Author: Riddone, G.
Paper Title Page
TUPME054 Experimental Study of the Effect of Beam Loading on RF Breakdown Rate in CLIC High-gradient Accelerating Structures 1691
  • F. Tecker, R. Corsini, M. Dayyani Kelisani, S. Döbert, A. Grudiev, O. Kononenko, S. Lebet, J.L. Navarro Quirante, G. Riddone, I. Syratchev, W. Wuensch
    CERN, Geneva, Switzerland
  • A. Solodko
    JINR, Dubna, Moscow Region, Russia
  RF breakdown is a key issue for the multi-TeV high-luminosity e+e Compact Linear Collider (CLIC). Breakdowns in the high-gradient accelerator structures can deflect the beam and decrease the desired luminosity. The limitations of the accelerating structures due to breakdowns have been studied so far without a beam present in the structure. The presence of the beam modifies the distribution of the electrical and magnetic field distributions, which determine the breakdown rate. Therefore an experiment has been designed for high power testing a CLIC prototype accelerating structure with a beam present in the CLIC Test Facility (CTF3). A special beam line allows extracting a beam with nominal CLIC beam current and duration from the CTF3 linac. The paper describes the beam optics design for this experimental beam line and the commissioning of the experiment with beam.  
WEPFI018 Comparison of High Gradient Performance in Varying Cavity Geometries 2741
  • T. Higo, T. Abe, Y. Arakida, Y. Higashi, S. Matsumoto, T. Shidara, T. Takatomi, M. Yamanaka
    KEK, Ibaraki, Japan
  • A. Grudiev, G. Riddone, W. Wuensch
    CERN, Geneva, Switzerland
  Four types of CLIC prototype TW accelerator structures were high-gradient tested at Nextef, KEK, up to 100 MV/m level and the fifth is under test now. The ramping speed of each processing and the resultant breakdown rate were compared among them. From this comparison, it was found that the ramping speed of the structures with opening ports for HOM damping with magnetic coupling became slow and the resultant breakdown rate became high. It was also found that that with lower surface magnetic field showed faster ramping in processing and lower breakdown rate. This indicates the role of the magnetic field on vacuum breakdowns in copper structure at the region of several tens to 100 MV/m. In this paper, we review the processing stage and the high gradient performance of these structures trying to discuss the relevant parameters, surface electric field, surface magnetic field and other parameters such as Sc, “complex pointing vector”, to the performance difference.  
WEPFI055 Experience on Fabrication and Assembly of the First Clic Two-Beam Module Prototype 2815
  • D. Gudkov, S. Lebet, G. Riddone, F. Rossi
    CERN, Geneva, Switzerland
  • A. Samoshkin
    JINR, Dubna, Moscow Region, Russia
  The CLIC two-beam module prototypes are intended to prove the design of all technical systems under the different operation modes. Two validation programs are currently under way and they foresee the construction of four prototype modules for mechanical tests without beam and three prototype modules for tests with RF and beam. The program without beam will show the capability of the technical solutions proposed to fulfil the stringent requirements on radio-frequency, supporting, pre-alignment, stabilization, vacuum and cooling systems. The engineering design was performed with the use of CAD/CAE software. Dedicated mock-ups of RF structures, with all mechanical interfaces and chosen technical solutions, are used for the tests and therefore reliable results are expected. The components were fabricated by applying different technologies for the part manufacturing and joining. The first full-size prototype module was assembled in 2012. This paper is focused on the production process including the comparison of several technical solutions adopted during the realization. The description of the module assembly and quality control measurements are also recalled.  
WEPFI056 Study of the Thermo-Mechanical Behavior of the CLIC Two-Beam Modules 2818
  • F. Rossi, R. Mondello, G. Riddone
    CERN, Geneva, Switzerland
  • D. Gudkov, A. Samoshkin
    JINR, Dubna, Moscow Region, Russia
  • I. Kossyvakis
    National Technical University of Athens, Zografou, Greece
  • K. Österberg
    HIP, University of Helsinki, Finland
  The final luminosity target of the Compact LInear Collider (CLIC) imposes a micron-level stability of the two-meter repetitive two-beam modules constituting the main linacs. Two-beam prototype modules have been assembled to extensively study their thermo-mechanical behaviour under different operation modes. The power dissipation occurring in the modules will be reproduced and the efficiency of the corresponding cooling systems validated. At the same time, the real environmental conditions present in the CLIC tunnel will be studied. Air conditioning and ventilation systems will be installed in the dedicated laboratory. Air temperature will be varied from 20 to 40 °C, while air flow rate will be regulated up to 0.8 m/s. During all experimental tests, the alignment of the RF structures will be monitored to investigate the influence of power dissipation and air temperature on the overall thermo-mechanical behaviour. This test program will allow for better understanding the behaviour of CLIC modules and the results will be propagated back to both numerical modelling and engineering design.