HB2023 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
TUA1I2	New Understanding of Longitudinal Beam Instabilities and Comparison with Measurements	impedance, synchrotron, damping, proton	45
	I. Karpov CERN, Meyrin, Switzerland
	Beam instabilities driven by broad- and narrowband impedance sources have been treated separately so far. In this contribution, we present the generalised beam stability analysis based on the concept of van Kampen modes. In the presence of broadband impedance, the loss of Landau damping (LLD) in the longitudinal plane can occur above a certain single-bunch intensity. For significantly higher intensities, the broad-band impedance can drive violent radial or azimuthal mode-coupling instabilities. We have shown that the synchrotron frequency spread due to RF field non-linearity, counter-intuitively, reduces the single-bunch instability threshold. We have also demonstrated that a multi-bunch instability driven by a narrow-band impedance source can be significantly affected by LLD when adding broad-band impedance. These findings are supported by macroparticle simulations and beam observations in the Super Proton Synchrotron and the Large Hadron Collider at CERN.
	Slides TUA1I2 [1.517 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA1I2
About •	Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 13 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUC4I2	Development of an Impedance Model for the ISIS Synchrotron and Predictions for the Head-Tail Instability	impedance, kicker, simulation, synchrotron	170
	D.W. Posthuma de Boer, B.A. Orton, C.M. Warsop, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is a pulsed, spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. The rapid cycling synchrotron which drives the facility accelerates 3·10¹³ protons-per-pulse from 70 to 800 MeV at 50 Hz, and delivers a mean beam power of 0.2 MW to two target stations. Beam-loss mechanisms must be understood to optimise performance and minimise equipment activation; and to develop mitigation methods for future operations and new accelerators. Substantial beam-losses are driven by a vertical head-tail instability, which has also limited beam intensity. Beam-based impedance measurements suggest the instability is driven by a low-frequency narrowband impedance, but its physical origin remains unknown. More generally, research into the nature of the instability is hindered without a detailed transverse impedance model. This paper presents a survey of vertical impedance estimates for ISIS equipment, using analytical methods, low frequency CST simulations and lab-based coil measurements. The final impedance estimate is then used as an input to a new linearised Vlasov solver, and predicted growth rates compared with previously obtained experimental results.
	Slides TUC4I2 [4.374 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4I2
About •	Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 31 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUC4C1	Beam Coupling Impedance of the Main Extraction Kickers in the CERN PS	impedance, kicker, simulation, extraction	178
	M. Neroni, M.J. Barnes, A. Lasheen, C. Vollinger CERN, Meyrin, Switzerland A. Mostacci Sapienza University of Rome, Rome, Italy B.K. Popovic ANL, Lemont, Illinois, USA
	In view of the High Luminosity (HL) upgrade of the LHC, the beam intensity must be doubled in the injector chain. To perform reliable beam dynamics simulations, the beam coupling impedance in the injectors, such as the Proton Synchrotron (PS), must be followed closely by including all contributing elements into the impedance model. The existing kicker magnets of the PS had been optimized for large kick strength and short rise/fall times, but not necessarily to minimise beam coupling impedance. Hence, unwanted beam induced voltage can build up in their electrical circuits, with an impact on the beam. The beam coupling impedances of the two main kicker magnets used for the fast extraction from PS, the KFA71 and KFA79, are extensively characterized in this study. In particular, electromagnetic simulation results for the longitudinal and transverse coupling impedance are shown. The critical impedance contributions are identified, and their effect on beam stability is discussed. Moreover, the impact of the cable terminations on the electromagnetic field pattern and possible mitigation techniques are presented, providing a complete impedance evaluation of the entire kicker installation.
	Slides TUC4C1 [2.715 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4C1
About •	Received ※ 30 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 15 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEA1I2	Analytical and Numerical Studies on Kicked Beams in the Context of Half-Integer Studies	resonance, space-charge, emittance, damping	188
	G. Franchetti GSI, Darmstadt, Germany F. Asvesta, H. Bartosik, T. Prebibaj CERN, Meyrin, Switzerland
	In the context of the half-integer studies an investigation of the dynamics of the kicked beam has revealed surprising properties. The coupling of space charge with chromatic- ity in addition to usual damping/non-damping dynamics, exhibits new properties typical of a linear coupling. This proceeding covers the status of these studies carried out with analytical and numerical approaches and the prelimi- nary results of experimental investigations in the CERN PS Booster.
