Publications

2016

  • A. Degiovanni, R. Wegner, M. N. Irazabal, M. Aicheler, P. A. Fontenla, W. Wuensch, and W. Farabolini, “Post-mortem analysis after high power operation of the td24-r05 tested in xbox_1,” Clic-note, iss. Nr. XXX, 2016.
    [Bibtex]
    @Article{Deg2016,
    Title = {Post-mortem analysis after high power operation of the TD24-R05 tested in XBox_1},
    Author = {A. Degiovanni and R. Wegner and N. Mouriz Irazabal and M. Aicheler and A. Perez Fontenla and W. Wuensch and W. Farabolini},
    Journal = {CLIC-Note},
    Year = {2016},
    Number = {Nr. XXX},
    Abstract = {The CLIC prototype structure TD24_R05 has been high power tested in Xbox_1 in 2013. This report summarizes all conducted examinations after the high power test, from bead-pull measurements over structure cutting to Metrology and SEM observations, and synthesises results available from various sources. The structure developed over the time of operation a hot cell and some detuning. The post mortem examination clearly showed a developed standing wave pattern which was further explained by the physical deformation of one of the coupler iris. An elevated breakdown count in the suspected hot cell however could not be confirmed. Neither any particular feature offering an explanation for the observed longitudinal breakdown distribution could be detected.},
    Project = {CLIC-K}
    }
  • [DOI] R. Montonen, I. Kassamakov, E. Haeggstroem, and K. Oesterberg, “Quantifying height of machined steps on copper disk using fourier domain short coherence interferometer,” Optical engineering, vol. 55, 2016.
    [Bibtex]
    @Article{Mon2016,
    Title = {Quantifying height of machined steps on copper disk using Fourier domain short coherence interferometer},
    Author = {R. Montonen and I. Kassamakov and E. Haeggstroem and K. Oesterberg},
    Journal = {Optical Engineering},
    Year = {2016},
    Volume = {55},
    Abstract = {The internal shape and alignment of accelerator discs is crucial for efficient collider operation at the future compact linear collider (CLIC). We applied a calibrated custom-made Fourier-domain short coherence interferometer to measure the height of 40 and 60 um ultraprecisely turned steps (surface roughness Ra < 25 nm, flatness < 2 um) on an oxygen-free electronic copper disc. The step heights were quantified to be (39.6 ± 2.6) um and (59.0 ± 2.3) um. The uncertainties are quoted at 95% confidence level and include contributions from calibration, refractive index of air, cosine error, surface roughness, and thermal expansion in comparison to standard temperature of 20°C. The results were verified by measuring the same steps using a commercial white light interferometer Veeco—NT3300. Our instrument can ensure that the accelerator discs of the CLIC are aligned within the tolerance required for efficient collider operation.},
    Doi = {http://dx.doi.org/10.1117/1.OE.55.1.014103},
    Project = {CLIC-K},
    Url = {http://opticalengineering.spiedigitallibrary.org/article.aspx?articleID=2484237}
    }
  • A. Xydou, M. Aicheler, R. E. Castro, N. J. Siakavellas, and S. Doebert, "Diffusion bonding of ofe copper discs at very high temperature for the production of the clic accelerating structures," Submitted to international journal of metallurgical & materials science and engineering,, 2016.
    [Bibtex]
    @Article{Xyd2016-1,
    Title = {Diffusion Bonding of OFE copper discs at very high temperature for the production of the CLIC Accelerating Structures},
    Author = {A. Xydou and M. Aicheler and E. Rodriguez Castro and N.J. Siakavellas and S. Doebert},
    Journal = {submitted to International Journal of Metallurgical \& Materials Science and Engineering,},
    Year = {2016},
    Project = {CLIC-K}
    }
  • A. Xydou, S. Parviainen, M. Aicheler, and F. Djurabekova, "Thermal stability of interface voids in cu grain boundaries with molecular dynamic simulations," Submitted to journal of physics d: applied physics, 2016.
    [Bibtex]
    @Article{Xyd2016-2,
    Title = {Thermal stability of interface voids in Cu grain boundaries with Molecular Dynamic Simulations},
    Author = {A. Xydou and S. Parviainen and M. Aicheler and F. Djurabekova},
    Journal = {submitted to Journal of Physics D: Applied Physics},
    Year = {2016},
    Abstract = {By means of molecular dynamic simulations, the stability of cylindrical voids is
    examined with respect to the diusion bonding procedure. To do this, the effect of
    grain boundaries between the grains of different crystallographic orientations on the
    void closing time was studied at high temperatures from 0.7 up to 0.94 of the bulk
    melting temperature (Tm). The size of the void varied from 3.5 to 6.5 nm. The
    thermal instability is consequent of the existence of a void on a grain boundary (GB).
    This instability leads to the void's closure of the examined temperatures. The closing
    time presents an exponential dependence on the temperature and the diameter of the
    void. The diffusion coeffcient in the grain boundaries was found to be higher than in
    the surface layer of the void. The activation energy for the grain boundary diffusion
    which is calculated through the diffusion coeffcient of the GB agrees with the value
    given by Coble.},
    Project = {CLIC-K}
    }

