HB2012 - List of Authors (Métral, E.)

Paper

Title

Page

Colliding High Brightness Beams in the LHC

180

T. Pieloni, X. Buffat, R. Giachino, W. Herr, E. Métral, G. Papotti
CERN, Geneva, Switzerland

The CERN-LHC is a high energy particle collider, where intense proton bunches are brought into collision. In order to achieve optimum performance, the bunches must have a high brightness, leading to strong and significant beam-beam effects. Experimental tests during the first two years of its operation have shown that beams with very high brightness can be collided head-on without detrimental effects on the beam dynamics. Such head-on collisions are therefore not expected to limit the LHC performance. Long range beam-beam interactions dominate the adverse effects on the dynamics but can profit from an increased beam brightness, in particular from small emittances. We summarize the experimental results and compare with the theoretical expectations. This allows to optimize the performance for future operation and a definition of promising upgrade scenarios.

TUO1A01

The High Intensity/High Brightness Upgrade Program at CERN: Status and Challenges

226

S.S. Gilardoni, G. Arduini, T. Argyropoulos, S. Aumon, H. Bartosik, E. Benedetto, N. Biancacci, T. Bohl, J. Borburgh, C. Carli, F. Caspers, H. Damerau, J.F. Esteban Müller, V. Forte, R. Garoby, M. Giovannozzi, B. Goddard, S. Hancock, K. Hanke, A. Huschauer, G. Iadarola, M. Meddahi, G. Métral, B. Mikulec, E. Métral, Y. Papaphilippou, S. Persichelli, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, R. Steerenberg, G. Sterbini, M. Taborelli, H. Timko, M. Vretenar, R. Wasef, C. Yin Vallgren, C. Zannini
CERN, Geneva, Switzerland
G. Franchetti
GSI, Darmstadt, Germany
M. Migliorati
University of Rome "La Sapienza", Rome, Italy
A.Y. Molodozhentsev
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
M.T.F. Pivi
SLAC, Menlo Park, California, USA
V.G. Vaccaro
Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy

The future beam brilliance and intensities required by the HL-LHC (High-Luminosity LHC) project and for possible new neutrino production beams triggered a deep revision of the LHC injector performances. The analysis, progressing in the framework of the LHC Injectors Upgrade (LIU) projects, outlined major limitations mainly related to collective effects - space charge in PSB and PS, electron cloud driven and TMCI instabilities in the SPS, longitudinal coupled bunch instabilities in the PS for example - but also to the existing hardware capability to cope with beam instabilities and losses. A summary of the observations and simulation studies carried out so far, as well as the future ones, will be presented. The solution proposed to overcome the different limitations and the plans for their implementation will be also briefly reviewed.

Slides TUO1A01 [12.748 MB]

WEO1A01

Impedance Studies of 2D Azimuthally Symmetric Devices of Finite Length

344

N. Biancacci, E. Métral, B. Salvant
CERN, Geneva, Switzerland
N. Biancacci
Rome University La Sapienza, Roma, Italy
M. Migliorati, L. Palumbo
URLS, Rome, Italy
V.G. Vaccaro
Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy

In circular accelerators, the beam quality can be strongly affected by the self-induced electromagnetic fields excited by the beam in the passage through the elements of the accelerator. The beam coupling impedance quantifies this interaction and allows predicting the stability of the dynamics of high intensity, high brilliance beams. The coupling impedance can be evaluated with finite element methods or using analytical methods, such as Field Matching or Mode Matching. In this paper we present an application of the Mode Matching technique for an azimuthally uniform structure of finite length: a cylindrical cavity loaded with a toroidal slab of lossy dielectric, connected with cylindrical beam pipes. In order to take into account the finite length of the structure, with respect to the infinite length approximation, we decompose the fields in the cavity into a set of orthonormal modes. We obtain a complete set of equations using the magnetic field matching and the non-uniform convergence of the electric field on the cavity boundaries. We present benchmarks done with CST Particle Studio simulations and existing analytical formulas, pointing out the effect of finite length and non-relativistic beta.

