Keyword: simulation
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MOPO016 Narrow-Band Terahertz Generation from Beam Pipe with Helix Wires electron, radiation, wakefield, impedance 65
 
  • D. Wang
    TUB, Beijing, People’s Republic of China
 
  We studied through analysis and numerical simulations the use of a relativistic electron bunch to drive a metallic beam pipe with helix wire inside, for the purpose of gen-erating narrow-band terahertz radiation. we have shown that the frequency is related to the radius of the pipe and that of the wire, thus one can generate a narrow-band radiation pulse with frequency tunable through this scheme with different pipes and wires. The total energy of a few milli-Joules. The pulse length tends to be on the order of hundreds of picoseconds. We have also shown that, if the pipe radius is tapered along its length, the generated pulse will end up with a frequency chirp.
*wangdan2016@mail.tsinghua.edu.cn
*yanlx@mail.tsinghua.edu.cn
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO016  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO018 Development of an Improved Capture Section for the S-DALINAC Injector* cavity, linac, electron, gun 68
 
  • S. Weih, M. Arnold, J. Enders, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • D.B. Bazyl, H. De Gersem, W.F.O. Müller
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  For the injector of the superconducting Darmstadt electron linear accelerator S-DALINAC, the design of a new capture cavity was recently completed. This beta-reduced structure will optimize the capture of low-energy electron bunches from the gun section and therefore improve the longitudinal beam quality of the injector beam, as simulations have shown. The existing cryomodule of the injector has to be modified for the installation of the new cavity. These modifications include adaptions of the tuner frame as well as modifications of other surrounding parts. To improve the diagnostics in the low-energy section, an energy-spread measurement setup is currently also under development. In this contribution the cryomodule modifications as well as simulation results for the longitudinal beam dynamics are presented.
*Work supported by DFG through GRK 2128 "AccelencE"
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO018  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO020 Beam Dynamics Studies and Instrumentation Tests for Bunch Length Measurements at CLEAR experiment, gun, electron, radiation 74
 
  • L. Garolfi, M. Bergamaschi, R. Corsini, A. Curcio, S. Döbert, W. Farabolini, D. Gamba, I. Gorgisyan
    CERN, Geneva, Switzerland
  • C. Bruni, P. Lepercq, H. Purwar, C. Vallerand
    LAL, Orsay, France
  • W. Farabolini
    CEA/DSM/IRFU, France
 
  A new CERN Linear Electron Accelerator for Research (named CLEAR) has been installed as a general-purpose user facility to study novel accelerating techniques, high-gradient structures, instrumentation and irradiation experiments. CLEAR is a flexible accelerator that can provide high quality bunched electron beams with a wide range of beam parameters up to an energy of 220 MeV, offering several testing capabilities. Among all the potential applications, novel accelerating techniques, such as plasma acceleration and THz generation are considered. These applications require shorter bunches, down to the 100 fs level. This paper reports on beam dynamics studies and instrumentation tests to establish a bunch length of this order in CLEAR. The short bunches are generated using adiabatic bunching in the first accelerating structure. For bunch length diagnostic CLEAR is equipped with a streak camera and a transverse deflecting cavity. Alternatively a phase-scan of the last accelerating structure could be used as well to estimate the bunch length. The experimental results with respect to these different techniques are presented and compared with simulations.  
slides icon Slides MOPO020 [0.864 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO020  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO070 Construction of the Side-coupled Standing-wave e-Linac cavity, linac, coupling, electron 151
 
  • S. Zarei
    Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
  • F. Abbasi
    Shahid Beheshti University, Tehran, Iran
  • M. Bahrami, M. Lamehi
    IPM, Tehran, Iran
  • F. Ghasemi
    NSTRI, Tehran, Iran
 
  Due to Iran’s growing need for accelerators in various applications, NSTRI electron linear accelerator project has been defined for medical and inspection applications. This accelerator is a 6 MeV side-coupled standing-wave that operate is π /2 mode in the frequency of 2998.5 MHz. In this paper the construction and measurement results of the tube of this accelerator are presented. The prototype tube was constructed from aluminum and was clamped with bolts. By using a network analyzer, electric and magnetic probes and a side-coupled cavity tuning method and a bead-pull measurement technique, RF measurements were carried out. The resonant frequency and quality factor have been achieved 2998.5 MHz and 7940 respectively .
low-energy accelerator, construction of linac, standing-wave linac
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO070  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO077 Design of the High Gradient Negative Harmonic Structure for Compact Ion Therapy Linac proton, linac, coupling, operation 160
 
  • S.V. Kutsaev, R.B. Agustsson, A.Yu. Smirnov, A. Verma
    RadiaBeam, Santa Monica, California, USA
  • A. Barcikowski, R.L. Fischer, B. Mustapha
    ANL, Argonne, Illinois, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE-SC0015717 and Accelerator Stewardship Grant, Proposal No. 0000219678
A novel concept for an Advanced Compact Carbon Ion Linac (ACCIL) that will deliver up to 1 pnA of carbon ions with variable energy from 45 MeV/u to 450 MeV/u in a 45 m footprint, has been developed by Argonne National Laboratory (ANL) in collaboration with RadiaBeam. The ACCIL will have a 35 MV/m real-estate accelerating gradients that became possible to achieve with the development of novel S-band high-gradient structures, capable of providing 50 MV/m accelerating gradients for particles with β>0.3. In particular, a β=0.3 structure based on the novel approach of operation at the first negative spatial harmonic with the increased distance between the accelerating gaps will be presented. This is the first attempt to reach such high gradients at such small velocities. RadiaBeam and ANL have demonstrated the feasibility of building this structure for accelerating carbon ions by means of advanced computer simulations and are currently working towards the fabrication of this structure for high power tests.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO077  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO087 Cold Test of Hybrid RFQ Prototype rfq, quadrupole, cavity, DTL 184
 
  • P.Y. Yu, Y. He, C.X. Li, F.F. Wang, Z.J. Wang, B. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator, which is combined by four-vane RFQ structure and CH-DTL structure. It has higher energy gain rate compared to conventional RFQ, and it is more compact than traditional DTL. In order to research on process exploration and RF parameters of this structure, an aluminium prototype is developed. The cold test of Hybrid RFQ prototype is completed. This paper will present the results and analysis of the test.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO087  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO090 Measurements of the First Room Temperature CH Cavity for MYRRHA at IAP Frankfurt cavity, resonance, status, rfq 193
 
  • K. Kümpel, S. Lamprecht, P. Müller, N.F. Petry, H. Podlech, S. Zimmermann
    IAP, Frankfurt am Main, Germany
 
  Funding: This work has been supported by MYRTE which is funded by the European Commission under Project-ID 662186.
The MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) Project is a planned accelerator driven system (ADS) for the transmutation of long-living radioactive waste. A critical passage for the beam quality and especially for the emittance is the injector, which for the MYRRHA project consists of a 4-Rod RFQ, two Quarter Wave Rebunchers (QWR) and a total of 16 normal conducting CH-DTL cavities. The first installment of the MYRRHA injector in Louvein-La-Neuve (Belgium) will include an ion source, a RFQ, the QWRs and the first seven CH DTL cavities. This paper will report on the status of the low level tests on CHs 1 and 2 as well as on further developments on CHs 8-15.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO090  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO093 A Study of a Cooling Configuration for an OFHC Copper Rebuncher cavity, linac, vacuum, pick-up 200
 
  • O. Mazor, M. Bukai, D. Nusbaum, J. Rodnizki
    Soreq NRC, Yavne, Israel
  • E. Dyunin
    Ariel University, Ariel, Israel
  • G. Ziskind
    Ben-Gurion University in the Negev, Beer Sheva, Israel
 
