Keyword: klystron
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MOPGW081 Measurements of Stray Magnetic Fields at CERN for CLIC site, proton, collider, dipole 289
 
  • C. Gohil, N. Blaskovic Kraljevic, D. Schulte
    CERN, Meyrin, Switzerland
  • P. Burrows
    JAI, Oxford, United Kingdom
  • B. Heilig
    MFGI, Budapest, Hungary
 
  Simulations have shown that the Compact Linear Collider (CLIC) is sensitive to external dynamic magnetic fields (stray fields) to the nT level. Magnetic fields are not typically measured to this precision at CERN. Past measurements of the background magnetic field at CERN are limited. In this paper new measurements are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW081  
About • paper received ※ 01 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB022 Current Status of the High-Power RF Systems During Phase2 Operation in SuperKEKB cavity, operation, GUI, status 619
 
  • K. Watanabe, K. Marutsuka, Ma. Yoshida, S.I. Yoshimoto
    KEK, Ibaraki, Japan
 
  The SuperKEKB is an asymmetric-energy two-ring collider consisting of the high-energy ring (HER) for 7 GeV electrons and the low-energy ring (LER) for 4 GeV positrons at KEK. Both the electron and positron beams are injected from the Linac injector complex, which includes a newly constructed 1.1 GeV positron damping ring (DR) to supply a high-quality low emittance positron beam to the LER. The high power RF system has a role to drive the ARES cavities and the superconducting RF cavities for the SuperKEKB. The operating frequency of RF system is 508.9 MHz. The required RF power from the klystron at maximum storage beam current is ~850 kW (CW). The number of RF stations is total 31 for the main ring (MR) and DR. The status of each high power RF components, troubles of them and operation condition that occurred during phase 2 commissioning from Feb 2018 to July 2018 will be reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB022  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB080 Transient Beam Loading and Mitigation in JLEIC Collider Rings electron, cavity, luminosity, beam-loading 758
 
  • J. Guo, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
  • J.D. Fox
    Stanford University, Stanford, California, USA
  • T. Mastoridis
    CalPoly, San Luis Obispo, California, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, with additional support from U.S. DOE Award Number DE-SC-0019287
The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB080  
About • paper received ※ 23 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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MOPTS001 Operational Experience with a Sled and Multibunch Injection at the Australian Synchrotron linac, operation, injection, cavity 830
 
  • M.P. Atkinson, G. LeBlanc
    AS - ANSTO, Clayton, Australia
  • K. Zingre
    ASCo, Clayton, Victoria, Australia
 
  The Australian third generation 3 GeV Synchrotron Light Source was originally commissioned with a 100 MeV linear accelerator (LINAC) fed by two 37 MW S band pulsed klystrons. A pulse compressor in form of a SLED cavity was added later to enable single klystron operation for redundancy in case of a modulator failure. The SLED was successfully commissioned in May 2017 including remote selection of single klystron with SLED operation without degradation of beam energy. Two years on there have been some unexpected operational benefits including reduced phase sensitivity and drift allowing repeatable injection based solely on diagnostic phase read backs. Temperature stabilised power amplifiers based on S band GaN radar technology are being trialed in the meantime with a goal to set and inject with minimal operator adjustment. The results from the SLED cavity upgrade are shown and the latest S band radar technology designs are outlined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS001  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPTS002 Linac Energy Jitter Measurements with SPARK BPMs at ALBA linac, electron, electronics, operation 833
 
  • R. Muñoz Horta, D. Lanaia, E. Marín, A. Olmos, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  At ALBA four Beam Position Monitors (BPMs) measure the beam position along the Linac to Booster Transfer Line. The BPM electronics (Libera Spark type) have been recently upgraded in order to be sensitive to single-pass beam detection. As a result, the position resolution measured in LTB BPMs has been increased by a factor 10 with respect to the former electronics. The increased resolution enables us to resolve the energy jitter of the Linac beam, providing an on-line measurement of the Linac energy during regular operation. In this paper a study of the Linac energy jitter is presented as well as its correlation with the jitter sources.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS002  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS018 First Electron Beam at the Linear Accelerator FLUTE at KIT electron, laser, MMI, linac 882
 
