IPAC2015 - List of Keywords (octupole)

Paper	Title	Other Keywords	Page
MOBC1	Towards Ultra-Low β^* in ATF2	optics, multipole, collider, linear-collider	38
	M. Patecki, A.V. Aloev, D.R. Bett, M. Modena, R. Tomás CERN, Geneva, Switzerland K. Kubo, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan E. Marín, G.R. White SLAC, Menlo Park, California, USA
	The Accelerator Test Facility 2 (ATF2) has already demonstrated the feasibility of Final Focus Systems based on the local chromaticity correction scheme and its focusing capabilities by reaching a vertical beam size at the virtual Interaction Point (IP) of less than 50 nm. The value of the chromaticity in ATF2 is comparable with the expected chromaticity in ILC, but 4 times lower than in a design of CLIC. ATF2 gives the unique possibility to test operation at CLIC chromaticity values by reducing the vertical beta function at the IP by a factor of 4 (the inverse proportionality of chromaticity with beta function value at IP is assumed). The experience collected in this way would be beneficial for both ILC and CLIC projects. Simulations show that the multipolar errors and Final Doublet fringe fields spoil the IP beam sizes at ATF2. Either increasing a value of the horizontal beta function or installing a pair of octupole magnets mitigate the impact of these aberrations. This paper summarizes the studies towards the realization of the ultra-low β^* optics in ATF2 and reports on the progress of the construction of the octupoles.
	Slides MOBC1 [1.566 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBC1
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MOPWA016	Increasing the Dynamic and Momentum Apertures of the ThomX Ring by Means of Octupole Correctors	sextupole, resonance, multipole, dipole	121
	J.F. Zhang, P. Bambade, A. Faus-Golfe, H. Monard LAL, Orsay, France A. Faus-Golfe IFIC, Valencia, Spain A. Loulergue SOLEIL, Gif-sur-Yvette, France
	Funding: Work is supported by ANR-10- EQPX-51 and ANR-11-IDEX-0003-02, and also by grants from Region Ile-de-France. The electron ring of the compact Compton-backscattering X-ray source ThomX which is being built at LAL featured with a small circumference of 18 meters and a low beam energy 50-70 MeV, and its long term single particle dynamics is dominated by the non linear effects in the transverse and longitudinal planes. In this paper, we study the feasibilities to reduce the sextupole resonances and then increase the dynamic aperture and momentum aperture of the ThomX ring, using octupoles correctors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA016
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MOPWA052	Formation of a Uniform Ion Beam Based on Nonlinear Focusing and its Applications at the JAEA TIARA Cyclotron	ion, cyclotron, scattering, target	236
	Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, K. Yoshida, T. Yuyama JAEA/TARRI, Gunma-ken, Japan
	A formation/irradiation technique of large-area uniform beams based on nonlinear focusing of multipole magnets has been developed toward advanced research and efficient industrial applications at the TIARA AVF cyclotron of Japan Atomic Energy Agency. The uniform beam is formed as follows: An ion beam extracted from the cyclotron is multiply-scattered with a thin foil so that the transverse beam intensity distribution can be smoothed into a Gaussian-like distribution, critical to the formation of a highly uniform distribution. Then, the tail of the Gaussian-like distribution is folded into the inside by the nonlinear force of octupole magnets and eventually a uniform intensity distribution can be formed on a target. Typically, the area and uniformity of the beam are over 100 cm² and below 10%, respectively. Such large-area uniform beams have already been applied to radiation degradation testing of space-use solar cells and a study on functional materials in TIARA. In the presentation, the latest R&D results and the utilization status of the uniform beam will be shown.
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MOPWA065	Uniformization of the Transverse Beam Profile by a New Type Nonlinear Magnet	target, multipole, dipole, simulation	272
	G. Gu, W.B. Liu IHEP, Beijing, People's Republic of China