  Funding: Pazy Fund (Israel Atomic Energy commission) https://pazy.org.il
A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction for the MEBT of SARAF Phase II proton/ deuteron linac. The rebuncher is designed to bunch a 5 mA CW beam at 176 MHz. The required cavity voltage according to beam dynamics evaluation is 150 kV with a beam aperture diameter of 40 mm at a beam energy of 1.3 MeV/u with a Q value of 8000. Considering utilizing this cavity for enhancing the beam energy, the cooling configuration is explored for a cavity voltage of 300 kV, consuming 20 kW dissipated power, at a peak electric field of 16 MV/m, equivalent to the Kilpatrick limit. The electro magnetic study conducted with the CST RF simulation package was reproduced at ANSYS HFSS. The simulated dissipated power along the rebuncher for 20 kW forward power injected through the coupler port with the HFSS driven model were assigned to the ANSYS Fluent model to explore the resulted temperature map. Several evolved cooling configurations were studied, including cooling of the drift tubes. In this configuration the temperature rise along the cavity is in the range of 30 K. A detailed design of the four gap rebuncher is following this study.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO093  
About • paper received ※ 03 September 2018      issue date ※ 18 January 2019  
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MOPO101 LINAC-multitool - an Open Source Java-toolkit linac, cavity, GUI, MMI 217
 
  • M. Schwarz, D. Bade, J. Corbet, H. Podlech
    IAP, Frankfurt am Main, Germany
 
  Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR
Dedicating more precious time to advanced research instead of spending it towards timeconsuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute’s R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO101  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO116 Study on the Control Technology of Large-load Time Constant Accelerator Magnet Power Supply controls, power-supply, collider, quadrupole 239
 
  • X. Wang, F. Long
    IHEP, Beijing, People’s Republic of China
 
  With the increasing application of power supply to industrial system, digital control system has become the mainstream of modern industrial control system. The wide application of digital control system has also led to the rapid development of digital controller. In the field of accelerator magnet power supply, the adoption of digital closed-loop control has become a trend in recent years. Due to the system’s tracking and regulation characteristics, the output current will slowly track the change of the given value in the course of the given current gradually rising. When the system reaches steady state, the disturbance of the system requires the regulator to adjust at a faster rate to correct the impact of the disturbance on the system. Today’s digital power supply control method mainly reflected in when load time constant is large, interference or load change, the power output is prone to overshoot or adjust the time is long, so the tracking and adjustment features cannot be met simultaneously. Therefore, this paper will study the power supply digital control technology for large - load time constant and the independent control method of tracking and regulating.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO116  
About • paper received ※ 21 August 2018      issue date ※ 18 January 2019  
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MOPO119 Design of a Fully Automated Test Bench for Measuring the Field Distribution in Standing Wave Cavity cavity, controls, coupling, network 246
 
  • Y. Lu, G. Feng, T. Hu, J. Jiang, X.D. Tu, Y.Q. Xiong
    HUST, Wuhan, People’s Republic of China
 
  The resonant cavity plays a great role in the linear accelerator. An accurate measurement of the cavity field distribution is very important to design linear accelerators. A fully computer controlled bench for the electric field distribution has been developed in this context. Based on the perturbation theory, the acquisition of the resonant frequency shift is proportional to the square of E (electric field). In order to verify the reliability of the test bench, a standard cylindrical cavity has been tested in this measurement system. The simulation by HFSS (High Frequency Structure Simulator) and the practice will be both presented in this paper. And the result demonstrates that, because of its high concentricity, the automated test bench achieves high precision in measuring the distribution of electric field.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO119  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO127 Recent Results from MICE on Multiple Coulomb Scattering and Energy Loss scattering, emittance, detector, radiation 267
 
  • J.Y. Tang
    IHEP, Beijing, People’s Republic of China
  • J.C. Nugent
    University of Glasgow, Glasgow, United Kingdom
 
  Funding: STFC, DOE, NSF, INFN, CHIPP and more
Multiple Coulomb scattering and energy loss are well known phenomena experienced by charged particles as they traverse a material. However, from recent measurements by the MuScat collaboration, available simulation codes (GEANT4, for example) are known to overestimate the scattering of muons in low Z materials. This is of particular interest to the Muon Ionization Cooling Experiment (MICE) collaboration which has the goal of measuring the reduction of the emittance of a muon beam induced by energy loss in low Z absorbers. MICE took data without magnetic field suitable for multiple scattering measurements in the fall of 2015 with the absorber vessel filled with xenon and in the spring of 2016 using a lithium hydride absorber. In the fall of 2016 MICE took data with magnetic fields on and measured the energy loss of muons in a lithium hydride absorber. These data are all compared with the Bethe-Bloch formula and with the predictions of various models, including the default GEANT4 model.
Submitted by the MICE speakers Bureau. If accepted a member of the collaboration will be selected for the mission
 
poster icon Poster MOPO127 [0.842 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO127  
About • paper received ※ 19 September 2018      issue date ※ 18 January 2019  
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MOPO132 The 7 MeV APF DTL for Proton Therapy DTL, proton, rfq, acceleration 277
 
  • X.C. Xie, D.M. Li, X. Li, Y.H. Pu, J. Qiao, M.H. Zhao, Z.T. Zhao
    SINAP, Shanghai, People’s Republic of China
  • Y.H. Pu, X.C. Xie, F. Yang
    Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China
 
  Funding: This work is fund by Ministry of Science and Technology of the People’s Repulic of China, under Grant Number 2016YFC0105408
A 7MeV alternating phase focused (APF) drift tube linear (DTL) for proton therapy has been designed, and a design code has been developed based on a sinusoidal synchronous phase formula and a linearly increasing electrode voltage assumption. The design procedure includes the radio frequency quadrupole (RFQ) to drift tube linac (DTL) matching, and end-to-end simulation that conducted by Trace Win. Moreover, a cutting method has been performed to correct the integral electric field deviation of RF gaps.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO132  
About • paper received ※ 20 August 2018      issue date ※ 18 January 2019  
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TUPO004 RF Design and Cold Model Measurement of an IH-DTL for HIMM Injector DTL, cavity, linac, quadrupole 329
 
  • H. Du, Q.Y. Kong, Z.S. Li, K.D. Wang, X. Yin
    IMP/CAS, Lanzhou, People’s Republic of China
 
  An interdigital H-mode drift tube linac (IH-DTL) will be constructed as a postinjector linac for the Heavy Ion Medical Machine (HIMM). Its resonant frequency, injec-tion and final energies are determined from beam dynamics and hardware parameters considerations of the entire machine to be 162.5MHz, 600keV/u and 4MeV/u, respectively. The beam duty cycle of the injector linac is less than 0.1% based on the injection requirements of the synchrotron. Beam dynamics and RF structure design and optimize of the IH-DTL has been finished. The maximum surface electric field is less than 2.0-times the Kilpatric limit for accelerating C4+ beam. This IH-DTL contains 42 accelerating gaps and two focusing quadrupole triplets. In order to examine the field distribution of the IH-DTL which reaches the length of 3.17m, an aluminum alloy 1:1 cold model cavity with 4 moveable tuners and 2 empty focusing magnet shell was constructed. The relative intertube-distance errors are less than ±50μm. The measurements show that the gap voltage values can match the CST-MWS simulating results within relative difference of ±3% by adjusting the 4 moveable tuners.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO004  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO010 Muon Acceleration Test with the RFQ Towards the Development of the Muon Linac experiment, acceleration, rfq, diagnostics 342
 
  • R. Kitamura
    University of Tokyo, Tokyo, Japan
  • S. Bae, S. Choi, B. Kim
    SNU, Seoul, Republic of Korea
  • Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, T. Yamazaki
    KEK, Tsukuba, Japan
  • K. Hasegawa, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Iijima, Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Hitachi, Ibaraki, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • S. Li
    The University of Tokyo, Graduate School of Science, Tokyo, Japan
  • M. Otani, N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • G.P. Razuvaev
    Budker INP & NSU, Novosibirsk, Russia
 
