, replacement of the electrostatic septa and impedance reduction. These major upgrades present an opportunity to perform additional impedance reduction in areas not normally modified due to the large amount of work being performed across the accelerator complex. In this paper, we look at the impedance minimization in the sections near the large aperture quadrupoles of the extraction regions in the CERN SPS. By optimizing the locations of existing equipment and the introduction of a new, more impedance optimised type of bellows, significant reductions in the beam-coupling impedance can be achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW077  
About • paper received ※ 08 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW087 GALACTIC and GALACLIC: Two Vlasov Solvers for the Transverse and Longitudinal Planes impedance, synchrotron, resonance, simulation 312
 
  • E. Métral
    CERN, Geneva, Switzerland
 
  GALACTIC and GALACLIC, two Vlasov solvers for the study, in the transverse and longitudinal plane respectively, of single-bunch coherent oscillation modes, were recently developed starting from the Vlasov equation and using a decomposition on the low-intensity eigenvectors, as proposed by Laclare and Garnier. The first Vlasov solver was used for instance to shed light on the destabilising effect of resistive transverse dampers and the second helped understanding the details of the mode-coupling behind some longitudinal microwave instabilities. Both theories are reviewed in detail, highlighting in particular the similarities and peculiarities of the two approaches.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW087  
About • paper received ※ 23 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW088 A Two-Mode Model to Study the Effect of Space Charge on TMCI in the "Long-Bunch" Regime space-charge, impedance, optics, simulation 316
 
  • E. Métral
    CERN, Geneva, Switzerland
 
  Using a two-mode approach for the Transverse Mode-Coupling Instability (TMCI) in the ’short-bunch’ regime (where the mode-coupling takes place between the modes 0 and -1, such as in the CERN LHC), both a reactive damper (ReaD) and Space Charge (SC) are expected to be beneficial: the ReaD would shift the mode 0 up while SC would shift the mode -1 down, but in both cases the coupling (and related instability) would occur at higher intensities. However, the situation is more involved in the ’long-bunch’ regime (where the mode-coupling takes place between higher-order modes, such as in the CERN SPS). As the ReaD modifies only the (main) mode 0 and not the others, it is expected to have no effect for the main mode-coupling. As concerns SC, it modifies all the modes except the mode 0, and the result has been a subject of discussion for two decades. A two-mode approach is discussed in detail in this contribution for the case of a single bunch interacting with a broad-band resonator impedance in the ’long-bunch’ regime. This model reveals in particular that in the presence of space charge, the intensity threshold can only be similar to or lower than that in the absence of space charge.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW088  
About • paper received ※ 23 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPGW089 Longitudinal Mode-Coupling Instability: GALACLIC Vlasov Solver vs. Macroparticle Tracking Simulations impedance, simulation, synchrotron, proton 320
 
  • E. Métral
    CERN, Geneva, Switzerland
  • M. Migliorati
    Rome University La Sapienza, Roma, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
 
  Following the same approach as for the recently developed GALACTIC Vlasov solver in the transverse plane and taking into account the potential-well distortion, a new Vlasov solver, called GALACLIC, was developed for the longitudinal plane. In parallel, a new mode analysis was implemented for the post-processing of the results obtained through macroparticle tracking simulations. The results of the several benchmarks performed between the two methods are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW089  
About • paper received ※ 23 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPGW093 Optics Calibration for Routine Operations In Taiwan Photon Source optics, lattice, quadrupole, operation 335
 
  • F.H. Tseng, C.H. Chen, P.J. Chou
    NSRRC, Hsinchu, Taiwan
 
  To ensure a stable performance of Taiwan Photon Source (TPS), we perform the calibration of accelerator optics using LOCO (Linear Optics from Closed Orbit) technique every month. After the optics and coupling corrections, the rms beta beatings in both planes are reduced to less than 1%. The emittance coupling ratio is also restored to within the design value.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW093  
About • paper received ※ 06 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPMP001 Optic Corrections for FCC-hh quadrupole, injection, insertion, dipole 417
 
  • D. Boutin
    CEA-DRF-IRFU, France
  • A. Chancé, B. Dalena
    CEA-IRFU, Gif-sur-Yvette, France
  • B.J. Holzer, D. Schulte
    CERN, Geneva, Switzerland
 
  The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the options considered for the next generation accelerator in high-energy physics as recommended by the European Strategy Group. The evaluation of the various magnets mechanical error and field error tolerances in the arc sections of FCC-hh, as well as an estimation of the required correctors strengths, are important aspects of the collider design. In this study the mechanical tolerances, dipole and quadrupole field error tolerances for the arc sections of FCC-hh are evaluated. The consolidated correction schemes of the linear coupling (with skew quadrupoles) and of the beam tunes (with normal quadrupoles) are presented. The integration of the different ring insertions (interaction region, collimation, injection, etc) is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP001  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPMP027 Second Order Dispersion Measurements in LHC optics, dipole, quadrupole, betatron 496
 
  • J. Keintzel, M. Hofer
    TU Vienna, Wien, Austria
  • J. M. Coello De Portugal - Martinez Vazquez, J. Dilly, E. Fol, A. Garcia-Tabares, M. Hofer, J. Keintzel, E.H. Maclean, L. Malina, T. H. B. Persson, R. Tomás, A. Wegscheider
    CERN, Geneva, Switzerland
 
  The quadratic dependence of the orbit on the relative momentum offset, also known as second order dispersion, is analysed for the first time for the LHC. In this paper, the measurement and analysis procedure are described. Results and implications on future optics are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP027  
About • paper received ※ 02 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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MOPMP033 LHC Run 2 Optics Commissioning Experience in View of HL-LHC optics, luminosity, simulation, experiment 508
 
  • R. Tomás, F.S. Carlier, J. Coello, J. Dilly, S.D. Fartoukh, E. Fol, D. Gamba, A. Garcia-Tabares, M. Giovannozzi, M. Hofer, E.H. Maclean, L. Malina, T. H. B. Persson, P.K. Skowroński, M. Solfaroli, M.L. Spitznagel, A. Wegscheider, J. Wenninger, D.W. Wolf
    CERN, Geneva, Switzerland
 
  LHC Run 2 has achieved a beta lower than a factor 2 below design. This has significantly challenged optics measurement and correction techniques in the linear and non-linear regimes, leading to the development of new approaches. Furthermore, experimenting with a large variety of optics has allowed facing the difficulties of future optics and gaining understanding of the machine imperfections. A summary of these aspects is given in view of their implications for the HL-LHC Project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP033  
About • paper received ※ 07 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB001 Low Emittance Tuning of FCC-ee emittance, lattice, quadrupole, sextupole 574
 
