HB2016 - List of Keywords (quadrupole)

Paper	Title	Other Keywords	Page
MOPR014	Corrector Magnets for the CBETA and eRHIC Projects and Other Hadron Facilities*	dipole, electron, permanent-magnet, hadron	87
	N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the U.S. Department of Energy under contract DE- SC0012704. The Cbeta project[1] is a prototype electron accelerator for the proposed eRHIC project[2]. The electron accelerator is based on the Energy Recovery Linac (ERL) and the Fixed Field Alternating Gradient (FFAG) principles. The FFAG arcs of the accelerator are comprised of one focusing and one defocusing quadrupoles which are designed as Halbach-type permanent magnet quadrupoles[3]. We propose window frame electro-magnets surrounding the Halbach magnets to be used as normal and skew dipoles correctors and quadrupole correctors. We will present results from OPERA-3D calculations of the effect of these corrector magnets on the magnetic field of the main quadrupole magnets and the results will be compared with experimental measurements. We will also discuss applications of permanent magnets with such correctors for hadron beam facilities. [1] http://arxiv.org/abs/1504.00588 [2] http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf [3] K. Halbach, NIM 169 (1980) pp. 1-10
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPR027	Dynamic Beta and Beta-Beating Effects in the Presence of the Beam-Beam Interactions	optics, lattice, collider, luminosity	136
	T. Pieloni, X. Buffat, L.E. Medina Medrano, C. Tambasco, R. Tomás CERN, Geneva, Switzerland J. Barranco, P. Concalves Jorge, C. Tambasco EPFL, Lausanne, Switzerland
	The Large Hadron Collider (LHC) has achieved correction of beta beat down to better than 5%. The beam-beam interactions at the four experiments result as extra quadrupole error in the lattice. This will produce a change of the β^* at the experiments and a beating along the arcs which for the High Luminosity LHC (HL-LHC) will be very large. Estimations of these effects will be given with the characterisation of the amplitude dependency. A first attempt to correct his beating is also discussed.
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPL002	The DESIR Facility at GANIL-SPIRAL2: The Transfer Beam Lines	ion, diagnostics, optics, emittance	179
	L. Perrot, P. Blache, S. Rousselot IPN, Orsay, France
	Funding: French ANR, Investissements d'Avenir, EQUIPEX. Contract number ANR-11-EQPX-0012. The new ISOL facility SPIRAL2 is currently being built at GANIL, Caen France. The commissioning of the accelerator is in progress since 2015. SPIRAL2 will produce a large number of new radioactive ion beams (RIB) at high intensities. In 2019, the DESIR facility will receive beams from the upgraded SPIRAL1 facility of GANIL (stable beam and target fragmentation), from the S3 Low Energy Branch (fusion-evaporation and deep-inelastic reactions). In order to deliver the RIB to the experimental set-ups installed in the DESIR hall, 110 meters of beam line are studied since 2014. This paper will focus on the recent studies which have been done on these transfer lines: beam optics and errors calculations, quadrupoles, diagnostics and mechanical designs.
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPL003	Status of the Beam Dynamics Design of the New Post-Stripper DTL for GSI - FAIR	DTL, simulation, ion, emittance	184
	A. Rubin, D. Daehn, X. Du, L. Groening, M. Kaiser, S. Mickat GSI, Darmstadt, Germany
	The GSI UNILAC has served as injector for all ion species since 40 years. Its 10⁸ MHz Alvarez DTL providing acceleration from 1.4 MeV/u to 11.4 MeV/u has suffered from material fatigue and has to be replaced by a new section. The design of the new post-stripper DTL is now under development in GSI. An optimized drift tube shape increases the shunt impedance and varying stem orientations mitigate parasitic rf-modes. This contribution is on the beam dynamics layout.
	Poster MOPL003 [2.176 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPL007	Beam Steering Studies for the Superconducting Linac of the RAON Accelerator	linac, GUI, simulation, lattice	199
	H. Jin, J.-H. Jang, D. Jeon IBS, Daejeon, Republic of Korea
