SRF2015 - List of Authors (Macpherson, A.)

Paper	Title	Page
MOPB049	High Flux Three Dimensional Heat Transport in Superfluid Helium and Its Application to a Trilateration Algorithm for Quench Localization With OSTs	201
	T. Junginger TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada P. Horn TU Dresden, Dresden, Germany T. Koettig, K.C. Liao, A. Macpherson CERN, Geneva, Switzerland B.J. Peters KIT, Karlsruhe, Germany
	Oscillating superleak transducers of second sound can be used to localize quench spots on superconducting cavities by trilateration. However propagation speeds faster than the velocity of second sound are usually observed imped- ing the localization. Dedicated experiments show that the fast propagation cannot be correlated to the dependence of the velocity on the heat flux density, but rather to boiling effects in the vicinity of the hot spot. 17 OSTs were used to detect quenches on a 704MHz one-cell elliptical cavity. Two different algorithms for quench localization have been tested and implemented in a computer program enabling direct crosschecks. The new algorithm gives more consis- tent results for different OST signals analyzed for the same quench spot.
	Poster MOPB049 [0.901 MB]
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MOPB074	CERN’s Bulk Niobium High Gradient SRF Programme: Developments and Recent Cold Test Results	291
	A. Macpherson, K.G. Hernández-Chahín, C. Jarrige, P. Maesen, F. Pillon, K.M. Schirm, R. Torres-Sanchez, N. Valverde Alonso CERN, Geneva, Switzerland K.G. Hernández-Chahín DCI-UG, León, Mexico
	Recent results from the bulk niobium high-gradient cavity development program at CERN are presented, with particular focus on test results for the 704 MHz bulk niobium 5-cell elliptical cavity prototypes produced for the Superconducting Proton Linac (SPL) project. Successive cold tests of bare cavities have been used to refine the cavity preparation and testing process, with all steps done in-house at CERN. Current performance results are discussed with reference to observables such as ambient magnetic field, field emission levels, and quenches.
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TUPB080	Diagnostic Developments at CERN’s SRF Testing Facility	778
	A. Macpherson, S. Aull, A. Benoit, P.F. Fernández López, K.G. Hernández-Chahín, C. Jarrige, P. Maesen, K.M. Schirm, R. Torres-Sanchez, R. Valera Teruel CERN, Geneva, Switzerland K.G. Hernández-Chahín DCI-UG, León, Mexico T. Junginger HZB, Berlin, Germany T. Junginger TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	As part of CERN’s re-establishment of an SRF cold testing facility for bulk niobium cavities, diagnostic instrumentation and testing procedures on our vertical cryostat have been upgraded, with particular attention given to quench location, ambient magnetic field control, thermometry and thermal cycling techniques. In addition, preparation and measurement procedures have been addressed, allowing for improved measurement of cavity properties and detailed study of transient effects during the course of cavity testing.
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THPB050	Performance Evaluation of HL-LHC Crab Cavity Prototypes in a CERN Vertical Test Cryostat	1210
	K.G. Hernández-Chahín DCI-UG, León, Mexico G. Burt Cockcroft Institute, Warrington, Cheshire, United Kingdom C. Christophe, A. Macpherson, M. Navarro-Tapia, R. Torres-Sanchez CERN, Geneva, Switzerland S.U. De Silva ODU, Norfolk, Virginia, USA A.R.J. Tutte Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S. Verdú-Andrés BNL, Upton, Long Island, New York, USA
	Funding: My work is supported by the Mexican CONACYT(Consejo Nacional de Ciencia y Tecnologia) program through the Mexican national scholarship (Becas Nacionales y Becas Mixtas). Three proof-of-principle compact crab cavity designs have been fabricated in bulk niobium and cold tested at their home labs, as a first validation step towards the High Luminosity LHC project. As a cross check, all three bare cavities have been retested at CERN, in order to cross check their performance, and cross-calibrate the CERN SRF cold test facilities. While achievable transverse deflecting voltage is the key performance indicator, secondary performance aspects derived from multiple cavity monitoring systems are also discussed. Temperature mapping profiles, quench detection, material properties, and trapped magnetic flux effects have been assessed, and the influence on performance discussed. The significant effort invested in developing expertise in preparation and testing of these crab cavities has already been fruitful for all partners, and more is to come within this ongoing program.
