HB2012 - List of Keywords (resonance)

Paper	Title	Other Keywords	Page
MOI1C02	Challenges in Benchmarking of Simulation Codes against Real High Intensity Accelerators	simulation, space-charge, emittance, linac	30
	I. Hofmann GSI, Darmstadt, Germany
	Benchmarking of simulation codes for linear or circular accelerators involves several levels of complexity, which will be revisited and discussed in this talk. As ultimate goal of benchmarking it is hoped that a predictive capacity and a practical control over emittance growth and/or beam loss can be obtained. We first give some examples of how simulation codes can be used to gain as much understanding of the underlying physics mechanisms as possible, which is an almost inevitable first step. With more and more experimental data from running high intensity accelerators having become available in recent years more questions need to be raised: Besides the proper physics, can we feed our codes with an accurate enough model of the real machine? What actually is the required accuracy, and does a specific accelerator have enough diagnostics to enable this accuracy? In the paper we explore these questions by discussing several examples of benchmarking efforts, their achievements as well as the limits and difficulties that have been encountered.
	Slides MOI1C02 [2.838 MB]

MOP257	Space Charge Limits on the ISIS Synchrotron including the Effects of Images	simulation, space-charge, synchrotron, injection	206
	B.G. Pine, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS synchrotron provides a pulsed, 50 Hz, 800 MeV proton beam for spallation neutron production. Each pulse from the synchrotron contains ~2.8×10¹³ ppp, and at this beam intensity space charge and image forces have a strong effect on transverse beam dynamics. In order to increase intensity in the present machine, and to prepare for possible upgrades running at a higher intensity, studies are under way aimed at understanding the most critical features of such forces and their impact on beam loss. These studies are focused on working point optimisation, including resonances due to space charge and images. A 2D simulation code, Set, has been developed to improve understanding of transverse dynamics at ISIS, using a particle-in-cell algorithm to include space charge and image forces self-consistently. The ISIS synchrotron has profiled vacuum vessels and RF shields which conform to the shape of the beam envelope, and have a distinctive influence on the beam dynamics. Set is specifically designed to include these image forces. A systematic simulation study of possible working points is presented, along with an assessment of the effect on apertures.

TUO1A04	Plasma Traps for Space-charge Studies: Status and Perspectives	plasma, ion, laser, quadrupole	235
	H. Okamoto, K. Fukushima, H. Higaki, K. Ito, K. Moriya, T. Okano, S. Yamaguchi HU/AdSM, Higashi-Hiroshima, Japan M. Endo Hiroshima University, Higashi-Hiroshima, Japan A. Mohri Kyoto University, Graduate School of Human and Environmental Studies, Kyoto, Japan
	Funding: Work supported in part by a Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science. The beam physics group of Hiroshima University has developed non-neutral plasma traps dedicated solely to a wide range of beam dynamics studies. Those unique experimental tools approximately reproduce, in the laboratory frame, a many-body Coulomb system that is physically equivalent to a charged-particle beam observed in the center-of-mass frame. We have designed and constructed two different types of traps that employ either a radio-frequency electric quadrupole field or an axial magnetic field for transverse particle confinement. The former type is commonly referred to as "linear Paul trap" and the latter as "Penning trap". At present, three Paul traps and one Penning trap are operational while a new Penning trap for beam halo experiments is under construction. Each of these compact experimental facilities consists of a trap, many power supplies, a vacuum system, a computer control system, etc., and is called "S-POD (Simulator for Particle Orbit Dynamics)". S-POD is particularly useful for fundamental studies of high-intensity and high-brightness hadron beams. We here report on recent experimental outputs from S-POD and also briefly describe some future plans.
	Slides TUO1A04 [7.790 MB]

TUO3A01	Dynamical Aspects of Emittance Coupling in Intense Beams	emittance, linac, coupling, simulation	240
	I. Hofmann GSI, Darmstadt, Germany I. Hofmann HIJ, Jena, Germany
	In this paper we study in an idealized lattice model the dynamical behavior of non-equipartitioned beams and of approach to equipartition. It is shown that emittance transfer depends on times scales of tune change, but also the direction of crossing the stopbands of space charge resonances. This provides additional information to support the stability charts suggested previously as design tool for high current linacs.
	Slides TUO3A01 [4.897 MB]