	The RAON accelerator of Rare Isotope Science Project (RISP) has been developed to accelerate various kinds of stable ion beams and rare isotope beams for a wide range of science experiments. In the RAON accelerator, the superconducting linac (SCL) will be installed for the acceleration of the beams and it is composed of tens of cryomodules which include superconducting radio frequency cavities. Between two cryomodules, there is a warm section and two quadrupoles are located in the warm section with a beam diagnostics box in between. Also, in this warm section, one horizontal corrector and one beam position monitor (BPM) are mounted inside of first quadrupole, and one vertical corrector is located inside of second quadrupole for the beam steering. With these correctors and BPMs, the beam steering studies are carried out as varying the number of correctors and BPMs in the SCL of the RAON accelerator and the results are presented.
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPL009	Analytical Approach for Achromatic Structure Study and Design	emittance, dipole, cyclotron, factory	203
	H.Y. Barminova MEPhI, Moscow, Russia A.S. Chikhachev Allrussian Electrotechnical Institute, Moskow, Russia
	The analytical approach is proposed to study the various achromatic structures. The method is based on the self-consistent time-dependent models, which allow to describe the dynamics of both continuous and bunched beam in external magnetic fields. The fully kinetic models are implemented in this approach. The kinetic distribution functions dependent on the motion integrals allow to obtain accurate Vlasov equation solutions as KV-model does it. The method allows to solve the envelope equation both analytically and by ODE system numerical integration, and to predict the beam phase portrait behavior in magnetic fields of the structure. The advantages of the method are the possibility of easy scaling and the wide physical generality, which is important for the multi-parameter problem of the high-intensity high-brightness beam formation. The results of the method application for the bending magnets and the quadrupoles are presented.
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPL015	Effect of Beam Losses on Wire Scanner Scintillator Readout, Hypothesis and Preliminary Results	detector, simulation, linac, beam-losses	216
	B. Cheymol ESS, Lund, Sweden
	In hadron accelerators, the characterization of the beam transverse halo can lead to a better understanding of the beam dynamics and ultimately to a reduction of the beam losses. Unfortunately the effect of losses on beam instrumentation implies a reduction of the instrument sensitivity due to the background noise. In this paper, we will discuss the effect of losses on the wire scanner scintillator foreseen for the ESS linac, in particular the different hypothesis for the input will be described and preliminary results will be presented.
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPL021	Fermilab Booster Transition Crossing Simulations and Beam Studies	booster, proton, simulation, space-charge	242
	C.M. Bhat, C.-Y. Tan Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy The Fermiab Booster accelerates beam from 400 MeV to 8 GeV at 15 Hz. In the PIP (Proton Improvement Plan) era, it is required that Booster deliver 4.2·10¹² protons per pulse to extraction. One of the obstacles for providing quality beam to the users is the longitudinal quadrupole oscillation that the beam suffers from right after transition. Although this oscillation is well taken care of with quadrupole dampers, it is important to understand the source of these oscillation in light of the PIP II requirements that require 6.5·10¹² protons per pulse at extraction. This paper explores the results from computer simulations, machine studies and solutions to prevent the quadrupole oscillation after transition. Author would like to thank S. Chaurize, C. Drennan, W. Pellico, K. Seiya, T. Sullivan and K. Triplett
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPL024	Study of Magnets Sorting of the CSNS/RCS Dipoles and Quadrupoles*	dipole, closed-orbit, injection, lattice	247
	Y.W. An, H.F. Ji, Y. Li, S. Wang, S.Y. Xu IHEP, Beijing, People's Republic of China J. Peng CSNS, Guangdong Province, People's Republic of China