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THPB081	FPC and HOM Coupler Test Boxes for HL-LHC Crab Cavities	1321
	A.R.J. Tutte, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R. Calaga, A. Macpherson, E. Montesinos CERN, Geneva, Switzerland S.U. De Silva ODU, Norfolk, Virginia, USA Z. Li SLAC, Menlo Park, California, USA B. P. Xiao BNL, Upton, Long Island, New York, USA
	The LHC luminosity upgrade will involve the installation of thirty-two 400 MHz SRF crab cavities. The cavities have two variants known as the RF dipole and double quarter-wave crab cavities. Each cavity has a fundamental power coupler (FPC) at 400 MHz and two or three HOM couplers. Before integration onto the cavities it is necessary to condition the FPC, and to measure the transmission on the HOM couplers at low power to ensure the operate as designed, each requiring a special test box. The FPC test box should provide a high transmission between two couplers without creating high surface fields. The low power HOM test boxes should be terminated to a load such that the natural stop and pass-bands of the couplers are preserved allowing the reflection to me measured and compared to simulations. In addition, due to the possibility of high HOM power in the LHC crab cavities, the concept of creating a broadband high power HOM coupler test box in order to condition and test the couplers at high power has been investigated. The Rf design of all test boxes is presented and discussed.
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FRBA02	Crab Cavity and Cryomodule Development for HL-LHC	1460
	F. Carra, A. Amorim Carvalho, K. Artoos, S. Atieh, I. Aviles Santillana, A.B. Boucherie, J.P. Brachet, K. Brodzinski, R. Calaga, O. Capatina, T. Capelli, L. Dassa, T. Dijoud, H.M. Durand, G. Favre, L.M.A. Ferreira, P. Freijedo Menendez, M. Garlaschè, M. Guinchard, N. Kuder, S.A.E. Langeslag, R. Leuxe, A. Macpherson, P. Minginette, E. Montesinos, F. Motschmann, C. Parente, L. Prever-Loiri, D. Pugnat, E. Rigutto, V. Rude, M. Sosin, G. Vandoni, G. Villiger, C. Zanoni CERN, Geneva, Switzerland S.A. Belomestnykh, S. Verdú-Andrés, Q. Wu, B. P. Xiao BNL, Upton, Long Island, New York, USA G. Burt Lancaster University, Lancaster, United Kingdom S.U. De Silva, J.R. Delayen, R.G. Olave, R.G. Olave, H. Park ODU, Norfolk, Virginia, USA T.J. Jones, N. Templeton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom Z. Li SLAC, Menlo Park, California, USA K.B. Marinov, S.M. Pattalwar STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom T.H. Nicol Fermilab, Batavia, Illinois, USA A. Ratti LBNL, Berkeley, California, USA
	The HL-LHC project aims at increasing the LHC luminosity by a factor 10 beyond the design value. The installation of a set of RF Crab Cavities to increase bunch crossing angle is one of the key upgrades of the program. Two concepts, Double Quarter Wave (DQW) and RF Dipole (RFD) have been proposed and are being produced in parallel for test in the SPS beam before the next long shutdown of CERN accelerator’s complex. In the retained concept, two cavities are hosted in one single cryomodule, providing thermal insulation and interfacing with RF coupling, tuning, cryogenics and beam vacuum. This paper overviews the main design choices for the cryomodule and its different components, which have the goal of optimizing the structural, thermal and electro-magnetic behavior of the system, while respecting the existing constraints in terms of integration in the accelerator environment. Prototyping and testing of the most critical components, manufacturing, preparation and installation strategies are also described.
	Slides FRBA02 [4.678 MB]
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Paper

