HB2023 - List of Keywords (synchrotron)

Paper	Title	Other Keywords	Page
MOA4I1	Design of a Fixed-Field Accelerating Ring for High Power Applications	injection, extraction, resonance, lattice	38
	S. Machida STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	A fixed field accelerating ring (FFA) has some advantage to achieve high beam power over conventional ring accelerators. It would be also a sustainable option as future proton drivers. We will discuss the design of an FFA taking a future upgrade plan of ISIS (ISIS-II) as an example.
	Slides MOA4I1 [14.313 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA4I1
About •	Received ※ 01 October 2023 — Revised ※ 05 October 2023 — Accepted ※ 15 October 2023 — Issued ※ 21 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUA1I2	New Understanding of Longitudinal Beam Instabilities and Comparison with Measurements	impedance, coupling, 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)

TUA2C2	Recent Advances in the CERN PS Impedance Model and Instability Simulations	impedance, kicker, simulation, proton	86
	S. Joly La Sapienza University of Rome, Rome, Italy G. Iadarola, N. Mounet, B. Salvant, C. Zannini CERN, Meyrin, Switzerland M. Migliorati INFN-Roma1, Rome, Italy
	Transverse instability growth rates in the CERN Proton Synchrotron are studied thanks to the recently updated impedance model of the machine. Using this model, macroparticle tracking simulations were performed with a new method well-suited for the slicing of short wakes, which achieves comparable performance to the originally implemented method while reducing the required number of slices by a factor of 5 to 10. Dedicated beam-based measurement campaigns were carried out to benchmark the impedance model. Until now, the model underestimated instability growth rates at injection energy. Thanks to a recent addition to the impedance model, namely the kicker magnets¿ connecting cables and their external circuits, the simulated instability growth rates are now comparable to the measured ones.
	Slides TUA2C2 [0.736 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2C2
About •	Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 21 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, coupling	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)