  The muon linac to accelerate muons 212 MeV is planned in order to measure the muon dipole moments precisely in the J-PARC. The muon acceleration with a RF accelerator hasn’t been demonstrated yet in the world. Therefore the muon acceleration test with the RFQ as the feasibility test of the muon linac was demonstrated at the Muon D line in the J-PARC MLF. Conventional muons are cooled with producing ultra-slow muons using the muonium production and the ionization laser for the muon linac. However these apparatuses couldn’t be used because of the limitation of the experimental area in the acceleration test. Therefore the conventional muon was converted to the negative muonium ion (Mu-) with less than 2 keV using the thin aluminum foil target as the easy cooling method. The Mu- was finally accelerated to 90 keV using the RFQ. The accelerated Mu- was selected with a diagnostic beam line and identified with the Time-Of-Flight measurement using a MCP detector. The result of the world’s first muon acceleration test with the RFQ will be reported in this presentation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO010  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO023 Preserving Micron Tolerances Through the Assembly Process of an X-band Accelerating Structure cavity, damping, linac, HOM 377
 
  • J. Sauza-Bedolla, N. Catalán Lasheras, A. Grudiev, S. Lebet, E. Rodriguez-Castro, P. Sobrino-Mompean, A. Solodko, K. T. Szypula
    CERN, Geneva, Switzerland
  • H. Bursali
    IZTECH, Izmir, Turkey
 
  The CLIC structures are designed for operating at X-Band, 2π/3 traveling wave mode with a loaded 100 MV/m gradient. Mechanical tolerances, at the submicron level, are required to satisfy the RF design constraints and beam dynamics and are reachable using ultra-precision diamond machining. However, inherent to the manufacturing process, there is a deviation from the nominal specifications and as a result; incorrect cavity dimensions produce a less efficient linac. Moreover, the assembly process increase the difference from the original geometry. As part of a cost and manufacturability optimization of the structures for mass production, this study aims to identify a correlation between frequency deviations and geometrical errors of the individual discs of the accelerating structures caused by the production process. A sensitivity analysis has been carried out to determine the most critical parameters. Cell frequency deviations have been monitored by bead pull measurements before and after bonding. Several accelerating structure prototypes have been tested to determine our assumptions and to assess if the assembly process preserves the tight tolerances achieved by machining.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO023  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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TUPO039 Tests of the Balloon Single Spoke Resonator cavity, multipactoring, linac, TRIUMF 417
 
  • Z.Y. Yao, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, H. Liu, Y. Ma, B. Matheson, B.S. Waraich, Q. Zheng, V. Zvyagintsev
    TRIUMF, Vancouver, Canada
 
  A balloon variant of the single spoke resonator (SSR) has been designed, fabricated and tested. The cavity is the SSR1 prototype for the Rare Isotope Science Project (RISP) in Korea. It is specifically designed to reduce the likelihood of multipacting barriers near the operating point. A systematic multipacting study leads to a novel geometry, a spherical cavity with re-entrant irises and a spoke. Other than eliminating multipacting around operational gradient, the balloon shape also provides competitive RF parameters and robust mechanical structure. Cryostat cold tests demonstrated cavity performance on each design aspect. The cold tests will be reported in this paper.  
slides icon Slides TUPO039 [25.279 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO039  
About • paper received ※ 17 September 2018      issue date ※ 18 January 2019  
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TUPO051 Design Considerations of a Balloon-shaped SSR Superconducting Cavity cavity, distributed, electron, multipactoring 448
 
  • H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, S. H. Park, J.Y. Yoon
    Korea University Sejong Campus, Sejong, Republic of Korea
 
  A single spoke resonator (SSR, β = 0.51 and f = 325 MHz) is being developed at Korea University. It is well-known that a traditional spoke cavity having flat or round end walls has broad multipacting ranges in acceleration gradient, sometimes including operation region. In general, quite long conditioning time is consumed to overcome such multipacting barriers. In this study, we introduce a balloon-shaped SSR superconducting cavity for the multipacting mitigation due to structural simplicity. The electromagnetic modeling of the SSR was made based on the RF parameter optimization. The simulation results show much narrower multipacting bandwidth, compared to those for the traditional spoke cavity. Mechanical analyses with stiffening structure at maximum allowable working pressures indicate acceptable stresses at the SSR cavity wall. In addition, the resonant frequency shifts due to fabrication and processing for cold tests are predicted and power coupling and tuning mechanism are also investigated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO051  
About • paper received ※ 10 September 2018      issue date ※ 18 January 2019  
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TUPO052 Design Study of a Prototype 325MHz RF Power Coupler for Superconducting Cavity cavity, pick-up, superconducting-cavity, resonance 451
 
  • J.Y. Yoon, J.B. Bhang, H.J. Cha, S.W. Jang, E.-S. Kim, K.R. Kim, C.S. Park, S. H. Park
    Korea University Sejong Campus, Sejong, Republic of Korea
  • E. Kako
    KEK, Ibaraki, Japan
  • D.Y. Kim, J. Lee
    Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea
  • I. Shin
    IBS, Daejeon, Republic of Korea
 
  Funding: Korea University (Sejong Campus) in South KOREA
We present design studies of a prototype RF input power coupler, which provides RF powers to 325MHz cavities up to 18.5 kW in CW mode. The prototype power coupler is a coaxial capacitive type with single ceramic window. In order to optimize the RF coupler design, we performed multi-physics simulations, including electromagnetic, thermal, and mechanical analyses.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO052  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO083 Beam Dynamics for the FAIR p-Linac Ladder RFQ rfq, linac, emittance, ion-source 522
 
  • M. Syha, U. Ratzinger, M. Schuett
    IAP, Frankfurt am Main, Germany
 
  After the successful measurements with a 0.8 m prototype a 3.3 m Ladder-RFQ is under construction at IAP, Goethe University Frankfurt. It is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the p-Linac at FAIR. Along the acceleration section modulation parameter, aperture and synchronous phase all course (quasi-)linear, which differentiates this design approach from other designs developed at IAP. The ratio of transversal vane curvature radius to mid-cell radial aperture as well as the vane radius itself are constant, which favors a flat voltage distribution along the RFQ. This was verified by implantation of the modulated vane geometry into MWS-CST RF field simulations. The development of adequate beam dynamics was done in close collaboration with the IAP resonator design team. The Los Alamos RFQGen-code was used for the RFQ design and the beam dynamics simulations.  
poster icon Poster TUPO083 [0.932 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO083  
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TUPO085 Modelling of Beam Parameters of RF Linac for GBS-ELI-NP linac, quadrupole, gun, cathode 528
 
  • P.S. Tracz
    IFIN-HH, Bucharest - Magurele, Romania
 
  The Gamma Beam System at the ELI-NP (Extreme Light Infrastructure - Nuclear Physics) currently being constructed in Magurele/Bucharest, Romania will be a high-brilliance advanced source of gamma rays based on laser Compton back-scattering. For a successful operation of the GBS a high brightness low emittance electron beam is of crucial importance. The warm RF linac is designed in two stages - one with the beam up to 300 MeV, and another one about 720 MeV. The S-band photo-injector is combined with a C-band linac. The beam is transported by transfer lines to the interaction points. In this paper we report the results of computer simulations of the electron beam transport in the low energy linac and transfer line up to the low energy interaction point (IP1). The simulation model makes it possible to predict the beam parameters to be recuperated in case of failure of any magnetic or accelerating elements as well as it enables to determine the optimal parameters of replaced components. It will be used for the development of the Gamma Beam System in the future.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO085  
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TUPO092 Beam Dynamics and Collimation Following MAGIX at MESA* target, electron, scattering, radiation 540
 
