IPAC2017 - List of Authors (Métral, E.)

Paper	Title	Page
MOPAB113	Usage of the Transverse Damper Observation Box for High Sampling Rate Transverse Position Data in the LHC	389
	L.R. Carver, X. Buffat, A.C. Butterworth, W. Höfle, G. Iadarola, G. Kotzian, K.S.B. Li, E. Métral, M. Ojeda Sandonís, M.E. Söderén, D. Valuch CERN, Geneva, Switzerland
	The transverse damper observation box (ADTObsBox) is a device that makes accessible the bunch-by-bunch turn-by-turn data recorded from the pickups of the LHC transverse damper. This device can provide online transient analysis of different beam dynamics effects (tunes and damping times at injection, for example), while also under development is an online coherent instability triggering system. This paper will provide an overview of the current setup and plans for future upgrades, as well as detailing how it deals with the large volume of data being generated. The results of some analysis that rely on the ADTObsBox will also be shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB113
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TUPIK119	Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration	2005
	J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut SLAC, Menlo Park, California, USA H. Bartosik, W. Höfle, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle CERN, Geneva, Switzerland S. De Santis LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x10¹¹ P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119
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WEOAB3	RF Quadrupole Structures for Transverse Landau Damping in Circular Accelerators	2516
	M. Schenk, X. Buffat, L.R. Carver, A. Grudiev, K.S.B. Li, E. Métral, K. Papke CERN, Geneva, Switzerland A. Maillard ENS, Paris, France
	The beams required for the high luminosity upgrade of the Large Hadron Collider (HL-LHC) and other potential future circular colliders (FCC) call for efficient mechanisms to suppress transverse collective instabilities. In addition to octupole magnets installed for the purpose of Landau damping in the transverse planes, we propose to use radio frequency (rf) quadrupole structures to considerably enhance the aforementioned stabilising effect. By means of the PyHEADTAIL macroparticle tracking code as well as analytical studies, the stabilising mechanism introduced by an rf quadrupole is studied and explained. It is, furthermore, compared to the influence of the second order chromaticity on transverse beam stability.
	Slides WEOAB3 [2.537 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOAB3
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WEPIK066	Calculation of Wakefields and Higher Order Modes for the Vacuum Chamber of the CMS, ATLAS, ALICE and LHCb Experiments for the HL-LHC	3081
	R. Wanzenberg, O. Zagorodnova DESY, Hamburg, Germany E. Métral, B. Salvant CERN, Geneva, Switzerland
	Funding: Partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The High Luminosity Large Hadron Collider (HL-LHC) project was started with the goal to extend the discovery potential of the Large Hadron Collider (LHC). The HL-LHC study implies also upgraded dimensions of the experimental beam pipes of the CMS, ATLAS, ALICE and LHCb experiments. The trapped monopole and dipole Higher Order Modes (HOMs) and the short range wakefields for the new design of the vacuum chambers were calculated with help of the computer codes MAFIA and ECHO2D. The results of the short range wakefields calculations and the HOMs calculations are presented in this report. The short range wakefields are presented in terms of longitudinal and transverse wake potentials and also in terms of loss and kick parameters. Selected results from the HOMs calculations , including the the frequency, the loss parameter, the R/Q and the Q value are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK066
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WEPIK094	LEIR Impedance Model and Coherent Beam Instability Observations	3159
	N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens CERN, Geneva, Switzerland M. Migliorati University of Rome La Sapienza, Rome, Italy
	The LEIR machine is the first synchrotron in the ion acceleration chain at CERN and it is responsible to deliver high intensity ion beams to the LHC. Following the recent progress in the understanding of the intensity limitations, detailed studies of the machine impedance started. In this work we describe the present LEIR impedance model, detailing the contribution to the total longitudinal and transverse impedance of several machine element. We then compare the machine tune shift versus intensity predictions against measurements at injection energy and summarize the coherent instability observations in absence of transverse damper feedback.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK094
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THPAB005	Improvement of the Analytic Vlasov Solver DELPHI	3688
	D. Amorim Université Grenoble Alpes, Grenoble, France N. Biancacci, K.S.B. Li, E. Métral CERN, Geneva, Switzerland
	The simulation code DELPHI is an analytic Vlasov solver which allows to evaluate the beam transverse stability with respect to impedance effects. It allows to perform fast scans over parameters such as chromaticity, damper gain or beam intensity for a given impedance model and particle distribution. In order to improve the simulation code, new longitudinal particle distributions have been implemented. The simulations results obtained with these distributions are compared to theoretical predictions. An additional post-processing of DELPHI's output has also been implemented, allowing to reconstruct the signal seen by head-tail stripline monitors, in particular in presence of bunch-by-bunch damper. The results are compared to theoretical models, to pyHEADTAIL simulations and to measurements performed in the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB005
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THPAB040	Destabilising Effect of Linear Coupling in the LHC	3791
	L.R. Carver, D. Amorim, N. Biancacci, X. Buffat, K.S.B. Li, E. Métral, B. Salvant, M. Schenk CERN, Geneva, Switzerland
	During operation in 2015 and 2016, some transverse instabilities were observed when either the coupling (or closest tune approach) C- was large, or when the tunes were moved closer together. This motivated a campaign of simulations on the effect of linear coupling on the transverse stability. Measurements made during operation and with dedicated beam time have been found to confirm the predictions. This paper will detail the results of the linear coupling studies and relate them to operation of the LHC in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB040
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THPVA026	Practical Stabilisation of Transverse Collective Instabilities with Second Order Chromaticity in the LHC	4477
SUSPSIK059	use link to see paper's listing under its alternate paper code
	M. Schenk, D. Amorim, N. Biancacci, X. Buffat, L.R. Carver, R. De Maria, K.S.B. Li, E. Métral, B. Salvant CERN, Geneva, Switzerland
	The study reports on dedicated measurements made with a single nominal bunch in the LHC at 6.5 TeV. First, we show that a significant amount of second order chromaticity Q'' can be introduced in the machine in a well-controlled manner. Second, we demonstrate that the incoherent betatron tune spread from Q'' can provide beam stability through the Landau damping mechanism. This is a first step in the development of a Q'' knob to be potentially applied during regular physics operation in the LHC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA026
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Usage of the Transverse Damper Observation Box for High Sampling Rate Transverse Position Data in the LHC

