Author: Wuensch, W.
Paper Title Page
MOYCA1 Ultimate Field Gradient in Metallic Structures 24
 
  • W. Wuensch
    CERN, Geneva, Switzerland
 
  Significant progress has been made over the past decade by studies of normal-conducting linear colliders, NLC/JLC (Next/Japanese Linear Collider) and CLIC (Compact Linear Collider), to raise achievable accelerating gradient from the range of 20-30 MV/m up to 100-120 MV/m. The gain has come through a greatly increased understanding of high-power rf phenomena, development of quantitative high-gradient rf design methods, refinements in cavity fabrication techniques and through development of high peak rf power sources. Recently accelerating gradients in excess of 100 MV/m, at very low breakdown rates, have been successfully achieved with new techniques of conditioning in numerous prototypes at different laboratories. The talk will report on the impact of these new results on the understanding of the physics of breakdown and of conditioning, and on the ultimate gradients that can be expected in metallic RF structures.  
slides icon Slides MOYCA1 [52.087 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOYCA1  
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MOPAB044 X-Band TDS Project 184
 
  • B. Marchetti, R.W. Aßmann, B. Beutner, J. Branlard, F. Christie, R.T.P. D'Arcy, W. Decking, U. Dorda, J. Herrmann, M. Hoffmann, M. Hüning, O. Krebs, G. Kube, S. Lederer, F. Ludwig, F. Marutzky, D. Marx, J. Osterhoff, I. Peperkorn, S. Pfeiffer, F. Poblotzki, J. Rönsch-Schulenburg, J. Rothenburg, H. Schlarb, M. Scholz, S. Schreiber, M. Vogt, A. Wagner, T. Wilksen, K. Wittenburg
    DESY, Hamburg, Germany
  • M. Bopp, H.-H. Braun, P. Craievich, M. Pedrozzi, E. Prat, S. Reiche, K. Rolli, R. Zennaro
    PSI, Villigen PSI, Switzerland
  • N. Catalán Lasheras, A. Grudiev, G. McMonagle, W. Wuensch
    CERN, Geneva, Switzerland
 
  Based on the success of the X-Band Transverse Deflecting Structure (TDS) diagnostic at LCLS*, a collaboration between DESY, PSI and CERN has formed with the aim of developing and building an advanced modular X-Band TDS system. The designed TDS has the new feature of providing variable polarization of the deflecting field**. The possibility of changing the orientation of the streaking field of the TDS to an arbitrary azimuthal angle allows for 3D characterization of the phase space using tomographic methods***. Moreover the complete 6D characterization of the beam phase space is possible by combining this technique with quadrupole scans and a dipole spectrometer. As this new cavity design requires very high manufacturing precision to guarantee highest azimuthal symmetry of the structure to avoid the deterioration of the polarization of the streaking field, the high precision tuning-free assembly procedures developed at PSI for the SwissFEL C-band accelerating structures will be used for the manufacturing****. The high-power rf system is based on the CERN-based X-band test stands. We summarize in this work the status of the projects and its main technical parameters.
* C. Behrens et al. , Nat. Comm. 4762 (2014).
** A. Grudiev, CLIC-note-1067 (2016).
*** D. Marx et al., contribution to this conference proceedings.
**** U. Ellenberger et al., FEL 2013, TUPS017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB044  
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TUPAB016 The CLIC Main Linac Module Updated Design 1345
 
  • C. Rossi, M. Aicheler, N. Catalán Lasheras, R. Corsini, S. Döbert, A. Grudiev, A. Latina, H. Mainaud Durand, M. Modena, H. Schmickler, D. Schulte, S. Stapnes, I. Syratchev, A.L. Vamvakas, W. Wuensch
    CERN, Geneva, Switzerland
  • M. Aicheler
    HIP, University of Helsinki, Finland
 
  In 2016, CLIC implementation working groups have started their reflection on how to finalize the CLIC design work in the different areas of the project, aiming for a technical design and an overall implementation plan for CLIC being available for the next European Strategy Update around 2019. One of the working groups has focused its attention on the Main Linac hardware, which has brought together the different competences of the study with the aim of producing an advanced set of specifications for the design, installation and operation of the CLIC module. As the fundamental unit for the construction of the Main Beam linac, the CLIC module needs to move from the existing prototypes exploring its performance into an advanced and functional unit where the full life cycle of the module is considered. The progress of the working group activity is summarized in this paper, with considerations on the requirements for the design of the next-phase CLIC module.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB016  
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TUPAB017 Results of the Beam-Loading Breakdown Rate Experiment at the CLIC Test Facility CTF3 1348
 
  • E. Senes, T. Argyropoulos, N. Catalán Lasheras, R. Corsini, D. Gamba, J. Giner Navarro, A. Grudiev, G. McMonagle, R. Rajamaki, X.F.D. Stragier, I. Syratchev, F. Tecker, W. Wuensch
    CERN, Geneva, Switzerland
  • J. Giner Navarro
    IFIC, Valencia, Spain
  • R. Rajamaki
    Aalto University, School of Science and Technology, Aalto, Finland
  • E. Senes
    Torino University, Torino, Italy
 
  The RF breakdown rate is crucial for the luminosity performance of the CLIC linear collider. The required breakdown rate at the design gradient of 100 MV/m has been demonstrated, without beam presence, in a number of 12 GHz CLIC prototype structures. Nevertheless, the beam-loading at CLIC significantly changes the field profile inside the structures, and the behaviour with beam needs to be understood. A dedicated experiment in the CLIC Test Facility CTF3 to determine the effect of beam on the breakdown rate has been collecting breakdown data throughout the year 2016. The complete results of the experiment and the effect of the beam-loading on the breakdown rate are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB017  
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THPAB039 Novel Manufacturing Concepts for 12 GHz High Gradient Accelerating Structures 3787
 
