Keyword: klystron
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MO1PA03 First Years of Linac4 RF Operation linac, operation, controls, rfq 25
 
  • S. Ramberger, R. Wegner
    CERN, Meyrin, Switzerland
 
  Following the construction, commissioning, run-in, and connection, in 2021 Linac4 at CERN saw its successful start-up to full operation. Being composed primarily of RF systems, occupying most of the tunnel and the equipment hall, a coordinated effort has been put in place by 4 RF teams providing cavities, amplifier chains, low-level RF and general control systems. While all parts came together with impressive performance from day one, many details required a considerable debugging effort to achieve the requested availability of at least 95% from first operation in the synchrotron complex. This talk will focus on issues in equipment reliability, radiation to electronics, thermal stability, systems interaction, as well as a few aspects of complex low-level RF setup. It will also discuss decisions taken with respect to spare policies and upgrades for the coming years.  
slides icon Slides MO1PA03 [3.992 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MO1PA03  
About • Received ※ 14 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 11 September 2022
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MOPOJO19 Programmable SLED System for Single Bunch and Multibunch Linac Operation linac, cavity, operation, LLRF 73
 
  • C. Christou, P. Gu, A. Tropp
    DLS, Oxfordshire, United Kingdom
 
  The Diamond Light Source pre-injector linac generates single bunch and multibunch 100 MeV electron beams for top-up and fill of the storage ring. The linac is powered by two high-power 3 GHz klystrons, and both klystrons are required for reliable injection into the booster and storage ring. In order to introduce redundancy, a SLED pulse compression cavity has been installed so that the linac can operate from just one klystron, with the second klystron held as a standby. A simple phase flip can be used to generate a high-power transient RF spike, suitable for single bunch linac operation, and a programmable amplitude and phase drive profile can be specified to generate a constant-power klystron output suitable for multibunch operation. Details are presented of design, installation and high-power operation of the SLED system, and the ability to generate a long pulse, including corrections for klystron nonlinearity and deviations from modulator flat-top, is demonstrated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO19  
About • Received ※ 09 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 08 September 2022
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MOPOPA22 High-Gradient Accelerating Structure for Hadron Therapy Linac, Operating at kHz Repetition Rates linac, GUI, operation, hadron 126
 
  • S.V. Kutsaev, R.B. Agustsson, A.C. Araujo Martinez, A.Yu. Smirnov, S.U. Thielk
    RadiaBeam, Santa Monica, California, USA
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • B. Mustapha, G. Ye
    ANL, Lemont, Illinois, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under STTR grant DE-SC0015717 and Accelerator Stewardship Grant, Proposal No. 0000219678.
Argonne National Laboratory and RadiaBeam have designed the Advanced Compact Carbon Ion Linac (ACCIL) for the acceleration of carbon an proton beams up to the energies of 450 MeV/u, required for image-guided hadron therapy. Recently, this project has been enhanced with the capability of fast tumour tracking and treatment through the 4D spot scanning technique. Such solution offers a promising approach to simultaneously reduce the cost and improve the quality of the treatment. In this paper, we report the design of an accelerating structure, capable of operating up to 1000 pulses per second. The linac utilizes an RF pulse compressor for use with commercially available klystrons, which will dramatically reduce the price of the system.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA22  
About • Received ※ 13 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 01 September 2022
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MOPORI23 High-Power Testing Results of X-Band RF-Window and 45 Degrees Spiral Load GUI, operation, Windows, controls 279
 
  • M. Boronat, H. Bursali, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev
    CERN, Meyrin, Switzerland
 
  The X-Band test facilities at CERN have been running for some years now qualifying CLIC structure prototypes but also developing and testing high power general-purpose X-Band components, used in a wide range of applications. Driven by operational needs, several components have been redesigned and tested aiming to optimize the reliability and the compactness of the full system and therefore enhancing the accessibility of this technology inside and outside CERN. To this extent, a new high-power RF-window has been designed and tested aiming to avoid unnecessary venting of high-power sections already conditioned, easing the interventions, and protecting the klystrons. A new spiral load prototype has also been designed, built, and tested, optimizing the compactness, and improving the fabrication process. In these pages, the design and manufacturing for each component will be shortly described, along with the last results on the high-power testing.  
poster icon Poster MOPORI23 [2.275 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI23  
About • Received ※ 24 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022
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TUPOPA03 Status and RF Devopments of ESS Bilbao RFQ rfq, operation, vacuum, coupling 410
 
  • N. Garmendia, I. Bustinduy, A. Conde, P.J. González, A. Kaftoosian, J. Martin, S. Masa, J.L. Muñoz, .A. Rodríguez Páramo
    ESS Bilbao, Zamudio, Spain
 
