HB2016 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOAM4P40	A Fifteen Year Perspective on the Design and Performance of the SNS Accelerator	linac, injection, target, operation	9
	S.M. Cousineau ORNL, Oak Ridge, Tennessee, USA
	Commissioning of the Spallation Neutron Source accelerator began approximately fifteen years ago. Since this time, the accelerator has broken new technological ground with the operation of the world’s first superconducting H⁻ linac, the first liquid mercury target, and 1.4 MW of beam power. This talk will reflect on the issues and concerns that drove key decisions during the design phase, and will consider those decisions in the context of the actual performance of the accelerator. Noteworthy successes will be highlighted and lessons-learned will be discussed. Finally, a look forward toward the challenges associated with a higher power future at SNS will be presented.
	Slides MOAM4P40 [8.952 MB]
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MOAM5P50	LHC Run 2: Results and Challenges	luminosity, proton, operation, ion	14
	R. Bruce, G. Arduini, H. Bartosik, R. De Maria, M. Giovannozzi, G. Iadarola, J.M. Jowett, M. Lamont, A. Lechner, K.S.B. Li, D. Mirarchi, E. Métral, T. Pieloni, S. Redaelli, G. Rumolo, B. Salvant, R. Tomás, J. Wenninger CERN, Geneva, Switzerland
	The first proton run of the LHC was very successful and resulted in important physics discoveries. It was followed by a two-year shutdown where a large number of improvements were carried out. In 2015, the LHC was restarted and this second run aims at further exploring the physics of the standard model and beyond at an increased beam energy. This article gives a review of the performance achieved so far and the limitations encountered, as well as the future challenges for the CERN accelerators to maximize the data delivered to the LHC experiments in Run 2. Furthermore, the status of the 2016 LHC run and commissioning is discussed.
	Slides MOAM5P50 [9.283 MB]
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MOPR014	Corrector Magnets for the CBETA and eRHIC Projects and Other Hadron Facilities*	quadrupole, dipole, 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
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MOPR035	Electron Lens for the Fermilab Integrable Optics Test Accelerator	solenoid, optics, gun, space-charge	170
	G. Stancari, A.V. Burov, K. Carlson, D.J. Crawford, V.A. Lebedev, J.R. Leibfritz, M.W. McGee, S. Nagaitsev, L.E. Nobrega, C.S. Park, E. Prebys, A.L. Romanov, J. Ruan, V.D. Shiltsev, Y.-M. Shin, J.C.T. Thangaraj, A. Valishev Fermilab, Batavia, Illinois, USA D. Noll IAP, Frankfurt am Main, Germany Y.-M. Shin Northern Illinois University, DeKalb, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy. The Integrable Optics Test Accelerator (IOTA) is a research machine currently being designed and built at Fermilab. The research program includes the study of nonlinear integrable lattices, beam dynamics with self fields, and optical stochastic cooling. One section of the ring will contain an electron lens, a low-energy magnetized electron beam overlapping with the circulating beam. The electron lens can work as a nonlinear element, as an electron cooler, or as a space-charge compensator. We describe the physical principles, experiment design, and hardware implementation plans for the IOTA electron lens.
	Poster MOPR035 [5.399 MB]
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TUAM2X01	Measurement and Interpretation of Transverse Beam Instabilities in the CERN Large Hadron Collider (LHC) and Extrapolations to HL-LHC	octupole, coupling, simulation, 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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TUAM4X01	Electron Cloud in the CERN Accelerator Complex	operation, emittance, simulation, quadrupole	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]
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TUPM6X01	H⁻ Charge Exchange Injection Issues at High Power	injection, proton, target, vacuum	304
	M.A. Plum ORNL, Oak Ridge, Tennessee, USA
	At low beam powers H− charge exchange injection into a storage ring or synchrotron is relatively simple. A thin stripper foil removes the two “convoy” electrons from the H− particle and the newly-created proton begins to circulate around the ring. At high beam powers there are complications due to the heat created in the stripper foil, the power in the H⁰ excited states, and the power in the convoy electrons. The charge-exchanged beam power at the Oak Ridge Spallation Neutron Source is the highest in the world. Although the SNS ring was carefully designed to operate at this level there have been surprises, primarily involving the convoy electrons. Examples include damage to the foil brackets due to reflected convoy electrons and damage to the electron collector due to the primary convoy electrons. The SNS Second Target Station project calls for doubling the beam power and thus placing even more stress on the charge-exchange-injection beam-line components. In this presentation we will compare charge-exchange-injection designs at high-power facilities around the world, discuss lessons learned, and describe the future plans at SNS.
	Slides TUPM6X01 [10.929 MB]
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TUPM9Y01	Observations of Coupling During Accumulation Using a Non-Destructive Electron Scanner in the Spallation Neutron Source Accumulator Ring	coupling, experiment, accumulation, quadrupole	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]
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WEAM3X01	Code Development for Collective Effects	simulation, interface, synchrotron, space-charge	362
	K.S.B. Li, H. Bartosik, G. Iadarola, A. Oeftiger, A. Passarelli, A. Romano, G. Rumolo, M. Schenk CERN, Geneva, Switzerland S. Hegglin ETH, Zurich, Switzerland A. Oeftiger, M. Schenk EPFL, Lausanne, Switzerland