	Slides WEA1I2 [24.966 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1I2
About •	Received ※ 02 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 24 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THA2C3	Periodic Solution for Transport of Intense and Coupled Coasting Beams Through Quadrupole Channels	solenoid, lattice, space-charge, quadrupole	372
	C. Xiao, L. Groening GSI, Darmstadt, Germany
	Imposing defined spinning to a particle beam increases its stability against perturbations from space charge [Y.-L. Cheon et al., Effects of beam spinning on the fourth-order particle resonance of 3D bunched beams in high intensity linear accelerators, Phys. Rev. Accel. & Beams 25, 064002 (2022)]. In order to fully explore this potential, proper matching of intense coupled beams along regular lattices is mandatory. Herein, a novel procedure assuming matched transport is described and bench-marked through simulations. The concept of matched transport along periodic lattices has been extended from uncoupled beams to those with considerable coupling between the two transverse degrees of freedom. For coupled beams, matching means extension of cell-to-cell periodicity from just transverse envelopes to the coupled beam moments and to quantities being derived from these.
	Slides THA2C3 [1.649 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THA2C3
About •	Received ※ 25 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 19 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THAFP01	Probing Transverse Impedances in the High Frequency Range at the CERN SPS	impedance, simulation, betatron, optics	393
	E. de la Fuente, H. Bartosik, I. Mases Solé, G. Rumolo, C. Zannini CERN, Meyrin, Switzerland
	Funding: CERN The SPS transverse impedance model, which includes the major impedance contributions in the machine, can be benchmarked through measurements of the Head-Tail mode zero instability. Since the SPS works above transition energy, the head tail mode zero is unstable for negative values of chromaticity. The measured instability growth rate is proportional to the real part of the transverse impedance. Studies performed after the LHC Injectors Upgrade (LIU) showed a relevant impedance around 2 GHz with high-gamma transition optics (Q26). This paper presents the follow-up studies to probe the behavior of this beam coupling impedance contribution.
	Slides THAFP01 [2.262 MB]
	Poster THAFP01 [1.149 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP01
About •	Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THAFP04	Investigation of Tail-dominated Instability in the Fermilab Recycler Ring	space-charge, operation, diagnostics, emittance	403
	O. Mohsen, R. Ainsworth, A.V. Burov Fermilab, Batavia, Illinois, USA
	In our recent operational run, a single bunch, tail-dominated instability was observed in the Fermilab Recycler ring. This instability exclusively occurs in the vertical plane when the chromaticity is close to zero. In this study, we conduct a detailed analysis of this instability under different operational parameters. We investigate the impact of space charge on the head-tail motion and propose potential interpretations of the underlying mechanism of the instability. Moreover, we explore methods to mitigate this instability in the future.
	Slides THAFP04 [1.429 MB]
	Poster THAFP04 [0.892 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP04
About •	Received ※ 25 September 2023 — Revised ※ 09 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 29 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THAFP05	A Wireless Method for Beam Coupling Impedance Measurements of the LHC Goniometer	impedance, cavity, simulation, scattering	407
	C. Antuono, C. Zannini CERN, Meyrin, Switzerland M. Migliorati, A. Mostacci LNF-INFN, Frascati, Italy
	The beam coupling impedance (BCI) of an accelerator component should be ideally evaluated exciting the device with the beam itself. However, this scenario is not always attainable and alternative methods must be exploited, such as the bench measurements techniques. The stretched Wire Method (WM) is a well established technique for BCI evaluations, although nowadays its limitations are well known. In particular, the stretched wire perturbs the electromagnetic boundary conditions. Therefore, the results obtained could be inaccurate, especially below the cut-off frequency of the beam pipe in the case of cavity-like structures. To overcome these limitations, efforts are being made to investigate alternative bench measurement techniques that will not require the modification of the device under test (DUT). In this framework, a wireless method has been identified and tested for a pillbox cavity. Its potential for more complex structures, such as the LHC crystal goniometer is explored.
	Slides THAFP05 [1.088 MB]
	Poster THAFP05 [1.151 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP05
About •	Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP11	MKP-L Impedance Mitigation and Expectations for MKP-S in the CERN-SPS	impedance, kicker, shielding, extraction	466
	C. Zannini, M.J. Barnes, M.S. Beck, M. Díaz Zumel, L. Ducimetière, G. Rumolo, D. Standen, P. Trubacova CERN, Meyrin, Switzerland