WEC4C1	Magnetic Alloy Loaded Cavities in J-PARC and CERN	cavity, booster, proton, operation	316
	C. Ohmori KEK, Ibaraki, Japan M.M. Paoluzzi CERN, Meyrin, Switzerland
	Funding: This work was supported by JSPS KAKENHI Grant Number 19KK0078 and 18K11930. Magnetic Alloy loaded cavities have been used in seven synchrotrons in J-PARC and CERN. In this paper, we will review variety of the cavity technologies to satisfy the requirements for the beam acceleration, deceleration, manipulation and instability damping. This paper also contains improvements of cavity cores by magnetic annealing scheme, quality control of cores during production, the cooling methods of magnetic alloy cores: direct water cooling and indirect one using copper discs, control of cavity bandwidths from broad to narrow bands, and the ways to drive RF cavities by tube and rad-hard solid-state amplifiers.
	Slides WEC4C1 [3.371 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4C1
About •	Received ※ 04 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THC2I2	Extraction of LHC Beam Parameters from Schottky Signals	betatron, diagnostics, simulation, octupole	382
	K. Łasocha, D. Alves, C. Lannoy, N. Mounet CERN, Meyrin, Switzerland C. Lannoy, T. Pieloni EPFL, Lausanne, Switzerland
	Analysis of Schottky signals provides rich insights into the dynamics of a hadron beam, with well-established methods of deriving the betatron tune and machine chromaticity. In this contribution, we will report on recent developments in the analysis and understanding of the signals measured at the Large Hadron Collider during proton and Pb⁸²⁺ fills. A fitting-based technique, where the measured spectra are iteratively compared with theoretical predictions, will be presented and compared with the previous methods. As a step beyond the classical theory of Schottky spectra, certain signal modifications due to the activity of the LHC machine systems will be discussed from the perspective of the applicability of the modified signal to the beam diagnostics.
	Slides THC2I2 [9.053 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THC2I2
About •	Received ※ 04 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 12 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THAFP11	FPGA-Based Digital IQ Demodulator Used in the Beam Position Monitors for HIAF BRing	electron, FPGA, electronics, pick-up	429
	F.F. Ni, Z.X. Li, R.X. Tian, Y. Wei, J.X. Wu IMP/CAS, Lanzhou, People’s Republic of China
	Funding: NSFC No. E911010301, Y913010GJ0, A digital beam position monitor processor has been developed for the High Intensity heavy ion Accelerator Facility (HIAF). The digital IQ demodulator is used in the Beam Position Monitor (BPM) signal processing. All data acquisition and digital signal processing algorithm routines are performed within the FPGA. In the BPM electronics system, a 250 MHz sample rates ADC was used to digitize the pick-ups signal. In the FPGA, the digital signal is filtered by ultra-narrow bandpass filters, then the digital IQ demodulator is used to calculate the beam position with difference-over-sum algorithm. The heavy ion synchrotron CSRm revolution frequency is changing from 0.2 MHz to 1.78 MHz when accelerates charged particles. In this design, a Direct Digital Synthesizer (DDS) whose output frequency changes over time is applied to generate the in-phase and quadrature components in the digital IQ demodulator. The performance of this designed BPM processor was evaluated with the online HIRFL-CSRm.
	Slides THAFP11 [1.332 MB]
	Poster THAFP11 [4.534 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP11
About •	Received ※ 28 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 19 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP17	Transverse Coherent Instability Studies for the High-Energy Part of the Muon Collider Complex	collider, impedance, cavity, simulation	491
	D. Amorim, F. Batsch, L. Bottura, D. Calzolari, C. Carli, H. Damerau, A. Grudiev, A. Lechner, E. Métral, D. Schulte, K. Skoufaris CERN, Geneva, Switzerland A. Chancé CEA-DRF-IRFU, France T. Pieloni EPFL, Lausanne, Switzerland
	Funding: This project has received funding from the European Union¿s Research and Innovation programme under GA No 101094300 and the Swiss Accelerator Research and Technology (CHART) program (www.chart.ch). The International Muon Collider Collaboration (IMCC) is studying a 3 TeV center-of-mass muon collider ring, as well as a possible next stage at 10 TeV. Muons being 200 times heavier than electrons, limitations from synchrotron radiation are mostly suppressed, but the muon decay drives the accelerator chain design. After the muon and anti-muon bunches are produced and 6D cooled, a series of Linac, recirculating Linac and Rapid Cycling Synchrotron (RCS) quickly accelerate the bunches before the collider ring. A large number of RF cavities are required in the RCS to ensure that over 90% of the muons survive in each ring. The effects of cavities higher-order modes on transverse coherent stability have been looked at in detail, including the one of a bunch offset in the cavities, along with possible mitigation measures. In the collider ring, the decay of high-energy muons is a challenge for heat load management and radiation shielding. A tungsten liner would protect the superconducting magnet from decay products. Impedance and related beam stability have been investigated to identify the minimum vacuum chamber radius and transverse damper properties required for stable beams.
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP17
About •	Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 01 November 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP36	Study of the Performance of the CERN Proton Synchrotron Internal Dump	simulation, beam-losses, proton, vacuum	555
	T. Pugnat, L.S. Esposito, M. Giovannozzi, C. Hernalsteens, A. Huschauer, S. Niang CERN, Meyrin, Switzerland D. Domange, E. Gnacadja, R. Tesse ULB, Bruxelles, Belgium
	In the framework of the LHC Injector Upgrade project, a new internal dump for the CERN Proton Synchrotron (PS) has been designed, installed, and successfully commissioned. This device is meant to move rapidly into the beam and stop charged particles over several turns to provide protection to the PS hardware against beam-induced damage. The performance of the dump should ensure efficient use throughout the PS energy range, i.e. from injection at 2 GeV (kinetic energy) to flat top at 26 GeV (total energy). In this paper, detailed numerical simulations are presented, carried out with a combination of sophisticated beam dynamics and beam-matter interaction codes, assessing the behaviour of stopped or scattered particles. The results of these numerical simulations are compared with the data collected during the routine operation of the PS and its internal dump.
	Poster THBP36 [0.609 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP36
About •	Received ※ 26 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 28 October 2023
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THBP38	Two-Dimensional Longitudinal Painting at Injection into the CERN PS Booster	injection, linac, target, emittance	563
	S.C.P. Albright, F. Asvesta, B. Bielawski, C. Bracco, P.K. Skowroński, R. Wegner CERN, Meyrin, Switzerland
	To inject highest beam intensities at the transfer from Linac4 into the four rings of the PS Booster (PSB) at CERN, protons must be accumulated during up to 148 turns in total. With the conventional, fixed chopping pattern this process results in an approximately rectangular distribution in the longitudinal phase space. As the bucket shape in the PSB does not correspond to this distribution, the process leads to longitudinal mismatch, contributing to emittance growth and reduced transmission. The field in the last accelerating cavity of Linac4 can be modulated, which leads to fine corrections of the extracted beam energy. At the same time, the chopping pattern can be varied. Combining both allows injecting a near uniform longitudinal distribution whose boundary corresponds to an iso-Hamiltonian contour of the RF bucket, hence significantly reducing mismatch. In an operational context, the longitudinal painting must be controlled in a way that allows easy intensity variation, and can even require different painting configurations for each of the four PSB rings. This contribution presents the first demonstration of longitudinal painting in the PSB, and its impact on beam performance.
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP38
About •	Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 24 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THBP42	Longitudinal Loss of Landau Damping in Double Harmonic RF Systems below Transition Energy	damping, impedance, space-charge, proton	575
	L. Intelisano, H. Damerau, I. Karpov CERN, Meyrin, Switzerland
	Landau damping plays a crucial role in ensuring single-bunch stability in hadron synchrotrons. In the longitudinal plane, loss of Landau damping (LLD) occurs when a coherent mode of oscillation moves out of the incoherent synchrotron frequency band. The LLD threshold is studied for a purely inductive impedance below transition energy, specifically considering the common case of double harmonic RF systems operating in counter-phase at the bunch position. The additional focusing force due to beam-induced voltage distorts the potential well, ultimately collapsing the bucket. The limiting conditions for a binomial particle distribution are calculated. Furthermore, the contribution focuses on the configuration of the higher-harmonic RF system at four times the fundamental RF frequency operating in phase. In this case, the LLD threshold shows a non-monotonic behavior with a zero threshold where the derivative of the synchrotron frequency distribution is positive. The findings are obtained employing semi-analytical calculations using the MELODY code.
	Poster THBP42 [1.710 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP42
About •	Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 14 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, coupling, 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)