	Funding: Work supported by National Natural Science Foundation of China (11405189)* The Rapid Cycling Synchrotron plays an important role in the China Spallation Neutron Source. RCS accumulates and accelerates the proton beams from 80MeV to 1.6GeV for striking the target with the repetition rate of 25Hz. RCS demands low uncontrolled loss for hands on maintenance, and one needs a tight tolerance on magnet field accuracy. Magnet sorting can be done to minimize linear effects of beam dynamics. Using closed-orbit distortion (COD) and beta-beating independently as the merit function, and considering maintaining the symmetry of the lattice, a code based on traversal algorithm is developed to get the dipoles and quadrupoles sorting for CSNS/RCS. The comparison of beam distribution, collimation efficiency and beam loss are also investigated according to beam injection and beam accelerating.
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUAM4X01	Electron Cloud in the CERN Accelerator Complex	operation, emittance, electron, simulation	266
	G. Rumolo, H. Bartosik, E. Belli, G. Iadarola, K.S.B. Li, L. Mether, A. Romano CERN, Geneva, Switzerland M. Schenk EPFL, Lausanne, Switzerland
	Operation with closely spaced bunched beams causes the build up of an Electron Cloud (EC) in both the LHC and the two last synchrotrons of its injector chain (PS and SPS). Pressure rise and beam instabilities are observed at the PS during the last stage of preparation of the LHC beams. The SPS was affected by coherent and incoherent emittance growth along the LHC bunch train over many years, before scrubbing has finally suppressed the EC in a large fraction of the machine. When the LHC started regular operation with 50 ns beams in 2011, EC phenomena appeared in the arcs during the early phases, and in the interaction regions with two beams all along the run. Operation with 25 ns beams (late 2012 and 2015), which is nominal for LHC, has been hampered by EC induced high heat load in the cold arcs, bunch dependent emittance growth and degraded beam lifetime. Dedicated and parasitic machine scrubbing is presently the weapon used at the LHC to combat EC in this mode of operation. This talk summarises the EC experience in the CERN machines (PS, SPS, LHC) and highlight the dangers for future operation with more intense beams as well as the strategies to mitigate or suppress the effect.
	Slides TUAM4X01 [9.785 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPM5Y01	ESS Linac Plans for Commissioning and Initial Operations	linac, rfq, target, dipole	342
	R. Miyamoto, M. Eshraqi, M. Muñoz ESS, Lund, Sweden
	Beam commissioning of the proton linac of the European Spallation Source (ESS) is planned to be conducted in 2018 and 2019. At this stage, the last 21 cryomodules are not yet installed and the maximum beam energy and power are 570 MeV and 1.4 MW, with respect to the nominal 2 GeV and 5 MW. The linac will be operated in this condition until the remaining cyromodules are installed in two stages in 2021 and 2022. On top of the common challenges of beam dynamics and machine protection, commissioning of a large scale machine, such as the ESS linac within a relatively short integrated time of less than 40 weeks imposes an additional challenge to the scheduling and planning. This paper lays out the current plans of the ESS linac for its beam commissioning as well as the initial operation.
	Slides TUPM5Y01 [3.651 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPM9Y01	Observations of Coupling During Accumulation Using a Non-Destructive Electron Scanner in the Spallation Neutron Source Accumulator Ring	electron, coupling, experiment, accumulation	351
	R.E. Potts ORNL RAD, Oak Ridge, Tennessee, USA W. Blokland, S.M. Cousineau, J.A. Holmes ORNL, Oak Ridge, Tennessee, USA
	An electron scanner has been installed in the accumulator ring of the Spallation Neutron Source (SNS). The non-destructive device permits turn-by-turn measurements of the horizontal and vertical profiles of the proton beam during accumulation with fine longitudinal resolution. In this study the device is used to identify the source of transverse coupling in the SNS ring and to understand the impact of space charge on the evolution of the coupled beam. We present experimental observations of coupling dependent on tune, injected intensity, and accumulated intensity for a simplified accumulation scenario with no RF and no injection painting. We also investigate the effects of varying the skew quadrupoles and tune for beams with the SNS production-style ring injection and ring RF patterns.
	Slides TUPM9Y01 [3.849 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	betatron, octupole, 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	octupole, lattice, distributed, 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)

