HB2016 - List of Keywords (octupole)

Paper	Title	Other Keywords	Page
TUAM2X01	Measurement and Interpretation of Transverse Beam Instabilities in the CERN Large Hadron Collider (LHC) and Extrapolations to HL-LHC	coupling, simulation, electron, injection	254
	E. Métral, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, G. Iadarola, K.S.B. Li, T. Pieloni, A. Romano, G. Rumolo, B. Salvant, M. Schenk, C. Tambasco CERN, Geneva, Switzerland J. Barranco EPFL, Lausanne, Switzerland
	Since the first transverse instability observed in 2010, many studies have been performed on both measurement and simulation sides and several lessons have been learned. In a machine like the LHC, not only all the mechanisms have to be understood separately, but the possible interplays between the different phenomena need to be analyzed in detail, including the beam-coupling impedance (with in particular all the necessary collimators to protect the machine but also new equipment such as crab cavities for HL-LHC), linear and nonlinear chromaticity, Landau octupoles (and other intrinsic nonlinearities), transverse damper, space charge, beam-beam (long-range and head-on), electron cloud, linear coupling strength, tune separation between the transverse planes, tune split between the two beams, transverse beam separation between the two beams, etc. This paper reviews all the transverse beam instabilities observed and simulated so far, the mitigation measures which have been put in place, the remaining questions and challenges and some recommendations for the future.
	Slides TUAM2X01 [36.385 MB]
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WEPM2X01	High Power Target Instrumentation at J-PARC for Neutron and Muon Sources	target, proton, neutron, optics	391
	S.I. Meigo, A. Akutsu, K. Ikezaki, T.K. Kawasaki, H. Kinoshita, M. Nishikawa, M. Ooi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Fujimori, S.F. Fukuta KEK/JAEA, Ibaraki-Ken, Japan
	Funding: This work is partly supported by the MEXT Grant-in-Aid for Scientific Research (C) Grant no. 26390114. At the J-PARC, spallation neutron and muon sources are injected 3-GeV proton beam with power of 1 MW extracted from 25 Hz Rapid Cycling Synchrotron (RCS). Recently several shots of the beam with equivalent power of 1 MW were successfully delivered to the targets without significant beam loss. Since the pitting erosion on the mercury target vessel utilized for spallation neutron source is known to be proportional to the 4th power of the beam current density, peak current density at the target should be kept as low as possible so that we have developed beam-flattening system by nonlinear beam optics using octupole magnets. To carry out the beam tuning efficiently, beam-tuning tool had been developed by using SAD code system. It is found that the shape of the beam can be controlled as designed. By using anti-correlated painting at the injection of the RCS, the beam was found to be shaped more flat distribution. The peak current density at the target can be reduced by 30 % with the present nonlinear optics without significant beam loss around at octupole magnets, which mitigates 76 % of the damage at the target vessel.
	Slides WEPM2X01 [9.327 MB]
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THPM7X01	Use of RF Quadrupole Structures to Enhance Stability in Accelerator Rings	quadrupole, betatron, simulation, synchrotron	505
	M. Schenk, A. Grudiev, K.S.B. Li, K. Papke CERN, Geneva, Switzerland
	The beams required for the high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN call for efficient mechanisms to suppress transverse collective instabilities. In addition to octupole magnets installed for the purpose of Landau damping, we propose to use radio frequency (rf) quadrupole structures to considerably enhance the aforementioned stabilising effect. By means of the PyHEADTAIL macroparticle tracking code, the stabilising mechanism introduced by an rf quadrupole is studied and discussed. As a specific example, the performance of an rf quadrupole system in presence of magnetic octupoles is demonstrated for HL-LHC. Furthermore, potential performance limitations such as the excitation of synchro-betatron resonances are pointed out. Finally, efforts towards possible measurements with the CERN Super Proton Synchrotron (SPS) are discussed aiming at studying the underlying stabilising mechanisms experimentally.
	Slides THPM7X01 [37.755 MB]
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THPM8X01	Early Tests and Simulation of Quasi-Integrable Octupole Lattices at the University of Maryland Electron Ring	lattice, distributed, quadrupole, simulation	511
	K.J. Ruisard, H. Baumgartner, B. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew UMD, College Park, Maryland, USA
	Funding: Work and travel supported by NSF GRFP, NSF Accelerator Science Program, DOE-HEP and UMD Graduate School ICSSA award. Nonlinear quasi-integrable optics is a promising development on the horizon of high-intensity ring design. Large amplitude-dependent tune spreads, driven by strong nonlinear magnet inserts, lead to decoherence from incoherent tune resonances. This reduces intensity-driven beam loss while quasi-integrability ensures contained orbits. The experimental program at the University of Maryland Electron Ring (UMER) will explore the performance of a strong octupole lattice at a range of operating points. Early measurements use a distributed octupole lattice, consisting of several small octupole inserts. We vary lattice tune to change the quasi-integrable condition as well as probe behavior near different resonant conditions. Simulation results show there should be invariant conservation under carefully chosen conditions. We discuss the effect of steering errors on the lattice performance and on-going efforts to reduce these errors. We also discuss plans for a single-channel insert.
	Slides THPM8X01 [56.742 MB]
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Paper