389

L.R. Carver, X. Buffat, A.C. Butterworth, W. Höfle, G. Iadarola, G. Kotzian, K.S.B. Li, E. Métral, M. Ojeda Sandonís, M.E. Söderén, D. Valuch
CERN, Geneva, Switzerland

The transverse damper observation box (ADTObsBox) is a device that makes accessible the bunch-by-bunch turn-by-turn data recorded from the pickups of the LHC transverse damper. This device can provide online transient analysis of different beam dynamics effects (tunes and damping times at injection, for example), while also under development is an online coherent instability triggering system. This paper will provide an overview of the current setup and plans for future upgrades, as well as detailing how it deals with the large volume of data being generated. The results of some analysis that rely on the ADTObsBox will also be shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB113

Export •

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

TUPIK119

Control of Intra-Bunch Vertical Instabilities at the SPS - Measurements and Technology Demonstration

2005

J.D. Fox, J.E. Dusatko, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA
H. Bartosik, W. Höfle, K.S.B. Li, E. Métral, B. Salvant, U. Wehrle
CERN, Geneva, Switzerland
S. De Santis
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under contract # DOE-AC02-76SF00515, the US LHC Accelerator Research Program ( LARP), the FP7 High Luminosity LHC Project and the US-Japan Cooperative Program in High Energy Physics
We present recent measurements demonstrating control of unstable beam motion in single bunch and bunch train configurations at the SPS. The work is motivated by anticipated intensity increases from the LIU and HL-LHC upgrade programs, and has included the development of a GHz bandwidth reconfigurable 4 GS/S signal processor with wideband kickers and associated amplifiers. The system was operated at 3.2GS/s with 16 samples across a 5 ns RF bucket (4.2 ns bunch at injection). The experimental results confirm damping of intra-bunch instabilities in both Q20 and Q26 optics configurations for intensities of 2x10¹¹ P/bunch. Instabilities with growth times of 200 turns are well-controlled from injection, consistent with the achievable gains for the 2 installed stripline kickers with 1 kW broadband power. Measurements from multiple studies in single-bunch and bunch train configurations show achieved damping rates, control of multiple intra-bunch modes, behavior of the system at injection and final damped noise floor. We present an analysis method to study the relative phase of slice motion during a transient to discriminate between TMCI and other types of Head-Tail instabilities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK119

Export •

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

WEOAB3

RF Quadrupole Structures for Transverse Landau Damping in Circular Accelerators

2516

M. Schenk, X. Buffat, L.R. Carver, A. Grudiev, K.S.B. Li, E. Métral, K. Papke
CERN, Geneva, Switzerland
A. Maillard
ENS, Paris, France

The beams required for the high luminosity upgrade of the Large Hadron Collider (HL-LHC) and other potential future circular colliders (FCC) call for efficient mechanisms to suppress transverse collective instabilities. In addition to octupole magnets installed for the purpose of Landau damping in the transverse planes, we propose to use radio frequency (rf) quadrupole structures to considerably enhance the aforementioned stabilising effect. By means of the PyHEADTAIL macroparticle tracking code as well as analytical studies, the stabilising mechanism introduced by an rf quadrupole is studied and explained. It is, furthermore, compared to the influence of the second order chromaticity on transverse beam stability.

