Keyword: coupling
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MOPO026 The Resonance Frequency Shift After Applying the Cooling System for a Side Coupled Standing Wave Linac cavity, controls, electron, resonance 81
 
  • M. Mohseni Kejani, F. Abbasi Davani
    Shahid Beheshti University, Tehran, Iran
  • S. Ahmadiannamin
    ILSF, Tehran, Iran
  • F. Ghasemi
    NSTRI, Tehran, Iran
  • S. Zarei
    Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
 
  A radio frequency accelerator tube used in linear medical accelerators includes three main sections of the radio frequency cavity, an electron gun and the X-ray target, which is vacuumed by a pump inside it. The electromagnetic energy loss in the structure of the cavity can increase the temperature of the tube, resulting in changes in the geometric dimensions and then changes in some of the cavity characteristics, such as the resonance frequency. A cooling system is required to prevent excessive change in the resonant frequency due to thermal loss. Also, it is necessary to perform some computer simulations to stabilize the cavity’s performance in the presence of electromagnetic energy thermal dissipation and the cooling system. In this paper, the simulation results of resonant frequency shifts after applying the cooling system have been reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO026  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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MOPO039 Status Update of the Fast Energy Corrector Cavity at FLASH cavity, electron, laser, free-electron-laser 112
 
  • S. Pfeiffer, J. Branlard, L. Butkowski, M. Hierholzer, M. Hoffmann, K. Honkavaara, H. Schlarb, Ch. Schmidt, S. Schreiber, M. Vogt, J. Zemella
    DESY, Hamburg, Germany
  • M. Fakhari
    CFEL, Hamburg, Germany
 
  Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453.
Linear accelerator facilities driving a free-electron laser require femtosecond precision synchronization between external laser systems and the electron beam. Such high precision is required for pump-probe experiments and also for example for the electron bunch injection into a plasma bubble for laser plasma acceleration. An upgrade of the fast intra-train beam-based feedback system is planned at the Free-Electron Laser FLASH in Hamburg, Germany. This linear accelerator is based on superconducting (SRF) technology operating with pulse trains of maximum 1 MHz bunch repetition rate. Arrival time fluctuations of the electron beam are correctable by introducing small energy modulations prior to the magnetic bunch compressor. This contribution focuses on the design and the characterization of a normal-conducting RF (NRF) cavity with large bandwidth, mandatory to correct fast arrival time fluctuations. The cavity has recently been installed in the FLASH beamline. First measurements with the new cavity will be presented.
 
poster icon Poster MOPO039 [1.884 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO039  
About • paper received ※ 13 September 2018      issue date ※ 18 January 2019  
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MOPO066 Simulation of the Transitional Process in Accelerating Sections by Equivalent Circuit Method operation, MMI, interface, distributed 145
 
  • S.V. Matsievskiy, V.I. Kaminskiy, Ya.V. Shashkov
    MEPhI, Moscow, Russia
 
  Nowadays linac accelerating RF systems design is usually done by the finite difference method. It provides high accuracy of calculations and freedom in topology choosing, but may draw considerable amounts of computer resources with long calculation times. Alternative to this method, equivalent circuit method exists. The basic idea of this method is to build a lumped element circuit, which with certain approximation acts as an original accelerating cell. It drastically reduces the number of equations to solve. This method is long known but usually only used for the particular accelerating structures when speed of calculation is a key-factor. Present paper describes a way to numerically simulate transition processes in arbitrary coupled accelerating cells using the equivalent circuit method. This approach allows simulating transitional processes in accelerating structures significantly faster and allows doing so for structures with high quality factor and many cells - a hard task for conventional transient solvers based on the finite difference method.  
poster icon Poster MOPO066 [0.519 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO066  
About • paper received ※ 23 August 2018      issue date ※ 18 January 2019  
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MOPO070 Construction of the Side-coupled Standing-wave e-Linac cavity, simulation, linac, 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, operation, simulation 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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MOPO119 Design of a Fully Automated Test Bench for Measuring the Field Distribution in Standing Wave Cavity cavity, simulation, controls, 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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MOPO124 Details of the Manufacturing Processes of the ESS-DTL Components DTL, alignment, vacuum, linac 260
 
  • P. Mereu, F. Borotto Dalla Vecchia, C. Mingioni, M. Nenni, R. Panero
    INFN-Torino, Torino, Italy
  • A. Battistello, P. Bottin, D. Conventi, L. Ferrari, F. Grespan, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • A.G. Colombo
    INFN- Sez. di Padova, Padova, Italy
 
  The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2MHz with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5mA pulse peak current from 3.62 to 90 MeV. This paper presents the details of the manufacturing processes with quality control reports of the components of the DTL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO124  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO045 Optimization of Dual Axis Asymmetric Cavity for Energy Recovery Linac cavity, linac, HOM, acceleration 435
 
  • Ya.V. Shashkov, A.M. Bulygin, M. Gusarova
    MEPhI, Moscow, Russia
  • I.V. Konoplev
    JAI, Oxford, United Kingdom
  • F. Marhauser
    JLab, Newport News, Virginia, USA
  • A. Seryi
    SLAC, Menlo Park, California, USA
 
