IPAC2022 - List of Keywords (damping)

Paper	Title	Other Keywords	Page
MOIYSP2	Touschek and Intrabeam Scattering in Ultralow Emittance Storage Rings	emittance, scattering, wiggler, lattice	25
	R. Bartolini DESY, Hamburg, Germany
	In next-generation synchrotron radiation sources targeting extremely low emittance around the so-called diffraction limit, the Touschek and intrabeam scattering (IBS) effects are important factors determining the performance of the facility. As the emittance decreases, the bunch volume decreases and the Touschek beam lifetime also decreases. However, this downward trend in beam lifetime is expected to turn to increase in the emittance region below a certain threshold. Since this threshold is determined by the emittance at equilibrium including the IBS effect, a self-consistent treatment is necessary for a correct and unified understanding of the beam characteristics. In currently operating facilities, such as MAX-IV, or in next-generation light sources under construction or in the planning stages, it is expected that such effects may be observed depending on the operating conditions. This talk will be reviewing Touschek and IBS Effects in terms of how these effects limit the ring performance.
	Slides MOIYSP2 [5.466 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOIYSP2
About •	Received ※ 12 June 2022 — Revised ※ 21 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 27 June 2022
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MOPOST051	Study of Transverse Resonance Island Buckets at CESR	lattice, resonance, sextupole, simulation	199
	S. Wang, V. Khachatryan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: Work supported by NSF PHYS-1416318 and DMR-1829070. A 6-GeV lattice with the horizontal tune near a 3rd-order resonance line at 3ν_x=2 is designed for studying the transverse resonance island buckets (TRIBs) at the Cornell Electron Storage Ring (CESR). The distribution of 76 sextupoles powered individually is optimized to maximize the dynamic aperture and achieve the desired amplitude-dependent tune shift α_xx and the resonant driving term h₃₀₀₀₀, which are necessary conditions to form stable island buckets. The particle tracking simulations are developed to check and confirm the formation of TRIBs at different tunes with clearing kicks in this TRIBs lattice. Finally, the lattice is loaded in CESR and the TRIBs are successfully observed when the horizontal fractional tune is adjusted to 0.665, close to the 3rd-order resonance line. Bunch-by-bunch feedback is also explored to clear the particles in the main bucket and the island buckets, respectively.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST051
About •	Received ※ 20 May 2022 — Revised ※ 09 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022
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MOPOPT003	Studying Instabilities in the Canadian Light Source Storage Ring Using the Transverse Feedback System	storage-ring, feedback, insertion, insertion-device	230
	S.J. Martens University of Saskatchewan, Saskatoon, Canada D. Bertwistle, M.J. Boland CLS, Saskatoon, Saskatchewan, Canada P. Hartmann DELTA, Dortmund, Germany
	The Transverse Feedback system at the Canadian Light Source can identify, categorize, and mitigate against periodic instabilities that arise in the storage ring beam. By quickly opening and closing the feedback loop, previously mitigated instabilities will be allowed to grow briefly before being damped by the system. The resulting growth in the beam oscillation amplitude curve can be analyzed to determine growth/damp rates and modes of the coupled bunch oscillations. Further measurements can be collected via active excitement of modes rather than passive growth. These Grow/damp and Excite/Damp curves have been collected and analyzed for various storage ring beam properties, including beam energy, machine chromaticity, and in-vacuum insertion device gap widths.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT003
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 09 July 2022
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MOPOTK047	Cooling Performance in a Dual Energy Storage Ring Cooler	electron, proton, storage-ring, cavity	568
	B. Dhital, G.A. Krafft ODU, Norfolk, Virginia, USA Y.S. Derbenev, D. Douglas, G.A. Krafft, H. Zhang, Y. Zhang JLab, Newport News, Virginia, USA F. Lin, V.S. Morozov ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: EIC fellowship at Jefferson Lab The longitudinal and transverse emittance growth in hadron beams due to intra-beam scattering (IBS) and other heating sources deteriorate the luminosity in a collider. Hence, a strong hadron beam cooling is required to reduce and preserve the emittance. The cooling of high energy hadron beam is challenging. We propose a dual energy storage ring-based electron cooler that uses an electron beam to extract heat away from hadron beam in the cooler ring while the electron beam is cooled by synchrotron radiation damping in the high energy damping ring. In this paper, we present a design of a dual energy storage ring-based electron cooler. Finally, the cooling performance is simulated using Jefferson Lab Simulation Package for Electron Cooling (JSPEC) for proton beams at the top energy of 275 GeV for Electron-Ion Collider.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK047