	The presentation will cover approaches and strategies of modeling and implementing collective effects in modern simulation codes. We will review some of the general approaches to numerically model collective beam dynamics in circular accelerators. We will then look into modern ways of implementing collective effects with a focus on plainness, modularity and flexibility, using the example of the PyHEADTAIL framework, and highlight some of the advantages and drawbacks emerging from this method. To ameliorate one of the main drawbacks, namely a potential loss of performance compared to the classical fully compiled codes, several options for speed improvements will be mentioned and discussed. Finally some examples and application will be shown together with future plans and perspectives.
	Slides WEAM3X01 [65.643 MB]
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WEAM4X01	Numerical Modeling of Fast Beam Ion Instabilities	ion, simulation, damping, linac	368
	L. Mether, G. Iadarola, G. Rumolo CERN, Geneva, Switzerland
	The fast beam ion instability may pose a risk to the operation of future electron accelerators with beams of high intensity and small emittances, including several structures of the proposed CLIC accelerator complex. Numerical models can be used to identify necessary vacuum specifications to suppress the instability, as well as requirements for a possible feedback system. Vacuum requirements imposed by the instability have previously been estimated for linear CLIC structures, using the strong-strong macroparticle simulation tool FASTION. Currently, efforts are being made to improve the simulation tools, and allow for equivalent studies of circular structures, such as the CLIC damping rings, on a multi-turn scale. In this contribution, we review the recent code developments, and present first simulation results.
	Slides WEAM4X01 [3.379 MB]
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WEPM8Y01	Simulation of Space-Charge Compensation of a Low-Energy Proton Beam in a Drift Section	simulation, emittance, ion, proton	458
	D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte IAP, Frankfurt am Main, Germany
	Space-charge compensation provided by the accumulation of particles of opposing charge in the beam potential is an important effect occuring in magnetostatic low energy beam transport sections of high-intensity accelerators. An improved understanding of its effects might provide valuable input for the design of these beam lines. One approach to model the compensation process are Particle-in-Cell (PIC) simulations including residual gas ionisation. In simulations of a drifting proton beam, using the PIC code bender [1], some features of thermal equilibrium for the compensation electrons were found. This makes it possible to predict their spatial distribution using the Poisson-Boltzmann equation and thus the influence on beam transport. In this contribution, we will provide a comparison between the PIC simulations and the model as well as some ideas concerning the source of the (partial) thermalization. [1] D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner - The Particle-in-Cell Code Bender and Its Application to Non-Relativistic Beam Transport, WEO4LR02, Proc. of HB2014
	Slides WEPM8Y01 [2.203 MB]
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THAM1X01	Reuse Recycler: High Intensity Proton Stacking at Fermilab	proton, operation, booster, vacuum	463
	P. Adamson Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy. After a successful career as an antiproton storage and cooling ring, Recycler has been converted to a high intensity proton stacker for the Main Injector. We discuss the commissioning and operation of the Recycler in this new role, and the progress towards the 700 kW design goal.
	Slides THAM1X01 [1.978 MB]
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THPM5X01	Using an Electron Cooler for Space Charge Compensation in the GSI Synchrotron SIS18	ion, space-charge, experiment, focusing	496
	W.D. Stem, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim GSI, Darmstadt, Germany
	Funding: Work is supported by BMBF contract FKZ:05P15RDRBA For the future operation of the SIS18 as a booster synchrotron for the FAIR SIS100, space charge and beam lifetime are expected to be the main intensity limitations. Intensity is limited in part by the space-charge-induced incoherent tune shift in bunched beams. A co-propagating, low energy electron lens can compensate for this tune shift by applying opposing space-charge fields in the ion beam. In this paper, we study the effect of using the existing electron cooler at the SIS18 as a space charge compensation device. We anticipate beta beating may arise due to the singular localized focusing error, and explore the possibility of adding additional lenses to reduce this error. We also study the effect of electron lenses on the coherent (collective) and incoherent (single-particle) stopbands. Furthermore, we estimate the lifetime of partially stripped heavy-ions due to charge exchange process in the lens.
	Slides THPM5X01 [4.731 MB]
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THPM10X01	Stripline Beam Position Monitors With Improved Frequency Response and Their Coupling Impedances	impedance, simulation, coupling, network	523
	Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y.H. Chin, K. Takata KEK, Ibaraki, Japan K.G. Nakamura Kyoto University, Kyoto, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	In J-PARC Main Ring, transverse intra-bunch oscillations have been observed during the injection and at the onset of acceleration. Up to now, the beam instability is suppressed by the intra-bunch feedback system, where the stripline beam position monitors operate at 10⁸.8 MHz. However, there is a concern that electron cloud instabilities may appear and limit the beam current at future higher power operations. For the case, we have developed a wider-band (several GHz) beam position monitor by deforming the electrode shapes. The modification of the electrode can be done not to enhance the beam coupling impedance. For the typical electrode shapes, we show the coupling impedances as well as the frequency responses of the electrodes.
	Slides THPM10X01 [5.240 MB]
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FRAM2P01	Summary WG-A	space-charge, resonance, simulation, experiment	575
	W. Fischer BNL, Upton, Long Island, New York, USA Y.H. Chin KEK, Ibaraki, Japan G. Franchetti GSI, Darmstadt, Germany
	Friday Summary
	Slides FRAM2P01 [6.325 MB]
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Paper