	The uniform particle beam is desirable in many beam applications. One method to get this type of beam distribution is using octupoles, but loss of particles in the halo will be produced by this method. To reduce the beam loss, a new type of magnet is proposed in this paper. The field in the middle region of the new type magnet is similar to the octupole magnet field, but the rate of rise decline quickly in the edge. So that the particle in the edge experience a lower magnet field, and this would result in less particle loss. We also add a mechanical structure on the new type magnet to make it possible to adjust the size of middle region. So that the magnet can adapt to different transverse dimensions of the beam, and this would further reduce particle loss. Some numerical simulations have been done respectively with octuples and the new type of magnet. The simulation results show that the new type of magnet could get the uniform distribution of particle beam with less particle loss. We are processing a magnet now, and an experiment to test the magnet will be arranged on CPHS.
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MOPJE030	Non-linear Dynamics model for the ESS Linac Simulator	linac, sextupole, proton, space-charge	345
	E. Laface ESS, Lund, Sweden
	The ESS Proton Linac will run a beam with 62.5 mA of current. In the first meters of the accelerator, the non- linear space-charge force dominates the dynamics of the beam. The Drift Tube Linac, the Spoke resonators and the elliptical cavities, which are responsible for the 99.8% of the total energy gained by the beam along the accelerator, produce a significant longitudinal non-linear force on the proton beam. In this paper, we introduce a new theory to transport the probability density function of the beam under the effect of non-linear forces. A model based on this theory can be implemented in the ESS Linac Simulator for the fast simulations to be performed during the operations of the proton Linac.
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MOPJE074	Optimizing SLS-2 Nonlinearities Using a Multi-Objective Genetic Optimizer	sextupole, resonance, optics, injection	486
	M.P. Ehrlichman, M. Aiba, A. Streun PSI, Villigen PSI, Switzerland
	An upgrade to the SLS is currently under development. This upgrade will likely utilize the same hall and same machine circumference, 288 m, of the SLS. Achieving a sufficiently low emittance with such a small circumference requires tight focusing and low dispersion. These conditions make chromaticity correction difficult and minimization of 1st and 2nd order non-linear driving terms does not yield sufficient dynamic aperture and Touschek lifetime. In this proceeding, we discuss the multi-objective genetic optimization method being implemented at SLS to aid the design of a chromaticity correction scheme for SLS2.
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MOPMA028	Chromaticity and Dispersion in Nonlinear Integrable Optics	lattice, optics, dynamic-aperture, focusing	608
	S.D. Webb, D.L. Bruhwiler RadiaSoft LLC, Boulder, Colorado, USA V.V. Danilov ORNL, Oak Ridge, Tennessee, USA S. Nagaitsev, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: This material is based upon work sup- ported by the U.S. Department of Energy, Office of Sci- ence, Office of High Energy Physics under Award Num- ber DE-SC0011340. Proton accumulator rings and other circular hadron accelerators are susceptible to intensity- driven parametric instabilities because the zero-current charged particle dynamics are characterized by a single tune. Landau damping can suppress these instabilities, which requires energy spread in the beam or introducing nonlinear magnets such as octupoles. However, this approach reduces dynamic aperture. Nonlinear integrable optics can suppress parametric instabilities independent of energy spread in the distribution, while preserving the dynamic aperture. This novel approach promises to reduce particle losses and enable order-of-magnitude increases in beam intensity. In this paper we present results, obtained using the Lie operator formalism, on how chromaticity and dispersion affect particle orbits in integrable optics. We conclude that chromaticity in general breaks the integrability, unless the vertical and horizontal chromaticities are equal. Because of this, the chromaticity correcting magnets can be weaker and fewer correcting magnet families are required, thus minimizing the impact on dynamic aperture.
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MOPMA046	Simulations and experiments in Support of Octupole Lattice Studies at the University of Maryland Electron Ring	lattice, space-charge, electron, quadrupole	653