	Beam coupling impedance mitigation is key in preventing intensity limitations due to beam stability issues, heating and sparking. In this framework, a very good example is the optimization of the SPS kickers beam-coupling impedance for beam-induced heating mitigation. After the optimization of the SPS extraction kickers, the SPS injection kickers became the next bottleneck for high intensity operation. This system is composed of three MKP-S tanks and one MKP-L. To accommodate LIU beam intensities, it was necessary to mitigate the beam induced heating of the MKP-L, using a shielding concept briefly reviewed in this paper. Moreover, temperature data from the 2023 run are analyzed to qualify the accuracy of the models and assess the effectiveness of the impedance mitigation. Finally, the expected limitations from the MKP-S, expected to become the new bottleneck in terms of beam induced heating, are discussed.
	Poster THBP11 [1.655 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP11
About •	Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 24 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP13	Recent Developments with the New Tools for Collimation Simulations in Xsuite	collimation, simulation, scattering, proton	474
	F.F. Van der Veken, A. Abramov, G. Broggi, F. Cerutti, M. D’Andrea, D. Demetriadou, L.S. Esposito, G. Hugo, G. Iadarola, B. Lindström, S. Redaelli, V. Rodin, N. Triantafyllou CERN, Meyrin, Switzerland
	Simulations of single-particle tracking involving collimation systems need dedicated tools to perform the different tasks needed. These include the accurate description of particle-matter interactions when a tracked particle impacts a collimator jaw; a detailed aperture model to identify the longitudinal location of losses; and others. One such tool is the K2 code in SixTrack, which describes the scattering of high-energy protons in matter. This code has recently been ported into the Xsuite tracking code that is being developed at CERN. Another approach is to couple the tracking with existing tools, such as FLUKA or Geant4, that offer better descriptions of particle-matter interactions and can treat lepton and ion beams. This includes the generation of secondary particles and fragmentation when tracking ions. In addition to the development of coupling with Geant4, the SixTrack-FLUKA coupling has recently been translated and integrated into the Xsuite environment as well. In this paper, we present the ongoing development of these tools. A thorough testing of the new implementation was performed, using as case studies various collimation layout configurations for the LHC Run 3.
	Poster THBP13 [2.785 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP13
About •	Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 23 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP47	Studies on the Effect of Beam-Coupling Impedance on Schottky Spectra of Bunched Beams	impedance, simulation, synchrotron, diagnostics	595
	C. Lannoy, D. Alves, K. Łasocha, N. Mounet CERN, Meyrin, Switzerland C. Lannoy, T. Pieloni EPFL, Lausanne, Switzerland
	Schottky monitors can be used for non-invasive beam diagnostics to estimate various bunch characteristics, such as tune, chromaticity, bunch profile or synchrotron frequency distribution. However, collective effects, in particular beam-coupling impedance, can significantly affect Schottky spectra when large bunch charges are involved. In such conditions, the available interpretation methods are difficult to apply directly to the measured spectra, thus preventing the extraction of beam and machine parameters, which is possible for lower bunch charges. To study the impact of impedance on such spectra, we perform here time-domain, macro-particle simulations and apply a semi-analytical method to compute the Schottky signal for various machine and beam conditions, including those corresponding to typical physics operation at the Large Hadron Collider. This study provides preliminary interpretations of the impact of beam-coupling impedance on Schottky spectra by incorporating longitudinal and transverse resonator-like impedance models into the simulations.
	Poster THBP47 [1.133 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP47
About •	Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 21 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP52	A Python Package to Compute Beam-Induced Heating in Particle Accelerators and Applications	impedance, vacuum, site, wakefield	611
	L. Sito, F. Giordano, G. Rumolo, B. Salvant, C. Zannini, E. de la Fuente CERN, Meyrin, Switzerland
	High-energy particle beams interact electromagnetically with their surroundings when they travel inside an accelerator. These interactions may cause beam-induced heating of the accelerator’s components, which could eventually lead to outgassing, equipment degradation and physical damage. The expected beam-induced heating can be related to the beam coupling impedance, an electromagnetic property of every accelerator device. Accounting for beam-induced heating is crucial both at the design phase of an accelerator component and for gaining an understanding of devices¿ failures. In this paper, an in-house developed Python tool to compute beam-induced heating due to impedance is introduced. The different features and capabilities will be showcased and applied to real devices in the LHC and the injector chain.
	Poster THBP52 [0.544 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP52
About •	Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 11 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