2015

  • [DOI] R. Montonen, I. Kassamakov, E. Haeggstroem, and K. Oesterberg, "Calibration of fourier domain short coherence interferometer for absolute distance measurements," Appl. opt., vol. 54, iss. 15, p. 4635–4639, 2015.
    [Bibtex]
    @Article{Mon2015,
    Title = {Calibration of Fourier domain short coherence interferometer for absolute distance measurements},
    Author = {R. Montonen and I. Kassamakov and E. Haeggstroem and K. Oesterberg},
    Journal = {Appl. Opt.},
    Year = {2015},
    Month = {May},
    Number = {15},
    Pages = {4635--4639},
    Volume = {54},
    Abstract = {We calibrated and determined the measurement uncertainty of a custom-made Fourier domain short coherence interferometer operated in laboratory conditions. We compared the optical thickness of two thickness standards and three coverslips determined with our interferometer to the geometric thickness determined by SEM. Using this calibration data, we derived a calibration function with a 95 % confidence level system uncertainty of (5.9 x 10^(-2) r + 2.3) um, where r is the optical distance in um, across the 240um optical measurement range. The confidence limit includes contributions from uncertainties in the optical thickness, geometric thickness, and refractive index measurements as well as uncertainties arising from cosine errors and thermal expansion. The results show feasibility for noncontacting absolute distance characterization with micrometer-level accuracy. This instrument is intended for verifying the alignment of the discs of an accelerating structure in the possible future compact linear collider.},
    Doi = {10.1364/AO.54.004635},
    File = {:http\://opticalengineering.spiedigitallibrary.org/article.aspx?articleID=2484237:URL},
    Keywords = {Height measurements; Interferometry; Metrology},
    Project = {CLIC-K},
    Publisher = {OSA},
    Url = {http://ao.osa.org/abstract.cfm?URI=ao-54-15-4635}
    }