Slides WEOAB3 [2.537 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOAB3

Export •

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

WEPIK066

Calculation of Wakefields and Higher Order Modes for the Vacuum Chamber of the CMS, ATLAS, ALICE and LHCb Experiments for the HL-LHC

3081

R. Wanzenberg, O. Zagorodnova
DESY, Hamburg, Germany
E. Métral, B. Salvant
CERN, Geneva, Switzerland

Funding: Partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The High Luminosity Large Hadron Collider (HL-LHC) project was started with the goal to extend the discovery potential of the Large Hadron Collider (LHC). The HL-LHC study implies also upgraded dimensions of the experimental beam pipes of the CMS, ATLAS, ALICE and LHCb experiments. The trapped monopole and dipole Higher Order Modes (HOMs) and the short range wakefields for the new design of the vacuum chambers were calculated with help of the computer codes MAFIA and ECHO2D. The results of the short range wakefields calculations and the HOMs calculations are presented in this report. The short range wakefields are presented in terms of longitudinal and transverse wake potentials and also in terms of loss and kick parameters. Selected results from the HOMs calculations , including the the frequency, the loss parameter, the R/Q and the Q value are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK066

Export •

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

WEPIK094

LEIR Impedance Model and Coherent Beam Instability Observations

3159

N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens
CERN, Geneva, Switzerland
M. Migliorati
University of Rome La Sapienza, Rome, Italy

The LEIR machine is the first synchrotron in the ion acceleration chain at CERN and it is responsible to deliver high intensity ion beams to the LHC. Following the recent progress in the understanding of the intensity limitations, detailed studies of the machine impedance started. In this work we describe the present LEIR impedance model, detailing the contribution to the total longitudinal and transverse impedance of several machine element. We then compare the machine tune shift versus intensity predictions against measurements at injection energy and summarize the coherent instability observations in absence of transverse damper feedback.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK094

Export •

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

THPAB005

Improvement of the Analytic Vlasov Solver DELPHI

3688

D. Amorim
Université Grenoble Alpes, Grenoble, France
N. Biancacci, K.S.B. Li, E. Métral
CERN, Geneva, Switzerland

The simulation code DELPHI is an analytic Vlasov solver which allows to evaluate the beam transverse stability with respect to impedance effects. It allows to perform fast scans over parameters such as chromaticity, damper gain or beam intensity for a given impedance model and particle distribution. In order to improve the simulation code, new longitudinal particle distributions have been implemented. The simulations results obtained with these distributions are compared to theoretical predictions. An additional post-processing of DELPHI's output has also been implemented, allowing to reconstruct the signal seen by head-tail stripline monitors, in particular in presence of bunch-by-bunch damper. The results are compared to theoretical models, to pyHEADTAIL simulations and to measurements performed in the LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB005

Export •

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

THPAB040

Destabilising Effect of Linear Coupling in the LHC

3791

L.R. Carver, D. Amorim, N. Biancacci, X. Buffat, K.S.B. Li, E. Métral, B. Salvant, M. Schenk
CERN, Geneva, Switzerland

During operation in 2015 and 2016, some transverse instabilities were observed when either the coupling (or closest tune approach) C- was large, or when the tunes were moved closer together. This motivated a campaign of simulations on the effect of linear coupling on the transverse stability. Measurements made during operation and with dedicated beam time have been found to confirm the predictions. This paper will detail the results of the linear coupling studies and relate them to operation of the LHC in the future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB040

Export •

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

THPVA026

Practical Stabilisation of Transverse Collective Instabilities with Second Order Chromaticity in the LHC

4477

SUSPSIK059

use link to see paper's listing under its alternate paper code

M. Schenk, D. Amorim, N. Biancacci, X. Buffat, L.R. Carver, R. De Maria, K.S.B. Li, E. Métral, B. Salvant
CERN, Geneva, Switzerland

The study reports on dedicated measurements made with a single nominal bunch in the LHC at 6.5 TeV. First, we show that a significant amount of second order chromaticity Q'' can be introduced in the machine in a well-controlled manner. Second, we demonstrate that the incoherent betatron tune spread from Q'' can provide beam stability through the Landau damping mechanism. This is a first step in the development of a Q'' knob to be potentially applied during regular physics operation in the LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA026

Export •

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