Paper

Title

Other Keywords

Page

MOPR014

Corrector Magnets for the CBETA and eRHIC Projects and Other Hadron Facilities*

dipole, electron, permanent-magnet, hadron

87

N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the U.S. Department of Energy under contract DE- SC0012704.
The Cbeta project[1] is a prototype electron accelerator for the proposed eRHIC project[2]. The electron accelerator is based on the Energy Recovery Linac (ERL) and the Fixed Field Alternating Gradient (FFAG) principles. The FFAG arcs of the accelerator are comprised of one focusing and one defocusing quadrupoles which are designed as Halbach-type permanent magnet quadrupoles[3]. We propose window frame electro-magnets surrounding the Halbach magnets to be used as normal and skew dipoles correctors and quadrupole correctors. We will present results from OPERA-3D calculations of the effect of these corrector magnets on the magnetic field of the main quadrupole magnets and the results will be compared with experimental measurements. We will also discuss applications of permanent magnets with such correctors for hadron beam facilities.
[1] http://arxiv.org/abs/1504.00588
[2] http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf
[3] K. Halbach, NIM 169 (1980) pp. 1-10

Export •

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

MOPR027

Dynamic Beta and Beta-Beating Effects in the Presence of the Beam-Beam Interactions

optics, lattice, collider, luminosity

136

T. Pieloni, X. Buffat, L.E. Medina Medrano, C. Tambasco, R. Tomás
CERN, Geneva, Switzerland
J. Barranco, P. Concalves Jorge, C. Tambasco
EPFL, Lausanne, Switzerland

The Large Hadron Collider (LHC) has achieved correction of beta beat down to better than 5%. The beam-beam interactions at the four experiments result as extra quadrupole error in the lattice. This will produce a change of the β^* at the experiments and a beating along the arcs which for the High Luminosity LHC (HL-LHC) will be very large. Estimations of these effects will be given with the characterisation of the amplitude dependency. A first attempt to correct his beating is also discussed.

Export •

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

MOPL002

The DESIR Facility at GANIL-SPIRAL2: The Transfer Beam Lines

ion, diagnostics, optics, emittance

179

L. Perrot, P. Blache, S. Rousselot
IPN, Orsay, France

Funding: French ANR, Investissements d'Avenir, EQUIPEX. Contract number ANR-11-EQPX-0012.
The new ISOL facility SPIRAL2 is currently being built at GANIL, Caen France. The commissioning of the accelerator is in progress since 2015. SPIRAL2 will produce a large number of new radioactive ion beams (RIB) at high intensities. In 2019, the DESIR facility will receive beams from the upgraded SPIRAL1 facility of GANIL (stable beam and target fragmentation), from the S3 Low Energy Branch (fusion-evaporation and deep-inelastic reactions). In order to deliver the RIB to the experimental set-ups installed in the DESIR hall, 110 meters of beam line are studied since 2014. This paper will focus on the recent studies which have been done on these transfer lines: beam optics and errors calculations, quadrupoles, diagnostics and mechanical designs.

Export •

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

MOPL003

Status of the Beam Dynamics Design of the New Post-Stripper DTL for GSI - FAIR

DTL, simulation, ion, emittance

184

A. Rubin, D. Daehn, X. Du, L. Groening, M. Kaiser, S. Mickat
GSI, Darmstadt, Germany

The GSI UNILAC has served as injector for all ion species since 40 years. Its 10⁸ MHz Alvarez DTL providing acceleration from 1.4 MeV/u to 11.4 MeV/u has suffered from material fatigue and has to be replaced by a new section. The design of the new post-stripper DTL is now under development in GSI. An optimized drift tube shape increases the shunt impedance and varying stem orientations mitigate parasitic rf-modes. This contribution is on the beam dynamics layout.