	K.J. Ruisard, B. Beaudoin, I. Haber, T.W. Koeth UMD, College Park, Maryland, USA
	Funding: This material is based on work supported by the NSF Graduate Research Fellowship and the NSF Accelerator Science Program We present plans for a nonlinear lattice at the University of Maryland Electron Ring (UMER). Theory predicts that a strong nonlinear lattice can limit resonant behavior without reducing dynamic aperture if the nonlinear fields preserve integrability or quasi-integrability. We discuss plans for a quasi-integrable octupole lattice, based on the work of Danilov and Nagaitsev.* We use Elegant and the WARP PIC code to estimate the octupole-induced tune spread. We discuss improvements to the ring in support of octupole lattice experiments, including generation and detection of emittance-dominated, negligible space charge beams. * V. Danilov, S. Nagaitsev, Phys. Rev. STAB 13, 084002 (2010).
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MOPHA004	Oide Limit Mitigation Studies	radiation, quadrupole, luminosity, focusing	781
	O.R. Blanco-García, P. Bambade LAL, Orsay, France R. Tomás CERN, Geneva, Switzerland
	Particle radiation when traversing a focusing quadrupole limits the minimum achievable beam size, known as the Oide limit. This effect may be compensated by a pair of multipoles which reduce the impact of the energy loss in the vertical beam size. Simulations in PLACET using the CLIC 3 TeV QD0 and L⃰ show a reduction of (4.3 ± 0.2)% in the vertical beam size.
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TUAB1	Correction of Nonlinear Coupling Resonances in the SPring-8 Storage Ring	coupling, resonance, injection, sextupole	1329
	M. Takao, K. Fukami, Y. Shimosaki, K. Soutome JASRI/SPring-8, Hyogo-ken, Japan
	The correction of the lattice nonlinearity of the storage rings is crucial for the enlargement of the dynamic aperture of the storage rings, which in general leads to the higher injection efficiency and the longer lifetime. At the SPring-8 storage ring, it is realized that the higher order coupling resonances are considerably excited. After the usual correction of the nonlinear dynamics in terms of the normal sextupole magnets, we suppress one of the resonances by using the skew sextupole magnets for the purpose of further improving the dynamic aperture. As a result of the correction by the skew sextupoles, the reckoned improvement of the injection efficiency and the lifetime is achieved. Furthermore, at the SPring-8 storage ring, it is observed that the error magnetic field of a particular insertion device (ID) excites the higher nonlinear coupling resonance of the skew octupoles, which remarkably deteriorates the injection efficiency. In order to correct the coupling resonance, we have installed the octupole magnets at the ID, by which we restore the injection efficiency.
	Slides TUAB1 [3.275 MB]
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TUPJE038	Impact of Insertion Devices on the MAX IV Storage Rings	storage-ring, lattice, optics, quadrupole	1696
	S.C. Leemann, H. Tarawneh MAX-lab, Lund, Sweden
	There will be multiple compensations employed for insertion devices in the MAX IV storage rings. Apart from well-known dipole corrections and previously detailed local and global linear optics matching, certain insertion devices in the MAX IV storage rings will also require nonlinear optics adjustments and/or skew quadrupole corrections. The goal of such corrections is ensuring sufficient dynamic aperture as well as low residual emittance coupling. This paper will present a few studies that rely on tracking through kick maps in order to quantify detrimental effects of insertion devices on dynamic aperture and vertical emittance, develop suitable countermeasures, and finally, verify restored storage ring performance.
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TUPTY042	Non-linear Coupling Studies in the LHC	coupling, hadron, collider, simulation	2105
	T. Persson, Y.I. Levinsen, E.H. Maclean, R. Tomás CERN, Geneva, Switzerland E.H. Maclean JAI, Oxford, United Kingdom
	The amplitude detuning has been observed to decrease significantly as the horizontal and vertical tunes are approaching each other. This effect is potentially harmful since it might cause a loss of Landau damping, hence giving rise to instabilities. The measured tune split (Qx-Qy) versus amplitude is several times bigger than what can be explained with linear coupling. In this paper we present studies performed to identify the dominant sources of the non-linear coupling observed in the LHC.