About •	Received ※ 06 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 26 June 2022
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TUOZSP1	Prospects for Optics Measuements in FCC-ee	optics, dipole, collider, radiation	827
	J. Keintzel, R. Tomás García, F. Zimmermann CERN, Meyrin, Switzerland
	Within the framework of the Future Circular Collider Feasibility Study, the design of the electron-positron collider FCC-ee is optimised, as a possible future double collider ring, currently foreseen to start operation during the 2040s. With close to 100 km of circumference and strong synchrotron radiation damping at highest beam energy, adequate beam measurements are needed to control the optics at the desired level. Various possible techniques to measure the optics in FCC-ee are explored, including the option of turn-by-turn measurements in combination with an AC-dipole.
	Slides TUOZSP1 [2.738 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOZSP1
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 28 June 2022
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TUPOTK015	HOM Coupler Design and Optimization for the FCC-ee W Working Point	cavity, HOM, impedance, multipactoring	1230
	S. Udongwo, S.G. Zadeh, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany R. Calaga CERN, Meyrin, Switzerland
	Funding: Funded by CERN under ADDENDUM FCC-GOV-CC-00213 (KE4978/ ATS) to FCC-GOV-CC- 0213/2431149/KE4978 VERSION 1.0. The Future Circular electron-positron Collider (FCC-ee) is planned to operate with beam energies from 45.6 to 182.5 GeV and beam currents from 5.4 to 1390 mA. The purpose is to study the properties of the Z-, W- and Higgs boson and the top and anti-top quarks in four operation points. The beam current of 147 mA of the W working point requires particular care to string damp HOMs. This paper proposes 2-cell 400 MHz SRF cavities with improved damping as an alternative to the baseline 4-cell cavities for this working point. The resulting impedance of the HOM-damped cavity is then calculated and compared with the impedance budget.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK015
About •	Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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TUPOMS014	PETRA IV Storage Ring Design	lattice, emittance, insertion, insertion-device	1431
	I.V. Agapov, S.A. Antipov, R. Bartolini, R. Brinkmann, Y.-C. Chae, D. Einfeld, T. Hellert, M. Hüning, M.A. Jebramcik, J. Keil, C. Li, R. Wanzenberg DESY, Hamburg, Germany
	PETRA IV will be a diffraction-limited 6 GeV synchrotron light source with an emittance of 20 pm rad at DESY Hamburg. The TDR phase is nearing completion, and the lattice design is being finalised. The lattice will be based on the six-bend achromat cell with extensive use of damping wigglers. The key challenges of the lattice design are finding the balance between emittance minimisation and non-linear beam dynamics performance, and adapting the lattice to a collider-type tunnel geometry of the PETRA facility, with the long straight sections and low degree of superperiodicity. We present the lattice design and the beam physics aspects, focusing on the beam dynamics performance and optimisation, and the projected beam parameters taking collective effects and lattice imperfections into account.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS014
About •	Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022
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TUPOMS057	Design Study of HOM Couplers for the C-Band Accelerating Structure	factory, GUI, dipole, cavity	1561
	D. Kim, E.I. Simakov LANL, Los Alamos, New Mexico, USA S. Biedron UNM-ECE, Albuquerque, USA Z. Li SLAC, Menlo Park, California, USA
	Funding: High Energy Physics (HEP) at the U.S. Department of Energy (DOE) A cold copper distributed coupling accelerator, with a high accelerating gradient at cryogenic temperatures (~77 K), is proposed as a baseline structure for the next generation of linear colliders. This novel technology improves accelerator performance and allows more degrees of freedom for optimization of individual cavities. It has been suggested that C-band accelerating structures at 5.712 GHz may allow to maintain high efficiency, achieve high accelerating gradient, and be suitable beam dynamics with wakefield damping and detuning of the cavities. The optimization of the cavity shape was performed and we computed quality factor, shunt impedance, and beam kick factor for each of the proposed cavity geometries using CST microwave studio. Next, we proposed a configuration for higher order mode (HOM) suppression that includes waveguide slots running parallel to the axis of the accelerator. This presentation will report details of the parametric study of performance of the HOM suppression waveguide, and the dependence of HOM Q-factors and kick-factors on the cavity’s and HOM waveguide’s geometries.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS057