  • M.J. Nasse, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, B. Härer, I. Križnar, A. Malygin, S. Marsching, W. Mexner, A.-S. Müller, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan
    KIT, Karlsruhe, Germany
 
  Funding: The SRR project has received funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement No 730871.
The first electron beams were generated in the 7 MeV section of the short-pulse linear accelerator test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) at the Karlsruhe Institute of Technology (KIT). In this contribution we show images of the electron beam on a YAG-screen (yttrium aluminum garnet) as well as signals from an integrating current transformer (ICT) and a Faraday cup. Furthermore, the progress of tuning the FLUTE electron bunches for experiments is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS018  
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS057 SSPA upgrade plan design for CiADS cavity, controls, coupling, simulation 990
 
  • Q. Chen, Z. Gao, Y. He, G. Huang, R. Huang, T.C. Jiang, S.H. Liu, L.P. Sun, X.W. Wang, Z.J. Wang, W.M. Yue
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Funding: Supported by the National natural science foundation of China (Grand No. 11525523 and 91426303)
For ADS application, both research and commercial facilities requires extremely large amount of RF power to drive several mega watts beam power, so proper RF power upgrade plan can reduce the budget per phase and increase the valuable experience in engineering. CiADS (China initiative Accelerator Drive System) proposes to employ SSPA (Solid State Power Amplifier) as RF power source for flexible configuring and upgrading in the future. In this paper, from an engineering point of view, it is acceptable if proper matching beam current was selected for adopting fixed-coupling input coupler while only sacrificed some RF power during the upgrade plan. SSPA upgrade plan start with the stablility requirement to determine bandwidth, then combined with other RF power requirements to select output level, finally, checking how much the surplus of selected level SSPA for detuning control. The calculation and evaluation results for a §I{545}{MeV} physical design lattice illustrate that some resonance cavities had very limited surplus RF power left for detuning control that provided necessary optimization direction and guidelines for both physical design and SSPA arrangement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS057  
About • paper received ※ 30 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUXXPLM3 First Operation of a Hybrid e-Gun at the Schlesinger Center for Compact Accelerators in Ariel University gun, laser, electron, solenoid 1171
 
  • A. N. Nause, A. Fukasawa, J.B. Rosenzweig, R.J. Roussel
    UCLA, Los Angeles, USA
  • A. Friedman
    Ariel University, Ariel, Israel
  • B. Spataro
    INFN/LNF, Frascati, Italy
 
  Funding: Israel Ministry of Defence Israel Ministry of Science
A novel hybrid photo injector was designed and partially tested at the UCLA Particle Beam Physics Laboratory. It was later commissioned at Ariel University in Israel as an on-going collaboration between the two universities. This unique, new generation design provides a radically simpler approach to RF feeding of a gun/buncher system, leading to a much shorter beam via velocity bunching owed to an attached traveling wave section of the photo-injector. This design results in better performance in beam parameters, providing a high quality electron beam, with energy of 6 MeV, emittance of app 3 μm, and a 150 fs pulse duration at up to 1 nC per pulse. The Hybrid gun is driven by a SLAC XK5 Klystron as the high power RF source, and third harmonic of a fs level IR Laser amplifier (266 nm) to drive the Cathode. The unique e-gun will produce an electron pulse for a THz FEL, which will operate at the super-radiance regime, and therefore requires extraordinary beam properties. This paper briefly describes the gun and presents initial operational results from the gun and its sub-systems.
 
slides icon Slides TUXXPLM3 [9.526 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLM3  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPGW001 Improvements to Injector System Efficiency at the Australian Synchrotron linac, booster, injection, synchrotron 1378
 
  • M.P. Lafky, M.P. Atkinson, L.N. Hearder
    AS - ANSTO, Clayton, Australia
  • P.J. Giansiracusa
    The University of Melbourne, Melbourne, Victoria, Australia
 