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TUPTY081	Design of a 6 TeV Muon Collider	sextupole, dynamic-aperture, quadrupole, collider	2226
	M.-H. Wang, Y. Cai, Y. Nosochkov SLAC, Menlo Park, California, USA M.A. Palmer Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the US Department of Energy contract DE-AC02-76SF00515 A design of a muon collider ring with the center of mass energy of 6 TeV is presented. The ring circumference is about 6.3 km, and the beta functions at collision point are 1 cm in both planes. The ring linear optics, the non-linear chromaticity correction scheme in the Interaction Region (IR), and the additional non-linear field orthogonal knobs are described in detail. The IR magnet specifications are based on the maximum pole tip field of 20 T in dipoles and 15 T in quadrupoles. The results of the beam dynamics optimization for maximum dynamic aperture are presented.
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WEPMA019	Status of the Super-FRS Magnet Devlopment for Fair	dipole, quadrupole, status, cryogenics	2792
	H. Müller, E.S. Fischer, H. Leibrock, P. Schnizer, M. Winkler GSI, Darmstadt, Germany J.-E. Munoz-Garcia, L. Quettier CEA/IRFU, Gif-sur-Yvette, France L. Serio CERN, Geneva, Switzerland
	The Super FRS is a two-stage in flight separator to be built next to the site of GSI, Darmstadt, Germany as part of FAIR (Facility for Anti-proton and Ion Research). Its purpose is to create and separate rare isotope beams and to enable the mass measurement also for very short lived nuclei. Due to its three branches a wide variety of experiments can be carried out in frame of the NUSTAR collaboration. Due to the large acceptance needed, the magnets of the Super-FRS have to have a large aperture and therefore only a superconducting solution is feasible. A superferric design with superconducting coils was chosen in which the magnetic field is shaped by an iron yoke. We will present the actual design status of the dipole- and multipole magnets as well as the status of the development of the dedicated test facility at CERN.
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WEPMN062	MAX IV 3 GeV Storage Ring Magnet Block Production Series Measurement Results	dipole, storage-ring, sextupole, synchrotron	3069
	M.A.G. Johansson, L.-J. Lindgren, M. Sjöström, P.F. Tavares MAX-lab, Lund, Sweden
	The magnet design of the MAX IV 3 GeV storage ring replaces the conventional support girder + discrete magnets scheme of previous third-generation synchrotron radiation light sources with a compact (Ø25 mm aperture) integrated design having several consecutive magnet elements precision-machined out of a common solid iron block, with mechanical tolerances of ±0.02 mm over the 2.3–3.4 m block length. The production series of 140 integrated magnet block units, which was totally outsourced to industry, was completed mid-2014, with mechanical/magnetic QA conforming to specifications. This article presents mechanical and magnetic field measurement results of the full production series.
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THPF137	Beam Dynamics Effects of High Order Multipoles in Non-Axisymmetric Superconducting RF Cavities	multipole, sextupole, linac, lattice	4045
	Z.Q. He, J. Wei, Y. Zhang FRIB, East Lansing, Michigan, USA
	Funding: The work is supported by the U.S. National Science Foundation under Grant No. PHY-11-02511, and the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. Non-axisymmetric superconducting RF cavities have been widely used in accelerator facilities. Because of the geometry, electric and magnetic multipole components, including steering terms, quadrupole terms, and higher order terms, would arise and have potential effects on beam dynamics. In this paper, we start with a simple linac periodic structure to study the effects of higher order terms. The action is defined as a figure of merit to quantify the effects. After that, we move to a more realistic situation of FRIB linac segment 1 (LS1). Multipole terms of quarter wave resonators (QWRs) are firstly calculated using multipole expansion scheme. Then, the scheme is tested using the FRIB linac lattice with QWRs, and the effects of higher order terms on FRIB LS1 are estimated.
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Paper