Title

Page

High Flux Three Dimensional Heat Transport in Superfluid Helium and Its Application to a Trilateration Algorithm for Quench Localization With OSTs

201

T. Junginger
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
P. Horn
TU Dresden, Dresden, Germany
T. Koettig, K.C. Liao, A. Macpherson
CERN, Geneva, Switzerland
B.J. Peters
KIT, Karlsruhe, Germany

Oscillating superleak transducers of second sound can be used to localize quench spots on superconducting cavities by trilateration. However propagation speeds faster than the velocity of second sound are usually observed imped- ing the localization. Dedicated experiments show that the fast propagation cannot be correlated to the dependence of the velocity on the heat flux density, but rather to boiling effects in the vicinity of the hot spot. 17 OSTs were used to detect quenches on a 704MHz one-cell elliptical cavity. Two different algorithms for quench localization have been tested and implemented in a computer program enabling direct crosschecks. The new algorithm gives more consis- tent results for different OST signals analyzed for the same quench spot.

Poster MOPB049 [0.901 MB]

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MOPB074

CERN’s Bulk Niobium High Gradient SRF Programme: Developments and Recent Cold Test Results

291

A. Macpherson, K.G. Hernández-Chahín, C. Jarrige, P. Maesen, F. Pillon, K.M. Schirm, R. Torres-Sanchez, N. Valverde Alonso
CERN, Geneva, Switzerland
K.G. Hernández-Chahín
DCI-UG, León, Mexico

Recent results from the bulk niobium high-gradient cavity development program at CERN are presented, with particular focus on test results for the 704 MHz bulk niobium 5-cell elliptical cavity prototypes produced for the Superconducting Proton Linac (SPL) project. Successive cold tests of bare cavities have been used to refine the cavity preparation and testing process, with all steps done in-house at CERN. Current performance results are discussed with reference to observables such as ambient magnetic field, field emission levels, and quenches.

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TUPB080

Diagnostic Developments at CERN’s SRF Testing Facility

778

A. Macpherson, S. Aull, A. Benoit, P.F. Fernández López, K.G. Hernández-Chahín, C. Jarrige, P. Maesen, K.M. Schirm, R. Torres-Sanchez, R. Valera Teruel
CERN, Geneva, Switzerland
K.G. Hernández-Chahín
DCI-UG, León, Mexico
T. Junginger
HZB, Berlin, Germany
T. Junginger
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

As part of CERN’s re-establishment of an SRF cold testing facility for bulk niobium cavities, diagnostic instrumentation and testing procedures on our vertical cryostat have been upgraded, with particular attention given to quench location, ambient magnetic field control, thermometry and thermal cycling techniques. In addition, preparation and measurement procedures have been addressed, allowing for improved measurement of cavity properties and detailed study of transient effects during the course of cavity testing.

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THPB050

Performance Evaluation of HL-LHC Crab Cavity Prototypes in a CERN Vertical Test Cryostat

1210

K.G. Hernández-Chahín
DCI-UG, León, Mexico
G. Burt
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C. Christophe, A. Macpherson, M. Navarro-Tapia, R. Torres-Sanchez
CERN, Geneva, Switzerland
S.U. De Silva
ODU, Norfolk, Virginia, USA
A.R.J. Tutte
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S. Verdú-Andrés
BNL, Upton, Long Island, New York, USA

Funding: My work is supported by the Mexican CONACYT(Consejo Nacional de Ciencia y Tecnologia) program through the Mexican national scholarship (Becas Nacionales y Becas Mixtas).
Three proof-of-principle compact crab cavity designs have been fabricated in bulk niobium and cold tested at their home labs, as a first validation step towards the High Luminosity LHC project. As a cross check, all three bare cavities have been retested at CERN, in order to cross check their performance, and cross-calibrate the CERN SRF cold test facilities. While achievable transverse deflecting voltage is the key performance indicator, secondary performance aspects derived from multiple cavity monitoring systems are also discussed. Temperature mapping profiles, quench detection, material properties, and trapped magnetic flux effects have been assessed, and the influence on performance discussed. The significant effort invested in developing expertise in preparation and testing of these crab cavities has already been fruitful for all partners, and more is to come within this ongoing program.