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022
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WEPOTK059	Suppression of Emittance Growth by a Collective Force: Van Kampen Approach	emittance, feedback, cavity, impedance	2197
	X. Buffat CERN, Meyrin, Switzerland
	In hadron synchrotrons, external sources of noise affecting the beam induce emittance growth through the mechanism of decoherence. Active feedbacks are often used to suppress this emittance growth. In the presence of beam-beam interactions, it was shown that coherent modes of oscillations with frequencies shifted outside of the incoherent spectrum significantly enhances the efficiency of the emittance growth suppression by active feedbacks. We show that the same enhancement of the emittance growth suppression may be driven by a beam coupling impedance generating a real tune shift larger than the detuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK059
About •	Received ※ 03 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 15 June 2022
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WEPOMS001	Effect of Betatron Coupling on Transverse Mode-Coupling and Head-Tail Instabilities	coupling, impedance, synchrotron, betatron	2225
	W. Foosang, A. Gamelin, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	In the context of SOLEIL Upgrade, the 4th generation storage ring project of SOLEIL, several methods are pursued to extend the beam lifetime and limit the emittance growth by reducing the Touschek effect and intra-beam scattering. Betatron coupling is one of the potential techniques to achieve this objective as it can increase the beam volume by transforming a flat beam into a round beam. However, the effect of the coupling on the collective effects is not fully comprehended, but some studies have shown an improvement in transverse instability thresholds. It was, therefore, crucial to investigate the impact of coupling on beam instability for SOLEIL Upgrade. This work presents numerical studies on the impact of coupling on the transverse mode-coupling and the head-tail instabilities. The results showed that coupling could be not only beneficial, but also detrimental.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS001
About •	Received ※ 08 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 04 July 2022
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WEPOMS008	Impact of Broadband Impedance on Longitudinal Coupled-Bunch Instability Threshold	impedance, HOM, synchrotron, cavity	2245
	I. Karpov, E.N. Shaposhnikova CERN, Meyrin, Switzerland
	Coupled-bunch instabilities (CBI) and the loss of Landau damping (LLD) in the longitudinal plane can affect the performance of high-current synchrotrons. The former is driven by the narrowband impedance of resonant structures, while the latter is mainly determined by the broadband impedance of the entire accelerator and is a single-bunch effect. Therefore, the CBI and LLD thresholds are usually evaluated separately in order to define the corresponding critical impedance budget for given beam parameters. In this paper, we show that the CBI threshold in the presence of broadband impedance can be significantly lower than the one defined by only the narrowband impedance, especially if the LLD threshold is below the CBI threshold. In some cases, the beam becomes unstable even below the LLD threshold. This explains the low CBI threshold observed for the LHC-type beams in the CERN SPS. For HL-LHC, the broadband impedance may also significantly reduce the CBI threshold driven by higher-order modes of the crab cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS008
About •	Received ※ 08 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 06 July 2022
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THPOST003	Collective Effects Estimates for the Damping Ring Design of the FCC-ee	electron, emittance, impedance, positron	2435
	O. Etisken Ankara University, Faculty of Sciences, Ankara, Turkey F. Antoniou, F. Zimmermann CERN, Meyrin, Switzerland A. De Santis INFN/LNF, Frascati, Italy C. Milardi LNF-INFN, Frascati, Italy
	The current injector complex design of the FCC-e⁺e⁻ project consists of e⁺/e⁻ linacs, which accelerate the beams up to 6 GeV, a damping ring at 1.54 GeV, a pre-booster ring, accelerating the beam up to 16 GeV and a booster synchrotron ring integrated in the collider tunnel accelerating the beams up to the collision energies. The purpose of the damping ring is to accept the 1.54 GeV beam coming from the linac-1, damp the positron/electron beams and provide the required beam characteristics for the injection into the linac-2. In this presentation the current damping ring design is introduced and analytical calculations on various collective effect such as space charge, intra-beam scattering, longitudinal micro-wave instability, transverse mode coupling instability, ion effects, electron cloud and coherent synchrotron radiation, are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST003
