SRF2017 - List of Authors (Capatina, O.)

Paper	Title	Page
MOPB089	Characterisation of Magnetic Shielding Material for HL-LHC Crab Cavities	273
	K. Eiler, P. Arpaia, M.C.L. Buzio, O. Capatina, S.A.E. Langeslag, A. Parrella CERN, Geneva, Switzerland P. Arpaia, A. Parrella Naples University Federico II, Science and Technology Pole, Napoli, Italy A. Parrella IT, Lisboa, Portugal N. Templeton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: CERN, 1211 Geneva 23 To guarantee optimum performance, the crab cavities for the high-luminosity upgrade of CERN's LHC need to be shielded from external magnetic fields. Consequently, they will be enclosed by two layers of magnetic shielding, of which the inner is immersed in superfluid helium at 2 K. A Ni-based high-permeability material with a tailored composition and a designated heat treatment is applied. Its magnetic properties at cryogenic temperature are however not yet fully assessed. Especially the effect of deformation on magnetic properties has not been thoroughly investigated, however strain effects may have severe consequences. A magnetic measurement set-up has been developed, and the magnetic permeability at room temperature and at cryogenic temperatures is evaluated, showing that the maximum relative permeability at 4 K exceeds the design criteria of 100, 000. Measurements of the magnetic permeability after introduction of uniaxial plastic deformation between 0% and 3% are conducted by means of an Epstein frame. Results show that deformation induces significant decrease of the magnetic performance, underlining that particular care must be taken during all stages of handling and operation. *konrad.eiler@cern.ch
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB089
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MOPB104	Development of a Novel Supporting System for High Luminosity LHC SRF Crab Cavities	304
	T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom K. Artoos, R. Calaga, O. Capatina, T. Capelli, M. Sosin, J.S. Swieszek, C. Zanoni CERN, Geneva, Switzerland G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom T.J. Jones Lancaster University, Lancaster, United Kingdom
	Compact SRF Crab Cavities are integral to the HL-LHC upgrade. This paper details the design of support structures within the SPS (Super Proton Synchrotron) Crab Cavity Cryomodule. For ease of alignment each cavity is supported with the mechanical tuner and RF Fundamental Power Coupler (FPC) via a common support plate. To reduce heat leak and remove bellows in the FPC it was determined that this would be the fixed support for the cavity (V. Parma, 2013). In addition, novel flexural blades were designed to give increased stiffness yet allow for thermal contraction of the cavity towards the fixed point of the FPC. This approach was superior when compared via simulation to several alternative techniques. A detailed simulation model was used for optimisation of directional stiffness, identification of vibration modes and minimising thermal stresses. A transmission matrix was developed in MS Excel to assess modal deflection for given ground vibration conditions. The spreadsheet gives an instantaneous yet comparable result to time consuming random vibration FE Analyses. The final engineering design of the supporting system is now complete and will also be described in this paper. References V. Parma, R. B. (2013). Status of the Superconducting Proton Linac (SPL) Cryomodule. SRF2013.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB104
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TUXAA02	HIE Isolde Cavity Production & Cryomodule Commissioning, Lessons Learned	338
	W. Venturini Delsolaro, K. Artoos, O. Brunner, O. Capatina, K.M. Dr. Schirm, Y. Kadi, Y. Leclercq, A. Miyazaki, E. Montesinos, V. Parma, G.J. Rosaz, A. Sublet, S. Teixeira Lopez, M. Therasse, L.R. Williams CERN, Geneva, Switzerland
	The lessons learned during the HIE Isolde Cavity Production, the Cryo Module Assembly and Commissioning will be presented
	Slides TUXAA02 [8.191 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUXAA02
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TUPB100	Determining BCP Etch Rate and Uniformity in High Luminosity LHC Crab Cavities	635
	T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R. Calaga, O. Capatina, L.M.A. Ferreira, R. Leuxe CERN, Geneva, Switzerland T.J. Jones, J.A. Mitchell Lancaster University, Lancaster, United Kingdom S.M. Pattalwar STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S. Verdú-Andrés, B. P. Xiao BNL, Upton, Long Island, New York, USA
	The compact SRF Crab Cavities required for HL-LHC have complex geometries making prediction of average and local BCP etch rates a difficult task. This paper describes a series of experiments and simulations used to determine the etch uniformity and rate within these structures. An initial experiment was conducted to determine the correlation between etch rate and flow rate in a Nb tube. These results were then incorporated into Computational Fluid Dynamics simulations of acid flow in the Double Quarter Wave (DQW) cavity to predict etch rates across the surface and allow optimisation of the BCP setup. There were several important findings from the work; one of which is that the flow rate in the relatively large body of the cavity is predominantly driven by natural convection due to the exothermic reaction. During BCP processing of the DQW cavity a significant difference in etching was observed between upper and lower horizontal surfaces which was mitigated by etching in several orientations. Two DQW cavities manufactured by CERN have received a heavy BCP of 200μm followed by 2 light BCPs of 30μm each with subsequent vertical cold tests showing performance exceeding specification.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB100
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Paper

