IPAC2022 - List of Authors (Buffat, X.)

Paper	Title	Page
WEOZSP2	Suppression of Crab Cavity Noise Induced Emittance Growth by Transverse Beam Coupling Impedance	1659
SUSPMF068	use link to see paper's listing under its alternate paper code
	N. Triantafyllou, A. Wolski The University of Liverpool, Liverpool, United Kingdom F. Antoniou, H. Bartosik, P. Baudrenghien, X. Buffat, R. Calaga, Y. Papaphilippou CERN, Meyrin, Switzerland T. Mastoridis CalPoly, San Luis Obispo, California, USA
	Crab Cavities are a key component of the High Luminosity LHC (HL-LHC) upgrade, as they aim to minimize the luminosity reduction caused by the crossing angle. Two superconducting crab cavities were installed in the Super Proton Synchrotron (SPS) at CERN in 2018 to test their operation in a proton machine for the first time. An important point to consider is the increase in transverse emittance induced by noise in the Low-Level RF (LLRF) system. During the first experimental campaign in 2018, the measured emittance growth was found to be a factor of 4 lower than predicted by the available analytical models. In this report, the effects of transverse beam impedance in the presence of CC LLRF noise on transverse emittance growth are presented and the results of the second experimental campaign, which took place in the SPS in 2021, are discussed.
	Slides WEOZSP2 [2.694 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP2
About •	Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOPT009	Operational Scenario of First High Luminosity LHC Run	1846
	R. Tomás García, G. Arduini, P. Baudrenghien, R. Bruce, O.S. Brüning, X. Buffat, R. Calaga, F. Cerutti, R. De Maria, J. Dilly, I. Efthymiopoulos, M. Giovannozzi, P.D. Hermes, G. Iadarola, O.R. Jones, S. Kostoglou, E.H. Maclean, N. Mounet, E. Métral, Y. Papaphilippou, S. Redaelli, G. Sterbini, H. Timko, F.F. Van der Veken, J. Wenninger, M. Zerlauth CERN, Meyrin, Switzerland
	A new scenario for the first operational run of the HL-LHC era (Run 4) has been recently developed to accommodate a period of performance ramp-up to achieve an annual integrated luminosity close to the nominal HL-LHC design. The operational scenario in terms of beam parameters and machine settings, as well as the different phases, are described here along with the impact of potential delays on key hardware components.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT009
About •	Received ※ 19 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 09 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOTK058	Experimental Study of the Transverse Mode Coupling Instability with Space-Charge at the CERN SPS	2193
	X. Buffat, H. Bartosik CERN, Meyrin, Switzerland
	Past studies on the Transverse Mode Coupling Instability (TMCI) suggested that it can be suppressed in the presence of space-charge forces. Recent developments in this field show that for higher strength, space-charge forces leads to other types of instabilities. We investigate the characteristics of these instabilities by means of stability threshold measurements at the CERN SPS for various intensities, longitudinal and transverse emittances. These observations are compared to numerical tracking simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK058
About •	Received ※ 03 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 18 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOTK059	Suppression of Emittance Growth by a Collective Force: Van Kampen Approach	2197
	X. Buffat CERN, Meyrin, Switzerland
	In hadron synchrotrons, external sources of noise affecting the beam induce emittance growth through the mechanism of decoherence. Active feedbacks are often used to suppress this emittance growth. In the presence of beam-beam interactions, it was shown that coherent modes of oscillations with frequencies shifted outside of the incoherent spectrum significantly enhances the efficiency of the emittance growth suppression by active feedbacks. We show that the same enhancement of the emittance growth suppression may be driven by a beam coupling impedance generating a real tune shift larger than the detuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK059
About •	Received ※ 03 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 15 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOTK062	Intrabunch Motion with Both Impedance and Beam-Beam Using the Circulant Matrix Approach	2209
	E. Métral, X. Buffat CERN, Meyrin, Switzerland
	In high-intensity high-brightness circular colliders such as the CERN LHC, coherent beam-beam effects and impedance cannot be treated independently. Coherent beam-beam dipole modes can couple with higher order head-tail modes and lead to the transverse mode coupling instability of colliding beams. This mechanism has been analysed in detail in the past through the eigenvalues, which describe the evolution of the beam oscillation mode-frequency shifts. In this contribution, the transverse mode coupling instability of colliding beams is studied using the eigenvectors, which describe the evolution of the intrabunch motion. As this instability exhibits several mode couplings and mode decouplings, the evolution of the intrabunch motion reveals quite some interesting features (such as a propagation of the traveling-wave not only from the head to the tail but also from the tail to the head and similar intrabunch signals for some mode coupling and mode decoupling), which are compared to past predictions in the presence of impedance only.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK062
About •	Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 03 July 2022 — Issue date ※ 06 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOPT035	A Second Generation Light Source Aiming at High Power on the Giant Dipole Resonance	2661
	X. Buffat, L.L. Cuanillon, E.N. Kneubuehler CERN, Meyrin, Switzerland
	We propose an accelerator concept which could enable nuclear waste transmutation and energy amplification using a second generation light source rather than a high power proton beam. The main parameters of the ring and insertion devices are estimated, targeting a photon beam power of 1 GW with a spectrum that maximizes the potential for nuclear reactions via the Giant Dipole Resonance. The synergies with technologies developed for high energy physics, in particular within the Future Circular Collider study (FCC), are highlighted.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT035
About •	Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