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 08 July 2022
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THPOPT006	Beam Dynamics Observations at Negative Momentum Compaction Factors at KARA	sextupole, synchrotron, optics, operation	2570
	P. Schreiber, M. Brosi, B. Härer, A. Mochihashi, A.-S. Müller, A.I. Papash, R. Ruprecht, M. Schuh KIT, Karlsruhe, Germany
	Funding: We are supported by the DFG-funded "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" and European Union’s Horizon 2020 research and innovation programme (No 730871) For the development of future synchrotron light sources new operation modes often have to be considered. One such mode is the operation with a negative momentum compaction factor to provide the possibility of increased dynamic aperture. For successful application in future light sources, the influence of this mode has to be investigated. At the KIT storage ring KARA (Karlsruhe Research Accelerator), operation with negative momentum compaction has been implemented and the dynamics can now be investigated. Using a variety of high-performance beam diagnostics devices it is possible to observe the beam dynamics under negative momentum compaction conditions. This contribution presents different aspects of the results of these investigations in the longitudinal and transversal plane.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT006
About •	Received ※ 08 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 08 July 2022
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THPOPT013	Emittance Reduction with the Variable Dipole for the ELETTRA 2.0 Ring	dipole, emittance, lattice, optics	2586
	A. Poyet, Y. Papaphilippou CERN, Meyrin, Switzerland M.A. Domínguez, F. Toral CIEMAT, Madrid, Spain R. Geometrante, E. Karantzoulis Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy R. Geometrante KYMA, Trieste, Italy
	ELETTRA is a 2/2.4 GeV third-generation electron storage ring, located near Trieste, Italy. In view of a substantial increase of the machine performance in terms of brilliance, the so-called ELETTRA 2.0 upgrade is currently on-going. This upgrade is based on a 6-bends achromat, four dipoles of which having a longitudinally variable field. So far, those dipoles are foreseen to provide a field with a two step profile. The VAriable Dipole for the ELETTRA Ring (VADER) task, driven by the I.FAST European project, aims at developing a new dipole design based on a trapezoidal shape of the bending radius, which would allow for a further reduction of the horizontal emittance. A prototype of this magnet should be designed by the CIEMAT laboratory and built by KYMA company. This paper discusses the new dipole field specification and describes the corresponding optics optimization that was performed in order to reduce at best the emittance of the ELETTRA ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT013
About •	Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022
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THPOTK057	ESS RFQ Experimental Modal Analysis	rfq, experiment, software, cavity	2907
	E. Trachanas, A. Bignami, N. Gazis, B. Jones ESS, Lund, Sweden
	The European Spallation Source-ESS, which is currently under construction and commissioning at Lund, Sweden is a neutron source that consists of a 2 GeV linear accelerator (LINAC) accelerating a proton beam to a solid Tungsten (W) target. The proton beam is produced by the Ion Source (ISRC) and transported through the Low Energy Beam Transport (LEBT) to the Radio Frequency Quadrupole (RFQ) that will then focus, bunch and accelerate it to 3.6 MeV. The RFQ beam commissioning started in October 2021, following the RF conditioning phase in summer 2021. This current work presents an experimental modal analysis performed on RFQ including the comparative analysis with the modal finite element simulation using the ANSYS software suite. Measurements were performed using accelerometer sensors connected to a data acquisition system excited with an impact hammer. Geophones were used in parallel to the modal measurements in order to monitor the seismic background of the accelerator tunnel. Acquired data were post-processed and analysed with dedicated software, juxtaposed with simulated results in order to determine the resonance frequencies, structural deformation patterns (mode shapes) and error margin between experimental and simulated results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK057
About •	Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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Paper