THBP59	Tomographic Longitudinal Phase Space Reconstruction of Bunch Compression at ISIS	proton, simulation, operation, extraction	625
	B.S. Kyle, H.V. Cavanagh, A. Seville, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is an 800 MeV, high intensity, rapid-cycling synchrotron (RCS) used as a driver for a spallation neutron and muon spectroscopy (¿SR) facility. The intensity-limited beam and RCS operation at ISIS poses significant challenges, with non-adiabatic acceleration and space charge forces resulting in distortions to the Hamiltonian longitudinal dynamics. Effective modelling of the machine and benchmarking of models with beam measurements is essential both to improving machine performance, and to the development of the proposed ISIS II facility. The tomographic principle is a well-established tool for the reconstruction of the longitudinal phase space (LPS) of synchrotron beams. Is it operationally desirable for the ISIS accelerator to provide longitudinally compressed proton beams for ¿SR instrumentation. A new bunch compression scheme has been developed and validated using tomography. A reconstruction of the LPS of the ISIS high-intensity proton beam is presented, along with accompanying benchmarking measurements and beam physics simulations.
	Poster THBP59 [0.907 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP59
About •	Received ※ 01 October 2023 — Revised ※ 09 October 2023 — Accepted ※ 20 October 2023 — Issued ※ 25 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

MOA4I1

Design of a Fixed-Field Accelerating Ring for High Power Applications

injection, extraction, resonance, lattice

38

S. Machida
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

A fixed field accelerating ring (FFA) has some advantage to achieve high beam power over conventional ring accelerators. It would be also a sustainable option as future proton drivers. We will discuss the design of an FFA taking a future upgrade plan of ISIS (ISIS-II) as an example.

Slides MOA4I1 [14.313 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-MOA4I1

About •

Received ※ 01 October 2023 — Revised ※ 05 October 2023 — Accepted ※ 15 October 2023 — Issued ※ 21 October 2023

Cite •

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

TUA1I2

New Understanding of Longitudinal Beam Instabilities and Comparison with Measurements

impedance, coupling, 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)

TUA2C2

Recent Advances in the CERN PS Impedance Model and Instability Simulations

impedance, kicker, simulation, proton

86

S. Joly
La Sapienza University of Rome, Rome, Italy
G. Iadarola, N. Mounet, B. Salvant, C. Zannini
CERN, Meyrin, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy

Transverse instability growth rates in the CERN Proton Synchrotron are studied thanks to the recently updated impedance model of the machine. Using this model, macroparticle tracking simulations were performed with a new method well-suited for the slicing of short wakes, which achieves comparable performance to the originally implemented method while reducing the required number of slices by a factor of 5 to 10. Dedicated beam-based measurement campaigns were carried out to benchmark the impedance model. Until now, the model underestimated instability growth rates at injection energy. Thanks to a recent addition to the impedance model, namely the kicker magnets¿ connecting cables and their external circuits, the simulated instability growth rates are now comparable to the measured ones.