Poster MOPL003 [2.176 MB]

Export •

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

MOPL007

Beam Steering Studies for the Superconducting Linac of the RAON Accelerator

linac, GUI, simulation, lattice

199

H. Jin, J.-H. Jang, D. Jeon
IBS, Daejeon, Republic of Korea

The RAON accelerator of Rare Isotope Science Project (RISP) has been developed to accelerate various kinds of stable ion beams and rare isotope beams for a wide range of science experiments. In the RAON accelerator, the superconducting linac (SCL) will be installed for the acceleration of the beams and it is composed of tens of cryomodules which include superconducting radio frequency cavities. Between two cryomodules, there is a warm section and two quadrupoles are located in the warm section with a beam diagnostics box in between. Also, in this warm section, one horizontal corrector and one beam position monitor (BPM) are mounted inside of first quadrupole, and one vertical corrector is located inside of second quadrupole for the beam steering. With these correctors and BPMs, the beam steering studies are carried out as varying the number of correctors and BPMs in the SCL of the RAON accelerator and the results are presented.

Export •

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

MOPL009

Analytical Approach for Achromatic Structure Study and Design

emittance, dipole, cyclotron, factory

203

H.Y. Barminova
MEPhI, Moscow, Russia
A.S. Chikhachev
Allrussian Electrotechnical Institute, Moskow, Russia

The analytical approach is proposed to study the various achromatic structures. The method is based on the self-consistent time-dependent models, which allow to describe the dynamics of both continuous and bunched beam in external magnetic fields. The fully kinetic models are implemented in this approach. The kinetic distribution functions dependent on the motion integrals allow to obtain accurate Vlasov equation solutions as KV-model does it. The method allows to solve the envelope equation both analytically and by ODE system numerical integration, and to predict the beam phase portrait behavior in magnetic fields of the structure. The advantages of the method are the possibility of easy scaling and the wide physical generality, which is important for the multi-parameter problem of the high-intensity high-brightness beam formation. The results of the method application for the bending magnets and the quadrupoles are presented.

Export •

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

MOPL015

Effect of Beam Losses on Wire Scanner Scintillator Readout, Hypothesis and Preliminary Results

detector, simulation, linac, beam-losses

216

B. Cheymol
ESS, Lund, Sweden

In hadron accelerators, the characterization of the beam transverse halo can lead to a better understanding of the beam dynamics and ultimately to a reduction of the beam losses. Unfortunately the effect of losses on beam instrumentation implies a reduction of the instrument sensitivity due to the background noise. In this paper, we will discuss the effect of losses on the wire scanner scintillator foreseen for the ESS linac, in particular the different hypothesis for the input will be described and preliminary results will be presented.

Export •

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

MOPL021

Fermilab Booster Transition Crossing Simulations and Beam Studies

booster, proton, simulation, space-charge

242

C.M. Bhat, C.-Y. Tan
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy
The Fermiab Booster accelerates beam from 400 MeV to 8 GeV at 15 Hz. In the PIP (Proton Improvement Plan) era, it is required that Booster deliver 4.2·10¹² protons per pulse to extraction. One of the obstacles for providing quality beam to the users is the longitudinal quadrupole oscillation that the beam suffers from right after transition. Although this oscillation is well taken care of with quadrupole dampers, it is important to understand the source of these oscillation in light of the PIP II requirements that require 6.5·10¹² protons per pulse at extraction. This paper explores the results from computer simulations, machine studies and solutions to prevent the quadrupole oscillation after transition.
Author would like to thank S. Chaurize, C. Drennan, W. Pellico, K. Seiya, T. Sullivan and K. Triplett

Export •

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

MOPL024

Study of Magnets Sorting of the CSNS/RCS Dipoles and Quadrupoles*

dipole, closed-orbit, injection, lattice

247

Y.W. An, H.F. Ji, Y. Li, S. Wang, S.Y. Xu
IHEP, Beijing, People's Republic of China
J. Peng
CSNS, Guangdong Province, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (11405189)*
The Rapid Cycling Synchrotron plays an important role in the China Spallation Neutron Source. RCS accumulates and accelerates the proton beams from 80MeV to 1.6GeV for striking the target with the repetition rate of 25Hz. RCS demands low uncontrolled loss for hands on maintenance, and one needs a tight tolerance on magnet field accuracy. Magnet sorting can be done to minimize linear effects of beam dynamics. Using closed-orbit distortion (COD) and beta-beating independently as the merit function, and considering maintaining the symmetry of the lattice, a code based on traversal algorithm is developed to get the dipoles and quadrupoles sorting for CSNS/RCS. The comparison of beam distribution, collimation efficiency and beam loss are also investigated according to beam injection and beam accelerating.