  Funding: Australian Nuclear Science and Technology Organisation
New instrumentation, software, and hardware upgrades have allowed Operations personnel to increase the overall injector system efficiency from 50% to 80% at the Australian Synchrotron. This paper will provide an overview of the methods used to achieve this result.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW001  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS024 Design of a Full C-Band Injector for Ultra-High Brightness Electron Beam gun, emittance, cathode, brightness 1979
 
  • D. Alesini, F. Cardelli, G. Castorina, M. Croia, M. Diomede, M. Ferrario, A. Gallo, A. Giribono, B. Spataro, C. Vaccarezza, A. Vannozzi
    INFN/LNF, Frascati (Roma), Italy
 
  High gradient rf photo-injectors have been a key development to enable several applications of high quality electron beams. They allow the generation of beams with very high peak current and low transverse emittance, satisfying the tight demands for free-electron lasers, energy recovery linacs, Compton/Thomson sources and high-energy linear colliders. In the paper we present the design of a new full C-band RF photo-injector recently developed in the framework of the XLS-Compact Light design study and of the EuPRAXIA@SPARC_LAB proposal. It allows to reach extremely good beam performances in terms of beam emittance (at the level of few hundreds nm), energy spread and peak current. The photo-injector is based on a very high gradient (>200 MV/m) ultra-fast (RF pulses <200 ns) C-band RF gun, followed by two C band TW structures. Different types of couplers for the 1.6 cell RF gun have been considered and also a new compact low pulsed heating coupler working on the TM020 mode on the full cell has been proposed. In the paper we report the design criteria of the gun, the powering system, and the results of the beam dynamics simulations. We also discuss the case of 1 kHz repetition rate.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS024  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS086 SNS Proton Power Upgrade Status power-supply, injection, DTL, linac 2124
 
  • M.A. Plum, D.E. Anderson, C.N. Barbier, M.S. Champion, M.S. Connell, J. Galambos, M.M. Harvey, M.P. Howell, S.-H. Kim, J. Moss, B.W. Riemer, R. W. Steffey
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: Work performed at (or work supported by) Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The Proton Power Upgrade (PPU) project at the Oak Ridge Spallation Neutron Source aims to double the beam power capability of the accelerator, from 1.4 to 2.8 MW. This will be done by a 30% increase in beam energy (from 1.0 to 1.3 GeV), and a 50% increase in beam current (from 25 to 38 mA averaged over a macropulse). The project is now well underway, after receiving approval to start preliminary design in April 2018. In this paper we will discuss recent technical developments in the project, including the warm linac RF system upgrade, a new topology for the high voltage converter modulators, an engineering review of the power capability of the injection dump, and a 2-MW-capability for the existing target station.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS086  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEXXPLS1 Magnetron R&D for High Efficiency CW RF Sources of Particle Accelerators injection, cavity, electron, controls 2233
 
  • H. Wang, R.M. Nelson, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • B.R.L. Coriton, C.P. Moeller
    GA, San Diego, California, USA
  • A. Dudas, M.L. Neubauer
    Muons, Inc, Illinois, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, DOE OS/NP STTR Grant DE-SC0013203 and DOE OS/HEP Accelerator Stewardship award 2019-2021.
The scheme of using a high efficiency magnetron to drive a superconducting or normal conducting radio frequency accelerator cavity needs not only injection phase locking but also amplitude modulation to compensate for the cavity’s microphonics, frequency change, variations of cavity voltage and beam current. To be able to do a fast and efficient modulation and to compensate the frequency pushing effect due to the anode current change, the magnetron’s magnetic field has to be trimmed by an external coil*. To facilitate this, a low eddy current magnetron body has been designed and built**. This paper will present the experimental results of such modulation on a conventional 2.45 GHz magnetron at the R&D test stand. In addition, the progresses on the injection lock test to a new 1497 MHz, 13kW magnetron prototype aimed for the CEBAF klystron replacement with newly built low level RF (LLRF) controller for the amplitude modulation will be reported. Based on these R&D results, a 915MHz, 2×75kW CW industrial heating type magnetron system is being developed to be used for the high efficiency (>80%) RF source to the electron accelerator for industrial applications.
* H. Wang, et al,THPAL145, proceedings of IPAC 2018.
** M. Neubauer, et al,THPAL042, proceedings of IPAC 2018.
 