2014

  • R. Rajamaki, "Breakdown localization in the fixed gap system," Clic-note, pp. 1-22, 2014.
    [Bibtex]
    @Article{Rajr2014,
    Title = {Breakdown localization in the fixed gap system},
    Author = {R. Rajamaki},
    Journal = {CLIC-Note},
    Year = {2014},
    Pages = {1-22},
    Abstract = {Accurate localization of breakdowns in vacuum could help shed light on breakdown related processes that are not yet fully understood. At the DC spark lab at CERN, an instrument called the Fixed Gap System (FGS) has been developed partially for this purpose. Among other things, the FGS has four built-in antennas, which are intended for breakdown localization. The capability of this aspect of the FGS was explored in this report. Specifically, the feasibility of using a method similar to that which is used in cavity Beam Position Monitors (BPMs) was investigated. The usable frequency range of the current experimental setup was also studied. Firstly, a modal analysis of the inner geometry of the FGS was done in HFSS. This showed that the two first modes to be expected in the spark gap quite differ from those of the ideal pillbox – both in field pattern and in frequency ( 4 and 6 GHz vs. 0.2 and 3 GHz). Secondly, S-parameters of the system were measured. These showed that the coupling between antennas is weak below 13 GHz, which is due to the high cut-off frequency of the waveguides in which the antennas are located. The breakdown signal was also measured using an oscilloscope connected to the antennas. However, it was determined that the detected signal was picked up from outside of the system, rendering it useless for localization purposes. It was concluded that either a new approach has to be adopted or the current system must be modified.},
    File = {1756445?ln=en:http\://cds.cern.ch/record/1712915?ln=enhttp\://cds.cern.ch/record/1756445?ln=en:PDF},
    Project = {CLIC}
    }
  • A. Xydou, "Thermo-mechanical tests for the clic two-beam module study," 5th international particle accelerator conference, pp. 1370-1373, 2014.
    [Bibtex]
    @Article{Xyd2014,
    Title = {Thermo-Mechanical tests for the CLIC two-beam module study},
    Author = {A. Xydou},
    Journal = {5th International Particle Accelerator Conference},
    Year = {2014},
    Pages = {1370-1373},
    Abstract = {The luminosity goal of CLIC requires micron level precision with respect to the alignment of the components on its two-meter long modules, composing the two main linacs. The power dissipated inside the module components introduces mechanical deformations affecting their alignment and therefore the resulting machine performance. Several two-beam prototype modules must be assembled to extensively measure their thermo-mechanical behavior under different operation modes. In parallel, the real environmental conditions present in the CLIC tunnel should be studied. The air conditioning and ventilation system providing specified air temperature and flow has been installed in the dedicated laboratory. The power dissipation occurring in the modules is being reproduced by the electrical heaters inserted inside the RF structure mock-ups and the quadrupoles. The efficiency of the cooling systems is being verified and the alignment of module components is monitored. The measurement results will be compared to finite element analysis model and propagated back to engineering design. Finally, simulation of the most possible CLIC machine cycles is accomplished and preliminary results are analysed.},
    File = {1742324?ln=en:http\://cds.cern.ch/record/1742324?ln=en:PDF},
    Project = {CLIC}
    }

2013

  • D. Gudkov, "Experience on fabrication and assembly of the first clic two-beam module prototype," 4th international particle accelerator conference, pp. 2815-2818, 2013.
    [Bibtex]
    @Article{Gud2013,
    Title = {Experience on Fabrication and Assembly of the First CLIC Two-Beam Module Prototype},
    Author = {D. Gudkov},
    Journal = {4th International Particle Accelerator Conference},
    Year = {2013},
    Pages = {2815-2818},
    Abstract = {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 and methods for 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 module assembly procedure and quality control measurements are also recalled.},
    File = {wepfi055.pdf:http\://accelconf.web.cern.ch/AccelConf/IPAC2013/papers/wepfi055.pdf:PDF},
    Project = {CLIC}
    }
  • F. Rossi, "Thermal joining studies of clic accelerating structures and establishment of a test bench and studies of thermomechanical behaviour of a clic two beam module," Clic-note, pp. 1-34, 2013.
    [Bibtex]
    @Article{Ros2013-1,
    Title = {Thermal joining studies of CLIC accelerating structures and Establishment of a test bench and studies of thermomechanical behaviour of a CLIC two beam module},
    Author = {F. Rossi},
    Journal = {CLIC-Note},
    Year = {2013},
    Pages = {1 - 34},
    Abstract = {The assembly procedure of the CLIC accelerating structures is constituted of several steps, involving ultra-precision machining, heating cycles at very high temperatures and many quality controls necessary to fulfil the very tight technical requirements. Diverse issues are related to the diffusion bonding process of CLIC accelerating structures; due to diffusion creep mechanisms occurring at high temperature and low stress, residual deformations might be present at the end of the joining process. A theoretical and experimental approach is presented here in order to understand this issue further and feedback on the design process. As a second issue tackled here, the final alignment of CLIC is also affected by the power dissipation occurring in the module during the normal operation modes and resulting in time-varying non-uniform thermal fields. The thermo-mechanical models of CLIC two-beam modules developed in the past are then useful to predict the structural deformations affecting the final alignment of the modules; nevertheless, the experimental validation of the numerical modelling is strictly necessary. To this aim, two-beam prototype modules are being assembled to extensively study their thermo-mechanical behaviour under different operation modes.},
    File = {1712916?ln=en:http\://cds.cern.ch/record/1712916?ln=en:PDF},
    Project = {MeChanICs}
    }
  • F. Rossi, "Study of the thermo-mechanical behavior of the clic two-beam modules," 4th international particle accelerator conference, pp. 2818-2820, 2013.
    [Bibtex]
    @Article{Ros2013-2,
    Title = {Study of the Thermo-Mechanical Behavior of the CLIC Two-Beam Modules},
    Author = {F. Rossi},
    Journal = {4th International Particle Accelerator Conference},
    Year = {2013},
    Pages = {2818-2820},
    Abstract = {The final luminosity target of the Compact LInear Collider (CLIC) imposes a micron-level stability requirement on the two-meter repetitive two-beam modules constituting the main linacs. Two-beam prototype modules are being 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 have been installed in the dedicated laboratory. The air temperature will be changed from 20 to 40°C, while the air flow rate will be varied 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. \nThis test program will allow for better understanding the behaviour of the CLIC modules and the results will be propagated back both to the numerical modelling and the engineering design.},
    File = {wepfi056.pdf:http\://accelconf.web.cern.ch/AccelConf/IPAC2013/papers/wepfi056.pdf:PDF},
    Project = {MeChanICs}
    }