  • T.K. Charles
    The University of Melbourne, Melbourne, Victoria, Australia
  • S. Aumon, B.J. Holzer, F. Zimmermann
    CERN, Geneva, Switzerland
  • K. Oide
    KEK, Ibaraki, Japan
 
  The FCC-ee project studies the design of a future 100 km e+/e circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1036 cm-2s-1. In order to reach these luminosity requirements, extreme focusing is needed in the interaction regions. For the Z energy (45.6 GeV) lattice, the maximum beta value is 8322 m, and the vertical beta function is 0.8 mm at the IP. These aspects of the FCC-ee lattice make it particularly susceptible to misalignments and field errors, and therefore present an appreciable challenge for emittance tuning. A challenging correction scheme is proposed to reduce the coupling and the vertical emittance. We describe a comprehensive correction strategy used for the low emittance tuning. The strategy includes special programs, that had been developed to optimise the lattice based on Dispersion Free Steering, linear coupling compensation based on Resonant Driving Terms and beta beat correction utilising response matrices. Thousands of misalignment and field error random seeds were introduced in MADX simulations and the final corrected lattices are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB001  
About • paper received ※ 09 April 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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MOPRB017 Development of Inter-Digital H-Mode Drift-Tube Linac Prototype with Alternative Phase Focusing for a Muon Linac in the J-PARC Muon G-2/EDM Experiment cavity, linac, DTL, experiment 606
 
  • Y. Nakazawa, H. Iinuma
    Ibaraki University, Ibaraki, Japan
  • K. Hasegawa, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • Y. Iwata
    NIRS, Chiba-shi, Japan
  • N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida
    KEK, Ibaraki, Japan
  • R. Kitamura, H.Y. Yasuda
    University of Tokyo, Tokyo, Japan
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP18H03707, JP16H03987, and JP16J07784.
An inter-digital H-mode drift-tube linac (IH-DTL) is developed in a muon linac at the J-PARC E34 experiment. IH-DTL will accelerate muons from 0.34 MeV to 4.5 MeV at a drive frequency of 324 MHz. Since IH-DTL adopts an APF method, with which the beam is focused in the transverse direction using the RF field only, the proper beam matching of the phase-space distribution is required before the injection into the IH-DTL. Thus, an IH-DTL prototype was fabricated to evaluate the performance of the cavity and beam transmission. As a preparation of the high-power test, a test coupler is designed and fabricated. In this paper, the development of the coupler and the result of the low-power measurement will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB017  
About • paper received ※ 29 April 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPTS008 ESS RFQ: Construction Status and Power Couplers Qualification rfq, vacuum, cavity, pick-up 855
 
  • O. Piquet, A.C. Chauveau, D. Chirpaz-Cerbat, M. Desmons, A.C. France, P. Hamel, B. Pottin
    CEA-IRFU, Gif-sur-Yvette, France
  • A. Dubois, A. Gaget, Y. Le Noa, L. Napoly, M. Oublaid, G. Perreu
    CEA-DRF-IRFU, France
 
  The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) will be de-livered during 2019. It is provided by CEA, IRFU, Sac-lay/France. It consists of five sections with a total length of 4.6 m and accelerates the proton beam from 75 keV up to 3.6 MeV. It will be feed with 1.6 MW peak power through two coaxial loop couplers. This paper will present the manufacturing status of the five sections and the qualification test of the RF power couplers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS008  
About • paper received ※ 07 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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MOPTS040 Beta Beating and Coupling Correction of the ILSF Storage Ring lattice, quadrupole, closed-orbit, alignment 946
 
  • A.M. Mash’al, E. Ahmadi, S. Dastan, J. Rahighi
    ILSF, Tehran, Iran
  • F.D. Dabbagh Kashani
    IUST, Narmac, Tehran, Iran
 
  The Iranian Light Source Facility (ILSF) is a 3 GeV synchrotron radiation facility, which is in the design stage. Inevitable errors like imperfection of magnetic field and misalignment of magnets will introduce various destructive effects on the performance of the machine. The possibility of correcting the errors should be thoroughly examined before settling the design. In this paper, the correction process of beta beating and coupling with LOCO is described. The rms beta beating in horizontal and vertical planes after correction are reduced to 1% and 2% respectively. The average coupling ratio of lattice for 100 random error distribution is corrected to 0.2%.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS040  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS045 The Betatron Equation with the Synchro-Betatron Coupling Term and Suppression of the Coupled Bunch Mode synchrotron, betatron, closed-orbit, dipole 957
 
  • K. Jimbo
    Kyoto University, Kyoto, Japan
 
  The synchrotron oscillation, which is both longitudinal and horizontal oscillations, occurs under a constant longitudinal velocity of revolving particle. The synchrotron and betatron equations for revolving particles are derived from the improved Hamiltonian. The betatron equation accompanys the shinchro-betatron resonant coupling term. The coherent synchrotron oscillation frequency of the bunch is defined from the integrated phase. Taking advantage of the resonant coupling term, an experiment to suppress magnetically the destabilized coupled-bunch mode of the synchrotron oscillation is proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS045  
About • paper received ※ 17 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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MOPTS050 VSWR Adjustment for ACS Cavity in J-PARC LINAC cavity, GUI, simulation, linac 974
 
  • J. Tamura, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • F. Naito, M. Otani
    KEK, Tokai, Ibaraki, Japan
  • Y. Nemoto
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
 
  In the Japan Proton Accelerator Research Complex (J-PARC) linac, negative hydrogen beams are accelerated from 190 MeV to 400 MeV by twenty-one Annular-ring Coupled Structure (ACS) accelerating cavities. The input coupler of the ACS high-beta cavity, which is the 21st accelerating cavity (ACS21) in the order of beam acceleration, had a comparatively larger value of the Voltage Standing Wave Ratio (VSWR) than those of the other ACS cavities. To adjust the VSWR of the ACS21, we designed and fabricated a rectangular waveguide with a capacitive iris which conduces to a better matching between the cavity and the waveguide. In the 2018 summer maintenance period, we installed the newly fabricated waveguide to the ACS21 in the position between the input coupler and the RF window. Consequently, the VSWR of the ACS21 was successfully decreased to the target value which leads to the critical coupling under the nominal accelerating condition with 50-mA peak beam current.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS050  
About • paper received ※ 01 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPTS052 Simulation of Electric and Thermal Behavior of Cryogenic Three-cell Copper Accelerating Cavity for High Gradient Experiments cavity, simulation, cryogenics, experiment 980
 