Title

Other Keywords

Page

Measurement and Interpretation of Transverse Beam Instabilities in the CERN Large Hadron Collider (LHC) and Extrapolations to HL-LHC

coupling, simulation, electron, injection

254

E. Métral, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, G. Iadarola, K.S.B. Li, T. Pieloni, A. Romano, G. Rumolo, B. Salvant, M. Schenk, C. Tambasco
CERN, Geneva, Switzerland
J. Barranco
EPFL, Lausanne, Switzerland

Since the first transverse instability observed in 2010, many studies have been performed on both measurement and simulation sides and several lessons have been learned. In a machine like the LHC, not only all the mechanisms have to be understood separately, but the possible interplays between the different phenomena need to be analyzed in detail, including the beam-coupling impedance (with in particular all the necessary collimators to protect the machine but also new equipment such as crab cavities for HL-LHC), linear and nonlinear chromaticity, Landau octupoles (and other intrinsic nonlinearities), transverse damper, space charge, beam-beam (long-range and head-on), electron cloud, linear coupling strength, tune separation between the transverse planes, tune split between the two beams, transverse beam separation between the two beams, etc. This paper reviews all the transverse beam instabilities observed and simulated so far, the mitigation measures which have been put in place, the remaining questions and challenges and some recommendations for the future.

Slides TUAM2X01 [36.385 MB]

Export •

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

WEPM2X01

High Power Target Instrumentation at J-PARC for Neutron and Muon Sources

target, proton, neutron, optics

391

S.I. Meigo, A. Akutsu, K. Ikezaki, T.K. Kawasaki, H. Kinoshita, M. Nishikawa, M. Ooi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
H. Fujimori, S.F. Fukuta
KEK/JAEA, Ibaraki-Ken, Japan

Funding: This work is partly supported by the MEXT Grant-in-Aid for Scientific Research (C) Grant no. 26390114.
At the J-PARC, spallation neutron and muon sources are injected 3-GeV proton beam with power of 1 MW extracted from 25 Hz Rapid Cycling Synchrotron (RCS). Recently several shots of the beam with equivalent power of 1 MW were successfully delivered to the targets without significant beam loss. Since the pitting erosion on the mercury target vessel utilized for spallation neutron source is known to be proportional to the 4th power of the beam current density, peak current density at the target should be kept as low as possible so that we have developed beam-flattening system by nonlinear beam optics using octupole magnets. To carry out the beam tuning efficiently, beam-tuning tool had been developed by using SAD code system. It is found that the shape of the beam can be controlled as designed. By using anti-correlated painting at the injection of the RCS, the beam was found to be shaped more flat distribution. The peak current density at the target can be reduced by 30 % with the present nonlinear optics without significant beam loss around at octupole magnets, which mitigates 76 % of the damage at the target vessel.

Slides WEPM2X01 [9.327 MB]

Export •

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

THPM7X01

Use of RF Quadrupole Structures to Enhance Stability in Accelerator Rings

quadrupole, betatron, simulation, synchrotron

505

M. Schenk, A. Grudiev, K.S.B. Li, K. Papke
CERN, Geneva, Switzerland

The beams required for the high luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN call for efficient mechanisms to suppress transverse collective instabilities. In addition to octupole magnets installed for the purpose of Landau damping, we propose to use radio frequency (rf) quadrupole structures to considerably enhance the aforementioned stabilising effect. By means of the PyHEADTAIL macroparticle tracking code, the stabilising mechanism introduced by an rf quadrupole is studied and discussed. As a specific example, the performance of an rf quadrupole system in presence of magnetic octupoles is demonstrated for HL-LHC. Furthermore, potential performance limitations such as the excitation of synchro-betatron resonances are pointed out. Finally, efforts towards possible measurements with the CERN Super Proton Synchrotron (SPS) are discussed aiming at studying the underlying stabilising mechanisms experimentally.

Slides THPM7X01 [37.755 MB]

Export •

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

THPM8X01

Early Tests and Simulation of Quasi-Integrable Octupole Lattices at the University of Maryland Electron Ring

lattice, distributed, quadrupole, simulation

511

K.J. Ruisard, H. Baumgartner, B. Beaudoin, I. Haber, T.W. Koeth, D.B. Matthew
UMD, College Park, Maryland, USA

Funding: Work and travel supported by NSF GRFP, NSF Accelerator Science Program, DOE-HEP and UMD Graduate School ICSSA award.
Nonlinear quasi-integrable optics is a promising development on the horizon of high-intensity ring design. Large amplitude-dependent tune spreads, driven by strong nonlinear magnet inserts, lead to decoherence from incoherent tune resonances. This reduces intensity-driven beam loss while quasi-integrability ensures contained orbits. The experimental program at the University of Maryland Electron Ring (UMER) will explore the performance of a strong octupole lattice at a range of operating points. Early measurements use a distributed octupole lattice, consisting of several small octupole inserts. We vary lattice tune to change the quasi-integrable condition as well as probe behavior near different resonant conditions. Simulation results show there should be invariant conservation under carefully chosen conditions. We discuss the effect of steering errors on the lattice performance and on-going efforts to reduce these errors. We also discuss plans for a single-channel insert.

Slides THPM8X01 [56.742 MB]

Export •

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