  • B. Ledroit, K. Aulenbacher
    IKP, Mainz, Germany
 
  Funding: * Supported by the DFG through GRK 2128
The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing operation in energy-recovery linac (ERL) mode, where beam energy is recovered by decelerating the beam in linac cryomodules and transferring kinetic energy to the RF. The ERL mode provides the opportunity to operate experiments at peak energy with thin targets, combining high luminosities typical for storage rings and high beam brightness typical for linacs. The MESA Internal Gas Target Experiment (MAGIX) aims to operate jet targets at high luminosities with different gases up to Xenon. As scattering effects in the beam rise with the atomic number, investigations on the impact of the target on beam dynamics and beam losses are required for machine safety. The goal of this work is to understand target induced halo, track halo particles through downstream sections and protect the machine with a suitable collimation system and shielding from direct and indirect damage through beam losses and radiation. The present status of the investigations is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO092  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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TUPO093 Excitation of Millimeter Wavelength Cavity Structure cavity, gun, cathode, focusing 543
 
  • M.V. Arsentyeva
    NSU, Novosibirsk, Russia
  • A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
 
  Excitation of millimeter wavelength cavity structure In this work excitation of W-band structure is studied. The structure consists of cylindrical cavities with the operating frequency of about 96 GHz. We plan to excite the structure by short bunches from the photocathode RF gun. In order to choose structure geometry and beam duration, we performed estimations and simulations; induced voltage was also estimated. Taking into account feasible parameters of the photocathode RF gun such as beam size and emittance, we studied exciting beam transverse dynamics to define its other characteristics (energy and charge). To lead the beam from the whole structure, focusing is needed. After estimation of required magnetic field, we considered possibility of focusing with help of permanent magnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO093  
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TUPO095 Beam Loading with the First Rebuncher of Spiral2, First Measurements cavity, experiment, controls, linac 546
 
  • M. Lechartier, R. Ferdinand, J.F. Leyge
    GANIL, Caen, France
 
  In the SPI2 project the middle energy line (LME) is equiped with a radio frequency qupole and three Rebunchers. The subject of this article is to measure and characterise the effect of the beam loading on the first Rebuncher cavity.  
poster icon Poster TUPO095 [1.146 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO095  
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TUPO109 Electron Cloud Estimates for the Jefferson Lab EIC electron, sextupole, proton, dipole 563
 
  • K.E. Deitrick, V.S. Morozov, T. Satogata
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In this work, we present preliminary estimates for electron cloud build-up and saturation for the ion ring of the Jefferson Laboratory Electron-Ion Collider (JLEIC) currently under development. Using the baseline ion ring design, we study the impact of various operational parameters on the behavior of the electron cloud for a 100 GeV proton beam, including estimated tune shifts.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO109  
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TUPO113 Beam Dynamics Studies Through Dielectric THz Accelerating Structures GUI, vacuum, accelerating-gradient, linac 569
 
  • R. Apsimon, G. Burt, A.L. Healy, S.P. Jamison
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • R.B. Appleby, E.J.H. Smith
    UMAN, Manchester, United Kingdom
  • A. Latina
    CERN, Geneva, Switzerland
 
  As conventional RF accelerating schemes approach the physical limit of accelerating gradient, the accelerator community is increasingly looking at novel accelerating techniques to overcome these limitations. Moving from the RF to the THz frequency range, higher acceleration gradients of high energy beams can be achieved in compact structures. Beam dynamics studies are crucial as part of the design of novel accelerating structures to maximise the output beam current as well as the accelerating gradient. In this paper we present beam dynamics simulations through dielectric lined waveguide structures using novel techniques to simulate broadband signals for particle tracking studies in RF-Track. The beam parameters through the structure are optimised and we study the dynamics of general broadband accelerating structures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO113  
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TUPO120 The Study of the Length and Shape of Beam in a High Power Electron Accelerator electron, radiation, extraction, industrial-accelerators 584
 
  • M. Salehi, F. Abbasi Davani, B.G. Ghasemi
    Shahid Beheshti University, Tehran, Iran
  • F. Ghasemi, A.P. Poursaleh
    NSTRI, Tehran, Iran
 
  The output beam of a high-power linear accelerator, used for industrial purposes, is irradiated on products and scanning them. In order to improve the dosimetry of radiation which products received and to prevent loss of the attacked- beams to the edge of products, the exact evaluation of scanning length is necessary . One of the other challenges of the scanning beam is the lack of uniformity in dosimetry of received radiation . The scanning beam does not collide in parallel to the products, which is also a challenge to accelerator efficiency. To improve dosimetry of received radiation, the use of trajectory correction magnets is suggested. These magnets correct the beams that do not scan in parallel. Also, using the Monte Carlo code, the dosing rate of received radiation to products is simulated and compared in two non-uniform and uniform modes (corrected by trajectory correction magnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO120  
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TH1A03 High Brightness Electron Beams from Plasma-based Acceleration plasma, electron, acceleration, FEL 637
 
  • A. Marocchino, A. Biagioni, E. Brentegani, E. Chiadroni, M. Ferrario, F. Filippi, A. Giribono, R. Pompili, A.R. Rossi
    INFN/LNF, Frascati (Roma), Italy
  • A. Bacci
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • V. Petrillo
    Universita’ degli Studi di Milano, Milano, Italy
 
  Funding: INFN-CNAF and CINECA for high performance computing resources. European Union Horizon 2020 programme N. 53782.
Plasma Wakefield acceleration is a promising new acceleration techniques that profit by a charged bunch, e.g. an electron bunch, to break the neutrality of a plasma channel to produce a wake where a trailing bunch is eventually accelerated. The quest to achieve extreme gradient conserving high brightness has prompted to a variety of new approaches and techniques. Most of the proposed schemes are however limited to the only plasma channel, assuming in the vast majority of cases, ideal scenarios (e.g. ideal bi-gaussian bunches and uniform density plasma channels). Realistic start-to-end simulations, from the photo-cathode to FEL via a high gradient, emittance and energy spread preserving plasma section, are mandatory for paving the way towards plasma-based user facilities.
 
slides icon Slides TH1A03 [25.814 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1A03  
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TH1A05 Jitter Study for the APS Linac Photo-injector Beam laser, timing, linac, experiment 647
 
  • D. Hui, M. Borland, J.M. Byrd, Y. Sun
    ANL, Argonne, Illinois, USA
 
  Funding: *Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Linac photo-injector can deliver high brightness electron beams to the Linac Extension Area (LEA) for beam experiments such as TESSA (Tapering Enhanced Stimulated Superradiant Amplification). Beam jitter in the device-under-test (DUT) area of the LEA can adversely affect the quality of data for such experiments. In this paper, a start-to-end simulation of jitter is studied. Sources of jitter include photo-cathode drive-laser arrival time, laser energy, and RF phases and voltages of the photo-cathode gun and accelerating cavities. It is found that at the DUT the relative mean energy jitter is the most significant concern, and that improvements in the Linac RF voltage stability can help to reduce it. RMS energy spread are more sensitive to the laser timing and charge jitter. The laser timing jitter itself can be compressed by the magnetic chicane by a factor of 5.6.
 
slides icon Slides TH1A05 [4.377 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TH1A05  
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THPO003 L-band Resonant Ring for Testing RF Windows for ILC collider, linear-collider, coupling, klystron 679
 
  • B. Du, N. Liu
    Sokendai - Hayama, Hayama, Japan
  • T. Matsumoto, S. Michizono, T. Miura, F. Qiu
    KEK, Ibaraki, Japan
  • T. Matsumoto, T. Miura, F. Qiu
    Sokendai, Ibaraki, Japan
 