Slides WEO1A01 [6.689 MB]

WEO1A02

LHC Impedance Model: Experience with High Intensity Operation in the LHC

349

B. Salvant, O. Aberle, G. Arduini, R.W. Aßmann, V. Baglin, M.J. Barnes, P. Baudrenghien, A. Bertarelli, C. Bracco, R. Bruce, X. Buffat, F. Carra, F. Caspers, G. Cattenoz, S.D. Claudet, H.A. Day, J.F. Esteban Müller, M. Garlaschè, L. Gentini, B. Goddard, A. Grudiev, B. Henrist, W. Herr, S. Jakobsen, R.J. Jones, G. Lanza, L. Lari, T. Mastoridis, N. Mounet, E. Métral, A.A. Nosych, J.L. Nougaret, S. Persichelli, T. Pieloni, A.M. Piguiet, S. Redaelli, F. Roncarolo, G. Rumolo, B. Salvachua, M. Sapinski, E.N. Shaposhnikova, L.J. Tavian, M.A. Timmins, J.A. Uythoven, A. Vidal, R. Wasef, D. Wollmann
CERN, Geneva, Switzerland
A.V. Burov
Fermilab, Batavia, USA
S.M. White
BNL, Upton, Long Island, New York, USA

The CERN Large Hadron Collider (LHC) is now in luminosity production mode and has been pushing its performance in the past months by increasing the proton beam brightness, the collision energy and the machine availability. As a consequence, collective effects have started to become more and more visible and have effectively slowed down the performance increase of the machine. Among these collective effects, the interaction of brighter LHC bunches with the longitudinal and transverse impedance of the machine has been observed to generate beam induced heating and transverse instabilities since 2010. This contribution reviews the current LHC impedance model obtained from theory, simulations and bench measurements as well as a selection of measured effects with the LHC beam.

Slides WEO1A02 [7.991 MB]

WEO1B05

PTC-Orbit Studies for the CERN LHC Injectors Upgrade Project

399

A.Y. Molodozhentsev, E. Forest
KEK, Ibaraki, Japan
G. Arduini, H. Bartosik, E. Benedetto, C. Carli, M. Fitterer, V. Forte, S.S. Gilardoni, M. Martini, N. Mounet, E. Métral, F. Schmidt, R. Wasef
CERN, Geneva, Switzerland

The future improvement of the beam brilliance and intensities required in the frame of the LIU (LHC Injectors Upgrade) project to reach the demands of the HL-LHC (High-Luminosity LHC) project triggered a comprehensive study of the combined effects of the space charge and the machine resonances for the CERN synchrotrons, which are the injector chain for LHC. In frame of this report we will summarize new features of the PTC-ORBIT code which allow the beam dynamics modeling in the LHC injectors taking into account the time variation of the machine parameters during the injection process. The measurements, obtained during recent MD companies, and simulations for the low-energy high-intensity beams, will be discussed.

Slides WEO1B05 [3.063 MB]

THO1D01

Fully 3D Long-term Simulation of the Coupling Resonance Experiments at the CERN PS

J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA
G. Franchetti, I. Hofmann
GSI, Darmstadt, Germany
E. Métral
CERN, Geneva, Switzerland

Funding: This work is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Space-charge driven nonlinear coupling resonance can have significant impact in high intensity linac and ring operation. Such a resonance causes emittance exchange between different degrees of freedom and may result in potential particle loss from the direction with smaller aperture size. In this paper, we will report on numerical simulation studies of the resonance crossing phenomena using a previous experiment at the CERN PS including detailed three-dimensional space-charge effects and machine nonlinearity.

Slides THO1D01 [0.589 MB]

FRO1A01

Summary of Working Group A: Beam Dynamics in High-Intensity Circular Machines

606

E. Métral
CERN, Geneva, Switzerland
G. Franchetti
GSI, Darmstadt, Germany
J.A. Holmes
ORNL, Oak Ridge, Tennessee, USA

In this proceeding we summarize the presentations of the HB2012 Workshop session on 'Beam Dynamics in High-Intensity Circular Machines' as well as the outcome of the discussion session. This working group hosted 29 presentations in dedicated sessions plus 5 presentations in a joint session with the working C.