slides icon Slides WEXXPLS1 [8.033 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS1  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB001 The Effect of the SLED Installation on Extracted and Lost Beam at the Australian Synchrotron Linac. linac, synchrotron, network, injection 2794
 
  • P.J. Giansiracusa, T.G. Lucas, R.P. Rassool, M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
  • M.J. Boland
    University of Saskatchewan, Saskatoon, Canada
  • M.J. Boland
    CLS, Saskatoon, Saskatchewan, Canada
  • M.P. Lafky
    AS - ANSTO, Clayton, Australia
 
  A recent upgrade to the high power RF network of the linac at the Australian Synchrotron included a SLED Type 1 Pulse Compressor allowing for the operation of its 100 MeV linac using a single klystron. We explore the effects of the SLED installation on the properties of the beam extracted from the linac with a particular focus on the energy spread and bunch train profile. Additionally, the optical fibre beam loss monitor (oBLM), also recently commissioned, was employed to provide shot-by-shot feedback on loss location and intensity to investigate the change in beam losses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB001  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB003 Parametric Pumped Oscillation by Lorentz Force in Superconducting Rf Cavity cavity, feedback, controls, acceleration 2798
 
  • K. Fong, R. Leewe
    TRIUMF, Vancouver, Canada
 
  Mechanical instabilities have been observed in superconducting RF cavities, when multiple cavities are driven by a single klystron and these cavities are regulated by vector-summing the outputs from these cavities. A nonlinear theory has been developed to study the source of this mechanical instability, which is due to the coupling between Lorentz force detuning and mechanical oscillation by parametric pumping. Analytical and numerical analysis of this model show regions of stability, limit cycles and instabilities. These results are in agreement with the observed oscillations by TRIUMF eLinac Acceleration Module.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB003  
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB022 RF System Upgrade for Elettra 2.0 cavity, storage-ring, HOM, LLRF 2849
 
  • C. Pasotti, M. Bocciai, M. Rinaldi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  The Elettra 2.0 low emittance light source project has triggered the review of the installed RF system’s performances and the analyses of the new machine requirement. This study includes the imperative revamp of the RF power sources. The trade off between the best theoretical RF system design and the available room for installation and budget for Elettra 2.0 has been translated into the operational plan reported here. The first planned step is the installation of 100 kW 500 MHz solid state based transmitters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB022  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPRB045 Suppression of Secondary Electron Yield Effect in the 650MHz/800kW Klystron for CEPC cavity, simulation, electron, multipactoring 2906
 
  • X. He, C. Meng, S. Pei, J.L. Wang, O. Xiao, N. Zhou
    IHEP, Beijing, People’s Republic of China
 
  The circular electron positron collider (CEPC) is in pre-research, it will need more than two hundred 650MHz/800kW klystrons. The secondary electron yield (SEY) effect suppression is very important for the klystron working stable. The simulation uses an incident primary electron source and considers all the phases and power levels of the input microwave. Two methods are simulated for the SEY suppression. The groove cutting on the nose of cavities is much simple while the TiN coating can suppress better. The effect after groove cutting on nose is also simulated and the corresponding compensations are adopted. For simplify the fabrication progress as well as some experience that can be referenced, the groove cutting method is adopted finally for the first klystron prototype, which is expected to be available in the summer of 2019.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB045  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB047 High-Power Test of a 12 Cell Accelerating Structure Build in Halves vacuum, shielding, GUI, ECR 2912
 
  • M.M. Peng, Y.L. Jiang, J.Y. Liu, Z.N. Liu, X.C. Meng, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
 
  An X-band 12 cell travelling-wave accelerating structure has been developed and high-power tested at Tsinghua University in China. This structure works at 2⁄3 π at the frequency of 11.424 GHz. It is a 12-cell constant-impedance structure build in halves and was silver-brazed as a vacuum tight structure. The high power test was conducted at Tsinghua X-band high power test facility [1] with a 50-MW X-band klystron at a repetition rate to 40 Hz. The final input power was 51.23 MW with a 200 ns pulse width, which means an accelerating gradient of 88.58 MV/m was reached. This paper presents the high power test results including the gradient and breakdown history.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB047  
About • paper received ※ 10 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB063 Connection of 12 GHz High Power RF from the XBOX 1 High Gradient Test Stand to the CLEAR Electron LINAC LLRF, linac, software, electron 2960
 