TUO3A03	Equipartition, Reality or Swindle?	coupling, linac, emittance, space-charge	250
	J.-M. Lagniel GANIL, Caen, France
	By way of introduction to a general discussion on space-charge induced energy equipartition (EQP), the following questions will be tackled: Why the formula presently used to define EQP is wrong? Why energy exchanges can occur although the EQP rule is respected? Why safe tunings can be find although the EQP rule is not respected? Why EQP is a swindle for a large majority of our accelerated beams? Why LINAC designers nevertheless like to use the EQP rule?
	Slides TUO3A03 [1.537 MB]

WEO1A01	Impedance Studies of 2D Azimuthally Symmetric Devices of Finite Length	impedance, coupling, simulation, cavity	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]

WEO1B04	On Scaling Properties of Third-order Resonance Crossing in Particle Accelerators	emittance, simulation, betatron, booster	394
	S.-Y. Lee Indiana University, Bloomington, Indiana, USA K.Y. Ng Fermilab, Batavia, USA
	Funding: Work supported by the US DOE under contract DEFG02-92ER40747, DE-AC02-07CH11359, and the NSF under contract PHY-0852368 with NSF. The effects of resonances on high power hadron accelerators are explored. These resonances include systematic space-charge resonances, third-order resonance, and other weak random resonances that are often present in FFAG and other RCS accelerators. The distortion of invariant torus during resonance crossing is used to set limit on emittance growth or fraction of particle trapped. The critical resonance strength in the ring lattice is determined from a simple scaling law derived as a function of the tune-ramp rate and initial emittance. Such scaling law can be useful in the evaluation of the performance in high power accelerators.
	Slides WEO1B04 [1.074 MB]

WEO1B05	PTC-Orbit Studies for the CERN LHC Injectors Upgrade Project	emittance, booster, space-charge, injection	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]

WEO1C01	Effect of Self-consistency on Periodic Resonance Crossing	simulation, space-charge, ion, synchrotron	429
	G. Franchetti GSI, Darmstadt, Germany
	In high intensity bunched beams resonance crossing gives rise to emittance growth and beam loss. Both these effects build up after many synchrotron oscillations. Up to now long term modeling have relied on frozen models neglecting the physics of self-consistency. We address here this issue and present the state of the art of simulations also applied to the SIS100.
	Slides WEO1C01 [3.657 MB]

WEO1C02	Simulation and Measurement of Half Integer Resonance in Coasting Beams in the ISIS Ring	injection, simulation, synchrotron, space-charge	434
	C.M. Warsop, D.J. Adams, B. Jones, S.J. Payne, B.G. Pine, H. V. Smith, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a high intensity proton synchrotron, accelerating 3·10¹³ ppp from 70-800 MeV, at a repetition rate of 50 Hz. Present studies are looking at key aspects of high intensity behaviour with a view to increasing operational intensity, identifying optimal upgrade routes and understanding loss mechanisms. Of particular interest is the space charge limit imposed by half integer resonance: we present results from coasting beam experiments with the ISIS ring in storage ring mode, along with detailed 3D (ORBIT) simulations to help interpret observations. The methods for experimentally approaching resonance, and the implications on beam behaviour, measurement and interpretation are discussed. In addition, results from simpler 2D simulations and analytical models are used to help interpret expected beam loss and halo evolution. Plans and challenges for the measurement and understanding of this important beam loss mechanism are summarised, as are some closely related areas of high intensity work on ISIS.
	Slides WEO1C02 [2.224 MB]

THO1A01	Beam-beam Effects in RHIC	proton, electron, simulation, emittance	479
	Y. Luo, M. Bai, W. Fischer, C. Montag, S.M. White BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In this article we will review the beam-beam effects in the Relativistic Heavy Ion Collider (RHIC). We will cover the experimental observations, beam-beam simulation techniques and results, and head-on beam-beam compensation with electron lenses. The next luminosity goal in the RHIC polarized proton operation is to double the luminosity with a higher proton bunch intensity. After the upgrade, the beam-beam parameter will reach 0.03. Head-on beam-beam compensation is aimed to reduce the beam-beam tune spread and non-linear beam-beam resonance driving terms.
	Slides THO1A01 [1.355 MB]