Slides FRO1A01 [7.420 MB]

Paper	Title	Page
MOP250	Colliding High Brightness Beams in the LHC	180
	T. Pieloni, X. Buffat, R. Giachino, W. Herr, E. Métral, G. Papotti CERN, Geneva, Switzerland
	The CERN-LHC is a high energy particle collider, where intense proton bunches are brought into collision. In order to achieve optimum performance, the bunches must have a high brightness, leading to strong and significant beam-beam effects. Experimental tests during the first two years of its operation have shown that beams with very high brightness can be collided head-on without detrimental effects on the beam dynamics. Such head-on collisions are therefore not expected to limit the LHC performance. Long range beam-beam interactions dominate the adverse effects on the dynamics but can profit from an increased beam brightness, in particular from small emittances. We summarize the experimental results and compare with the theoretical expectations. This allows to optimize the performance for future operation and a definition of promising upgrade scenarios.

TUO1A01	The High Intensity/High Brightness Upgrade Program at CERN: Status and Challenges	226
	S.S. Gilardoni, G. Arduini, T. Argyropoulos, S. Aumon, H. Bartosik, E. Benedetto, N. Biancacci, T. Bohl, J. Borburgh, C. Carli, F. Caspers, H. Damerau, J.F. Esteban Müller, V. Forte, R. Garoby, M. Giovannozzi, B. Goddard, S. Hancock, K. Hanke, A. Huschauer, G. Iadarola, M. Meddahi, G. Métral, B. Mikulec, E. Métral, Y. Papaphilippou, S. Persichelli, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, R. Steerenberg, G. Sterbini, M. Taborelli, H. Timko, M. Vretenar, R. Wasef, C. Yin Vallgren, C. Zannini CERN, Geneva, Switzerland G. Franchetti GSI, Darmstadt, Germany M. Migliorati University of Rome "La Sapienza", Rome, Italy A.Y. Molodozhentsev J-PARC, KEK & JAEA, Ibaraki-ken, Japan M.T.F. Pivi SLAC, Menlo Park, California, USA V.G. Vaccaro Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy
	The future beam brilliance and intensities required by the HL-LHC (High-Luminosity LHC) project and for possible new neutrino production beams triggered a deep revision of the LHC injector performances. The analysis, progressing in the framework of the LHC Injectors Upgrade (LIU) projects, outlined major limitations mainly related to collective effects - space charge in PSB and PS, electron cloud driven and TMCI instabilities in the SPS, longitudinal coupled bunch instabilities in the PS for example - but also to the existing hardware capability to cope with beam instabilities and losses. A summary of the observations and simulation studies carried out so far, as well as the future ones, will be presented. The solution proposed to overcome the different limitations and the plans for their implementation will be also briefly reviewed.
	Slides TUO1A01 [12.748 MB]

WEO1A01	Impedance Studies of 2D Azimuthally Symmetric Devices of Finite Length	344
	N. Biancacci, E. Métral, B. Salvant CERN, Geneva, Switzerland N. Biancacci Rome University La Sapienza, Roma, Italy M. Migliorati, L. Palumbo URLS, Rome, Italy V.G. Vaccaro Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy
	In circular accelerators, the beam quality can be strongly affected by the self-induced electromagnetic fields excited by the beam in the passage through the elements of the accelerator. The beam coupling impedance quantifies this interaction and allows predicting the stability of the dynamics of high intensity, high brilliance beams. The coupling impedance can be evaluated with finite element methods or using analytical methods, such as Field Matching or Mode Matching. In this paper we present an application of the Mode Matching technique for an azimuthally uniform structure of finite length: a cylindrical cavity loaded with a toroidal slab of lossy dielectric, connected with cylindrical beam pipes. In order to take into account the finite length of the structure, with respect to the infinite length approximation, we decompose the fields in the cavity into a set of orthonormal modes. We obtain a complete set of equations using the magnetic field matching and the non-uniform convergence of the electric field on the cavity boundaries. We present benchmarks done with CST Particle Studio simulations and existing analytical formulas, pointing out the effect of finite length and non-relativistic beta.
	Slides WEO1A01 [6.689 MB]