Title

Other Keywords

Page

MOAM4P40

A Fifteen Year Perspective on the Design and Performance of the SNS Accelerator

linac, injection, target, operation

9

S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA

Commissioning of the Spallation Neutron Source accelerator began approximately fifteen years ago. Since this time, the accelerator has broken new technological ground with the operation of the world’s first superconducting H⁻ linac, the first liquid mercury target, and 1.4 MW of beam power. This talk will reflect on the issues and concerns that drove key decisions during the design phase, and will consider those decisions in the context of the actual performance of the accelerator. Noteworthy successes will be highlighted and lessons-learned will be discussed. Finally, a look forward toward the challenges associated with a higher power future at SNS will be presented.

Slides MOAM4P40 [8.952 MB]

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MOAM5P50

LHC Run 2: Results and Challenges

luminosity, proton, operation, ion

14

R. Bruce, G. Arduini, H. Bartosik, R. De Maria, M. Giovannozzi, G. Iadarola, J.M. Jowett, M. Lamont, A. Lechner, K.S.B. Li, D. Mirarchi, E. Métral, T. Pieloni, S. Redaelli, G. Rumolo, B. Salvant, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland

The first proton run of the LHC was very successful and resulted in important physics discoveries. It was followed by a two-year shutdown where a large number of improvements were carried out. In 2015, the LHC was restarted and this second run aims at further exploring the physics of the standard model and beyond at an increased beam energy. This article gives a review of the performance achieved so far and the limitations encountered, as well as the future challenges for the CERN accelerators to maximize the data delivered to the LHC experiments in Run 2. Furthermore, the status of the 2016 LHC run and commissioning is discussed.