  Funding: The reported study was funded by RFBR according to the research project № 18-302-00990
Optimization of the dual axis asymmetric cavity was performed to minimize the ratio of the peak magnetic and electric fields values to the accelerating voltage, to increase the distance between operating and neighbouring modes as well as to reduce the manufacturing cost of the cavity. To reach the goals several solutions have been suggested bringing the ratios to the acceptable values and leading to simplification of the manufacturing of the structure.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO045  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO003 L-band Resonant Ring for Testing RF Windows for ILC collider, linear-collider, klystron, simulation 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  
About • paper received ※ 13 September 2018      issue date ※ 18 January 2019  
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THPO038 Status of the Power Couplers for the CSNS DTL DTL, cavity, vacuum, operation 767
 
  • M.X. Fan, A.H. Li, B. Li, P.H. Qu, 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
 
  There are four Drift Tube Linac (DTL) tanks in China Spallation Neutron Source (CSNS) Project. Each DTL tank requires a power coupler with a peak power of 2 MW and a duty cycle of 1.5% for beam operation. After approximately two years machining, all four couplers were already installed in the tunnel before year 2017. Up to now, the first phase of beam tuning has been completed, the maximum transmission power of the coupler exceeds 1.7 MW with a pulse width of 650 μs and a repetition rate of 25 Hz, meanwhile, the vacuum is maintained on the order of 10-6 Pa during the operation and no breakdown was observed. This paper describes the architecture, the fabrication, the low power test results and the high power conditioning process of the coupler. Some problems encountered are also presented.
This work was supported by Youth Innovation Promotion Association of CAS (2015011)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO038  
About • paper received ※ 30 August 2018      issue date ※ 18 January 2019  
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THPO064 Tuning of a Four-vane RFQ for Xi’an 200 MeV Proton Application Facility rfq, dipole, quadrupole, cavity 838
 
  • X.D. Yu, X. Guan, Q.K. Guo, Y. Lei, P.F. Ma, X.W. Wang, Q.Z. Xing, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • B.C. Wang, Z.M. Wang, C. Zhao
    NINT, Shannxi, People’s Republic of China
 
  This paper mainly describes the procedures and results of tuning a four-vane Radio Frequency Quadrupole (RFQ) accelerator for the Xi’an 200 MeV Proton Application Facility (XiPAF) project. The 3-meter-long RFQ will accelerate a 50 keV H beam from the ECR source to 3 MeV, and deliver it to the downstream drift tube linac (DTL) with a peak current of 5 mA, pulse length of 10-40 μs and maximum repetition rate of 0.5. The machining, assembly, and RF tuning of the RFQ cavity has been completed successfully. After tuning, the relative error of the operating quadrupole mode field is within ±2.7%, and the dipole mode com-ponent is within ±1.9% of the quadrupole mode. The RFQ now is ready for high-power RF conditioning.  
poster icon Poster THPO064 [1.413 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO064  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO082 Physical Design of a Rectangular RF Deflector for Ultrashort Bunch Length Measurement cavity, electron, FEL, simulation 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  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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THPO100 Development of a 1.5 GHz High-power CW Magnetron for SRF Accelerator cavity, simulation, electron, SRF 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  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO104 Development of 150.4MHz Continuous Wave Solid-state Amplifier power-supply, controls, insertion, radiation 917
 
  • L. Zhao
    Nanjing University of Aeronautics and Astronautics, Jiangning, People’s Republic of China
  • S. An, Y.J. Ke, Z. Pengjiao, L. Wenliang, B.Z. Zhou
    PLAI, Nanjing, People’s Republic of China
 
  A 150.4MHz to 155.4MHz, 300W continuous wave solid-state amplifier as an accelerator power source has been developed by us. In order to increase the lifetime of MOSFET and meet the requirements of every parameters, Drain voltage and quiescent current is set at a better point with a well-designed heat dissipation structure, we make the solid state amplifier stable in performance. Taking the microwave leakage into account, the chassis structure is optimized and designed, and the microwave absorption device is adopted to make the structure compact, protect other parts not affected by the microwave leakage. After the assembly is completed, the working parameters meet the design requirements very well. The MOSFET flange temperature and output parameters meet the design requirements.  
poster icon Poster THPO104 [1.405 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO104  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO108 Development of an High Gradient Side Coupled Cavity for PROBE cavity, proton, linac, cyclotron 924
 
  • S. Pitman, R. Apsimon, G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • N. Catalán Lasheras, A. Grudiev, W. Wuensch
    CERN, Geneva, Switzerland
  • H.L. Owen
    UMAN, Manchester, United Kingdom
 
  The PROBE project aims to develop a high gradient proton accelerator for protons with energy around 250-350 MeV for proton radiography. Detailed studies have shown that the optimum design is a side coupled cavity at S-band. With an aperture of 8 mm a gradient of 54 MV/m can be obtained with 13 MW of RF power in a 30 cm structure. A prototype cavity has been machined by VDL and diffusion bonded by Bodycote. We present initial measurements of the prototype.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO108  
About • paper received ※ 17 September 2018      issue date ※ 18 January 2019  
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THPO109 A New Spherical Pulse Compressor Working with Degenerated "Whispering Gallery" Mode cavity, GUI, simulation, 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  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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THPO118 Beam Transverse Coupling and 4D Emittance Measurement Simulation Studies for PITZ emittance, quadrupole, simulation, 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.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO118  
About • paper received ※ 08 September 2018      issue date ※ 18 January 2019  
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