TUA1I2

New Understanding of Longitudinal Beam Instabilities and Comparison with Measurements

impedance, synchrotron, damping, proton

45

I. Karpov
CERN, Meyrin, Switzerland

Beam instabilities driven by broad- and narrowband impedance sources have been treated separately so far. In this contribution, we present the generalised beam stability analysis based on the concept of van Kampen modes. In the presence of broadband impedance, the loss of Landau damping (LLD) in the longitudinal plane can occur above a certain single-bunch intensity. For significantly higher intensities, the broad-band impedance can drive violent radial or azimuthal mode-coupling instabilities. We have shown that the synchrotron frequency spread due to RF field non-linearity, counter-intuitively, reduces the single-bunch instability threshold. We have also demonstrated that a multi-bunch instability driven by a narrow-band impedance source can be significantly affected by LLD when adding broad-band impedance. These findings are supported by macroparticle simulations and beam observations in the Super Proton Synchrotron and the Large Hadron Collider at CERN.

Slides TUA1I2 [1.517 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA1I2

About •

Received ※ 01 October 2023 — Revised ※ 06 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 13 October 2023

Cite •

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

TUC4I2

Development of an Impedance Model for the ISIS Synchrotron and Predictions for the Head-Tail Instability

impedance, kicker, simulation, synchrotron

170

D.W. Posthuma de Boer, B.A. Orton, C.M. Warsop, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is a pulsed, spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. The rapid cycling synchrotron which drives the facility accelerates 3·10¹³ protons-per-pulse from 70 to 800 MeV at 50 Hz, and delivers a mean beam power of 0.2 MW to two target stations. Beam-loss mechanisms must be understood to optimise performance and minimise equipment activation; and to develop mitigation methods for future operations and new accelerators. Substantial beam-losses are driven by a vertical head-tail instability, which has also limited beam intensity. Beam-based impedance measurements suggest the instability is driven by a low-frequency narrowband impedance, but its physical origin remains unknown. More generally, research into the nature of the instability is hindered without a detailed transverse impedance model. This paper presents a survey of vertical impedance estimates for ISIS equipment, using analytical methods, low frequency CST simulations and lab-based coil measurements. The final impedance estimate is then used as an input to a new linearised Vlasov solver, and predicted growth rates compared with previously obtained experimental results.

Slides TUC4I2 [4.374 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4I2

About •

Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 31 October 2023

Cite •

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

TUC4C1

Beam Coupling Impedance of the Main Extraction Kickers in the CERN PS

impedance, kicker, simulation, extraction

178

M. Neroni, M.J. Barnes, A. Lasheen, C. Vollinger
CERN, Meyrin, Switzerland
A. Mostacci
Sapienza University of Rome, Rome, Italy
B.K. Popovic
ANL, Lemont, Illinois, USA

In view of the High Luminosity (HL) upgrade of the LHC, the beam intensity must be doubled in the injector chain. To perform reliable beam dynamics simulations, the beam coupling impedance in the injectors, such as the Proton Synchrotron (PS), must be followed closely by including all contributing elements into the impedance model. The existing kicker magnets of the PS had been optimized for large kick strength and short rise/fall times, but not necessarily to minimise beam coupling impedance. Hence, unwanted beam induced voltage can build up in their electrical circuits, with an impact on the beam. The beam coupling impedances of the two main kicker magnets used for the fast extraction from PS, the KFA71 and KFA79, are extensively characterized in this study. In particular, electromagnetic simulation results for the longitudinal and transverse coupling impedance are shown. The critical impedance contributions are identified, and their effect on beam stability is discussed. Moreover, the impact of the cable terminations on the electromagnetic field pattern and possible mitigation techniques are presented, providing a complete impedance evaluation of the entire kicker installation.

Slides TUC4C1 [2.715 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4C1

About •

Received ※ 30 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 15 October 2023

Cite •

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

WEA1I2

Analytical and Numerical Studies on Kicked Beams in the Context of Half-Integer Studies

resonance, space-charge, emittance, damping

188

G. Franchetti
GSI, Darmstadt, Germany
F. Asvesta, H. Bartosik, T. Prebibaj
CERN, Meyrin, Switzerland

In the context of the half-integer studies an investigation of the dynamics of the kicked beam has revealed surprising properties. The coupling of space charge with chromatic- ity in addition to usual damping/non-damping dynamics, exhibits new properties typical of a linear coupling. This proceeding covers the status of these studies carried out with analytical and numerical approaches and the prelimi- nary results of experimental investigations in the CERN PS Booster.