  • T. Tanaka, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, Y. Takahashi
    LEBRA, Funabashi, Japan
 
  A C-band three-cell pi-mode accelerating cavity made of high purity copper is under design for use in ultra-high accelerating gradient experiments at a cavity temperature of 20 K. The basic configuration, consisting of mode converter, short circular waveguide and cells with round periphery, is the same as that which was previously employed in the cold model for a 2.6-cell photocathode electron gun cavity. Though the 0.6-cell part in the previous model is replaced with a full cell having a beam duct, the overall electric property of the cavity will not change significantly. The RF input coupling coefficient is adjusted to around 10 at 20 K, which is expected to be lowered significantly due to the increase in the surface resistance by the rapid temperature rise during a high power RF input. The results of the simulations on the electric field and the temperature rise along the cavity surface during the RF pulse are discussed in the report.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS052  
About • paper received ※ 13 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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MOPTS057 SSPA upgrade plan design for CiADS cavity, controls, klystron, simulation 990
 
  • Q. Chen, Z. Gao, Y. He, G. Huang, R. Huang, T.C. Jiang, S.H. Liu, L.P. Sun, X.W. Wang, Z.J. Wang, W.M. Yue
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Funding: Supported by the National natural science foundation of China (Grand No. 11525523 and 91426303)
For ADS application, both research and commercial facilities requires extremely large amount of RF power to drive several mega watts beam power, so proper RF power upgrade plan can reduce the budget per phase and increase the valuable experience in engineering. CiADS (China initiative Accelerator Drive System) proposes to employ SSPA (Solid State Power Amplifier) as RF power source for flexible configuring and upgrading in the future. In this paper, from an engineering point of view, it is acceptable if proper matching beam current was selected for adopting fixed-coupling input coupler while only sacrificed some RF power during the upgrade plan. SSPA upgrade plan start with the stablility requirement to determine bandwidth, then combined with other RF power requirements to select output level, finally, checking how much the surplus of selected level SSPA for detuning control. The calculation and evaluation results for a §I{545}{MeV} physical design lattice illustrate that some resonance cavities had very limited surplus RF power left for detuning control that provided necessary optimization direction and guidelines for both physical design and SSPA arrangement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS057  
About • paper received ※ 30 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS102 Linear and Non-Linear Optics Measurements in PS using Turn-by-Turn BPM Data injection, optics, sextupole, betatron 1114
 
  • P.K. Skowroński, M. Giovannozzi, A. Huschauer
    CERN, Meyrin, Switzerland
 
  For the first time, the optics of the CERN Proton Synchrotron (PS) was measured using turn-by-turn BPM data of forced betatron oscillations excited with an AC dipole. We report results of phase advance and beta beating measurements. Linear coupling was globally minimized along the machine by measuring and correcting coupling resonance driving terms. Finally, non-linear properties of the ring were probed looking at third and fourth order resonance driving terms and amplitude detuning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS102  
About • paper received ※ 07 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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MOPTS112 Matrix Approach to Decouple Transverse-Coupled Beams quadrupole, emittance, solenoid, DTL 1144
 
  • P.F. Ma, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • Y.H. Pu, J. Qiao, C.P. Wang, X.C. Xie, F. Yang
    Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China
 
  Funding: Work supported by the National Key Research and Development Program of China (grant number 2016YFC0105408).
Transverse emittances, especially vertical emittance, are strictly required in the synchrotrons with multi-loop injection. Transverse emittances easily grow up if transverse beam phase spaces are coupled. The growth of the transverse emittance can be restained by decoupling the beam phase spaces. Based on the transfer matrix calculation, it can be theoretically proved that the decoupling can be implemented for general situations. A minimum number of rotated quadrupoles required for decoupling is given. Two quadrupoles can decouple the beam and suppress its emittance growth to 1% in the coupling DTL case.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS112  
About • paper received ※ 28 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUZPLM2 Optics Measurements at SuperKEKB Using Beam Based Calibration for BPM and BBA quadrupole, optics, betatron, emittance 1198
 
  • H. Sugimoto, H. Koiso, K. Mori, A. Morita, Y. Ohnishi, M. Tejima
    KEK, Ibaraki, Japan
 
  The beam-based calibration(BBC) technique for Beam-Position-Monitor(BPM) is applied in order to establish reliable optics measurement. In the BBC, a response model between beam position, charge and output signals of the BPM electrodes are introduced to calibrate the relative gain of the BPM electrodes. The gains are adjusted by total squares fitting so that the model reproduces the measured BPM signals. The Beam-Based Alignment(BBA) is also performed to determine the magnetic center of a quadrupole. Using BBC and BBA, the performance of the BPM system and optics correction are successfully improved. This talk presents what we experienced during the beam commissioning focusing on beam optics measurement and some details on the beam-based calibration scheme for BPM system.  
slides icon Slides TUZPLM2 [15.911 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZPLM2  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW004 Cls 2.2: Ultra-Brilliant Round Beams Using Pseudo Longitudinal Gradient Bends quadrupole, injection, lattice, emittance 1385
 
  • L.O. Dallin
    CLS, Saskatoon, Saskatchewan, Canada
 
  A preliminary design for a new storage for the Canadian Light Source was presented at IPAC’18 (Dallin). More recently a reconfigured lattice was presented at the 6th DLSR workshop. This lattice employed large βy and small βx in the straights. This has several advantages including: increased transverse coherence and brighter beams at small coupling; round beams at small coupling; flatter βy through the straights; and possible off-axis vertical injection at small amplitudes. Most recently longitudinal gradients in the dipoles have been implemented. This has lead to the unit cell bends being replaced by a ’pseudo longitudinal gradient’ bend array: bend1-bend2-bend1. This results in smaller emittance with simple magnet designs while maintaining adequate dynamic aperture for off-axis injection.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW004  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW031 Elettra, Present and Future dipole, emittance, operation, insertion-device 1468
 
  • E. Karantzoulis, A. Carniel, S. Krecic
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the final version of the upcoming upgrade, the diffraction limited light source Elettra 2.0.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW031  
About • paper received ※ 16 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW039 Error Study and Correction of Hefei Advanced Light Source lattice, optics, quadrupole, closed-orbit 1492
 