Title

Other Keywords

Page

MOBC1

Towards Ultra-Low β^* in ATF2

optics, multipole, collider, linear-collider

38

M. Patecki, A.V. Aloev, D.R. Bett, M. Modena, R. Tomás
CERN, Geneva, Switzerland
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
E. Marín, G.R. White
SLAC, Menlo Park, California, USA

The Accelerator Test Facility 2 (ATF2) has already demonstrated the feasibility of Final Focus Systems based on the local chromaticity correction scheme and its focusing capabilities by reaching a vertical beam size at the virtual Interaction Point (IP) of less than 50 nm. The value of the chromaticity in ATF2 is comparable with the expected chromaticity in ILC, but 4 times lower than in a design of CLIC. ATF2 gives the unique possibility to test operation at CLIC chromaticity values by reducing the vertical beta function at the IP by a factor of 4 (the inverse proportionality of chromaticity with beta function value at IP is assumed). The experience collected in this way would be beneficial for both ILC and CLIC projects. Simulations show that the multipolar errors and Final Doublet fringe fields spoil the IP beam sizes at ATF2. Either increasing a value of the horizontal beta function or installing a pair of octupole magnets mitigate the impact of these aberrations. This paper summarizes the studies towards the realization of the ultra-low β^* optics in ATF2 and reports on the progress of the construction of the octupoles.

Slides MOBC1 [1.566 MB]

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MOPWA016

Increasing the Dynamic and Momentum Apertures of the ThomX Ring by Means of Octupole Correctors

sextupole, resonance, multipole, dipole

121

J.F. Zhang, P. Bambade, A. Faus-Golfe, H. Monard
LAL, Orsay, France
A. Faus-Golfe
IFIC, Valencia, Spain
A. Loulergue
SOLEIL, Gif-sur-Yvette, France

Funding: Work is supported by ANR-10- EQPX-51 and ANR-11-IDEX-0003-02, and also by grants from Region Ile-de-France.
The electron ring of the compact Compton-backscattering X-ray source ThomX which is being built at LAL featured with a small circumference of 18 meters and a low beam energy 50-70 MeV, and its long term single particle dynamics is dominated by the non linear effects in the transverse and longitudinal planes. In this paper, we study the feasibilities to reduce the sextupole resonances and then increase the dynamic aperture and momentum aperture of the ThomX ring, using octupoles correctors.

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MOPWA052

Formation of a Uniform Ion Beam Based on Nonlinear Focusing and its Applications at the JAEA TIARA Cyclotron

ion, cyclotron, scattering, target

236

Y. Yuri, I. Ishibori, T. Ishizaka, S. Okumura, K. Yoshida, T. Yuyama
JAEA/TARRI, Gunma-ken, Japan

A formation/irradiation technique of large-area uniform beams based on nonlinear focusing of multipole magnets has been developed toward advanced research and efficient industrial applications at the TIARA AVF cyclotron of Japan Atomic Energy Agency. The uniform beam is formed as follows: An ion beam extracted from the cyclotron is multiply-scattered with a thin foil so that the transverse beam intensity distribution can be smoothed into a Gaussian-like distribution, critical to the formation of a highly uniform distribution. Then, the tail of the Gaussian-like distribution is folded into the inside by the nonlinear force of octupole magnets and eventually a uniform intensity distribution can be formed on a target. Typically, the area and uniformity of the beam are over 100 cm² and below 10%, respectively. Such large-area uniform beams have already been applied to radiation degradation testing of space-use solar cells and a study on functional materials in TIARA. In the presentation, the latest R&D results and the utilization status of the uniform beam will be shown.