  • A. Solodko, S. Atieh, N. Catalán Lasheras, A. Grudiev, S. Lebet, W. Wuensch
    CERN, Geneva, Switzerland
  • H. Zha
    TUB, Beijing, People's Republic of China
 
  CLIC high gradient accelerating structures (AS) work-ing in X-band are made of copper ultra-high precision discs, requiring both milling and turning operations. Discs are then joint together by diffusion bonding. The rest of important technical systems, such as vacuum, cooling and manifolds, to house damping silicon carbide absorbers, are brazed to the bonded disc stack afterwards. This manufacturing technique has been successfully demonstrated but it is very challenging and needs an accurate assembly at every production step. Main issues concern vacuum-tightness, misalignment, deformations during different assembly operations, defects of braz-ing/bonding operations (gaps, a leak of brazing material) etc. Preparation and repairs are time and resource con-suming and increase the final price of the accelerating structure. This paper describes the novel manufacturing concepts for 12 GHz high gradient AS and focuses on new joining techniques as electron beam welding or brazing, new engineering solutions, as rectangular cells or structures made of halves are being considered.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB039  
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THPIK081 Design and Construction of a High-Gradient RF Lab at IFIC-Valencia 4272
SUSPSIK096   use link to see paper's listing under its alternate paper code  
 
  • A. Vnuchenko, T. Argyropoulos, C. Blanch Gutiérrez, D. Esperante Pereira, A. Faus-Golfe, J. Giner Navarro
    IFIC, Valencia, Spain
  • N. Catalán Lasheras, G. McMonagle, I. Syratchev, W. Wuensch
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    LAL, Orsay, France
 
  The IFIC High-Gradient (HG) Radio Frequency (RF) laboratory is designed to host a high-power infrastructure for testing HG S-band normal-conducting RF accelerating structures and has been under construction since 2016. The main objective of the facility is to develop HG S-band accelerating structures and to contribute to the study of HG phenomena. A particular focus is RF structures for medical hadron therapy applications. The design of the laboratory has been made through collaboration between the IFIC and the CLIC RF group at CERN. The layout is inspired by the scheme of the Xbox-3 test facility at CERN, and it has been adapted to S-band frequency. In this paper we describe the design and construction status of such a facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK081  
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THPIK095 High Power X-Band Generation Using Multiple Klystrons and Pulse Compression 4311
 
  • B.J. Woolley, T. Argyropoulos, N. Catalán Lasheras, G. McMonagle, S.F. Rey, I. Syratchev, W. Wuensch
    CERN, Geneva, Switzerland
  • D. Esperante Pereira
    IFIC, Valencia, Spain
  • J. Tagg
    National Instruments Switzerland, Ennetbaden, Switzerland
  • M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
 
  CERN has constructed and is operating a new X-band test stand containing two pairs of 12 GHz, 6 MW klystrons. By power combination through hybrid couplers and the use of pulse compressors, up to 45 MW of peak power can be sent to any of 4 test slots at pulse repetition rates up to 400 Hz. The test stand is dedicated to RF conditioning and testing of high gradient accelerating structures for the CLIC study and also future X-band FELs. Operations have been ongoing for a few months, with initial operation dedicated to control algorithm development. Significant progress has been made in understanding the unique challenges of high power RF combination and phase switching using RF hybrids.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK095  
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THPIK097 High Power Tests of a Prototype X-Band Accelerating Structure for CLIC 4318
 
  • R. Zennaro, H. Blumer, M. Bopp, T. Garvey, L. Rivkin
    PSI, Villigen PSI, Switzerland
  • T. Argyropoulos, D. Esperante Pereira
    IFIC, Valencia, Spain
  • N. Catalán Lasheras, A. Grudiev, G. McMonagle, A. Solodko, I. Syratchev, R. Wegner, B.J. Woolley, W. Wuensch
    CERN, Geneva, Switzerland
  • T.G. Lucas, M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
 
  Funding: Partially funded by SNF FLARE grant 20FL20147463
We present the design, construction and high-power test of an X-band radio-frequency accelerating structure, built as a prototype for the CERN LInear Collider (CLIC) study. X-band structures have been attracting increasing attention in recent years with applications foreseen in the domains of compact free electron lasers, medical accelerators and as diagnostics for ultra-short (femtosecond) electron bunches (when used in deflecting mode). To date, the main motivation for developments in this field has been as accelerating structures for linear colliders such as CLIC. In the context of a CERN/PSI collaboration we have built a prototype structure based on an existing CERN design, but with some modification, and following, as closely as possible, the realization and vacuum brazing techniques employed in the production of the C-band structures for the Swiss Free Electron Laser, SwissFEL. We will present the basic design of the structure and describe the fabrication process. The results of high power conditioning of the structure at CERN on an X-box test stand, to assess conditioning times, accelerating field and measure breakdown rates, will also be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK097  
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THPVA135 ProBE: Proton Boosting Extension for Imaging and Therapy 4776
 
  • S. Pitman, R. Apsimon, G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • A.F. Green, H.L. Owen
    UMAN, Manchester, United Kingdom
  • A. Grudiev, A. Solodko, W. Wuensch
    CERN, Geneva, Switzerland
 
  Funding: This work was funded by STFC
The ProBE linac aims at accelerating protons from a particle therapy cyclotron to the c.330 MeV required for proton tomography. To obtain the c. 55 MV/m gradients required to achieve 100 MeV gain in a suitably short distance, we propose the use of a high-gradient S-band side-coupled standing-wave structure. In this paper we discuss the progress toward the testing of the prototype at the S-box facility at CERN.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA135  
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