  A resonant ring is widely used for the breakdown test of RF components under high power. It can reach power gain of more than 10dB, which is limited by the attenua-tion of the ring. An L-band resonant ring is constructed for testing RF components of International Linear Collid-er (ILC) which is based on an RF frequency of 1.3GHz. The target of the high power test is 5 MW. We have fin-ished the test of an input power of 500 W using a solid state amplifier, and the principle of the resonant ring is verified. The resonant ring is tuned to an optimal condi-tion, which is preparation for high power operation. This paper details the principle, construction, and test of the L-band resonant ring.  
poster icon Poster THPO003 [2.301 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO003  
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THPO005 High Aspect Ratio Beam Generation with the Phase-space Rotation Technique for Linear Colliders emittance, gun, collider, linear-collider 685
 
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto
    KEK, Ibaraki, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • J.G. Power
    ANL, Argonne, Illinois, USA
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  • M. Washio
    RISE, Tokyo, Japan
  • H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Funding: This work is partly supported by Grant-in-Aid for Scientific Research (B) and US-Japan Science and Technology Cooperation Program in High Energy Physics.
Linear colliders is the only way to realize e+ e collision at higher energy beyond the limit of ring colliders by the huge synchrotron radiation energy loss. In the linear collider, the beam current should be much smaller comparing to the ring collider to save the required electricity. A way to realize an enough luminosity with the small beam current and less energy spread by Beamstrahlung, is collision in flat beam. This high aspect ratio beam can be made by phase-space rotation technique instead of the conventional way with DR (Damping Ring). We present a simulation of this technique and pilot experiments at KEK-STF and ANL WFA.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO005  
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THPO007 MESA - Status of the Implementation of the MicroTCA.4-based LLRF Control System cavity, controls, LLRF, experiment 691
 
  • J.N. Bai, K. Aulenbacher, J. Diefenbach, F. Fichtner
    IKP, Mainz, Germany
  • P. Echevarria
    HZB, Berlin, Germany
  • R.G. Heine
    KPH, Mainz, Germany
 
  MESA at the Institut für Kernphysik (KPH) at Johannes Gutenberg-Universität Mainz is a multi-turn energy recovery linac (ERL), aiming to serve as user facility for particle physics experiments. The RF-accelerating systems of MESA consist of four 9-cell TESLA superconducting cavities, four normal conducting (NC) pre-accelerator cavities, two NC buncher cavities and two NC chopper cavities. They operate in continuous wave (CW) mode. In order to control the radio frequency (RF) amplitude and phase within the 12 cavities with the required accuracy and stability in the range of better than 0.01% and 0.01°, the MicroTCA.4 based digital low-level RF (LLRF) control system based on the development at DESY, Hamburg will be well adapted for the MESA cavities. In this paper, we describe the theoretical modelling of superconducting cavity and PID controller in SIMULINK which is useful to find the suitable control parameter for the PID controller and to predict the system performance. The progress to date of the implementation and tests of the LLRF system at MESA will also be presented.  
poster icon Poster THPO007 [1.274 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO007  
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THPO012 Once Recirculating Energy Recovery Linac Operation of S-DALINAC* linac, operation, acceleration, recirculation 710
 
  • M. Arnold, J. Birkhan, J. Pforr, N. Pietralla, F. Schließmann, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
 
  Funding: *Work supported by DFG through GRK 2128 and INST163/383-1/FUGG
Since 1991 the superconducting S-DALINAC is running in recirculating operation. It was built in a twice recirculating layout. A third recirculation beam line was added in 2015/2016 as an upgrade. The new recirculation beam line is installed in-between the two existing beam lines. It houses a path length adjustment system capable of changing the length of the orbit for recirculation by up to 10 cm corresponding to the RF wave length at the operation frequency of 3 GHz and consequently to a freedom of RF phase adjustment by 360°. The new beam line can, thus, be utilized for an accelerating operation or, if the change in phase is set to 180°, for an energy recovery linac (ERL) operation. In August 2017 the S-DALINAC was first operated in once recirculating ERL mode and became the first running ERL in Germany. Different aspects of this ERL run have been observed and were evaluated. The layout of the S-DALINAC allows a once or twice recirculating ERL mode. Beam dynamics simulations for both modes have been conducted or are currently under investigation. This contribution will discuss the once recirculating ERL operation, its results, and future plans concerning ERL measurements.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO012  
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THPO026 The Multi-physics Analysis of Dual-beam Drift Tube Linac DTL, cavity, operation, linac 735
 
  • T. He, L. Lu, W. Ma, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  The DB-DTL prototype is proposed to validate the fea-sibility of multi-beam accelerator in middle energy region. The main parameters are listed in Table.1. The DB-DTL will operate as pulse injector with the capacity of accelerating proton from 0.56 MeV to 2.5 MeV. The 35.83 kW normalized power dissipation of DB-DTL dis-sipated on the cavity internal surface will heat the cavity and cause cavity temperature rise and structural defor-mation, which will lead to resonant frequency shifting. The cooling water takes away the power to resolve this problem. In this paper, detailed multi-physics field simu-lation of DB-DTL is performed by using ANSYS multi-physics, which is a coupled electromagnetic, thermal and structural analysis.  
poster icon Poster THPO026 [0.759 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO026  
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THPO029 Quality Factor and Power Loss of the CSNS DTL cavity, DTL, operation, linac 741
 
  • P.H. Qu, M.X. Fan, A.H. Li, B. Li, J. Peng, Y. Wang, X.L. Wu
    CSNS, Guangdong Province, People’s Republic of China
  • Q. Chen, K.Y. Gong, H.C. Liu
    IHEP, Beijing, People’s Republic of China
 
  An Alvarez-type Drift tube linac (DTL) was utilized to accelerate the H ion beam of up to 15mA peak current from 3 to 80MeV of China Spallation neutron source (CSNS). For ease of manufacturing and measurement, the CSNS DTL was divided into four independent cavities. The Q factor of four cavities were given, including the measurement results of low-power[1] and high-power[2], and several reasons for the low Q factor of the cavity in the measurement process were analysed. During the op-eration of the DTL, the frequent alarm of the water flow switch causes the power of the cavity to fall to 0. Esti-mate the power loss of each component, under the cir-cumstances of ensuring adequate water flow, reduce the alarm threshold of the water flow switch of some compo-nents to improve the stability of the system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO029  
About • paper received ※ 22 August 2018      issue date ※ 18 January 2019  
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THPO035 Tuning and Low Power Test of the 325 MHz IH-DTL at Tsinghua University DTL, proton, cavity, linac 759
 
  • R. Tang, C.T. Du, X. Guan, Y. Lei, P.F. Ma, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, W.B. Ye, H.Y. Zhang, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • J. Li
    NUCTECH, Beijing, People’s Republic of China
 
  An interdigital H-mode drift tube linac (IH-DTL), which accelerates proton beam from 3 MeV to 7 MeV has been designed and assembled at Tsinghua University. There are 8 plungers in the 1 m tank and one co-axial coupler is used to feed the power. The frequency is tuned to 325 MHz. The field distribution is measured by the bead perturbation method. Finally, the gap voltage error has been tuned to be smaller than ±3.0%, which satisfies the design requirement. The Q factor of the tank is 7000 while the power dissipation is 244 kW. Details of the low power test is presented.  
poster icon Poster THPO035 [1.268 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO035  
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THPO042 An Optimization Method of the Nose-cone Buncher Cavity cavity, proton, radiation, bunching 778
 
  • W.L. Liu, P.T. Cong, Z.M. Wang
    NINT, Shannxi, People’s Republic of China
  • H. Jiang, S.X. Zheng
    TUB, Beijing, People’s Republic of China
 