  • D.R. Xu, Z.H. Bai, W. Li
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Hefei Advanced Light Source (HALS) is a future diffraction limited storage ring. The machine performance under all kinds of magnet errors is a vital component in physical design. In this paper, we present our work on the closed orbit correction, the linear beam optics compensation and the coupling control in HALS. After correction, the dynamical aperture can suffice the injection scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW039  
About • paper received ※ 23 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW108 Characterization of NEG Coatings for SLS 2.0 GUI, impedance, resonance, vacuum 1662
 
  • M.M. Dehler, A. Citterio
    PSI, Villigen PSI, Switzerland
  • S. Alberti, J.P. Hogge
    SPC-EPFL, Lausanne, Switzerland
  • M. Hahn, H.P. Marques
    ESRF, Grenoble, France
  • X.Y. Liu
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  To limit desorption and ameliorate pumping of the narrow 20 mm aperture vacuum chamber of SLS2.0, it is planned to fully coat it with nonevaporable getter (NEG) material. NEG coating can be produced with different structural characteristics, from dense films to columnar growth, with corresponding distinct electrical properties affecting the machine impedance and the instability threshold of the accelerator. In order to evaluate and characterize the coating process for geometries similar to the SLS chamber, we measured the resonance properties of coated and uncoated shorted waveguide pieces. First tests were done with standard X band waveguides at 12 and 7 GHz. Test setups using elliptical cross sections are in preparation, also for higher frequencies allowing the characterization of thin NEG layers. The final goal is to have a standardized process to test of samples coated by external producers. We describe the setups and first results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW108  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB050 The Optical Resonator of CTFEL for Range of 1 to 2 THz FEL, GUI, radiation, electron 1795
 
  • X.J. Shu, Y.H. Dou
    Institute of Applied Physics and Computational Mathematics, People’s Republic of China
 
  A high power THz free electron laser (FEL) facility is under construction at China Academy of Engineering Physics (CTFEL). The radiation frequency of the FEL facility will be tuned in range of 1~3 THz and the average output power is about 10 W. The system mainly consists of a GaAs photoemission DC gun, superconductor accelerator, hybrid wiggler, optical cavity. The first lasing is obtained on Aug. 29, 2017, and CTFEL is operated in range of 2-4THz, but cannot lasing at the frequency below 1.8 THz. The optical resonator of CTFEL must be optimized to ensure lasing in range of 1 to 2 THz.. The lasing strongly depends on the performance of the optical resonator including output efficiency, gain and round-trip loss. The optical resonator consists of metal-coated reflect mirror, the centre-hole output mirror, waveguide. The influence of waveguide on the quality of optical cavity is evaluated by the 3D OSIFEL code. The waveguide size and output hole radius is optimized to different frequencies between 1 THz to 2 THz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB050  
About • paper received ※ 13 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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TUPTS001 Improvements in Rf Multi Cusp Negative Ion Source plasma, ion-source, simulation, operation 1928
 
  • A.M. George, M.P. Dehnel, S.V. Melanson, D.E. Potkins, T.M. Stewart
    D-Pace, Nelson, British Columbia, Canada
  • N. Broderick
    University of Auckland, Auckland, New Zealand
  • Y. Shimabukuro
    Doshisha University, Graduate School of Engineering, Kyoto, Japan
 
  D-Pace’s 13.56 MHz Radio Frequency (RF) multi cusp negative ion source uses an Aluminium Nitride (AlN) dielectric window for coupling RF power from an external antenna to the plasma chamber. Ion source operation was limited to low RF power (< 3500 W) due to failures (cracks) occurring on the window during experiments. Such events can cause damages to the vacuum system and plasma chamber. The current work deals with simulations performed on the ion source to study the factors leading to the failure of the window. Based on results from the simulations, a new design was introduced. The improved design yielded positive results in terms of source performance and stability of the AlN window.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS001  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS113 Microwave Thermionic Electron Gun for Synchrotron Light Sources gun, cathode, electron, cavity 2189
 
  • S.V. Kutsaev, R.B. Agustsson, R.D. Berry, D. Chao, O. Chimalpopoca, A.Yu. Smirnov, K.V. Taletski, A. Verma
    RadiaBeam, Santa Monica, California, USA
  • M. Borland, A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents
    ANL, Argonne, Illinois, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Science, under contracts DE-SC0015191 and DE- AC02-06CH11357.
Thermionic RF guns are the source of electrons used in many practical applications, such as drivers for synchrotron light sources, preferred for their compactness and efficiency. RadiaBeam Technologies has developed a new thermionic RF gun for the Advanced Photon Source at Argonne National Laboratory, which would offer substantial improvements in reliable operations with a robust interface between the thermionic cathode and the cavity, as well as better RF performance, compared to existing models. This improvement became possible by incorporating new pi-mode electromagnetic design, robust cavity back plate design, and a cooling system that will allow stable operation for up to 1 A of beam current and 100 Hz rep rate at 1.5 μs RF pulse length, and 70 MV/m peak on-axis field in the cavity. In this paper, we discuss the electromagnetic and engineering design of the cavity and provide the test results of the new gun.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS113  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEYPLS1 Building the Impedance Model of a Real Machine impedance, simulation, wakefield, cavity 2249
 
  • B. Salvant, D. Amorim, S. A. Antipov, S. Arsenyev, M.S. Beck, N. Biancacci, O.S. Brüning, J.V. Campelo, E. Carideo, F. Caspers, A. Farricker, A. Grudiev, T. Kaltenbacher, E. Koukovini-Platia, P. Kramer, A. Lasheen, M. Migliorati, N. Mounet, E. Métral, N. Nasr Esfahani, S. Persichelli, B.K. Popovic, T.L. Rijoff, G. Rumolo, E.N. Shaposhnikova, V.G. Vaccaro, C. Vollinger, N. Wang, C. Zannini, B. Zotter
    CERN, Geneva, Switzerland
  • D. Amorim
    Grenoble-INP Phelma, Grenoble, France
  • T. Dalascu
    EPFL, Lausanne, Switzerland
  • M. Migliorati
    Sapienza University of Rome, Rome, Italy
  • R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
  • V.V. Smaluk
    BNL, Upton, Long Island, New York, USA
  • B. Spataro
    INFN/LNF, Frascati, Italy
  • N. Wang
    IHEP, Beijing, People’s Republic of China
  • S.M. White
    ESRF, Grenoble, France
 