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MOPWA065

Uniformization of the Transverse Beam Profile by a New Type Nonlinear Magnet

target, multipole, dipole, simulation

272

G. Gu, W.B. Liu
IHEP, Beijing, People's Republic of China

The uniform particle beam is desirable in many beam applications. One method to get this type of beam distribution is using octupoles, but loss of particles in the halo will be produced by this method. To reduce the beam loss, a new type of magnet is proposed in this paper. The field in the middle region of the new type magnet is similar to the octupole magnet field, but the rate of rise decline quickly in the edge. So that the particle in the edge experience a lower magnet field, and this would result in less particle loss. We also add a mechanical structure on the new type magnet to make it possible to adjust the size of middle region. So that the magnet can adapt to different transverse dimensions of the beam, and this would further reduce particle loss. Some numerical simulations have been done respectively with octuples and the new type of magnet. The simulation results show that the new type of magnet could get the uniform distribution of particle beam with less particle loss. We are processing a magnet now, and an experiment to test the magnet will be arranged on CPHS.

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MOPJE030

Non-linear Dynamics model for the ESS Linac Simulator

linac, sextupole, proton, space-charge

345

E. Laface
ESS, Lund, Sweden

The ESS Proton Linac will run a beam with 62.5 mA of current. In the first meters of the accelerator, the non- linear space-charge force dominates the dynamics of the beam. The Drift Tube Linac, the Spoke resonators and the elliptical cavities, which are responsible for the 99.8% of the total energy gained by the beam along the accelerator, produce a significant longitudinal non-linear force on the proton beam. In this paper, we introduce a new theory to transport the probability density function of the beam under the effect of non-linear forces. A model based on this theory can be implemented in the ESS Linac Simulator for the fast simulations to be performed during the operations of the proton Linac.

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MOPJE074

Optimizing SLS-2 Nonlinearities Using a Multi-Objective Genetic Optimizer

sextupole, resonance, optics, injection

486

M.P. Ehrlichman, M. Aiba, A. Streun
PSI, Villigen PSI, Switzerland

An upgrade to the SLS is currently under development. This upgrade will likely utilize the same hall and same machine circumference, 288 m, of the SLS. Achieving a sufficiently low emittance with such a small circumference requires tight focusing and low dispersion. These conditions make chromaticity correction difficult and minimization of 1st and 2nd order non-linear driving terms does not yield sufficient dynamic aperture and Touschek lifetime. In this proceeding, we discuss the multi-objective genetic optimization method being implemented at SLS to aid the design of a chromaticity correction scheme for SLS2.

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MOPMA028

Chromaticity and Dispersion in Nonlinear Integrable Optics

lattice, optics, dynamic-aperture, focusing

608

S.D. Webb, D.L. Bruhwiler
RadiaSoft LLC, Boulder, Colorado, USA
V.V. Danilov
ORNL, Oak Ridge, Tennessee, USA
S. Nagaitsev, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: This material is based upon work sup- ported by the U.S. Department of Energy, Office of Sci- ence, Office of High Energy Physics under Award Num- ber DE-SC0011340.
Proton accumulator rings and other circular hadron accelerators are susceptible to intensity- driven parametric instabilities because the zero-current charged particle dynamics are characterized by a single tune. Landau damping can suppress these instabilities, which requires energy spread in the beam or introducing nonlinear magnets such as octupoles. However, this approach reduces dynamic aperture. Nonlinear integrable optics can suppress parametric instabilities independent of energy spread in the distribution, while preserving the dynamic aperture. This novel approach promises to reduce particle losses and enable order-of-magnitude increases in beam intensity. In this paper we present results, obtained using the Lie operator formalism, on how chromaticity and dispersion affect particle orbits in integrable optics. We conclude that chromaticity in general breaks the integrability, unless the vertical and horizontal chromaticities are equal. Because of this, the chromaticity correcting magnets can be weaker and fewer correcting magnet families are required, thus minimizing the impact on dynamic aperture.