Slides MOAM5P50 [9.283 MB]

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MOPR014

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

quadrupole, dipole, 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

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MOPR035

Electron Lens for the Fermilab Integrable Optics Test Accelerator

solenoid, optics, gun, space-charge

170

G. Stancari, A.V. Burov, K. Carlson, D.J. Crawford, V.A. Lebedev, J.R. Leibfritz, M.W. McGee, S. Nagaitsev, L.E. Nobrega, C.S. Park, E. Prebys, A.L. Romanov, J. Ruan, V.D. Shiltsev, Y.-M. Shin, J.C.T. Thangaraj, A. Valishev
Fermilab, Batavia, Illinois, USA
D. Noll
IAP, Frankfurt am Main, Germany
Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
The Integrable Optics Test Accelerator (IOTA) is a research machine currently being designed and built at Fermilab. The research program includes the study of nonlinear integrable lattices, beam dynamics with self fields, and optical stochastic cooling. One section of the ring will contain an electron lens, a low-energy magnetized electron beam overlapping with the circulating beam. The electron lens can work as a nonlinear element, as an electron cooler, or as a space-charge compensator. We describe the physical principles, experiment design, and hardware implementation plans for the IOTA electron lens.

Poster MOPR035 [5.399 MB]

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TUAM2X01

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

octupole, coupling, simulation, 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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TUAM4X01

Electron Cloud in the CERN Accelerator Complex

operation, emittance, simulation, quadrupole

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]

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TUPM6X01

H⁻ Charge Exchange Injection Issues at High Power

injection, proton, target, vacuum

304

M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

At low beam powers H− charge exchange injection into a storage ring or synchrotron is relatively simple. A thin stripper foil removes the two “convoy” electrons from the H− particle and the newly-created proton begins to circulate around the ring. At high beam powers there are complications due to the heat created in the stripper foil, the power in the H⁰ excited states, and the power in the convoy electrons. The charge-exchanged beam power at the Oak Ridge Spallation Neutron Source is the highest in the world. Although the SNS ring was carefully designed to operate at this level there have been surprises, primarily involving the convoy electrons. Examples include damage to the foil brackets due to reflected convoy electrons and damage to the electron collector due to the primary convoy electrons. The SNS Second Target Station project calls for doubling the beam power and thus placing even more stress on the charge-exchange-injection beam-line components. In this presentation we will compare charge-exchange-injection designs at high-power facilities around the world, discuss lessons learned, and describe the future plans at SNS.

Slides TUPM6X01 [10.929 MB]

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TUPM9Y01

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

coupling, experiment, accumulation, quadrupole

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]

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WEAM3X01

Code Development for Collective Effects

simulation, interface, synchrotron, space-charge

362

K.S.B. Li, H. Bartosik, G. Iadarola, A. Oeftiger, A. Passarelli, A. Romano, G. Rumolo, M. Schenk
CERN, Geneva, Switzerland
S. Hegglin
ETH, Zurich, Switzerland
A. Oeftiger, M. Schenk
EPFL, Lausanne, Switzerland

The presentation will cover approaches and strategies of modeling and implementing collective effects in modern simulation codes. We will review some of the general approaches to numerically model collective beam dynamics in circular accelerators. We will then look into modern ways of implementing collective effects with a focus on plainness, modularity and flexibility, using the example of the PyHEADTAIL framework, and highlight some of the advantages and drawbacks emerging from this method. To ameliorate one of the main drawbacks, namely a potential loss of performance compared to the classical fully compiled codes, several options for speed improvements will be mentioned and discussed. Finally some examples and application will be shown together with future plans and perspectives.

Slides WEAM3X01 [65.643 MB]

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WEAM4X01

Numerical Modeling of Fast Beam Ion Instabilities

ion, simulation, damping, linac

368

L. Mether, G. Iadarola, G. Rumolo
CERN, Geneva, Switzerland

The fast beam ion instability may pose a risk to the operation of future electron accelerators with beams of high intensity and small emittances, including several structures of the proposed CLIC accelerator complex. Numerical models can be used to identify necessary vacuum specifications to suppress the instability, as well as requirements for a possible feedback system. Vacuum requirements imposed by the instability have previously been estimated for linear CLIC structures, using the strong-strong macroparticle simulation tool FASTION. Currently, efforts are being made to improve the simulation tools, and allow for equivalent studies of circular structures, such as the CLIC damping rings, on a multi-turn scale. In this contribution, we review the recent code developments, and present first simulation results.