  The nose-cone buncher cavity is widely used on proton accelerators. It’s important to properly optimize the cavity geometry for fine RF performance. Howev-er, currently the optimization is usually carried out manually and the criteria are not objective enough. In this paper, an optimization method using the multi-objective, multi-variable optimization approach is presented. The geometry and RF parameters are con-sidered as the variables and objectives respectively. The goal function is defined as the weighted sum of multiple RF parameters. The multi-variable functions are approximately derived from the single-variable functions based on electromagnetic simulation. And an optimization code is developed accordingly which has been applied to the XiPAF debuncher optimization.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO042  
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THPO049 Field Tuning of a Radio-frequency Quadrupole Using Full 3D Modeling rfq, cavity, insertion, linac 798
 
  • T. Morishita, K. Hasegawa, Y. Kondo, H. Oguri
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • M. Otani
    KEK, Ibaraki, Japan
 
  The radio-frequency quadrupole linac (RFQ) is operating in the frontend of the J-PARC linac to accelerates 50 mA negative hydrogen beams from 0.05 MeV to 3 MeV. As a backup, the spare RFQ has been fabricated in 2018. The vane-voltage ramping is adopted to improve the acceleration efficiency so that the cross-sectional shape is adjusted longitudinally to produce the designed voltage distribution. Then, the three-dimensional cavity models including modulations and cutbacks were created in CST Micro-Wave Studio. The vane-base widths and cutback depths were optimized to produce the desired vane-voltage distribution. In the final tuning, the heights of the stub turners were also determined based on the tuner responses obtained from the full 3D models. In this paper, the detailed design process of the cavity dimensions and the result of the low-power measurements are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO049  
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THPO050 Research on the New Cavity Structure of RFQ Accelerator With Bent Vanes at IMP rfq, cavity, impedance, ECR 802
 
  • L. Yang, T. He, Y. He, C.X. Li, L. Lu, L.P. Sun, C.C. Xing
    IMP/CAS, Lanzhou, People’s Republic of China
  • L. Yang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  A new cavity structure of RFQ accelerator with bent vanes is proposed to meet the miniaturization requirement of low frequency heavy ion accelerators at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The new structure has a downsized cross section by bending vanes while keeping a certain vane lengths. It also possesses the advantages of simple cooling structure and high power efficient when used in low frequency. The new structure has obvious advantages in reducing manufacturing difficulty of cavity, cutting down project cost, enhancing facility reliability and stability.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO050  
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THPO051 The Multi-physics Analysis of LEAF RFQ rfq, cavity, heavy-ion, beam-transport 805
 
  • X.B. Xu, T. He, Y. He, C.X. Li, L. Lu, W. Ma, A. Shi, L.B. Shi, L.P. Sun, C.C. Xing, L. Yang, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
 
  The 81.25 MHz CW RFQ is designed to accelerate heavy ions with Q/A from 1/7 to 1/2 at 0.5 MeV/u for the Low Energy Accelerator Facility (LEAF) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). The four-vane RFQ consists of six mod-ules with a total length of 5.95 meters, For the CW oper-ating mode, thermal management will be a very important issue, Therefore a multi-physics analysis is necessary to ensure that the cavity can stably operate at the high RF power . The multi-physics analysis process includes RF electromagnetic analysis, thermal analysis, mechanical analysis, and the frequency shift, the cooling water system is used for frequency tunning by the temperature adjustment, and also analyze RFQ undercuts, fixed tuners, and pi-mode rods, the results show that the thermal and structural design of this RFQ is reasonable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO051  
About • paper received ※ 17 September 2018      issue date ※ 18 January 2019  
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THPO057 Redesign of CERN Linac3 RFQ for Lead 29+ rfq, linac, emittance, cavity 818
 
  • S. Benedetti, G. Bellodi, J.-B. Lallement, A.M. Lombardi
    CERN, Geneva, Switzerland
 
  CERN Linac3 is at the start of the CERN Heavy Ion Facility, providing 4.2 MeV/u ion beams to the Low Energy Ion Ring (LEIR). It mostly accelerates 208Pb29+, though in recent years runs were performed with 40Ar11+ and 129Xe22+, in view of the increasing interest of the physics community towards lighter ions experiments. In the framework of the LHC Injectors Upgrade (LIU) project, measurements and beam dynamics simulations showed that a transmission bottleneck of Linac3 is represented by the RFQ. As this accelerator was originally designed for 208Pb25+, the lower beam rigidity of the heavy ions currently in use and planned for the future permits a redesign of the RFQ optics aimed at increasing its transverse acceptance, and thus the transmitted beam current. A study of this has been performed, and the methodology adopted and the results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO057  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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THPO058 RF Design of a High-frequency RFQ Linac for PIXE Analysis rfq, cavity, linac, proton 822
 
  • H.W. Pommerenke, A. Bilton, A. Grudiev, A.M. Lombardi, S.J. Mathot, E. Montesinos, M.A. Timmins, M. Vretenar
    CERN, Geneva, Switzerland
  • H.W. Pommerenke, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
 
  Funding: This work has been sponsored by the Wolfgang Gentner Program of the German Federal Ministry of Education and Research (grant no. 05E12CHA).
Protons with an energy of few MeV are commonly used for Ion Beam Analysis of materials, in particular with the Proton Induced X-ray Emission technique (PIXE). Because of its non-damaging character, PIXE is used in a variety of fields, in particular for the diagnosis of cultural heritage artwork. A compact accelerator based on a high frequency RFQ (Radio Frequency Quadrupole) linac has been designed and is being built at CERN. The length of the RFQ is only one meter and it allows the acceleration of a proton beam up to an energy of 2 MeV. The complete system is conceived to be transportable, allowing PIXE analysis almost anywhere. This paper covers the RF design of the compact RFQ operating at 750 MHz. We present general accelerator parameters and the current state of the RF design, which includes RFQ geometry and coupler design, thermal simulation and first particle tracking results.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO058  
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THPO060 First RF Measurements of the 325 MHz Ladder RFQ rfq, linac, proton, GUI 826
 
  • M. Schuett, U. Ratzinger, M. Syha
    IAP, Frankfurt am Main, Germany
 
  Funding: BMBF 05P15RFRBA
Based on the positive results of the unmodulated 325 MHz Ladder-RFQ prototype from 2013 to 2016, we developed and designed a modulated 3.3 m Ladder-RFQ*. The unmodulated prototype Ladder-RFQ features a very constant voltage along the axis. The RFQ was high power tested at the GSI test stand. It accepted 3 times the RF power level needed in operation**. That level corresponds to a Kilpatrick factor of 3.1 with a pulse length of 200 µs. The 325 MHz RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the proton linac within the FAIR project. This particular high frequency creates difficulties for a 4-ROD type RFQ, which triggered the development of a Ladder RFQ with its higher symmetry. The results of the unmodulated prototype have shown, that the Ladder-RFQ is a suitable candidate for that frequency. For the present design duty cycles are feasible up to 5%. The basic design and tendering of the RFQ has been successfully completed in 2016. Manufacturing will be completed in August 2018. We will show the the finalization of manufacturing as well as first low level RF measurements of the Ladder RFQ.
*Journal of Physics: Conf. Series 874 (2017) 012048
**Proceedings of LINAC2016, East Lansing, TUPLR053
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO060  
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THPO061 Beam Characterization of the MYRRHA-RFQ rfq, diagnostics, proton, injection 830
 
  • P.P. Schneider, M. Droba, O. Meusel, H. Podlech, A. Schempp
    IAP, Frankfurt am Main, Germany
  • D. Noll
    CERN, Geneva, Switzerland
 
  Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) #05P15RFRBA and HORIZON 2020 for the MYRRHA project #662186 and HIC for FAIR.
The Linear Accelerator for the MYRRHA project* is under construction. In a first step the linac up to 100 MeV will be realized. The LEBT section has been set into operation in Belgium and the RFQ is installed in summer 2018. A system to analyze the ion beam consisting of a slit-grid emittance scanner, a beam dump and a momentum spectrometer, called diagnostic train descripted in **, will be set on the rails to characterize the beam at the RFQ injection point. The results will be used to adjust the optimal matching for the RFQ. After the measurements downstream the LEBT, the diagnostic train begins its journey along the beam line and at the first station the RFQ is installed. The accelerated beam of the RFQ is then analyzed and optimized. In addition to optimization of transmission the artificial production of beam offsets in the LEBT is of special interest. These will be measured at the injection point to estimate the range of possible offsets. In the following measurements these offsets will be used to study the influence of the offsets on the RFQ performance. Furthermore, the RFQ parameters are varied to see their influence on the beam transport, transmission and beam quality.
* H.Aı̈t Abderrahim et al. "MYRRHA: A multipurpose accelerator driven system for research & development", 2001
** 1st Experiments at the CW-Operated RFQ for Intense Proton Beams, LINAC16
 
poster icon Poster THPO061 [4.610 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO061  
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THPO062 IFMIF/EVEDA RFQ Preliminary Beam Characterization rfq, MMI, proton, operation 834
 
  • E. Fagotti, L. Antoniazzi, L. Bellan, M. Comunian, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo
    INFN/LNL, Legnaro (PD), Italy
  • T. Akagi, K. Kondo, K. Sakamoto, T. Shinya, M. Sugimoto
    QST, Aomori, Japan
  • P. Cara
    IFMIF/EVEDA, Rokkasho, Japan
  • H. Dzitko, I.M. Moya
    F4E, Germany
  • R. Heidinger, A. Marqueta
    Fusion for Energy, Garching, Germany
  • I. Podadera
    CIEMAT, Madrid, Spain
 
  The IFMIF/EVEDA RFQ is the longest and powerful operated. Therefore, it requires a careful characterization from several aspects: beam dynamics, RF, mechanics, installation and commissioning. Due to the very large power handling, the preliminary beam operation was decided to be performed with a low proton beam current at one half of the voltage needed for deuteron accelera-tion, i.e. from 8 mA to 30 mA at 2.5 MeV in pulsed mode, with respect to the nominal 130-mA deuteron beam at 5 MeV in CW. In this framework, it will be presented the characterization of the RFQ in terms of simulation and measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO062  
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THPO076 Multiphysics Design Studies of a Superconducting Quarter-wave Resonator at Peking University cavity, multipactoring, SRF, heavy-ion 863
 
  • M. Chen, S. Chen, A.Q. Cheng, W. Cheng, J.K. Hao, S.W. Quan, F. Zhu
    PKU, Beijing, People’s Republic of China
 
  Funding: This work is supported by National Basic Research Program (2014CB845504)
A 81.25MHz, geometric β=0.046 quarter-wave resonator has been designed and analysed at Peking University. This paper mainly presents the multi-physics studies of this cavity, include electromagnetic design, mechanical analysis and multipacting simulation, to predict its behaviour under practical operating process. Various transverse vibration modes of inner conductor were found under different fixed conditions and an asymmetric shorting plate was adopted to avoid high possibility of multipacting
"quarter-wave resonator"
"multiphysics"
"multipacting"
"frequency detuning"
"stiffening design"
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO076  
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THPO080 Design Validation of a Chopping and Deflecting System for the High Current Injector at IUAC experiment, vacuum, diagnostics, power-supply 869
 
  • S. Kedia, R. Ahuja, R. Kumar, R. Mehta
    IUAC, New Delhi, India
 
  A chopping and deflecting system has been designed and developed to provide the chopped beam with various repetition rates at the IUAC experimental facilities. It consists of four pairs of deflecting plates with increasing gap from 15 mm to 21 mm to maximize the effective electric field, preserve the beam emittance and to maximize the transmission efficiency within the same voltage conditions. The design of CDS has been validated with various simulation codes like CST MWS, Solid Works, Python and TRACE 3D. The deflecting plates have been fabricated, and assembled with in the design accuracy of 100 microns. A vacuum chamber has been designed and fabricated to incorporate the deflector plate assembly. The CDS unit has been installed in the Low Energy Ion Beam Facility at the IUAC to validate the design value of ion beam deflection. A slit has been installed to cut the deflected charge particles. Since the pulse power electronics required for chopping is presently under design we have used DC voltage across the four pairs of deflecting plates and amount of deflection was measured accordingly. The design, development, and DC beam test will be discussed in the article.  
poster icon Poster THPO080 [2.037 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO080  
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THPO082 Physical Design of a Rectangular RF Deflector for Ultrashort Bunch Length Measurement cavity, electron, FEL, coupling 872
 
  • J. Bai, Q.S. Chen, K. Fan
    HUST, Wuhan, People’s Republic of China
 
  Cylindrical deflectors which are now widely used for bunch length measurement suffer from the degeneration of polarization, while rectangular deflectors can separate polarization mode easily. This paper is focused on the study of a one-cell rectangular deflector, which is considerably different from cylindrical structure or multi-cell structure. A one-cell structure is free of π mode restriction and can achieve higher deflection efficiency per unit length. The proposed scheme is expected to achieve time resolution better than 200fs with the driving power less than 1MW. Cavity optimization and beam dynamic simulation are introduced in this paper.  
poster icon Poster THPO082 [0.484 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO082  
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THPO084 BPM Time of Flight Measurements for Setting-up the RF Cavities of the CERN Linac4 linac, cavity, DTL, electron 879
 
  • M. Bozzolan
    CERN, Geneva, Switzerland
 
  The newly constructed H LINAC4 at CERN has recently completed its first extended reliability run. It is equipped with Beam Position Monitors (BPMs) based on shorted-stripline pick-up electrodes to measure both position and Time of Flight (ToF). The ToF, in turn used to calculate the kinetic energy of the beam, is determined through signal phase shift measurements between pairs of BPMs. ToF measurements are performed by scanning of the phase of the RF injected into the cavities to find the nominal RF settings for optimal beam acceleration. This paper focuses on the technical aspects of the ToF measurement as well as on the results obtained during beam commissioning and their comparison with beam dynamics simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO084  
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THPO090 The Analysis of Module Failure in High Solid-state Amplifier for High Current RFQ scattering, experiment, rfq, cavity 886
 
  • L.P. Sun, Y. He, G. Huang, C.X. Li, L. Lu, A. Shi, L.B. Shi, X.B. Xu, H.W. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
 
  New accelerator RF system was upgraded to the solid-state amplifier in ADS project due to its stable, sustainable and reliable. Until now, newest 80kW SSA was adopted in IMP, operating in 162.5MHz, and over 120 power modules were combined through several synthesizers for 80kW output. but since too many modules were optimized for amplitude and phase in the same time, one or some failure of circulator will lead to injure of whole RF system, when wavelength meets a specific condition, injure would turn out severe accident and heavy loss. In this paper, analyzing and simulating the multi-level synthetic matrix was the important method for ADS accident happened in June 20. 2017, the failure simulated results for RF amplify links under the specific circumstances also was presented simultaneously.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO090  
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THPO096 Design Study of a High Efficiency Klystron for SuperKEKB Linac klystron, cavity, gun, linac 901
 
  • F. Qiu, S. Fukuda, S. Matsumoto, T. Matsumoto, T. Miura, T. Natsui
    KEK, Ibaraki, Japan
 