  Within the framework of the plans for study of a light-ion linear accelerator, ESS Bilbao is manufacturing a radio frequency quadrupole (RFQ) aimed at accelerating up to 3 MeV the protons generated in the ion source. The progress made and the difficulties encountered with the RFQ are discussed in this paper. A power coupler proto-type for the RFQ has been developed while several me-chanical constraints were also studied in the final cou-pler. This prototype operates at a lower power, then it can work using PEEK window for the vacuum interface and it does not require neither brazing nor cooling system. Also, a complete RF test stand is being implemented to perform the high-power conditioning in traveling and standing wave mode, to verify the power handling capa-bility of the coupler and its thermal behaviour. The RF test stand, based on EPICS environment, can provide up to 2 MW peak power at 352.2 MHz in a pulse operation of 14 Hz and a duty cycle of 4.9%.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA03  
About • Received ※ 09 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022
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TUPOPA27 Conceptual Analysis of a Compact High Efficiency Klystron cavity, bunching, wiggler, focusing 466
 
  • J.P. Edelen, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • K.E. Nichols
    LANL, Los Alamos, New Mexico, USA
 
  Traditional klystron efficiencies are limited by the output electron beam harmonic current and energy spread. Increasing the amount of harmonic current produced in the klystron requires increasing the velocity bunching in the input cavity. Additional cavities may be used to improve the bunching, however they do so at additional cost and space requirements for the klystron. Moreover, at higher currents space charge counteracts this velocity bunching reducing the amount of harmonic current that can be produced. Our concept resolves these challenges by employing a new type of high-efficiency, multi-beam klystron. Our design consists of a single two-frequency input cavity, a wiggler, and an output cavity. The two-frequency input cavity approximates a linear function in time thereby increasing the harmonic content of the beam, while the wiggler provides strong longitudinal focusing to mitigate the effects of space charge. In this paper we provide the theoretical foundation for our design and present initial numerical calculations showing improved bunching from the harmonic mode and the wiggler.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA27  
About • Received ※ 14 August 2022 — Revised ※ 24 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 31 August 2022
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TH1AA06 Low Level RF Control Algorithms for the CERN Proton LINAC4 cavity, linac, LLRF, beam-loading 673
 
  • P. Baudrenghien, B. Bielawski, R.B. Borner
    CERN, Meyrin, Switzerland
 
  The CERN Linac4 Low Level RF (LLRF) uses a Linear Gaussian Regulator and an Adaptive Feed Forward to regulate the accelerating field in the cavities in the presence of strong beam loading. A Klystron Polar Loop is also implemented to compensate the RF perturbations caused by the ripples and droop in the klystron High Voltage supply. The talk presents the important parts of the regulation, shows results as the system has evolved from first prototype (2013) to operational beams (2020), and mentions some important issues encountered during the commissioning and the first years of operation, with their mitigations.  
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slides icon Slides TH1AA06 [4.183 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA06  
About • Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 06 September 2022
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TH2AA02 RF System Performance in the SwissFEL Linac linac, operation, FEL, multipactoring 679
 
  • C.D. Beard, J. Alex, H.-H. Braun, P. Craievich, Z. Geng, N. Hiller, R. Kalt, C. Kittel, T. Lippuner, T.G. Lucas, M. Pedrozzi, E. Prat, S. Reiche, T. Schietinger, W.T. Tron, D. Voulot, R. Zennaro
    PSI, Villigen PSI, Switzerland
 
  The Hard X-ray FEL machine SwissFEL at the Paul Scherrer Institut in Switzerland is commissioned and transiting to user operation smoothly. FEL operation requires stringent requirements for the beam stability at the linac output, such as the electron bunch arrival time, peak current and beam energy. Among other things, a highly stable RF system is required to guarantee the beam stability. RF performance often dominates the overall performance and availability of FELs, and for this reason the SwissFEL RF system has been designed based on the state-of-the-art technologies that have enabled excellent RF stability, resulting in an arrival time jitter of ~10 fs rms and relative beam energy stability of 10-4 rms. This paper aims to provide an understanding of the peak performance of the RF systems and to highlight possible limitation currently faced, focusing on the S-, C- and X-Band systems.  
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slides icon Slides TH2AA02 [4.813 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH2AA02  
About • Received ※ 20 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022
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THPOJO07 Status and Reliability Enhancements of the ALBA Linac linac, operation, booster, gun 703
 
  • D. Lanaia, R. Muñoz Horta, F. Pérez
    ALBA-CELLS, Cerdanyola del Vallès, Spain
 
  Along the years, efforts to enhance the ALBA Linac performances and reliability have been devoted, resulting in an improvement of the Linac to Booster beam transmission efficiency, and of its mean time between failures. The performance enhancement has been based on the use of optimization and control routines of the beam parameters, but also by the application of regular preventive hardware maintenance procedures. Besides, the Linac reliability has been improved also by the implementation of alternative working modes in case of hardware failures, like operating at 67 MeV, with only one klystron and one accelerating section. In this respect, a new upgrade of the RF waveguide system is being implemented, with the aim to produce 80 MeV electron beam using only one klystron that will feed both accelerating sections. Furthermore, the possibility to install a thermionic RF-gun to inject directly into the first accelerating section is under study, ensuring the Linac’s reliability even in case of a major event. Details of the Linac performance during the past years and a description of the new hardware upgrades are presented in this work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO07  
About • Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 07 September 2022 — Issue date ※ 15 September 2022
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THPOJO08 RF Design of Traveling-Wave Accelerating Structures for the FCC-ee Pre-injector Complex linac, positron, electron, impedance 707
 