  A reliable impedance model of a particle accelerator can be built by combining the beam coupling impedances of all the components. This is a necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics nonlinearities, transverse damper, noise, space charge, electron cloud, beam-beam (in a collider). The main phases to create a realistic impedance model, and verify it experimentally, will be reviewed, highlighting the main challenges. Some examples will be presented revealing the levels of precision of machine impedance models that have been achieved.  
slides icon Slides WEYPLS1 [5.648 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYPLS1  
About • paper received ※ 10 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPGW020 Next Generation Cryogenic Current Comparator (CCC) for nA Intensity Measurement shielding, cryogenics, pick-up, detector 2510
 
  • T. Sieber, D.M. Haider, H. Reeg, M. Schwickert, T. Stöhlker
    GSI, Darmstadt, Germany
  • H. De Gersem, N. Marsic, W.F.O. Müller
    TEMF, TU Darmstadt, Darmstadt, Germany
  • J. Golm, F. Schmidl, P. Seidel, V. Tympel
    FSU Jena, Jena, Germany
  • M. Schmelz, R. Stolz, V. Zakosarenko
    IPHT, Jena, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  • T. Stöhlker
    HIJ, Jena, Germany
  • J. Tan, G. Tranquille
    CERN, Geneva, Switzerland
 
  A Cryogenic Current Comparator (CCC) is an extremely sensitive DC-Beam Transformer based on superconducting SQUID technology. Recently, a CCC without a toroidal core and with an axially oriented magnetic shielding has been developed at the Institute of Photonic Technologies (IPHT) Jena/Germany. It represents a compact and lightweight alternative to the ’classical’ CCC, which was originally developed at PTB Braunschweig and is successfully in operation in accelerators at GSI and CERN. Excellent low-frequency noise performance was demonstrated with a prototype of this new CCC-type. Current measurements and further tests are ongoing, first results are presented together with simulation calculations for the magnetic shielding. The construction from lead as well as simplified manufacturing results in drastically reduced costs compared to formerly used Nb-CCCs. Reduced weight also puts less constraints on the cryostat. Based on highly sensitive SQUIDs, the new prototype device shows a current sensitivity of about 6 pA/Hz1/2 in the white noise region. The measured and calculated shielding factor is ~135 dB. These values, together with a significant cost reduction - resulting also from a compact cryostat design - opens up the way for widespread use of CCCs in modern accelerator facilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW020  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW058 Orbit Correction With Machine Learning lattice, storage-ring, closed-orbit, simulation 2608
 
  • D.J. Xiao, C.P. Chu, Y.S. Qiao
    IHEP, Beijing, People’s Republic of China
 
  Orbit correction is usually an important task in the operation of accelerators. In practice, due to various errors, many devices can not operate in ideal state. By correcting the errors of magnets with corrector magnets, the beam can return to the correct position to ensure the stable operation of the accelerator. In the process of orbit correction, inaccurate BPM output will lead to incorrect correction magnet strength setting, so that the orbit correction will be impacted. BPM may make mistakes in the process of signal acquisition and current conversion. A BPM anomaly detection and predict method based on machine learning and its using in orbit correction optimization is reported in this paper. This method does not need to observe the details of BPM system, electronics technology and so on. It can monitor and predict the BPM status directly by machine learning with the information of the beam inferred from BPM and others, and optimize the orbit correction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW058  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPGW109 Double Quarter Wave Deflector Cavity Design & Simulation cavity, operation, simulation, diagnostics 2749
 
  • M.S. Stefani
    ODU, Norfolk, Virginia, USA
  • G.-T. Park
    JLab, Newport News, Virginia, USA
 
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
A Double Quarter Wave (DQW) Cavity has been designed, tested and installed for use in longitudinal measurements as part of a diagnostic beamline. This report will describe the design and testing used to characterize this cavity before its use in the study of a magnetized electron beam.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW109  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPGW116 LHC Optics Measurement and Correction Software Progress and Plans optics, software, MMI, GUI 2773
 
  • R. Tomás, F.S. Carlier, J. Coello, J. Dilly, E. Fol, A. Garcia-Tabares, M. Hofer, E.H. Maclean, L. Malina, T. H. B. Persson, P.K. Skowroński, M.L. Spitznagel, A. Wegscheider, J. Wenninger
    CERN, Geneva, Switzerland
  • J.F. Cardona, Y. Rodriguez
    UNAL, Bogota D.C, Colombia
  • F.S. Carlier
    NIKHEF, Amsterdam, The Netherlands
  • D. Esperante Pereira, J. Fuster, D. Gonzalez-Iglesias
    IFIC, Valencia, Spain
  • R. Hoekstra
    KVI, Groningen, The Netherlands
 
  LHC Optics Measurements and Corrections (OMC) require efficient on-line software applications to acquire and analyze data and to compute the necessary corrections. During Run 2 various measurement and correction techniques have been merged to yield unprecedented optics quality, increasing the required number of steps to finalize the optics commissioning and the size of the software project. In turn, this calls for a higher level of automation, where machine learning techniques are being implemented. During the Long Shutdown 2 a large refactoring of the codes will be in place to improve performance, maintainability and extensibility. A description of the current status of the software and future plans is given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW116  
About • paper received ※ 07 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW123 Full Acceptance Interaction Region Design of JLEIC electron, detector, dipole, interaction-region 2787
 
  • V.S. Morozov, R. Ent, Y. Furletova, F. Lin, T.J. Michalski, R. Rajput-Ghoshal, M. Wiseman, R. Yoshida, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Cai, Y.M. Nosochkov, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • G.L. Sabbi
    LBNL, Berkeley, California, USA
 
  Funding: This material is based upon work supported by the U.S. DoE under Contracts No. DE-AC05-06OR23177, DE-AC02-76SF00515, and DE-AC03-76SF00098.
Nuclear physics experiments envisioned at a proposed future Electron-Ion Collider (EIC) require high luminosity of 1033-1034 cm-2s-1 and a full-acceptance detector capable of reconstruction of a whole electron-ion collision event. Due to a large asymmetry in the electron and ion momenta in an EIC, the particles associated with the initial ion tend to go at very small angles and have small rigidity offsets with respect to the initial ion beam. They are detected after they pass through the apertures of the final focusing quadrupoles. Therefore, the apertures must be sufficiently large to provide the acceptance required by experiments. In addition, to maximize the luminosity, the final focusing quadrupoles must be placed as close to the interaction point as possible. A combination of these requirements presents serious detection, optics and engineering design challenges. We present a design of a full-acceptance interaction region of Jefferson Lab Electron-Ion Collider (JLEIC). The paper presents how this design addresses the above requirements up to an ion momentum of 200 GeV/c. We summarize the magnet parameters, which are kept consistent with the Nb-Ti superconducting magnet technology.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW123  
About • paper received ※ 23 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB030 Commissioning of RF System of the 200 MeV Proton Cyclotron cavity, cyclotron, multipactoring, MMI 2877
 