Title

Other Keywords

Page

MOIYSP2

Touschek and Intrabeam Scattering in Ultralow Emittance Storage Rings

emittance, scattering, wiggler, lattice

25

R. Bartolini
DESY, Hamburg, Germany

In next-generation synchrotron radiation sources targeting extremely low emittance around the so-called diffraction limit, the Touschek and intrabeam scattering (IBS) effects are important factors determining the performance of the facility. As the emittance decreases, the bunch volume decreases and the Touschek beam lifetime also decreases. However, this downward trend in beam lifetime is expected to turn to increase in the emittance region below a certain threshold. Since this threshold is determined by the emittance at equilibrium including the IBS effect, a self-consistent treatment is necessary for a correct and unified understanding of the beam characteristics. In currently operating facilities, such as MAX-IV, or in next-generation light sources under construction or in the planning stages, it is expected that such effects may be observed depending on the operating conditions. This talk will be reviewing Touschek and IBS Effects in terms of how these effects limit the ring performance.

Slides MOIYSP2 [5.466 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOIYSP2

About •

Received ※ 12 June 2022 — Revised ※ 21 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 27 June 2022

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MOPOST051

Study of Transverse Resonance Island Buckets at CESR

lattice, resonance, sextupole, simulation

199

S. Wang, V. Khachatryan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by NSF PHYS-1416318 and DMR-1829070.
A 6-GeV lattice with the horizontal tune near a 3rd-order resonance line at 3ν_x=2 is designed for studying the transverse resonance island buckets (TRIBs) at the Cornell Electron Storage Ring (CESR). The distribution of 76 sextupoles powered individually is optimized to maximize the dynamic aperture and achieve the desired amplitude-dependent tune shift α_xx and the resonant driving term h₃₀₀₀₀, which are necessary conditions to form stable island buckets. The particle tracking simulations are developed to check and confirm the formation of TRIBs at different tunes with clearing kicks in this TRIBs lattice. Finally, the lattice is loaded in CESR and the TRIBs are successfully observed when the horizontal fractional tune is adjusted to 0.665, close to the 3rd-order resonance line. Bunch-by-bunch feedback is also explored to clear the particles in the main bucket and the island buckets, respectively.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST051

About •

Received ※ 20 May 2022 — Revised ※ 09 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022

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MOPOPT003

Studying Instabilities in the Canadian Light Source Storage Ring Using the Transverse Feedback System

storage-ring, feedback, insertion, insertion-device

230

S.J. Martens
University of Saskatchewan, Saskatoon, Canada
D. Bertwistle, M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada
P. Hartmann
DELTA, Dortmund, Germany

The Transverse Feedback system at the Canadian Light Source can identify, categorize, and mitigate against periodic instabilities that arise in the storage ring beam. By quickly opening and closing the feedback loop, previously mitigated instabilities will be allowed to grow briefly before being damped by the system. The resulting growth in the beam oscillation amplitude curve can be analyzed to determine growth/damp rates and modes of the coupled bunch oscillations. Further measurements can be collected via active excitement of modes rather than passive growth. These Grow/damp and Excite/Damp curves have been collected and analyzed for various storage ring beam properties, including beam energy, machine chromaticity, and in-vacuum insertion device gap widths.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT003

About •

Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 09 July 2022

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

MOPOTK047

Cooling Performance in a Dual Energy Storage Ring Cooler

electron, proton, storage-ring, cavity

568

B. Dhital, G.A. Krafft
ODU, Norfolk, Virginia, USA
Y.S. Derbenev, D. Douglas, G.A. Krafft, H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA
F. Lin, V.S. Morozov
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: EIC fellowship at Jefferson Lab
The longitudinal and transverse emittance growth in hadron beams due to intra-beam scattering (IBS) and other heating sources deteriorate the luminosity in a collider. Hence, a strong hadron beam cooling is required to reduce and preserve the emittance. The cooling of high energy hadron beam is challenging. We propose a dual energy storage ring-based electron cooler that uses an electron beam to extract heat away from hadron beam in the cooler ring while the electron beam is cooled by synchrotron radiation damping in the high energy damping ring. In this paper, we present a design of a dual energy storage ring-based electron cooler. Finally, the cooling performance is simulated using Jefferson Lab Simulation Package for Electron Cooling (JSPEC) for proton beams at the top energy of 275 GeV for Electron-Ion Collider.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK047