  • A.V. Edwards
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Pitman, B.J. Woolley, V. del Pozo Romano
    CERN, Meyrin, Switzerland
 
  A new RF system is being established at XBOX1 to drive two §I{100}{MV/m} CLIC structures in the CLEAR electron linac. In the past, these structures had been powered by RF from PET structures excited by a drive beam. This drive beam is no longer available. The upgrade will reroute power from the §I{50}{MW} klystron and pulse compressor which was previously used to power the structure in XBOX1. During the upgrade, the LLRF system will be optimised to improve the modulation of the output signals and down-mixing of the returning signals to obtain accurate phase and amplitude information. The design of the improved LLRF and software, along with phase noise measurements and comparisons with the old system are made in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB063  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB064 High Power Conditioning of X-Band Variable Power Splitter and Phase Shifter simulation, GUI, ISOL, operation 2964
 
  • V. del Pozo Romano, H. Bursali, N. Catalán Lasheras, A. Grudiev, S. Pitman, I. Syratchev
    CERN, Meyrin, Switzerland
  • C. Serpico
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
 
  The three X-band test facilities currently at CERN aim at qualifying CLIC structures prototypes but are also exten- sively used to qualify X-band components operation at high power. In order to upgrade one of the facilities from a single test line to a double test line facility, a high power variable splitter and variable phase shifter have been designed and manufactured at CERN. They have been power tested, first in a dedicated test and also in their final configuration, to en- sure stable power operation before installing them together with an accelerating structure. In this paper, we broadly describe the RF and mechanical design, manufacturing and low power measurements agreement with simulations. We report the high power qualification of both components and their suitability to be used in existing and planned X-band facilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB064  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB068 Ka-Band Linearizer Studies for a Compact Light Source wakefield, impedance, FEL, flattop 2976
 
  • A. Castilla, G. Burt, W.L. Millar
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • A. Latina, X. Liu, W.L. Millar, X.W. Wu, W. Wuensch
    CERN, Geneva, Switzerland
 
  Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431.
The CompactLight project is currently developing the design of a next generation hard X-ray FEL facility, based on high-gradient X-band (12 GHz) structures, bright electron photo-injectors, and compact short period undulators. However, to improve the brightness limitations due to the non-linear energy spread of the electron bunches, a K-band (36 GHz) linearizer is being considered to provide a harmonic compensation during the bunch compression. In this paper, we analyze the feasibility of such linearizer.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB068  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB113 Toolbox for Optimization of RF Efficiency for Linacs linac, booster, RF-structure, software 3074
 
  • J. Ögren, A. Latina, D. Schulte
    CERN, Meyrin, Switzerland
 
  We present a toolbox for optimizing the rf efficiency for linacs and as an example we use it to re-optimize the Compact Linear Collider booster linac. We have implemented a numerical model of a SLED-type pulse compressor that can generate a single or a double pulse. Together with the CERN CLICopti library, an RF structure parameter estimator, we created the toolbox which enables thorough optimizations of linacs in terms of RF efficiency, beam stability, and cost simultaneously, via a simple and concise Octave script. This toolbox was created for the optimization of X-band-based linacs, however it can also be used at lower frequencies, e.g. in the S- and in the C- bands of frequencies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB113  
About • paper received ※ 06 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPGW084 Corrections of Klystron Output Pulse in SW Accelerator Testing controls, feedback, linac, ISOL 3772
 