THO1A02	Effects of Magnetic Field Tracking Errors and Space Charge on Beam Dynamics at CSNS/RCS	space-charge, quadrupole, simulation, lattice	484
	S.Y. Xu, N. Wang, S. Wang IHEP, Beijing, People's Republic of China
	The China Spallation Neutron Source (CSNS) is an accelerator-based facility. It operates at 25 Hz repetition rate with an design beam power of 100 kW. CSNS consists of a 1.6-GeV Rapid Cycling Synchrotron (RCS) and a 80-MeV linac. The lattice of the CSNS/RCS is triplet based four-fold structure. The preferred working points of CSNS/RCS are (4.86, 4.78) which can avoid the major low-order structure resonances. But because of the chromatic tune shift, space-charge incoherent tune shift and the tune shift caused by magnetic field tracking errors between the quadrupoles and the dipoles, some structure resonances are unavoidable. The chromaticity, space charge effects and magnetic field tracking errors can also induce beta function distortion, and influence the transverse acceptance and the collimation efficiency of the collimation system. In this paper we show results of space-charge simulations introducing magnetic field tracking errors and discuss the combined effects of chromaticity, magnetic field tracking errors and space charge on the beam dynamics for CSNS/RCS.
	Slides THO1A02 [1.613 MB]

THO3C06	On-line Calibration Schemes for RF-based Beam Diagnostics	pick-up, target, proton, diagnostics	601
	P.-A. Duperrex, U. Müller PSI, Villigen PSI, Switzerland
	RF-based beam diagnostics such as BPMs and beam current monitors rely on precise RF signal measurements. Temperature drifts and differences in the overall measurement chain gain make such measurements very challenging and calibration validity over time is an issue. Over some years, on-line calibration schemes for BPMs and current monitors have been developed. These innovative schemes are based on the use of a pilot signal at a frequency offset from the measurement frequency. Results, advantages and disadvantages of such schemes are discussed.
	Slides THO3C06 [2.742 MB]

FRO1A01	Summary of Working Group A: Beam Dynamics in High-Intensity Circular Machines	simulation, space-charge, luminosity, ion	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]

FRO1A02	WG-B: Beam Dynamics In High Intensity Linacs	linac, rfq, emittance, DTL	612
	D. Raparia BNL, Upton, Long Island, New York, USA Z. Li IHEP, Beijing, People's Republic of China P.A.P. Nghiem CEA/DSM/IRFU, France
	Emittance coupling, equipartioning and losses were a few topics, which were discussed thoroughly during parallel session for beam dynamics in high intensity linacs (Group B). Linac designs for the future, under construction, upgrade and the existing linacs from around the world were presented in three working sessions. A total of 18 talks were presented. Five presentations are general beam dynamics in nature and twelve talks were project specific. The detail of each contribution can be found in these proceedings. Here we report the summary of the discussions and some concluding remarks of the general interest to all the projects presented in the working group.
	Slides FRO1A02 [14.464 MB]

Paper

Title

Other Keywords

Page

MOI1C02

Challenges in Benchmarking of Simulation Codes against Real High Intensity Accelerators

simulation, space-charge, emittance, linac

30

I. Hofmann
GSI, Darmstadt, Germany

Benchmarking of simulation codes for linear or circular accelerators involves several levels of complexity, which will be revisited and discussed in this talk. As ultimate goal of benchmarking it is hoped that a predictive capacity and a practical control over emittance growth and/or beam loss can be obtained. We first give some examples of how simulation codes can be used to gain as much understanding of the underlying physics mechanisms as possible, which is an almost inevitable first step. With more and more experimental data from running high intensity accelerators having become available in recent years more questions need to be raised: Besides the proper physics, can we feed our codes with an accurate enough model of the real machine? What actually is the required accuracy, and does a specific accelerator have enough diagnostics to enable this accuracy? In the paper we explore these questions by discussing several examples of benchmarking efforts, their achievements as well as the limits and difficulties that have been encountered.

Slides MOI1C02 [2.838 MB]

MOP257

Space Charge Limits on the ISIS Synchrotron including the Effects of Images

simulation, space-charge, synchrotron, injection

206

B.G. Pine, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS synchrotron provides a pulsed, 50 Hz, 800 MeV proton beam for spallation neutron production. Each pulse from the synchrotron contains ~2.8×10¹³ ppp, and at this beam intensity space charge and image forces have a strong effect on transverse beam dynamics. In order to increase intensity in the present machine, and to prepare for possible upgrades running at a higher intensity, studies are under way aimed at understanding the most critical features of such forces and their impact on beam loss. These studies are focused on working point optimisation, including resonances due to space charge and images. A 2D simulation code, Set, has been developed to improve understanding of transverse dynamics at ISIS, using a particle-in-cell algorithm to include space charge and image forces self-consistently. The ISIS synchrotron has profiled vacuum vessels and RF shields which conform to the shape of the beam envelope, and have a distinctive influence on the beam dynamics. Set is specifically designed to include these image forces. A systematic simulation study of possible working points is presented, along with an assessment of the effect on apertures.