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Received ※ 06 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 26 June 2022

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TUOZSP1

Prospects for Optics Measuements in FCC-ee

optics, dipole, collider, radiation

827

J. Keintzel, R. Tomás García, F. Zimmermann
CERN, Meyrin, Switzerland

Within the framework of the Future Circular Collider Feasibility Study, the design of the electron-positron collider FCC-ee is optimised, as a possible future double collider ring, currently foreseen to start operation during the 2040s. With close to 100 km of circumference and strong synchrotron radiation damping at highest beam energy, adequate beam measurements are needed to control the optics at the desired level. Various possible techniques to measure the optics in FCC-ee are explored, including the option of turn-by-turn measurements in combination with an AC-dipole.

Slides TUOZSP1 [2.738 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOZSP1

About •

Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 28 June 2022

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TUPOTK015

HOM Coupler Design and Optimization for the FCC-ee W Working Point

cavity, HOM, impedance, multipactoring

1230

S. Udongwo, S.G. Zadeh, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
R. Calaga
CERN, Meyrin, Switzerland

Funding: Funded by CERN under ADDENDUM FCC-GOV-CC-00213 (KE4978/ ATS) to FCC-GOV-CC- 0213/2431149/KE4978 VERSION 1.0.
The Future Circular electron-positron Collider (FCC-ee) is planned to operate with beam energies from 45.6 to 182.5 GeV and beam currents from 5.4 to 1390 mA. The purpose is to study the properties of the Z-, W- and Higgs boson and the top and anti-top quarks in four operation points. The beam current of 147 mA of the W working point requires particular care to string damp HOMs. This paper proposes 2-cell 400 MHz SRF cavities with improved damping as an alternative to the baseline 4-cell cavities for this working point. The resulting impedance of the HOM-damped cavity is then calculated and compared with the impedance budget.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK015

About •

Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022

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TUPOMS014

PETRA IV Storage Ring Design

lattice, emittance, insertion, insertion-device

1431

I.V. Agapov, S.A. Antipov, R. Bartolini, R. Brinkmann, Y.-C. Chae, D. Einfeld, T. Hellert, M. Hüning, M.A. Jebramcik, J. Keil, C. Li, R. Wanzenberg
DESY, Hamburg, Germany

PETRA IV will be a diffraction-limited 6 GeV synchrotron light source with an emittance of 20 pm rad at DESY Hamburg. The TDR phase is nearing completion, and the lattice design is being finalised. The lattice will be based on the six-bend achromat cell with extensive use of damping wigglers. The key challenges of the lattice design are finding the balance between emittance minimisation and non-linear beam dynamics performance, and adapting the lattice to a collider-type tunnel geometry of the PETRA facility, with the long straight sections and low degree of superperiodicity. We present the lattice design and the beam physics aspects, focusing on the beam dynamics performance and optimisation, and the projected beam parameters taking collective effects and lattice imperfections into account.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS014

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Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 26 June 2022

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TUPOMS057

Design Study of HOM Couplers for the C-Band Accelerating Structure

factory, GUI, dipole, cavity

1561

D. Kim, E.I. Simakov
LANL, Los Alamos, New Mexico, USA
S. Biedron
UNM-ECE, Albuquerque, USA
Z. Li
SLAC, Menlo Park, California, USA

Funding: High Energy Physics (HEP) at the U.S. Department of Energy (DOE)
A cold copper distributed coupling accelerator, with a high accelerating gradient at cryogenic temperatures (~77 K), is proposed as a baseline structure for the next generation of linear colliders. This novel technology improves accelerator performance and allows more degrees of freedom for optimization of individual cavities. It has been suggested that C-band accelerating structures at 5.712 GHz may allow to maintain high efficiency, achieve high accelerating gradient, and be suitable beam dynamics with wakefield damping and detuning of the cavities. The optimization of the cavity shape was performed and we computed quality factor, shunt impedance, and beam kick factor for each of the proposed cavity geometries using CST microwave studio. Next, we proposed a configuration for higher order mode (HOM) suppression that includes waveguide slots running parallel to the axis of the accelerator. This presentation will report details of the parametric study of performance of the HOM suppression waveguide, and the dependence of HOM Q-factors and kick-factors on the cavity’s and HOM waveguide’s geometries.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS057