2012

  • J. Nurminen, "Material studies in the frame of clic accelerating structures production conducted within the mechanics program together with metso oy," Clic-note, pp. 1-29, 2012.
    [Bibtex]
    @Article{Nur2012,
    Title = {Material studies in the frame of CLIC Accelerating structures production conducted within the Mechanics program together with Metso Oy},
    Author = {J. Nurminen},
    Journal = {CLIC-Note},
    Year = {2012},
    Pages = {1-29},
    Abstract = {MeChanICs (Marie Curie Linking Industry to CERN) is an Industry to Academia Partnership and Pathways (IAPP) platform for precision manufacturing knowledge exchange bringing together five Finnish manufacturing companies with Helsinki Insitute of Physics (HIP) and CERN. The scientific objective of MeChanICs project is to contribute to the manufacturing RTD of CLIC enabling technologies. The focus is on the design, materials, machining, brazing and assembly of A CLIC accelerating structure. This study deals with the materials work package of the program and wants to explore the following items: 1) producing copper accelerating structures for CLIC from raw copper powder by near net shape hot isostatic pressing (HIP). 2) The feasibility to use HIP diffusion bonding of the accelerator structures as a function of surface quality and applied temperature and pressure. 3) Brazing for CLIC AS auxiliary systems, like water cooling or damping manifolds, to the disc stack by coating one of the brazing partners with an enabling layer prior to the heat treatment. The chosen coating method is electrodeposition of pure Cu/Au layers.},
    File = {1712915?ln=en:http\://cds.cern.ch/record/1712915?ln=en:PDF},
    Project = {MeChanICs}
    }
  • R. Raatikainen, "Improved modelling of the thermo-mechanical behavior of the clic two beam module," 3rd international particle accelerator conference, pp. 1891-1893, 2012.
    [Bibtex]
    @Article{Raa2012,
    Title = {Improved Modelling of the Thermo-Mechanical behavior of the CLIC Two Beam Module},
    Author = {R. Raatikainen},
    Journal = {3rd International Particle Accelerator Conference},
    Year = {2012},
    Pages = {1891-1893},
    Abstract = {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 and methods for 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 module assembly procedure and quality control measurements are also recalled.},
    File = {TUPPR033.pdf:http\://accelconf.web.cern.ch/AccelConf/IPAC2012/papers/TUPPR033.pdf:PDF},
    Project = {CLIC}
    }