  • G. Chen, C. Chao, G. Liu, X.Y. Long, Z. Peng, C.S. Yu, X. Zhang, Y. Zhao
    ASIPP, Hefei, People’s Republic of China
  • L. Calabretta, A.C. Caruso
    INFN/LNS, Catania, Italy
  • O. Karamyshev, G.A. Karamysheva, G. Shirkov
    JINR, Dubna, Moscow Region, Russia
 
  Funding: (1) National Natural Science Foundation of China under grant No. 11775258, 11575237; (2) International Sci-entific and Technological Cooperation Project of An-hui (grant No. 1704e1002207).
The SC200 superconducting accelerator which is designed for proton therapy is currently under con-struction. The RF (Radio Frequency) system has been designed and constructed as a subsystem of the SC200. To verify the stability of the RF system, a high-power feeding test was performed for the cavity. This paper mainly reports on the overview of RF systems and the prelimary high-power commissioning, as well as the problems found and improvements made during the commissioning process. The results show that the RF system has initially achieved the designed goal, and each loop (amplitude, tuning, phase) can work effec-tively. The cavity can operate in a ~50 kW continuous wave state. Next, the formal RF conditioning will be carried out after the complete assembly of cyclotron, so as to confirm the cavity can run smoothly under 80 kW, which is part of the whole commissioning process.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB030  
About • paper received ※ 22 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB039 Tuning of a Tapered Ridge-Loaded Waveguide Coupler for a Drift Tube LINAC of the Compact Pulsed Hadron Source GUI, DTL, linac, target 2893
 
  • Y. Lei, C.T. Du, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, S.X. Zheng
    TUB, Beijing, People’s Republic of China
 
  This paper presents the tuning result of a tapered ridge-loaded waveguide coupler for the drift tube linac (DTL) of the compact pulsed hadron source (CPHS) at Tsinghua University. The coupler has been designed, manufactured, and mounted on the DTL cavity for the cold measurement and tuning. The iris diameter of the coupler which is related to the coupling coefficient needs to be determined in the tuning experiment, due to the difference between the designed and measured quality factors. Meanwhile, we found that the relationship between the coupling coefficient and iris diameter from the traditional analytical design method is not applicable when the iris diameter is relatively large. In this paper, the target coupling coeffi-cient is analysed, and the limit of the original analytical design is presented. The measurement method is intro-duced to improve the measurement efficiency and the tuning process of the coupling coefficient to the target value is described. After several iterations, the coupling coefficient is tuned to 1.54 which is close to the desired value of 1.56.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB039  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB052 Design of Two Types of X-Band High Power Directional Coupler GUI, simulation, scattering, operation 2928
 
  • G. Wang, X. Lin, Y.G. Tang, C.-F. Wu
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  The directional coupler is one of the most widely used components in many microwave systems, which is used to distribute the power of the input microwave signal according to a desired ratio. Directional coupler may be a three-port component or a four-port component with certain specification such as frequencies, bandwidth and structure. To meet the requirements of stable coupling degree and high directivity, we designed two types of directional coupler working at 11.424 GHz with high power handling capacity. One consists of two parallel rectangular waveguides with four holes drilled along the central line of the narrow-wall for coupling the electromagnetic power from the main-waveguide to the sub-waveguide which is called H-plane directional coupler. Simulations show that the coupling degree of H-face directional coupler is 49.9 dB and the directivity is 54.5 dB .The peak electric field is about 29MV/m while operating at 200 MW peak power. The other consists of a circular main-waveguide transmitting TM01 mode and a rectangular sub-waveguide transmitting TE10 mode, called circular-rectangle waveguide directional coupler. These two waveguide are connected by six holes drilled on the side of the circular main-waveguide and along the central line of the wide-wall of the sub-waveguide. The coupling degree of this directional coupler is 50.14 dB and the directivity is 37.93 dB due to the simulation. The bandwidth is about 800MHz. The peak electric field is 404.5V/m while operating at 200 MW peak power. Comparing with the H-plane directional coupler, peak electric field of this directional coupler is lower. Low peak electric field can reduce the risk of RF breakdown and the Multipactor effect, which ensures the stable high power operation of the directional coupler.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB052  
About • paper received ※ 27 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB055 Design of 3 MeV S-band Electron Linac Structure With 2.5 Bunching Cells electron, bunching, linac, simulation 2934
 
  • Y. Joo, P. Buaphad, H.R. Lee
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • Y. Kim
    KAERI, Daejon, Republic of Korea
  • J.Y. Lee, S. Lee
    Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
 
  Funding: UST (University of Science and Technology), KAERI (Korea Atomic Energy Research Institute)
The Korea Atomic Energy Research Institute (KAERI) has been designing several 3 MeV S-band RF electron linear accelerators (linacs) for non-destructive testing. Until now, the bunching cell of the linac has a full-cell geometry. However, to maximize the acceleration of electrons after emission from the electron gun, the geometry of the first bunching cell is modified from a full-cell to a half cell. To accelerate electron beams more gently, recently, we increased the total number of bunching cells from 1.5 to 2.5. In this paper, we describe design concepts and detailed optimization processes of a 3 MeV linac with the 2.5 bunching cells to optimize RF parameters such as the quality factor, resonance frequency, and uniformity of electric field distribution along the linac. Lastly, we will discuss the application of 3 MeV linac.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB055  
About • paper received ※ 04 June 2019       paper accepted ※ 16 June 2019       issue date ※ 21 June 2019  
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WEPRB066 Utilizing the High Shunt Impedance TM020-Mode Cavity in the Double RF Systems for the Storage Ring of the Thailand New Light Source cavity, storage-ring, impedance, damping 2972
 
  • N. Juntong, T. Phimsen
    SLRI, Nakhon Ratchasima, Thailand
  • N. Chulakham, S. Malichan
    Udon Thani Rajabhat University, Udon Thani, Thailand
 