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022

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WEPOTK059

Suppression of Emittance Growth by a Collective Force: Van Kampen Approach

emittance, feedback, cavity, impedance

2197

X. Buffat
CERN, Meyrin, Switzerland

In hadron synchrotrons, external sources of noise affecting the beam induce emittance growth through the mechanism of decoherence. Active feedbacks are often used to suppress this emittance growth. In the presence of beam-beam interactions, it was shown that coherent modes of oscillations with frequencies shifted outside of the incoherent spectrum significantly enhances the efficiency of the emittance growth suppression by active feedbacks. We show that the same enhancement of the emittance growth suppression may be driven by a beam coupling impedance generating a real tune shift larger than the detuning.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK059

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Received ※ 03 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 15 June 2022

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WEPOMS001

Effect of Betatron Coupling on Transverse Mode-Coupling and Head-Tail Instabilities

coupling, impedance, synchrotron, betatron

2225

W. Foosang, A. Gamelin, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

In the context of SOLEIL Upgrade, the 4th generation storage ring project of SOLEIL, several methods are pursued to extend the beam lifetime and limit the emittance growth by reducing the Touschek effect and intra-beam scattering. Betatron coupling is one of the potential techniques to achieve this objective as it can increase the beam volume by transforming a flat beam into a round beam. However, the effect of the coupling on the collective effects is not fully comprehended, but some studies have shown an improvement in transverse instability thresholds. It was, therefore, crucial to investigate the impact of coupling on beam instability for SOLEIL Upgrade. This work presents numerical studies on the impact of coupling on the transverse mode-coupling and the head-tail instabilities. The results showed that coupling could be not only beneficial, but also detrimental.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS001

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Received ※ 08 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 04 July 2022

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WEPOMS008

Impact of Broadband Impedance on Longitudinal Coupled-Bunch Instability Threshold

impedance, HOM, synchrotron, cavity

2245

I. Karpov, E.N. Shaposhnikova
CERN, Meyrin, Switzerland

Coupled-bunch instabilities (CBI) and the loss of Landau damping (LLD) in the longitudinal plane can affect the performance of high-current synchrotrons. The former is driven by the narrowband impedance of resonant structures, while the latter is mainly determined by the broadband impedance of the entire accelerator and is a single-bunch effect. Therefore, the CBI and LLD thresholds are usually evaluated separately in order to define the corresponding critical impedance budget for given beam parameters. In this paper, we show that the CBI threshold in the presence of broadband impedance can be significantly lower than the one defined by only the narrowband impedance, especially if the LLD threshold is below the CBI threshold. In some cases, the beam becomes unstable even below the LLD threshold. This explains the low CBI threshold observed for the LHC-type beams in the CERN SPS. For HL-LHC, the broadband impedance may also significantly reduce the CBI threshold driven by higher-order modes of the crab cavities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS008

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Received ※ 08 June 2022 — Accepted ※ 04 July 2022 — Issue date ※ 06 July 2022

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THPOST003

Collective Effects Estimates for the Damping Ring Design of the FCC-ee

electron, emittance, impedance, positron

2435

O. Etisken
Ankara University, Faculty of Sciences, Ankara, Turkey
F. Antoniou, F. Zimmermann
CERN, Meyrin, Switzerland
A. De Santis
INFN/LNF, Frascati, Italy
C. Milardi
LNF-INFN, Frascati, Italy