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THPB081

FPC and HOM Coupler Test Boxes for HL-LHC Crab Cavities

1321

A.R.J. Tutte, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R. Calaga, A. Macpherson, E. Montesinos
CERN, Geneva, Switzerland
S.U. De Silva
ODU, Norfolk, Virginia, USA
Z. Li
SLAC, Menlo Park, California, USA
B. P. Xiao
BNL, Upton, Long Island, New York, USA

The LHC luminosity upgrade will involve the installation of thirty-two 400 MHz SRF crab cavities. The cavities have two variants known as the RF dipole and double quarter-wave crab cavities. Each cavity has a fundamental power coupler (FPC) at 400 MHz and two or three HOM couplers. Before integration onto the cavities it is necessary to condition the FPC, and to measure the transmission on the HOM couplers at low power to ensure the operate as designed, each requiring a special test box. The FPC test box should provide a high transmission between two couplers without creating high surface fields. The low power HOM test boxes should be terminated to a load such that the natural stop and pass-bands of the couplers are preserved allowing the reflection to me measured and compared to simulations. In addition, due to the possibility of high HOM power in the LHC crab cavities, the concept of creating a broadband high power HOM coupler test box in order to condition and test the couplers at high power has been investigated. The Rf design of all test boxes is presented and discussed.

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FRBA02

Crab Cavity and Cryomodule Development for HL-LHC

1460

F. Carra, A. Amorim Carvalho, K. Artoos, S. Atieh, I. Aviles Santillana, A.B. Boucherie, J.P. Brachet, K. Brodzinski, R. Calaga, O. Capatina, T. Capelli, L. Dassa, T. Dijoud, H.M. Durand, G. Favre, L.M.A. Ferreira, P. Freijedo Menendez, M. Garlaschè, M. Guinchard, N. Kuder, S.A.E. Langeslag, R. Leuxe, A. Macpherson, P. Minginette, E. Montesinos, F. Motschmann, C. Parente, L. Prever-Loiri, D. Pugnat, E. Rigutto, V. Rude, M. Sosin, G. Vandoni, G. Villiger, C. Zanoni
CERN, Geneva, Switzerland
S.A. Belomestnykh, S. Verdú-Andrés, Q. Wu, B. P. Xiao
BNL, Upton, Long Island, New York, USA
G. Burt
Lancaster University, Lancaster, United Kingdom
S.U. De Silva, J.R. Delayen, R.G. Olave, R.G. Olave, H. Park
ODU, Norfolk, Virginia, USA
T.J. Jones, N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
Z. Li
SLAC, Menlo Park, California, USA
K.B. Marinov, S.M. Pattalwar
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
T.H. Nicol
Fermilab, Batavia, Illinois, USA
A. Ratti
LBNL, Berkeley, California, USA

The HL-LHC project aims at increasing the LHC luminosity by a factor 10 beyond the design value. The installation of a set of RF Crab Cavities to increase bunch crossing angle is one of the key upgrades of the program. Two concepts, Double Quarter Wave (DQW) and RF Dipole (RFD) have been proposed and are being produced in parallel for test in the SPS beam before the next long shutdown of CERN accelerator’s complex. In the retained concept, two cavities are hosted in one single cryomodule, providing thermal insulation and interfacing with RF coupling, tuning, cryogenics and beam vacuum. This paper overviews the main design choices for the cryomodule and its different components, which have the goal of optimizing the structural, thermal and electro-magnetic behavior of the system, while respecting the existing constraints in terms of integration in the accelerator environment. Prototyping and testing of the most critical components, manufacturing, preparation and installation strategies are also described.

Slides FRBA02 [4.678 MB]

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