WEO1A02	LHC Impedance Model: Experience with High Intensity Operation in the LHC	349
	B. Salvant, O. Aberle, G. Arduini, R.W. Aßmann, V. Baglin, M.J. Barnes, P. Baudrenghien, A. Bertarelli, C. Bracco, R. Bruce, X. Buffat, F. Carra, F. Caspers, G. Cattenoz, S.D. Claudet, H.A. Day, J.F. Esteban Müller, M. Garlaschè, L. Gentini, B. Goddard, A. Grudiev, B. Henrist, W. Herr, S. Jakobsen, R.J. Jones, G. Lanza, L. Lari, T. Mastoridis, N. Mounet, E. Métral, A.A. Nosych, J.L. Nougaret, S. Persichelli, T. Pieloni, A.M. Piguiet, S. Redaelli, F. Roncarolo, G. Rumolo, B. Salvachua, M. Sapinski, E.N. Shaposhnikova, L.J. Tavian, M.A. Timmins, J.A. Uythoven, A. Vidal, R. Wasef, D. Wollmann CERN, Geneva, Switzerland A.V. Burov Fermilab, Batavia, USA S.M. White BNL, Upton, Long Island, New York, USA
	The CERN Large Hadron Collider (LHC) is now in luminosity production mode and has been pushing its performance in the past months by increasing the proton beam brightness, the collision energy and the machine availability. As a consequence, collective effects have started to become more and more visible and have effectively slowed down the performance increase of the machine. Among these collective effects, the interaction of brighter LHC bunches with the longitudinal and transverse impedance of the machine has been observed to generate beam induced heating and transverse instabilities since 2010. This contribution reviews the current LHC impedance model obtained from theory, simulations and bench measurements as well as a selection of measured effects with the LHC beam.
	Slides WEO1A02 [7.991 MB]

WEO1B05	PTC-Orbit Studies for the CERN LHC Injectors Upgrade Project	399
	A.Y. Molodozhentsev, E. Forest KEK, Ibaraki, Japan G. Arduini, H. Bartosik, E. Benedetto, C. Carli, M. Fitterer, V. Forte, S.S. Gilardoni, M. Martini, N. Mounet, E. Métral, F. Schmidt, R. Wasef CERN, Geneva, Switzerland
	The future improvement of the beam brilliance and intensities required in the frame of the LIU (LHC Injectors Upgrade) project to reach the demands of the HL-LHC (High-Luminosity LHC) project triggered a comprehensive study of the combined effects of the space charge and the machine resonances for the CERN synchrotrons, which are the injector chain for LHC. In frame of this report we will summarize new features of the PTC-ORBIT code which allow the beam dynamics modeling in the LHC injectors taking into account the time variation of the machine parameters during the injection process. The measurements, obtained during recent MD companies, and simulations for the low-energy high-intensity beams, will be discussed.
	Slides WEO1B05 [3.063 MB]

THO1D01	Fully 3D Long-term Simulation of the Coupling Resonance Experiments at the CERN PS
	J. Qiang, R.D. Ryne LBNL, Berkeley, California, USA G. Franchetti, I. Hofmann GSI, Darmstadt, Germany E. Métral CERN, Geneva, Switzerland
	Funding: This work is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Space-charge driven nonlinear coupling resonance can have significant impact in high intensity linac and ring operation. Such a resonance causes emittance exchange between different degrees of freedom and may result in potential particle loss from the direction with smaller aperture size. In this paper, we will report on numerical simulation studies of the resonance crossing phenomena using a previous experiment at the CERN PS including detailed three-dimensional space-charge effects and machine nonlinearity.
	Slides THO1D01 [0.589 MB]

FRO1A01	Summary of Working Group A: Beam Dynamics in High-Intensity Circular Machines	606
	E. Métral CERN, Geneva, Switzerland G. Franchetti GSI, Darmstadt, Germany J.A. Holmes ORNL, Oak Ridge, Tennessee, USA
	In this proceeding we summarize the presentations of the HB2012 Workshop session on 'Beam Dynamics in High-Intensity Circular Machines' as well as the outcome of the discussion session. This working group hosted 29 presentations in dedicated sessions plus 5 presentations in a joint session with the working C.
	Slides FRO1A01 [7.420 MB]