The current injector complex design of the FCC-e⁺e⁻ project consists of e⁺/e⁻ linacs, which accelerate the beams up to 6 GeV, a damping ring at 1.54 GeV, a pre-booster ring, accelerating the beam up to 16 GeV and a booster synchrotron ring integrated in the collider tunnel accelerating the beams up to the collision energies. The purpose of the damping ring is to accept the 1.54 GeV beam coming from the linac-1, damp the positron/electron beams and provide the required beam characteristics for the injection into the linac-2. In this presentation the current damping ring design is introduced and analytical calculations on various collective effect such as space charge, intra-beam scattering, longitudinal micro-wave instability, transverse mode coupling instability, ion effects, electron cloud and coherent synchrotron radiation, are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST003

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Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 08 July 2022

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THPOPT006

Beam Dynamics Observations at Negative Momentum Compaction Factors at KARA

sextupole, synchrotron, optics, operation

2570

P. Schreiber, M. Brosi, B. Härer, A. Mochihashi, A.-S. Müller, A.I. Papash, R. Ruprecht, M. Schuh
KIT, Karlsruhe, Germany

Funding: We are supported by the DFG-funded "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology" and European Union’s Horizon 2020 research and innovation programme (No 730871)
For the development of future synchrotron light sources new operation modes often have to be considered. One such mode is the operation with a negative momentum compaction factor to provide the possibility of increased dynamic aperture. For successful application in future light sources, the influence of this mode has to be investigated. At the KIT storage ring KARA (Karlsruhe Research Accelerator), operation with negative momentum compaction has been implemented and the dynamics can now be investigated. Using a variety of high-performance beam diagnostics devices it is possible to observe the beam dynamics under negative momentum compaction conditions. This contribution presents different aspects of the results of these investigations in the longitudinal and transversal plane.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT006

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Received ※ 08 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 08 July 2022

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THPOPT013

Emittance Reduction with the Variable Dipole for the ELETTRA 2.0 Ring

dipole, emittance, lattice, optics

2586

A. Poyet, Y. Papaphilippou
CERN, Meyrin, Switzerland
M.A. Domínguez, F. Toral
CIEMAT, Madrid, Spain
R. Geometrante, E. Karantzoulis
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
R. Geometrante
KYMA, Trieste, Italy

ELETTRA is a 2/2.4 GeV third-generation electron storage ring, located near Trieste, Italy. In view of a substantial increase of the machine performance in terms of brilliance, the so-called ELETTRA 2.0 upgrade is currently on-going. This upgrade is based on a 6-bends achromat, four dipoles of which having a longitudinally variable field. So far, those dipoles are foreseen to provide a field with a two step profile. The VAriable Dipole for the ELETTRA Ring (VADER) task, driven by the I.FAST European project, aims at developing a new dipole design based on a trapezoidal shape of the bending radius, which would allow for a further reduction of the horizontal emittance. A prototype of this magnet should be designed by the CIEMAT laboratory and built by KYMA company. This paper discusses the new dipole field specification and describes the corresponding optics optimization that was performed in order to reduce at best the emittance of the ELETTRA ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT013

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Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 03 July 2022

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THPOTK057

ESS RFQ Experimental Modal Analysis

rfq, experiment, software, cavity

2907

E. Trachanas, A. Bignami, N. Gazis, B. Jones
ESS, Lund, Sweden

The European Spallation Source-ESS, which is currently under construction and commissioning at Lund, Sweden is a neutron source that consists of a 2 GeV linear accelerator (LINAC) accelerating a proton beam to a solid Tungsten (W) target. The proton beam is produced by the Ion Source (ISRC) and transported through the Low Energy Beam Transport (LEBT) to the Radio Frequency Quadrupole (RFQ) that will then focus, bunch and accelerate it to 3.6 MeV. The RFQ beam commissioning started in October 2021, following the RF conditioning phase in summer 2021. This current work presents an experimental modal analysis performed on RFQ including the comparative analysis with the modal finite element simulation using the ANSYS software suite. Measurements were performed using accelerometer sensors connected to a data acquisition system excited with an impact hammer. Geophones were used in parallel to the modal measurements in order to monitor the seismic background of the accelerator tunnel. Acquired data were post-processed and analysed with dedicated software, juxtaposed with simulated results in order to determine the resonance frequencies, structural deformation patterns (mode shapes) and error margin between experimental and simulated results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK057

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Received ※ 07 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022

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