  The injector linear accelerator (linac) for the SuperKEKB particle accelerator requires a higher efficiency klystron than the currently used 50 MW, S-band, pulsed unit (PV3050/E3730), which operates at the same voltage, to increase the power redundancy. The efficiency is expected to improve from the currently observed 45% to more than 60%. We propose a type of high efficiency klystron using novel bunching mechanisms. The 1-D disk model based code is used for preliminary optimization of the tube parameters; these parameters are further checked by 2-D codes known as field charge interaction (FCI) and MAGIC. In this paper, the design consideration of the high efficiency klystron is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO096  
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THPO100 Development of a 1.5 GHz High-power CW Magnetron for SRF Accelerator cavity, electron, SRF, coupling 908
 
  • L. Wenliang
    College of Engineering and Applied Sciences for Nanjing University, Nanjing, People’s Republic of China
  • S. An, Y.J. Ke, S. Lingbin, Z. Pengjiao, L. Youchun, L. Zhao, B.Z. Zhou
    PLAI, Nanjing, People’s Republic of China
  • J.Z. Li, L.P. Zhang, Hou, R. Rui
    ADS, Jiangsu Province, People’s Republic of China
 
  An 1.5 GHz, 13.5 kW CW high-power magnetron for a superconducting RF accelerator has been developed by Andesun Technology Group Co., Ltd. with Nanjing Sanle Electronic Information Industry Group Co., Ltd., in order to replace the klystron, that could reduce the power source cost to about one-third. The cavity, output power antenna and coupling door-nob have been optimized by using CST Studio. Testing results have shown that the resonance frequency and output power have met the requirements, and the efficiency of the magnetron is higher that 78.45%.  
poster icon Poster THPO100 [0.574 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO100  
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THPO102 Design Studies of Output Window for CEPC Klystron klystron, multipactoring, electron, operation 911
 
  • Z.J. Lu, Y.L. Chi, S. Fukuda, G. Pei, S. Pei, S.C. Wang, O. Xiao, U. N. Zaib, Z.S. Zhou
    IHEP, Beijing, People’s Republic of China
  • S. Fukuda
    KEK, Ibaraki, Japan
 
  A high power and high efficiency klystron of the 650MHz, 800kW CW klystron for the Circular Electron Positron Collider (CEPC) is designed and developed at IHEP. This paper presents the design and simulation for the high power coaxial window for it. Plan of the hot test (high power testing before installing to the klystron) are also described. Simulation software of CST, ANSYS and Multipac 2.1 are used for design of window microwave structure, thermal analysis and multipacting effects. We obtained the good simulation results successively; the coaxial window S-parameter analysis, has revealed a low reflection at the operating frequency of 650 MHz. The thermal simulation shows a good temperature distribution under the cw 800kW propagation; maximum temperature has been found to be 33 °C at ceramic with water cooling in the inner and outer conductor. The multipacting at the window is possible source of the failure and it is shown that multipacting has less chance to be happened on the surface of ceramic.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO102  
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THPO107 High Power Coupler R&D for Superconducting CH-cavities cavity, linac, Windows, heavy-ion 920
 
  • J. List, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
    HIM, Mainz, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • W.A. Barth, M. Heilmann, J. Salvatore, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • M. Basten, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  The upcoming demands of the future research programs at GSI exceed the technical opportunities of the existing UNIversal Linear ACcelerator (UNILAC). Besides, the machine will be exclusively used as an injector for FAIR (Facility for Antiproton and Ion Research) providing high power heavy ion beams at a low repetition rate for injection into the synchrotron. A new dedicated superconducting (sc) continuous wave (cw) Linac is crucial to keep the research program competitive. The first part of the cw-linac, comprising a 217 MHz multi gap Crossbar-H-mode (CH) cavity surrounded by two sc solenoids inside a cryostat, already served as a prototype demonstrating reliable operability in a realistic accelerator environment. A sufficient high power RF-coupling concept is needed to feed this newly developed cw-RF cavity with up to 5 kW of RF-power. A high power coupler test stand was recently built to provide for a testing environment; further upgrade measures of this test area are foreseen. This contribution deals with the recent coupler R&D for the demonstrator set up. Besides simulations of thermal losses at the coupler (inside the RF-cavity) will be shown as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO107  
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THPO109 A New Spherical Pulse Compressor Working with Degenerated "Whispering Gallery" Mode cavity, coupling, GUI, focusing 928
 
  • Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao
    SINAP, Shanghai, People’s Republic of China
  • A. Grudiev
    CERN, Geneva, Switzerland
 
  CLIC is focusing on the Compact Linear Collider. To obtain a relatively high accelerating gradient, CLIC utilizes Pulse Compressors to increase the input power of accelerators. This work is to make an alternative design for CLIC pulse compression scheme. There are several kinds of pulse compressor: SLED, BOC, SLED-Ⅱ, spherical pulse compressor and so on. Usually, a spherical cavity, including BOC, can offer a higher Q factor compared with a cylindrical cavity. This design utilizes a spherical cavity working with degenerated Whispering Gallery mode.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO109  
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THPO111 The Test of RF Breakdowns of CPHS RFQ rfq, pick-up, linac, proton 931
 
  • W.B. Ye, C. Cheng, X. Guan, J. Shi, X.W. Wang, Q.Z. Xing, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • M.C. Wang
    NINT, Shannxi, People’s Republic of China
 
  The high accelerating gradient is significant for a compact linear accelerator, and RF breakdowns is a limitation for the high gradient. This work aims to research RF breakdowns of a 325MHz proton Radio Frequency Quadrupole (RFQ) accelerator of the Compact Pulsed Hadron Source(CPHS). The breakdown rate (BDR) of the RFQ has been measured. Breakdown waveforms have been recorded, which have been used for counting breakdown time distribution and analyzing the location of RF breakdowns.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO111  
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THPO118 Beam Transverse Coupling and 4D Emittance Measurement Simulation Studies for PITZ emittance, quadrupole, coupling, gun 945
 
  • Q.T. Zhao, M. Krasilnikov, H.J. Qian, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • Q.T. Zhao
    IMP/CAS, Lanzhou, People’s Republic of China
 
  The Photo Injector Test Facility at DESY, Zeuthen site (PITZ) was built to test and optimize high brightness electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. Although the beam emittance has been optimized and experimentally demonstrated to meet the requirements of FLASH and XFEL, transverse beam asymmetries were observed during operation of the RF guns. Based on previous studies [1], the beam asymmetries most probably stem from beam transverse coupling by quadrupole field errors in the gun section. A pair of normal and skew gun quadrupoles was successfully used for reducing the beam asymmetries in experiment. In this paper, we discuss the beam transverse coupling between X and Y planes due to quadrupole field errors and its impact onto horizontal and vertical rms emittance. Multi-quads scan and two quads with rotated slits scan were proposed to measure the 4D beam matrix for PITZ and tested by simulation, which will give the residual beam coupling after gun quadrupoles compensation and would be helpful for minimizing the 2D rms emittance experimentally.  
poster icon Poster THPO118 [1.521 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO118  
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FR1A01 Results From the 6D Diagnostics Test Bench at SNS experiment, quadrupole, diagnostics, emittance 966
 
  • B.L. Cathey
    ORNL RAD, Oak Ridge, Tennessee, USA
  • A.V. Aleksandrov, S.M. Cousineau, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This work has been partially supported by NSF Accelerator Science grant 1535312.
This paper presents the method and results for measuring the full six-dimensional phase space of a low energy, high intensity hadron beam. This was done by combining four-dimensional emittance measurement techniques along with dispersion measurement and a beam shape monitor to provide the energy and arrival time components. The measurements were performed on the new Beam Test Facility (BTF) at the Spallation Neutron Source (SNS), a 2.5 MeV functional duplicate of the SNS accelerator front end. The results include a correlation the had not previously been observed.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-FR1A01  
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