  The utilization of the TM020-mode cavity for the storage ring based light source was pioneered by SPring-8 with its high quality factor and hence its high shunt impedance. KEK-LS has also studied the possibility of using this type of cavity for their storage ring. The TM020-mode cavity has larger transverse dimension compared to the traditional TM010-mode cavity, but with its higher shunt impedance it can be designed to fit in the new low emittance storage ring regardless. The new storage ring based light source project in Thailand aims to optimum the low emittance beam in nano-meters region with the energy of 3 GeV. The TM020-mode cavity was considered as the main cavity and the harmonic cavity for the storage ring. They have been designed to have their pipe aperture fits the storage ring beam ducts. The main cavity has a high shunt impedance of 8.3 Mega Ohms with the 51,000 unloaded quality factor. The harmonic cavity has a high shunt impedance and an unloaded quality factor of 2.45 Mega Ohms and 36,000, respectively. The damping mechanism of the parasitic modes and the tuning mechanism of the operating mode of these cavities were also studied. There will be four main cavities and six harmonic cavities in the new storage ring. Detailed design and study of these cavities will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB066  
About • paper received ※ 29 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB090 The Design of Parallel-Feed SC RF Accelerator Structure cavity, SRF, niobium, alignment 3024
 
  • M.H. Nasr, Z. Li, S.G. Tantawi, P.B. Welander
    SLAC, Menlo Park, California, USA
 
  Funding: Research funded by a SLAC Laboratory-Directed Research and Development award, supported by the U.S. Department of Energy, contract number DE-AC02-76SF00515
Development of superconducting RF (SRF) accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed normal-conducting RF structure at SLAC has served as a proof-of-concept. Instead of coupled elliptical cells, the structure employs isolated re-entrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Applied to SRF, simulations suggest such a structure could nearly double the achievable gradient, while reducing cryogenic RF loss by more than half. We are experimentally verifying the concept using an X-band SRF design to be tested at SLAC.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB090  
About • paper received ※ 24 May 2019       paper accepted ※ 27 May 2019       issue date ※ 21 June 2019  
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WEPRB099 Status Update of a Harmonic Kicker Development for JLEIC kicker, multipole, cavity, simulation 3047
 
  • G.-T. Park, J. Guo, J. Henry, M. Marchlik, F. Marhauser, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
An effort to develop the second prototype of the harmonic kicker for the Circulator Cooler Ring (CCR) of the Jefferson Lab Electron-Ion Collider (JLEIC) is under way. After beam dynamics studies and completion of a conceptual RF design of the kicker [1], further progress has been made toward the final mechanical design including the input power coupler (loop) design, tuner ports, multipacting studies. Furthermore, concerning the kicker’s compatibility with beam dynamics, the impact of RF multipole components was investigated and a scheme was developed to cancel out detrimental beam effects.
1. G. Park, et al, The Development of a New Fast Harmonic Kicker for the JLEIC Circulator Cooler Ring, TUPAL068, proceedings of IPAC 2018.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB099  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS011 Intra-Beam Scattering Effect in the SOLEIL Storage Ring Upgrade emittance, lattice, simulation, cavity 3106
 
  • A. Vivoli, A. Bence, P. Brunelle, A. Gamelin, L. Hoummi, A. Loulergue, L.S. Nadolski, R. Nagaoka, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette, France
 
  As the work on the design of the upgrade of SOLEIL storage ring advances, the study of the impact of Intra-Beam Scattering (IBS) on the equilibrium emittance is also progressing, showing a significant contribution of this effect. Different measures can be taken to mitigate the emittance dilution, like operating the machine with full transverse coupling and using harmonic cavities to increase bunch length. The calculation of the IBS effect needs then to take into account the different beam dynamics and its effect on the particle distribution. In this paper the current state of the ongoing study is presented, reporting on the results obtained for the different options considered, and comparing the results of different codes and their implicit assumptions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS011  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPTS012 RF Design Studies of a 1.3 GHz Normal Conducting CW Buncher for European X-FEL multipactoring, simulation, impedance, cavity 3109
 
  • S. Lal, Y. Chen, H.J. Qian, H. Shaker, S. Shu, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • V.V. Paramonov
    RAS/INR, Moscow, Russia
 
  A CW upgrade of European XFEL is under consideration, and CW electron injector is under R&D at DESY. One of the injector solutions is the LCLS-II like injector based on a normal conducting CW gun and buncher. RF design of a 1.3 GHz normal conducting buncher structure with accelerating voltage of ~ 400 kV, for such a CW injector is carried out at DESY Zeuthen site. The buncher structures with different geometrical shapes and numbers of cells are studied. The designs are optimized to have higher shunt impedance, higher mode separation and lower thermal power density for CW operation. Multipacting analysis and beam dynamics simulations are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS012  
About • paper received ※ 12 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPTS028 Transverse-Longitudinal Coupling for Harmonic Generation and Bunch Length Manipulation emittance, bunching, lattice, storage-ring 3160
 
  • X.J. Deng, W.-H. Huang, C.-X. Tang, Y. Zhang
    TUB, Beijing, People’s Republic of China
  • A. Chao
    SLAC, Menlo Park, California, USA
 
  A general harmonic generation and bunch length manipulation scheme using transverse-longitudinal coupling is presented. The method makes use of the freedom in projecting the three beam eigen-emittances into different physical dimensions. A realization of this coupling lattice, a PEHG variant, is given as an example. For the purpose of harmonic generation and bunch compression, this method is advantageous when the transverse emittance is small. The combination with sawtooth waveform modulation is proposed to boost the bunching further. Transverse-longitudinal coupling in storage rings are briefly discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS028  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPTS041 Coupling and Space Charge Studies at the CERN PSB resonance, optics, emittance, space-charge 3192
 
  • F. Asvesta
    NTUA, Athens, Greece
  • F. Antoniou, H. Bartosik, G.P. Di Giovanni, Y. Papaphilippou
    CERN, Meyrin, Switzerland
 
  In the nominal optics of the CERN PS-Booster (PSB), the fourth order coupling resonance is excited by space charge (Montague resonance) due to the same integer tune values. This resonance can be avoided by changing the tunes to different integers. A new PSB optics is presented and emittance measurements crossing the coupling resonance for the nominal and the new optics are shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS041  
About • paper received ※ 17 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPTS072 Application of Bayesian Inference in Accelerator Commissioning of FRIB diagnostics, MMI, emittance, experiment 3289
 