Slides WEA1I2 [24.966 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-WEA1I2

About •

Received ※ 02 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 24 October 2023

Cite •

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

THA2C3

Periodic Solution for Transport of Intense and Coupled Coasting Beams Through Quadrupole Channels

solenoid, lattice, space-charge, quadrupole

372

C. Xiao, L. Groening
GSI, Darmstadt, Germany

Imposing defined spinning to a particle beam increases its stability against perturbations from space charge [Y.-L. Cheon et al., Effects of beam spinning on the fourth-order particle resonance of 3D bunched beams in high intensity linear accelerators, Phys. Rev. Accel. & Beams 25, 064002 (2022)]. In order to fully explore this potential, proper matching of intense coupled beams along regular lattices is mandatory. Herein, a novel procedure assuming matched transport is described and bench-marked through simulations. The concept of matched transport along periodic lattices has been extended from uncoupled beams to those with considerable coupling between the two transverse degrees of freedom. For coupled beams, matching means extension of cell-to-cell periodicity from just transverse envelopes to the coupled beam moments and to quantities being derived from these.

Slides THA2C3 [1.649 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THA2C3

About •

Received ※ 25 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 19 October 2023

Cite •

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

THAFP01

Probing Transverse Impedances in the High Frequency Range at the CERN SPS

impedance, simulation, betatron, optics

393

E. de la Fuente, H. Bartosik, I. Mases Solé, G. Rumolo, C. Zannini
CERN, Meyrin, Switzerland

Funding: CERN
The SPS transverse impedance model, which includes the major impedance contributions in the machine, can be benchmarked through measurements of the Head-Tail mode zero instability. Since the SPS works above transition energy, the head tail mode zero is unstable for negative values of chromaticity. The measured instability growth rate is proportional to the real part of the transverse impedance. Studies performed after the LHC Injectors Upgrade (LIU) showed a relevant impedance around 2 GHz with high-gamma transition optics (Q26). This paper presents the follow-up studies to probe the behavior of this beam coupling impedance contribution.

Slides THAFP01 [2.262 MB]

Poster THAFP01 [1.149 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP01

About •

Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023

Cite •

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

THAFP04

Investigation of Tail-dominated Instability in the Fermilab Recycler Ring

space-charge, operation, diagnostics, emittance

403

O. Mohsen, R. Ainsworth, A.V. Burov
Fermilab, Batavia, Illinois, USA

In our recent operational run, a single bunch, tail-dominated instability was observed in the Fermilab Recycler ring. This instability exclusively occurs in the vertical plane when the chromaticity is close to zero. In this study, we conduct a detailed analysis of this instability under different operational parameters. We investigate the impact of space charge on the head-tail motion and propose potential interpretations of the underlying mechanism of the instability. Moreover, we explore methods to mitigate this instability in the future.

Slides THAFP04 [1.429 MB]

Poster THAFP04 [0.892 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP04

About •

Received ※ 25 September 2023 — Revised ※ 09 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 29 October 2023

Cite •

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

THAFP05

A Wireless Method for Beam Coupling Impedance Measurements of the LHC Goniometer

impedance, cavity, simulation, scattering

407

C. Antuono, C. Zannini
CERN, Meyrin, Switzerland
M. Migliorati, A. Mostacci
LNF-INFN, Frascati, Italy

The beam coupling impedance (BCI) of an accelerator component should be ideally evaluated exciting the device with the beam itself. However, this scenario is not always attainable and alternative methods must be exploited, such as the bench measurements techniques. The stretched Wire Method (WM) is a well established technique for BCI evaluations, although nowadays its limitations are well known. In particular, the stretched wire perturbs the electromagnetic boundary conditions. Therefore, the results obtained could be inaccurate, especially below the cut-off frequency of the beam pipe in the case of cavity-like structures. To overcome these limitations, efforts are being made to investigate alternative bench measurement techniques that will not require the modification of the device under test (DUT). In this framework, a wireless method has been identified and tested for a pillbox cavity. Its potential for more complex structures, such as the LHC crystal goniometer is explored.