  • H.W. Pommerenke, A. Grudiev, A. Latina
    CERN, Meyrin, Switzerland
  • S. Bettoni, P. Craievich, J.-Y. Raguin, M. Schaer
    PSI, Villigen PSI, Switzerland
 
  Funding: This project received funding from the EU’s Horizon 2020 research program (grant No 951754), and was done under the auspices of CHART (Swiss Accelerator Research and Technology Collaboration).
The linacs of the FCCee (Future Circular Electron-Positron Collider) injector complex will both provide the drive beam for positron production and accelerate nominal electron and positron beams up to 6 GeV. Several linacs comprise different traveling-wave (TW) accelerating structures fulfilling the beam dynamics and rf constraints. Notably, high-phase advance large-aperture structures accelerate the positron beam at low energies. All TW structures are rotationally symmetric for easier production. Long-range wakes are damped by HOM detuning. Operating mode and HOM parameters were calculated based on lookup tables and analytic formulas, allowing for rapidly scanning large parameter spaces. In this paper, we present both methodology and realization of the rf design of the TW structures including their pulse compressors.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO08  
About • Received ※ 24 August 2022 — Accepted ※ 08 September 2022 — Issue date ※ 15 September 2022  
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THPOPA01 FLASH2020+ Upgrade - Modification of RF Power Waveguide Distribution for the Free-electron Laser FLASH at DESY GUI, cryomodule, cavity, FEL 747
 
  • B. Yildirim, S. Choroba, V.V. Katalev, P. Morozov, Y. Nachtigal, N.V. Vladimirov
    DESY, Hamburg, Germany
 
  The goal of FLASH2020+ upgrade is to increase the energy of the FLASH accelerator, which allows the use of even shorter wavelengths, which, in turn, will allow new research. For this purpose, during the shutdown in 2022, two superconducting accelerator modules for ACC2 and ACC3 will be replaced by new ones. To fully realize the potential of these cryomodules XFEL type of waveguide distributions will be installed on them. In addition, the existing ACC4 and ACC5 cryomodules will also be equipped with the new waveguide distributions, similar XFEL type. These waveguide distributions will be modified and improved so that the machine can operate with the maximum energy due to individual power supply for each cavity. Furthermore, three RF stations will receive a new klystron waveguide distribution, which will improve the reliability of all systems. The specific waveguide distributions have been developed, produced and tested at the Waveguide Assembly and Test Facility (WATF) at DESY. All together will lead to increasing the electron beam energy from 1.25 to 1.35 GeV. This paper presents data on the production and tuning of waveguide distribution systems for the FLASH2020+ upgrade at DESY.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA01  
About • Received ※ 16 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 02 September 2022
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THPOPA09 High Stability Klystron Modulator for Commercial Accelerator Application controls, power-supply, high-voltage, operation 762
 
  • M.K. Kempkes, M. Benjnane, C. Chipman, M.P.J. Gaudreau, A. Heindel, Z. Ruan, R.E. Simpson, H. von Kelsch
    Diversified Technologies, Inc., Bedford, Massachusetts, USA
 
  Diversified Technologies, Inc. (DTI) designed and developed a high stability modulator system for a commercial linear accelerator application. The DTI modulator delivers significant advantages in klystron performance through highly reliable functionality as well as flicker- and droop-free operation from 50-500 microseconds up to 400 Hz (duty limited). The main assemblies on the DTI system consist of a controls rack, high voltage power supply (HVPS), modulator, and cooling manifolds for the modulator, high voltage power supply and klystron tube. Two HVPS (upgradeable to four) provide stable and accurate DC voltage which is used to drive a CPI VKP-8352C UHF-band pulsed klystron for the linear accelerator. A solid state series switch, based on DTI’s patented design, provides both pulse control and arc protection to the klystron. Operating with four HVPS, the DTI modulator is able to operate at a maximum average power of ~750 kW at 105 kV, 47 A nominal. At the end of the initial contract, DTI provided two systems and a total of four HVPS (two of which are used with each system).  
poster icon Poster THPOPA09 [0.736 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA09  
About • Received ※ 19 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022
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THPOPA23 Digital LLRF System Development and Implementation at the APS Linac linac, LLRF, operation, controls 792
 
  • Y. Yang, J.M. Byrd, G.I. Fystro, D.A. Meyer, A. Nassiri, A.F. Pietryla, T.L. Smith, Y. Sun
    ANL, Lemont, Illinois, USA
  • B. Baričevič
    I-Tech, Solkan, Slovenia
 
  The current analog LLRF systems which have supported the APS linac operation for over 25 years, will be replaced with digital LLRF systems utilizing the latest commercially available electronics technology. A customized LLRF system has been developed as the next-generation APS linac controller. Two systems have been manufactured and delivered to the APS. On-site tests demonstrated they met the APS linac operation requirements with the first system expected to be integrated into APS linac operation this year.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOPA23  
About • Received ※ 22 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022
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