  • Y. Hao, L.M. Neufcourt
    FRIB, East Lansing, USA
 
  We will report the preliminary application of the Bayesian Inference of the unknown parameters of accelerator model using the FRIB commissioning data. The inference result not only indicates the value of the unknown parameter, but also the confidence of adopting the value. The Bayesian approach provides an alternative method to understand the difference between accelerator model and the hardware and may help achieving ultimate beam parameters of FRIB.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS072  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPTS101 A General Comparison on Impedance Theory and CST Simulation of Discontinuities impedance, simulation, vacuum, storage-ring 3352
 
  • N. Khosravi, E. Ahmadi, M. Akhyani, S. Dastan, A.M. Mash’al
    ILSF, Tehran, Iran
  • H. Karimi
    Isfahan University of Technology, Isfahan, Iran
 
  Inhomogeneity of vacuum chamber components is the main source of coupling impedance. Nowadays, wake potential is mostly predictable by 3D codes. Analytical prediction of impedance theories can be helpful as a side solution. On the other hand, some asymmetries in the geometry of components might make troubles and lead to imprecise numerical results in 3D simulations. Analytical approximation of discontinuities, holes, and grooves can give us an estimation of expected results and can be used as a benchmark in the case that we do not have any experimental data. To clarify the validity of theoretical expressions, general discontinuities are simulated in CST. The comparison of final results is presented here. At last, resistive wall impedance and some general discontinuities of components at ILSF storage ring are compared from the theoretical and simulation point of view.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS101  
About • paper received ※ 01 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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THPGW005 Recent Developments of the 520 MeV Cyclotron’s High-Power RF System at TRIUMF cyclotron, operation, simulation, rf-amplifier 3591
 
  • N.V. Avreline, Y. Bylinskii, D. Gregoire, B. Jakovljevic, R.E. Laxdal, X. Wang, B.S. Waraich, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
 
  520 MeV Cyclotron’s High-Power RF System has been in the state of continuous operation for over 50 years since its commissioning. This paper describes the recent upgrades of the RF System, the main goal of which was to improve reliability. Specially, we discuss the upgrades done to the RF Transmission Line (TL), the RF Power Amplifier (PA) components and their diagnostics tools. We upgraded the structure of Intermediate Power Amplifier (IPA), installed Solid State (SS) driver and are in the process of replacing tubes with a SS option for IPA and PA.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW005  
About • paper received ※ 08 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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THPRB008 Ponderomotive Instability of Two Self-Excited Cavities cavity, resonance, controls, linac 3812
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  We consider the ponderomotive instability of two superconducting RF cavities self-driven from a single RF source with vector-sum control.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB008  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB009 Vector Sum & Diffference Control of SRF Cavities cavity, controls, resonance, linac 3816
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  We consider the ponderomotive instability of multiple superconducting RF cavities driven from a single RF source. We add vector difference control to the usual the technique of vector sum control, in order to increase the accelerating gradient threshold for ponderomotive instability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB009  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB045 A Novel Microwave Switch-Based LLRF System for Long-Term System Phase Drift Calibration LLRF, controls, ISOL, experiment 3915
 
  • Z.Y. Lin, Y.-C. Du, W.-H. Huang, C.-X. Tang, J. Tang
    TUB, Beijing, People’s Republic of China
  • G. Huang, Y.L. Xu
    LBNL, Berkeley, California, USA
  • Z. Sun, D. Zhang
    HZCY Technologies Co., Ltd., Beijing, People’s Republic of China
 
  The long-term phase drift is one of the important issue for the stability of the Low level RF system. The signal crosstalk and temperature effect on the RF field detectors will significantly limited the performance of the phase detecting precise and the phase locking. A novel micro-wave switch-based LLRF system has been developed in Tsinghua accelerator lab. The microwave switch are ap-plied to in the chopper circuit to turn continuous signal into pulse signal in the time domain to avoid the mutual signal interference. In this paper the LLRF system based on microwave switch is present. The preliminary long-term experiments result shows the phase stability can achieve about 50fs RMS slow drift; and the peak-to-peak value of the slow drift was (~2°C p-p) over 4 days.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB045  
About • paper received ※ 22 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB075 Transverse Impedance Measurements and Simulations of the LHC Injection Kicker Magnet impedance, simulation, kicker, injection 3986
 
  • V. Vlachodimitropoulos, M.J. Barnes, A. Chmielinska, L. Ducimetière
    CERN, Geneva, Switzerland
  • A. Chmielinska
    EPFL, Lausanne, Switzerland
 
  Kicker magnets contribute significantly to the total impedance budget of many accelerators. Of particular interest, from a beam stability point of view, is the transverse beam coupling impedance (TBCI) that is used to determine intensity limitations of a machine. Until recently, no conclusive TBCI data for the Large Hadron Collider (LHC) injection kicker magnets (MKIs) was available. However, in view of the upgrade of the MKIs for the High-Luminosity LHC (HL-LHC) project, the TBCI of the existing design needed to be estimated to be used as reference for an upgraded version. To that end, electromagnetic simulations were carried out to determine the dipolar and quadrupolar components of the TBCI in the two transverse planes. To validate the simulations, test bench measurements were performed using standard RF measurement techniques. In the present work, the results from TBCI simulations and measurements are reported and compared. Detailed descriptions of the methods and techniques used as well as the realization of the experimental set-up are also given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB075  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS095 High Efficiency High Power Resonant Cavity Amplifier For PIP-II cavity, impedance, network, operation 4335
 
  • M.P.J. Gaudreau, D.B. Cope, E.G. Johnson, M.K. Kempkes, R.E. Simpson, N.A. Stuart
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
 
  Funding: Work funded under US DOE Grant No. DE-SC0015780
Diversified Technologies, Inc. (DTI) is developing an integrated resonant-cavity combined solid-state amplifier for the Proton Improvement Plan-II (PIP-II) at Fermilab. The prototype has demonstrated multiple-transistor combining at 70% efficiency, at 675 watts per transistor at 650 MHz. The patent pending design simplifies solid-state transmitters to create straightforward scaling to 200 kW and higher high power levels. A crucial innovation is the reliable "soft-failure" mode of operation; a failure in one or more of the transistors has negligible performance impact. This design couples the transistor drains directly to the cavity without first transforming to 50 Ohms, avoiding the circulators, cables, and connectors that would normally be required. Under an ongoing SBIR grant from the US Department of Energy, DTI designed the system to accommodate over 96 transistors in each 50 kW cavity, with minimal RF, DC, and cooling connections. By the end of the SBIR, DTI will build and demonstrate a complete 100 kW-class (~200 kW) transmitter by combining four cavity modules to show the expandability of the design to very high power levels, comparable to large VEDs.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS095  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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