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MOPMA046

Simulations and experiments in Support of Octupole Lattice Studies at the University of Maryland Electron Ring

lattice, space-charge, electron, quadrupole

653

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

Funding: This material is based on work supported by the NSF Graduate Research Fellowship and the NSF Accelerator Science Program
We present plans for a nonlinear lattice at the University of Maryland Electron Ring (UMER). Theory predicts that a strong nonlinear lattice can limit resonant behavior without reducing dynamic aperture if the nonlinear fields preserve integrability or quasi-integrability. We discuss plans for a quasi-integrable octupole lattice, based on the work of Danilov and Nagaitsev.* We use Elegant and the WARP PIC code to estimate the octupole-induced tune spread. We discuss improvements to the ring in support of octupole lattice experiments, including generation and detection of emittance-dominated, negligible space charge beams.
* V. Danilov, S. Nagaitsev, Phys. Rev. STAB 13, 084002 (2010).

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MOPHA004

Oide Limit Mitigation Studies

radiation, quadrupole, luminosity, focusing

781

O.R. Blanco-García, P. Bambade
LAL, Orsay, France
R. Tomás
CERN, Geneva, Switzerland

Particle radiation when traversing a focusing quadrupole limits the minimum achievable beam size, known as the Oide limit. This effect may be compensated by a pair of multipoles which reduce the impact of the energy loss in the vertical beam size. Simulations in PLACET using the CLIC 3 TeV QD0 and L⃰ show a reduction of (4.3 ± 0.2)% in the vertical beam size.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA004

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TUAB1

Correction of Nonlinear Coupling Resonances in the SPring-8 Storage Ring

coupling, resonance, injection, sextupole

1329

M. Takao, K. Fukami, Y. Shimosaki, K. Soutome
JASRI/SPring-8, Hyogo-ken, Japan

The correction of the lattice nonlinearity of the storage rings is crucial for the enlargement of the dynamic aperture of the storage rings, which in general leads to the higher injection efficiency and the longer lifetime. At the SPring-8 storage ring, it is realized that the higher order coupling resonances are considerably excited. After the usual correction of the nonlinear dynamics in terms of the normal sextupole magnets, we suppress one of the resonances by using the skew sextupole magnets for the purpose of further improving the dynamic aperture. As a result of the correction by the skew sextupoles, the reckoned improvement of the injection efficiency and the lifetime is achieved. Furthermore, at the SPring-8 storage ring, it is observed that the error magnetic field of a particular insertion device (ID) excites the higher nonlinear coupling resonance of the skew octupoles, which remarkably deteriorates the injection efficiency. In order to correct the coupling resonance, we have installed the octupole magnets at the ID, by which we restore the injection efficiency.

Slides TUAB1 [3.275 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAB1

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TUPJE038

Impact of Insertion Devices on the MAX IV Storage Rings

storage-ring, lattice, optics, quadrupole

1696

S.C. Leemann, H. Tarawneh
MAX-lab, Lund, Sweden

There will be multiple compensations employed for insertion devices in the MAX IV storage rings. Apart from well-known dipole corrections and previously detailed local and global linear optics matching, certain insertion devices in the MAX IV storage rings will also require nonlinear optics adjustments and/or skew quadrupole corrections. The goal of such corrections is ensuring sufficient dynamic aperture as well as low residual emittance coupling. This paper will present a few studies that rely on tracking through kick maps in order to quantify detrimental effects of insertion devices on dynamic aperture and vertical emittance, develop suitable countermeasures, and finally, verify restored storage ring performance.

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TUPTY042

Non-linear Coupling Studies in the LHC

coupling, hadron, collider, simulation

2105

T. Persson, Y.I. Levinsen, E.H. Maclean, R. Tomás
CERN, Geneva, Switzerland
E.H. Maclean
JAI, Oxford, United Kingdom

The amplitude detuning has been observed to decrease significantly as the horizontal and vertical tunes are approaching each other. This effect is potentially harmful since it might cause a loss of Landau damping, hence giving rise to instabilities. The measured tune split (Qx-Qy) versus amplitude is several times bigger than what can be explained with linear coupling. In this paper we present studies performed to identify the dominant sources of the non-linear coupling observed in the LHC.