Title

Page

Characterisation of Magnetic Shielding Material for HL-LHC Crab Cavities

273

K. Eiler, P. Arpaia, M.C.L. Buzio, O. Capatina, S.A.E. Langeslag, A. Parrella
CERN, Geneva, Switzerland
P. Arpaia, A. Parrella
Naples University Federico II, Science and Technology Pole, Napoli, Italy
A. Parrella
IT, Lisboa, Portugal
N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Funding: CERN, 1211 Geneva 23
To guarantee optimum performance, the crab cavities for the high-luminosity upgrade of CERN's LHC need to be shielded from external magnetic fields. Consequently, they will be enclosed by two layers of magnetic shielding, of which the inner is immersed in superfluid helium at 2 K. A Ni-based high-permeability material with a tailored composition and a designated heat treatment is applied. Its magnetic properties at cryogenic temperature are however not yet fully assessed. Especially the effect of deformation on magnetic properties has not been thoroughly investigated, however strain effects may have severe consequences. A magnetic measurement set-up has been developed, and the magnetic permeability at room temperature and at cryogenic temperatures is evaluated, showing that the maximum relative permeability at 4 K exceeds the design criteria of 100, 000. Measurements of the magnetic permeability after introduction of uniaxial plastic deformation between 0% and 3% are conducted by means of an Epstein frame. Results show that deformation induces significant decrease of the magnetic performance, underlining that particular care must be taken during all stages of handling and operation.
*konrad.eiler@cern.ch

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB089

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MOPB104

Development of a Novel Supporting System for High Luminosity LHC SRF Crab Cavities

304

T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
K. Artoos, R. Calaga, O. Capatina, T. Capelli, M. Sosin, J.S. Swieszek, C. Zanoni
CERN, Geneva, Switzerland
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.J. Jones
Lancaster University, Lancaster, United Kingdom

Compact SRF Crab Cavities are integral to the HL-LHC upgrade. This paper details the design of support structures within the SPS (Super Proton Synchrotron) Crab Cavity Cryomodule. For ease of alignment each cavity is supported with the mechanical tuner and RF Fundamental Power Coupler (FPC) via a common support plate. To reduce heat leak and remove bellows in the FPC it was determined that this would be the fixed support for the cavity (V. Parma, 2013). In addition, novel flexural blades were designed to give increased stiffness yet allow for thermal contraction of the cavity towards the fixed point of the FPC. This approach was superior when compared via simulation to several alternative techniques. A detailed simulation model was used for optimisation of directional stiffness, identification of vibration modes and minimising thermal stresses. A transmission matrix was developed in MS Excel to assess modal deflection for given ground vibration conditions. The spreadsheet gives an instantaneous yet comparable result to time consuming random vibration FE Analyses. The final engineering design of the supporting system is now complete and will also be described in this paper.
References
V. Parma, R. B. (2013). Status of the Superconducting Proton Linac (SPL) Cryomodule. SRF2013.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-MOPB104

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXAA02

HIE Isolde Cavity Production & Cryomodule Commissioning, Lessons Learned

338

W. Venturini Delsolaro, K. Artoos, O. Brunner, O. Capatina, K.M. Dr. Schirm, Y. Kadi, Y. Leclercq, A. Miyazaki, E. Montesinos, V. Parma, G.J. Rosaz, A. Sublet, S. Teixeira Lopez, M. Therasse, L.R. Williams
CERN, Geneva, Switzerland

The lessons learned during the HIE Isolde Cavity Production, the Cryo Module Assembly and Commissioning will be presented

Slides TUXAA02 [8.191 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUXAA02

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPB100

Determining BCP Etch Rate and Uniformity in High Luminosity LHC Crab Cavities

635

T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R. Calaga, O. Capatina, L.M.A. Ferreira, R. Leuxe
CERN, Geneva, Switzerland
T.J. Jones, J.A. Mitchell
Lancaster University, Lancaster, United Kingdom
S.M. Pattalwar
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S. Verdú-Andrés, B. P. Xiao
BNL, Upton, Long Island, New York, USA

The compact SRF Crab Cavities required for HL-LHC have complex geometries making prediction of average and local BCP etch rates a difficult task. This paper describes a series of experiments and simulations used to determine the etch uniformity and rate within these structures. An initial experiment was conducted to determine the correlation between etch rate and flow rate in a Nb tube. These results were then incorporated into Computational Fluid Dynamics simulations of acid flow in the Double Quarter Wave (DQW) cavity to predict etch rates across the surface and allow optimisation of the BCP setup. There were several important findings from the work; one of which is that the flow rate in the relatively large body of the cavity is predominantly driven by natural convection due to the exothermic reaction. During BCP processing of the DQW cavity a significant difference in etching was observed between upper and lower horizontal surfaces which was mitigated by etching in several orientations. Two DQW cavities manufactured by CERN have received a heavy BCP of 200μm followed by 2 light BCPs of 30μm each with subsequent vertical cold tests showing performance exceeding specification.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUPB100

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)