TUO1A04

Plasma Traps for Space-charge Studies: Status and Perspectives

plasma, ion, laser, quadrupole

235

H. Okamoto, K. Fukushima, H. Higaki, K. Ito, K. Moriya, T. Okano, S. Yamaguchi
HU/AdSM, Higashi-Hiroshima, Japan
M. Endo
Hiroshima University, Higashi-Hiroshima, Japan
A. Mohri
Kyoto University, Graduate School of Human and Environmental Studies, Kyoto, Japan

Funding: Work supported in part by a Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science.
The beam physics group of Hiroshima University has developed non-neutral plasma traps dedicated solely to a wide range of beam dynamics studies. Those unique experimental tools approximately reproduce, in the laboratory frame, a many-body Coulomb system that is physically equivalent to a charged-particle beam observed in the center-of-mass frame. We have designed and constructed two different types of traps that employ either a radio-frequency electric quadrupole field or an axial magnetic field for transverse particle confinement. The former type is commonly referred to as "linear Paul trap" and the latter as "Penning trap". At present, three Paul traps and one Penning trap are operational while a new Penning trap for beam halo experiments is under construction. Each of these compact experimental facilities consists of a trap, many power supplies, a vacuum system, a computer control system, etc., and is called "S-POD (Simulator for Particle Orbit Dynamics)". S-POD is particularly useful for fundamental studies of high-intensity and high-brightness hadron beams. We here report on recent experimental outputs from S-POD and also briefly describe some future plans.

Slides TUO1A04 [7.790 MB]

TUO3A01

Dynamical Aspects of Emittance Coupling in Intense Beams

emittance, linac, coupling, simulation

240

I. Hofmann
GSI, Darmstadt, Germany
I. Hofmann
HIJ, Jena, Germany

In this paper we study in an idealized lattice model the dynamical behavior of non-equipartitioned beams and of approach to equipartition. It is shown that emittance transfer depends on times scales of tune change, but also the direction of crossing the stopbands of space charge resonances. This provides additional information to support the stability charts suggested previously as design tool for high current linacs.

Slides TUO3A01 [4.897 MB]

TUO3A03

Equipartition, Reality or Swindle?

coupling, linac, emittance, space-charge

250

J.-M. Lagniel
GANIL, Caen, France

By way of introduction to a general discussion on space-charge induced energy equipartition (EQP), the following questions will be tackled: Why the formula presently used to define EQP is wrong? Why energy exchanges can occur although the EQP rule is respected? Why safe tunings can be find although the EQP rule is not respected? Why EQP is a swindle for a large majority of our accelerated beams? Why LINAC designers nevertheless like to use the EQP rule?

Slides TUO3A03 [1.537 MB]

WEO1A01

Impedance Studies of 2D Azimuthally Symmetric Devices of Finite Length

impedance, coupling, simulation, cavity

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]

WEO1B04

On Scaling Properties of Third-order Resonance Crossing in Particle Accelerators

emittance, simulation, betatron, booster

394

S.-Y. Lee
Indiana University, Bloomington, Indiana, USA
K.Y. Ng
Fermilab, Batavia, USA

Funding: Work supported by the US DOE under contract DEFG02-92ER40747, DE-AC02-07CH11359, and the NSF under contract PHY-0852368 with NSF.
The effects of resonances on high power hadron accelerators are explored. These resonances include systematic space-charge resonances, third-order resonance, and other weak random resonances that are often present in FFAG and other RCS accelerators. The distortion of invariant torus during resonance crossing is used to set limit on emittance growth or fraction of particle trapped. The critical resonance strength in the ring lattice is determined from a simple scaling law derived as a function of the tune-ramp rate and initial emittance. Such scaling law can be useful in the evaluation of the performance in high power accelerators.

Slides WEO1B04 [1.074 MB]

WEO1B05

PTC-Orbit Studies for the CERN LHC Injectors Upgrade Project

emittance, booster, space-charge, injection

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]

WEO1C01

Effect of Self-consistency on Periodic Resonance Crossing

simulation, space-charge, ion, synchrotron

429

G. Franchetti
GSI, Darmstadt, Germany

In high intensity bunched beams resonance crossing gives rise to emittance growth and beam loss. Both these effects build up after many synchrotron oscillations. Up to now long term modeling have relied on frozen models neglecting the physics of self-consistency. We address here this issue and present the state of the art of simulations also applied to the SIS100.