WEOZSP2

Suppression of Crab Cavity Noise Induced Emittance Growth by Transverse Beam Coupling Impedance

1659

SUSPMF068

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

N. Triantafyllou, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
F. Antoniou, H. Bartosik, P. Baudrenghien, X. Buffat, R. Calaga, Y. Papaphilippou
CERN, Meyrin, Switzerland
T. Mastoridis
CalPoly, San Luis Obispo, California, USA

Crab Cavities are a key component of the High Luminosity LHC (HL-LHC) upgrade, as they aim to minimize the luminosity reduction caused by the crossing angle. Two superconducting crab cavities were installed in the Super Proton Synchrotron (SPS) at CERN in 2018 to test their operation in a proton machine for the first time. An important point to consider is the increase in transverse emittance induced by noise in the Low-Level RF (LLRF) system. During the first experimental campaign in 2018, the measured emittance growth was found to be a factor of 4 lower than predicted by the available analytical models. In this report, the effects of transverse beam impedance in the presence of CC LLRF noise on transverse emittance growth are presented and the results of the second experimental campaign, which took place in the SPS in 2021, are discussed.

Slides WEOZSP2 [2.694 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP2

About •

Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022

Cite •

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

WEPOPT009

Operational Scenario of First High Luminosity LHC Run

1846

R. Tomás García, G. Arduini, P. Baudrenghien, R. Bruce, O.S. Brüning, X. Buffat, R. Calaga, F. Cerutti, R. De Maria, J. Dilly, I. Efthymiopoulos, M. Giovannozzi, P.D. Hermes, G. Iadarola, O.R. Jones, S. Kostoglou, E.H. Maclean, N. Mounet, E. Métral, Y. Papaphilippou, S. Redaelli, G. Sterbini, H. Timko, F.F. Van der Veken, J. Wenninger, M. Zerlauth
CERN, Meyrin, Switzerland

A new scenario for the first operational run of the HL-LHC era (Run 4) has been recently developed to accommodate a period of performance ramp-up to achieve an annual integrated luminosity close to the nominal HL-LHC design. The operational scenario in terms of beam parameters and machine settings, as well as the different phases, are described here along with the impact of potential delays on key hardware components.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT009

About •

Received ※ 19 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 09 July 2022

Cite •

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

WEPOTK058

Experimental Study of the Transverse Mode Coupling Instability with Space-Charge at the CERN SPS

2193

X. Buffat, H. Bartosik
CERN, Meyrin, Switzerland

Past studies on the Transverse Mode Coupling Instability (TMCI) suggested that it can be suppressed in the presence of space-charge forces. Recent developments in this field show that for higher strength, space-charge forces leads to other types of instabilities. We investigate the characteristics of these instabilities by means of stability threshold measurements at the CERN SPS for various intensities, longitudinal and transverse emittances. These observations are compared to numerical tracking simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK058

About •

Received ※ 03 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 18 June 2022

Cite •

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

WEPOTK059

Suppression of Emittance Growth by a Collective Force: Van Kampen Approach

2197

X. Buffat
CERN, Meyrin, Switzerland

In hadron synchrotrons, external sources of noise affecting the beam induce emittance growth through the mechanism of decoherence. Active feedbacks are often used to suppress this emittance growth. In the presence of beam-beam interactions, it was shown that coherent modes of oscillations with frequencies shifted outside of the incoherent spectrum significantly enhances the efficiency of the emittance growth suppression by active feedbacks. We show that the same enhancement of the emittance growth suppression may be driven by a beam coupling impedance generating a real tune shift larger than the detuning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK059

About •

Received ※ 03 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 15 June 2022

Cite •

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

WEPOTK062

Intrabunch Motion with Both Impedance and Beam-Beam Using the Circulant Matrix Approach

2209

E. Métral, X. Buffat
CERN, Meyrin, Switzerland

In high-intensity high-brightness circular colliders such as the CERN LHC, coherent beam-beam effects and impedance cannot be treated independently. Coherent beam-beam dipole modes can couple with higher order head-tail modes and lead to the transverse mode coupling instability of colliding beams. This mechanism has been analysed in detail in the past through the eigenvalues, which describe the evolution of the beam oscillation mode-frequency shifts. In this contribution, the transverse mode coupling instability of colliding beams is studied using the eigenvectors, which describe the evolution of the intrabunch motion. As this instability exhibits several mode couplings and mode decouplings, the evolution of the intrabunch motion reveals quite some interesting features (such as a propagation of the traveling-wave not only from the head to the tail but also from the tail to the head and similar intrabunch signals for some mode coupling and mode decoupling), which are compared to past predictions in the presence of impedance only.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK062

About •

Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 03 July 2022 — Issue date ※ 06 July 2022

Cite •

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

THPOPT035

A Second Generation Light Source Aiming at High Power on the Giant Dipole Resonance

2661

X. Buffat, L.L. Cuanillon, E.N. Kneubuehler
CERN, Meyrin, Switzerland

We propose an accelerator concept which could enable nuclear waste transmutation and energy amplification using a second generation light source rather than a high power proton beam. The main parameters of the ring and insertion devices are estimated, targeting a photon beam power of 1 GW with a spectrum that maximizes the potential for nuclear reactions via the Giant Dipole Resonance. The synergies with technologies developed for high energy physics, in particular within the Future Circular Collider study (FCC), are highlighted.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT035

About •

Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022

Cite •

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