Slides THAFP05 [1.088 MB]

Poster THAFP05 [1.151 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP05

About •

Received ※ 29 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 11 October 2023

Cite •

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

THBP11

MKP-L Impedance Mitigation and Expectations for MKP-S in the CERN-SPS

impedance, kicker, shielding, extraction

466

C. Zannini, M.J. Barnes, M.S. Beck, M. Díaz Zumel, L. Ducimetière, G. Rumolo, D. Standen, P. Trubacova
CERN, Meyrin, Switzerland

Beam coupling impedance mitigation is key in preventing intensity limitations due to beam stability issues, heating and sparking. In this framework, a very good example is the optimization of the SPS kickers beam-coupling impedance for beam-induced heating mitigation. After the optimization of the SPS extraction kickers, the SPS injection kickers became the next bottleneck for high intensity operation. This system is composed of three MKP-S tanks and one MKP-L. To accommodate LIU beam intensities, it was necessary to mitigate the beam induced heating of the MKP-L, using a shielding concept briefly reviewed in this paper. Moreover, temperature data from the 2023 run are analyzed to qualify the accuracy of the models and assess the effectiveness of the impedance mitigation. Finally, the expected limitations from the MKP-S, expected to become the new bottleneck in terms of beam induced heating, are discussed.

Poster THBP11 [1.655 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP11

About •

Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 24 October 2023

Cite •

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

THBP13

Recent Developments with the New Tools for Collimation Simulations in Xsuite

collimation, simulation, scattering, proton

474

F.F. Van der Veken, A. Abramov, G. Broggi, F. Cerutti, M. D’Andrea, D. Demetriadou, L.S. Esposito, G. Hugo, G. Iadarola, B. Lindström, S. Redaelli, V. Rodin, N. Triantafyllou
CERN, Meyrin, Switzerland

Simulations of single-particle tracking involving collimation systems need dedicated tools to perform the different tasks needed. These include the accurate description of particle-matter interactions when a tracked particle impacts a collimator jaw; a detailed aperture model to identify the longitudinal location of losses; and others. One such tool is the K2 code in SixTrack, which describes the scattering of high-energy protons in matter. This code has recently been ported into the Xsuite tracking code that is being developed at CERN. Another approach is to couple the tracking with existing tools, such as FLUKA or Geant4, that offer better descriptions of particle-matter interactions and can treat lepton and ion beams. This includes the generation of secondary particles and fragmentation when tracking ions. In addition to the development of coupling with Geant4, the SixTrack-FLUKA coupling has recently been translated and integrated into the Xsuite environment as well. In this paper, we present the ongoing development of these tools. A thorough testing of the new implementation was performed, using as case studies various collimation layout configurations for the LHC Run 3.

Poster THBP13 [2.785 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP13

About •

Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 13 October 2023 — Issued ※ 23 October 2023

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THBP47

Studies on the Effect of Beam-Coupling Impedance on Schottky Spectra of Bunched Beams

impedance, simulation, synchrotron, diagnostics

595

C. Lannoy, D. Alves, K. Łasocha, N. Mounet
CERN, Meyrin, Switzerland
C. Lannoy, T. Pieloni
EPFL, Lausanne, Switzerland

Schottky monitors can be used for non-invasive beam diagnostics to estimate various bunch characteristics, such as tune, chromaticity, bunch profile or synchrotron frequency distribution. However, collective effects, in particular beam-coupling impedance, can significantly affect Schottky spectra when large bunch charges are involved. In such conditions, the available interpretation methods are difficult to apply directly to the measured spectra, thus preventing the extraction of beam and machine parameters, which is possible for lower bunch charges. To study the impact of impedance on such spectra, we perform here time-domain, macro-particle simulations and apply a semi-analytical method to compute the Schottky signal for various machine and beam conditions, including those corresponding to typical physics operation at the Large Hadron Collider. This study provides preliminary interpretations of the impact of beam-coupling impedance on Schottky spectra by incorporating longitudinal and transverse resonator-like impedance models into the simulations.

Poster THBP47 [1.133 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP47

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Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 21 October 2023

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THBP52

A Python Package to Compute Beam-Induced Heating in Particle Accelerators and Applications

impedance, vacuum, site, wakefield

611

L. Sito, F. Giordano, G. Rumolo, B. Salvant, C. Zannini, E. de la Fuente
CERN, Meyrin, Switzerland

High-energy particle beams interact electromagnetically with their surroundings when they travel inside an accelerator. These interactions may cause beam-induced heating of the accelerator’s components, which could eventually lead to outgassing, equipment degradation and physical damage. The expected beam-induced heating can be related to the beam coupling impedance, an electromagnetic property of every accelerator device. Accounting for beam-induced heating is crucial both at the design phase of an accelerator component and for gaining an understanding of devices¿ failures. In this paper, an in-house developed Python tool to compute beam-induced heating due to impedance is introduced. The different features and capabilities will be showcased and applied to real devices in the LHC and the injector chain.

Poster THBP52 [0.544 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP52

About •

Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 11 October 2023

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