Slides WEO1C01 [3.657 MB]

WEO1C02

Simulation and Measurement of Half Integer Resonance in Coasting Beams in the ISIS Ring

injection, simulation, synchrotron, space-charge

434

C.M. Warsop, D.J. Adams, B. Jones, S.J. Payne, B.G. Pine, H. V. Smith, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a high intensity proton synchrotron, accelerating 3·10¹³ ppp from 70-800 MeV, at a repetition rate of 50 Hz. Present studies are looking at key aspects of high intensity behaviour with a view to increasing operational intensity, identifying optimal upgrade routes and understanding loss mechanisms. Of particular interest is the space charge limit imposed by half integer resonance: we present results from coasting beam experiments with the ISIS ring in storage ring mode, along with detailed 3D (ORBIT) simulations to help interpret observations. The methods for experimentally approaching resonance, and the implications on beam behaviour, measurement and interpretation are discussed. In addition, results from simpler 2D simulations and analytical models are used to help interpret expected beam loss and halo evolution. Plans and challenges for the measurement and understanding of this important beam loss mechanism are summarised, as are some closely related areas of high intensity work on ISIS.

Slides WEO1C02 [2.224 MB]

THO1A01

Beam-beam Effects in RHIC

proton, electron, simulation, emittance

479

Y. Luo, M. Bai, W. Fischer, C. Montag, S.M. White
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In this article we will review the beam-beam effects in the Relativistic Heavy Ion Collider (RHIC). We will cover the experimental observations, beam-beam simulation techniques and results, and head-on beam-beam compensation with electron lenses. The next luminosity goal in the RHIC polarized proton operation is to double the luminosity with a higher proton bunch intensity. After the upgrade, the beam-beam parameter will reach 0.03. Head-on beam-beam compensation is aimed to reduce the beam-beam tune spread and non-linear beam-beam resonance driving terms.

Slides THO1A01 [1.355 MB]

THO1A02

Effects of Magnetic Field Tracking Errors and Space Charge on Beam Dynamics at CSNS/RCS

space-charge, quadrupole, simulation, lattice

484

S.Y. Xu, N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) is an accelerator-based facility. It operates at 25 Hz repetition rate with an design beam power of 100 kW. CSNS consists of a 1.6-GeV Rapid Cycling Synchrotron (RCS) and a 80-MeV linac. The lattice of the CSNS/RCS is triplet based four-fold structure. The preferred working points of CSNS/RCS are (4.86, 4.78) which can avoid the major low-order structure resonances. But because of the chromatic tune shift, space-charge incoherent tune shift and the tune shift caused by magnetic field tracking errors between the quadrupoles and the dipoles, some structure resonances are unavoidable. The chromaticity, space charge effects and magnetic field tracking errors can also induce beta function distortion, and influence the transverse acceptance and the collimation efficiency of the collimation system. In this paper we show results of space-charge simulations introducing magnetic field tracking errors and discuss the combined effects of chromaticity, magnetic field tracking errors and space charge on the beam dynamics for CSNS/RCS.

Slides THO1A02 [1.613 MB]

THO3C06

On-line Calibration Schemes for RF-based Beam Diagnostics

pick-up, target, proton, diagnostics

601

P.-A. Duperrex, U. Müller
PSI, Villigen PSI, Switzerland

RF-based beam diagnostics such as BPMs and beam current monitors rely on precise RF signal measurements. Temperature drifts and differences in the overall measurement chain gain make such measurements very challenging and calibration validity over time is an issue. Over some years, on-line calibration schemes for BPMs and current monitors have been developed. These innovative schemes are based on the use of a pilot signal at a frequency offset from the measurement frequency. Results, advantages and disadvantages of such schemes are discussed.

Slides THO3C06 [2.742 MB]

FRO1A01

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

simulation, space-charge, luminosity, ion

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]

FRO1A02

WG-B: Beam Dynamics In High Intensity Linacs

linac, rfq, emittance, DTL

612

D. Raparia
BNL, Upton, Long Island, New York, USA
Z. Li
IHEP, Beijing, People's Republic of China
P.A.P. Nghiem
CEA/DSM/IRFU, France

Emittance coupling, equipartioning and losses were a few topics, which were discussed thoroughly during parallel session for beam dynamics in high intensity linacs (Group B). Linac designs for the future, under construction, upgrade and the existing linacs from around the world were presented in three working sessions. A total of 18 talks were presented. Five presentations are general beam dynamics in nature and twelve talks were project specific. The detail of each contribution can be found in these proceedings. Here we report the summary of the discussions and some concluding remarks of the general interest to all the projects presented in the working group.

Slides FRO1A02 [14.464 MB]