Export •

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

TUAM4X01

Electron Cloud in the CERN Accelerator Complex

operation, emittance, electron, simulation

266

G. Rumolo, H. Bartosik, E. Belli, G. Iadarola, K.S.B. Li, L. Mether, A. Romano
CERN, Geneva, Switzerland
M. Schenk
EPFL, Lausanne, Switzerland

Operation with closely spaced bunched beams causes the build up of an Electron Cloud (EC) in both the LHC and the two last synchrotrons of its injector chain (PS and SPS). Pressure rise and beam instabilities are observed at the PS during the last stage of preparation of the LHC beams. The SPS was affected by coherent and incoherent emittance growth along the LHC bunch train over many years, before scrubbing has finally suppressed the EC in a large fraction of the machine. When the LHC started regular operation with 50 ns beams in 2011, EC phenomena appeared in the arcs during the early phases, and in the interaction regions with two beams all along the run. Operation with 25 ns beams (late 2012 and 2015), which is nominal for LHC, has been hampered by EC induced high heat load in the cold arcs, bunch dependent emittance growth and degraded beam lifetime. Dedicated and parasitic machine scrubbing is presently the weapon used at the LHC to combat EC in this mode of operation. This talk summarises the EC experience in the CERN machines (PS, SPS, LHC) and highlight the dangers for future operation with more intense beams as well as the strategies to mitigate or suppress the effect.

Slides TUAM4X01 [9.785 MB]

Export •

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

TUPM5Y01

ESS Linac Plans for Commissioning and Initial Operations

linac, rfq, target, dipole

342

R. Miyamoto, M. Eshraqi, M. Muñoz
ESS, Lund, Sweden

Beam commissioning of the proton linac of the European Spallation Source (ESS) is planned to be conducted in 2018 and 2019. At this stage, the last 21 cryomodules are not yet installed and the maximum beam energy and power are 570 MeV and 1.4 MW, with respect to the nominal 2 GeV and 5 MW. The linac will be operated in this condition until the remaining cyromodules are installed in two stages in 2021 and 2022. On top of the common challenges of beam dynamics and machine protection, commissioning of a large scale machine, such as the ESS linac within a relatively short integrated time of less than 40 weeks imposes an additional challenge to the scheduling and planning. This paper lays out the current plans of the ESS linac for its beam commissioning as well as the initial operation.

Slides TUPM5Y01 [3.651 MB]

Export •

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

TUPM9Y01

Observations of Coupling During Accumulation Using a Non-Destructive Electron Scanner in the Spallation Neutron Source Accumulator Ring

electron, coupling, experiment, accumulation

351

R.E. Potts
ORNL RAD, Oak Ridge, Tennessee, USA
W. Blokland, S.M. Cousineau, J.A. Holmes
ORNL, Oak Ridge, Tennessee, USA

An electron scanner has been installed in the accumulator ring of the Spallation Neutron Source (SNS). The non-destructive device permits turn-by-turn measurements of the horizontal and vertical profiles of the proton beam during accumulation with fine longitudinal resolution. In this study the device is used to identify the source of transverse coupling in the SNS ring and to understand the impact of space charge on the evolution of the coupled beam. We present experimental observations of coupling dependent on tune, injected intensity, and accumulated intensity for a simplified accumulation scenario with no RF and no injection painting. We also investigate the effects of varying the skew quadrupoles and tune for beams with the SNS production-style ring injection and ring RF patterns.

Slides TUPM9Y01 [3.849 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

betatron, octupole, 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

octupole, lattice, distributed, 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)