  • M.H. Nasr, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Accelerator testing requires a good control over the shape of the used pulse. Usually, flat or stepped square pulses are used for testing. Producing a perfectly flat output pulse from the klystron can be challenging especially for testing standing wave (SW) accelerators. SW accelerator structures reflect high power back to the klystron and no isolator can withstand the reflected power level for high gradient operation. This results in a distorted output pulse from the Klystron. We developed a modulation technique that solves this problem using a negative feedback loop. This technique can also overcome a poor modulator performance and other system errors. The pulse correction feedback was successfully implemented for high gradient SW accelerator testing at SLAC and KEK.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW084  
About • paper received ※ 24 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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THPRB097 Analysis of RF System Stability on CLARA gun, linac, controls, cavity 4053
 
  • N.Y. Joshi, J.K. Jones, A.J. Moss, E.W. Snedden, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.C. Dexter, J. Henderson
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.K. Jones
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  The Compact Linear Accelerator for Research and Applications (CLARA) facility at STFC Daresbury Laboratory will test underpinning concepts and technology for a next generation X-ray free electron laser (FEL). CLARA will use four S-band normal conducting traveling wave linacs to accelerate electron bunches to a maximum energy of 250 MeV. The amplitude and phase stability of the collected RF systems is critical in enabling CLARA to achieve low (10 fs) shot-to-shot timing jitter of the photon output. Here we present initial measurements and model of the amplitude and phase jitter of the CLARA RF systems, achieved by experimentally correlating the klystron output with controls from modulator, driver, and other environment parameters. The effect of the RF jitter on the CLARA beam momentum is also integrated in the model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB097  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB105 ESS Klystron Production Test Stand high-voltage, controls, power-supply, cathode 4074
 
  • I. Roth, M.P.J. Gaudreau, M.K. Kempkes, N. Silverman, R.E. Simpson
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
 
  Diversified Technologies, Inc. (DTI) has delivered a new long-pulse modulator klystron test stand to Communication and Power Industries (CPI) in Palo Alto, CA for full power testing of production VKP-8292A klystrons for the European Spallation Source (ESS). This test stand was built using hardware and designs from an earlier SBIR effort for the US Department of Energy, with modifications to support ESS requirements and klystron testing operation. Earlier versions of this design are in use at IPN Orsay and CEA Saclay in France to test RF components for ESS. This new klystron test stand allows testing of klystrons at the full ESS specifications: 100 kV, 50 A, 3.5 ms pulse, 14 Hz,. This design is based on a (patent pending) non-dissipative regulator that compensates for the capacitor droop voltage (~20%) during the pulse. This allows a much smaller capacitor than would nominally be required for the long ESS pulse, eliminating the need for larger, more expensive capacitor bank. This test stand will speed delivery of ESS klystrons, and similar, long pulse, high power klystrons at CPI.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB105  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB117 Stability and Reliability Issues of PAL-XFEL Modulator FEL, operation, power-supply, electron 4096
 
  • S.H. Kim, H.-S. Kang, K.H. Kim, H.-S. Lee, C.-K. Min, S.S. Park, Y.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: This work is supported by Ministry of Science, ICT(Information/Communication Technology) and Future Planning.
The Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) employs 51 units of the pulse modulator in order to obtain the 10 GeV electron beam, which drive one X-band to linearize and 50 S-band klystrons. The PAL-XFEL requires very tight control of the klystron RF phase jitter 0.03-degree for S-band RF, 0.1-degree for X-band RF and the beam voltage stability of below 50 ppm. The RF phase jitter is directly related to the amplitude stability of modulator output pulses. There are several factors to satisfy the stability and reliability for the PAL-XFEL modulator. The largest sources of pulse-to-pulse instability are a current charging power supply (CCPS) for PFN charging, a thyratron switch, and a klystron focusing magnet power supply (MPS). In this paper, the operation and debugging results of those devices are described.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB117  
About • paper received ※ 16 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS006 Upgrade of the Canadian Light Source Booster RF System to Solid State booster, controls, operation, cavity 4112
 
  • J.M. Patel, D. Bertwistle, J. Stampe
    CLS, Saskatoon, Saskatchewan, Canada
  • A. Bachtior, A. Borisov, N. Pupeter
    CRE, Wuppertal, Germany
  • P. Hartmann
    DELTA, Dortmund, Germany
 