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TUPTY081

Design of a 6 TeV Muon Collider

sextupole, dynamic-aperture, quadrupole, collider

2226

M.-H. Wang, Y. Cai, Y. Nosochkov
SLAC, Menlo Park, California, USA
M.A. Palmer
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the US Department of Energy contract DE-AC02-76SF00515
A design of a muon collider ring with the center of mass energy of 6 TeV is presented. The ring circumference is about 6.3 km, and the beta functions at collision point are 1 cm in both planes. The ring linear optics, the non-linear chromaticity correction scheme in the Interaction Region (IR), and the additional non-linear field orthogonal knobs are described in detail. The IR magnet specifications are based on the maximum pole tip field of 20 T in dipoles and 15 T in quadrupoles. The results of the beam dynamics optimization for maximum dynamic aperture are presented.

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WEPMA019

Status of the Super-FRS Magnet Devlopment for Fair

dipole, quadrupole, status, cryogenics

2792

H. Müller, E.S. Fischer, H. Leibrock, P. Schnizer, M. Winkler
GSI, Darmstadt, Germany
J.-E. Munoz-Garcia, L. Quettier
CEA/IRFU, Gif-sur-Yvette, France
L. Serio
CERN, Geneva, Switzerland

The Super FRS is a two-stage in flight separator to be built next to the site of GSI, Darmstadt, Germany as part of FAIR (Facility for Anti-proton and Ion Research). Its purpose is to create and separate rare isotope beams and to enable the mass measurement also for very short lived nuclei. Due to its three branches a wide variety of experiments can be carried out in frame of the NUSTAR collaboration. Due to the large acceptance needed, the magnets of the Super-FRS have to have a large aperture and therefore only a superconducting solution is feasible. A superferric design with superconducting coils was chosen in which the magnetic field is shaped by an iron yoke. We will present the actual design status of the dipole- and multipole magnets as well as the status of the development of the dedicated test facility at CERN.

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WEPMN062

MAX IV 3 GeV Storage Ring Magnet Block Production Series Measurement Results

dipole, storage-ring, sextupole, synchrotron

3069

M.A.G. Johansson, L.-J. Lindgren, M. Sjöström, P.F. Tavares
MAX-lab, Lund, Sweden

The magnet design of the MAX IV 3 GeV storage ring replaces the conventional support girder + discrete magnets scheme of previous third-generation synchrotron radiation light sources with a compact (Ø25 mm aperture) integrated design having several consecutive magnet elements precision-machined out of a common solid iron block, with mechanical tolerances of ±0.02 mm over the 2.3–3.4 m block length. The production series of 140 integrated magnet block units, which was totally outsourced to industry, was completed mid-2014, with mechanical/magnetic QA conforming to specifications. This article presents mechanical and magnetic field measurement results of the full production series.

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THPF137

Beam Dynamics Effects of High Order Multipoles in Non-Axisymmetric Superconducting RF Cavities

multipole, sextupole, linac, lattice

4045

Z.Q. He, J. Wei, Y. Zhang
FRIB, East Lansing, Michigan, USA

Funding: The work is supported by the U.S. National Science Foundation under Grant No. PHY-11-02511, and the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
Non-axisymmetric superconducting RF cavities have been widely used in accelerator facilities. Because of the geometry, electric and magnetic multipole components, including steering terms, quadrupole terms, and higher order terms, would arise and have potential effects on beam dynamics. In this paper, we start with a simple linac periodic structure to study the effects of higher order terms. The action is defined as a figure of merit to quantify the effects. After that, we move to a more realistic situation of FRIB linac segment 1 (LS1). Multipole terms of quarter wave resonators (QWRs) are firstly calculated using multipole expansion scheme. Then, the scheme is tested using the FRIB linac lattice with QWRs, and the effects of higher order terms on FRIB LS1 are estimated.

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