Slides WEAM4X01 [3.379 MB]

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WEPM8Y01

Simulation of Space-Charge Compensation of a Low-Energy Proton Beam in a Drift Section

simulation, emittance, ion, proton

458

D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte
IAP, Frankfurt am Main, Germany

Space-charge compensation provided by the accumulation of particles of opposing charge in the beam potential is an important effect occuring in magnetostatic low energy beam transport sections of high-intensity accelerators. An improved understanding of its effects might provide valuable input for the design of these beam lines. One approach to model the compensation process are Particle-in-Cell (PIC) simulations including residual gas ionisation. In simulations of a drifting proton beam, using the PIC code bender [1], some features of thermal equilibrium for the compensation electrons were found. This makes it possible to predict their spatial distribution using the Poisson-Boltzmann equation and thus the influence on beam transport. In this contribution, we will provide a comparison between the PIC simulations and the model as well as some ideas concerning the source of the (partial) thermalization.
[1] D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner - The Particle-in-Cell Code Bender and Its Application to Non-Relativistic Beam Transport, WEO4LR02, Proc. of HB2014

Slides WEPM8Y01 [2.203 MB]

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THAM1X01

Reuse Recycler: High Intensity Proton Stacking at Fermilab

proton, operation, booster, vacuum

463

P. Adamson
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
After a successful career as an antiproton storage and cooling ring, Recycler has been converted to a high intensity proton stacker for the Main Injector. We discuss the commissioning and operation of the Recycler in this new role, and the progress towards the 700 kW design goal.

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THPM5X01

Using an Electron Cooler for Space Charge Compensation in the GSI Synchrotron SIS18

ion, space-charge, experiment, focusing

496

W.D. Stem, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim
GSI, Darmstadt, Germany

Funding: Work is supported by BMBF contract FKZ:05P15RDRBA
For the future operation of the SIS18 as a booster synchrotron for the FAIR SIS100, space charge and beam lifetime are expected to be the main intensity limitations. Intensity is limited in part by the space-charge-induced incoherent tune shift in bunched beams. A co-propagating, low energy electron lens can compensate for this tune shift by applying opposing space-charge fields in the ion beam. In this paper, we study the effect of using the existing electron cooler at the SIS18 as a space charge compensation device. We anticipate beta beating may arise due to the singular localized focusing error, and explore the possibility of adding additional lenses to reduce this error. We also study the effect of electron lenses on the coherent (collective) and incoherent (single-particle) stopbands. Furthermore, we estimate the lifetime of partially stripped heavy-ions due to charge exchange process in the lens.

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THPM10X01

Stripline Beam Position Monitors With Improved Frequency Response and Their Coupling Impedances

impedance, simulation, coupling, network

523

Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y.H. Chin, K. Takata
KEK, Ibaraki, Japan
K.G. Nakamura
Kyoto University, Kyoto, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

In J-PARC Main Ring, transverse intra-bunch oscillations have been observed during the injection and at the onset of acceleration. Up to now, the beam instability is suppressed by the intra-bunch feedback system, where the stripline beam position monitors operate at 10⁸.8 MHz. However, there is a concern that electron cloud instabilities may appear and limit the beam current at future higher power operations. For the case, we have developed a wider-band (several GHz) beam position monitor by deforming the electrode shapes. The modification of the electrode can be done not to enhance the beam coupling impedance. For the typical electrode shapes, we show the coupling impedances as well as the frequency responses of the electrodes.

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FRAM2P01

Summary WG-A

space-charge, resonance, simulation, experiment

575

W. Fischer
BNL, Upton, Long Island, New York, USA
Y.H. Chin
KEK, Ibaraki, Japan
G. Franchetti
GSI, Darmstadt, Germany

Friday Summary

Slides FRAM2P01 [6.325 MB]

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