  Funding: CFI, NSERC, NRC, CIHR, the Province of Saskatchewan, WD, and the University of Saskatchewan
The Canadian Light Source synchrotron (CLS) had first light in 2004. For the last 14 years of operation we have exclusively used klystrons to provide RF power to our linac, booster, and storage ring. The klystrons represent a single point of failure for the operation of our booster and storage ring. This is especially poignant in the case of our booster ring klystron which is no longer manufactured. We have chosen to move to solid state amplifier (SSA) RF technology for its implicit high redundancy, modularity, ease of maintenance, and efficiency. Herein we review the performance parameters of our upgraded booster RF to a 100 kW 500 MHz transmitter built by Cryoelectra.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS006  
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS038 There-Dimensional Simulation of a C-Band 32-Beam Klystron electron, cavity, simulation, bunching 4190
 
  • Z.N. Liu, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
 
  A 32-beam klystron working at 5.712 GHz has been designed with efficiency of 70% and output power of 3.4 MW. Core oscillations method (COM) is chosen to bunch electrons. The code KlyC is used for 1-D and 1.5-D calculation and a series of parameters are given after optimizing, including the position, frequency, R/Q, Q0 and Qe of cavities. CST/PIC is used to make the final design and coaxial cavities are used. This paper describes 1-D, 1.5-D and 3-D beam dynamics of the klystron, compares their differences, and analyses effect of these differences on efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS038  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS039 DESIGN OF A COMPACT VARIABLE X-BAND RF POWER SPLITTER GUI, impedance, electron, network 4194
 
  • F. Liu, H.B. Chen, J.Y. Liu, Z.N. Liu, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
 
  This paper presents a design of a compact variable X-band RF power splitter. The RF power splitter includes one input port and two output ports, and the power divi-sion ratio can be adjusted by changing the position of a short circuit piston. This system keeps a good match (less than -40 dB) at any power division ratio. An E-bend waveguide structure is selected to make the geometry more compact (11cm in length, 3.5cm in width and 5 cm in height). Special studies was conducted to sustain a low surface electrical field (maximum 65 MV/m at 100 MW input), and large bandwidth (250MHz). This power split-ter is designed for high-power test stand at Tsinghua Uni-versity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS039  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS052 Beam Loss Suppression by Beam Matching in Klystron simulation, gun, beam-losses, injection 4218
 
  • S.J. Park, Y.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  • S.C. Cha, D.H. Kim, D.H. Yu
    VITZRONEXTECH, Ansan-si, Gyeonggi-do, Republic of Korea
  • J.H. Hwang
    POSTECH, Pohang, Kyungbuk, Republic of Korea
 
  Funding: The work was supported by the National R&D Program (grant number: 2016R1A6B2A01016828) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT in Korea.
High power klystrons usually employ large cathodes to generate high currents which are compressed inside the gun to provide optimum beam sizes at the cavity section. We compress the beam by using electrostatic and magnetostatic focusing fields which are established by gun electrodes and external magnets respectively. The geometry of the gun elecrodes and the external magnet is carefully designed to meet the matching condition which results in scalloping-free beam. We have established a systematic design procedures to achieve the beam matching condition at arbitrary beam sizes. In this article we report on the beam-matching design and simulation results with an example case of the 80-MW S-band klystron in the Pohang Accelerator Laboratory.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS052  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS090 Injection Locked 1497 MHz Magnetron status, cathode, operation, injection 4322
 
  • M.L. Neubauer, M.A. Cummings, A. Dudas, R.P. Johnson, S.A. Kahn, G.M. Kazakevich, M. Popovic
    Muons, Inc, Illinois, USA
  • R.A. Rimmer, H. Wang
    JLab, Newport News, Virginia, USA
 
  Muons, In is building an amplitude modulated phase-locked magnetron to replace the klystrons in CEBAF. To do that requires changing the magnetic field at a rate that would induce eddy currents in the standard magnetron. We report on the status of the project to make a stainless steel anode with copper elements to minimize heating while the stainless steel reduces eddy current effects. The construction of the magnetron is two months from completion, while the test stand is ready for delivery of the magnetron  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS090  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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