Slides TUA2C2 [0.736 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-TUA2C2

About •

Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 21 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, coupling

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)

WEC4C1

Magnetic Alloy Loaded Cavities in J-PARC and CERN

cavity, booster, proton, operation

316

C. Ohmori
KEK, Ibaraki, Japan
M.M. Paoluzzi
CERN, Meyrin, Switzerland

Funding: This work was supported by JSPS KAKENHI Grant Number 19KK0078 and 18K11930.
Magnetic Alloy loaded cavities have been used in seven synchrotrons in J-PARC and CERN. In this paper, we will review variety of the cavity technologies to satisfy the requirements for the beam acceleration, deceleration, manipulation and instability damping. This paper also contains improvements of cavity cores by magnetic annealing scheme, quality control of cores during production, the cooling methods of magnetic alloy cores: direct water cooling and indirect one using copper discs, control of cavity bandwidths from broad to narrow bands, and the ways to drive RF cavities by tube and rad-hard solid-state amplifiers.

Slides WEC4C1 [3.371 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4C1

About •

Received ※ 04 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023

Cite •

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

THC2I2

Extraction of LHC Beam Parameters from Schottky Signals

betatron, diagnostics, simulation, octupole

382

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

Analysis of Schottky signals provides rich insights into the dynamics of a hadron beam, with well-established methods of deriving the betatron tune and machine chromaticity. In this contribution, we will report on recent developments in the analysis and understanding of the signals measured at the Large Hadron Collider during proton and Pb⁸²⁺ fills. A fitting-based technique, where the measured spectra are iteratively compared with theoretical predictions, will be presented and compared with the previous methods. As a step beyond the classical theory of Schottky spectra, certain signal modifications due to the activity of the LHC machine systems will be discussed from the perspective of the applicability of the modified signal to the beam diagnostics.

Slides THC2I2 [9.053 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THC2I2

About •

Received ※ 04 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 12 October 2023

Cite •

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

THAFP11

FPGA-Based Digital IQ Demodulator Used in the Beam Position Monitors for HIAF BRing

electron, FPGA, electronics, pick-up

429

F.F. Ni, Z.X. Li, R.X. Tian, Y. Wei, J.X. Wu
IMP/CAS, Lanzhou, People’s Republic of China

Funding: NSFC No. E911010301, Y913010GJ0,
A digital beam position monitor processor has been developed for the High Intensity heavy ion Accelerator Facility (HIAF). The digital IQ demodulator is used in the Beam Position Monitor (BPM) signal processing. All data acquisition and digital signal processing algorithm routines are performed within the FPGA. In the BPM electronics system, a 250 MHz sample rates ADC was used to digitize the pick-ups signal. In the FPGA, the digital signal is filtered by ultra-narrow bandpass filters, then the digital IQ demodulator is used to calculate the beam position with difference-over-sum algorithm. The heavy ion synchrotron CSRm revolution frequency is changing from 0.2 MHz to 1.78 MHz when accelerates charged particles. In this design, a Direct Digital Synthesizer (DDS) whose output frequency changes over time is applied to generate the in-phase and quadrature components in the digital IQ demodulator. The performance of this designed BPM processor was evaluated with the online HIRFL-CSRm.

Slides THAFP11 [1.332 MB]

Poster THAFP11 [4.534 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THAFP11

About •

Received ※ 28 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 19 October 2023

Cite •

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

THBP17

Transverse Coherent Instability Studies for the High-Energy Part of the Muon Collider Complex

collider, impedance, cavity, simulation

491

D. Amorim, F. Batsch, L. Bottura, D. Calzolari, C. Carli, H. Damerau, A. Grudiev, A. Lechner, E. Métral, D. Schulte, K. Skoufaris
CERN, Geneva, Switzerland
A. Chancé
CEA-DRF-IRFU, France
T. Pieloni
EPFL, Lausanne, Switzerland

Funding: This project has received funding from the European Union¿s Research and Innovation programme under GA No 101094300 and the Swiss Accelerator Research and Technology (CHART) program (www.chart.ch).
The International Muon Collider Collaboration (IMCC) is studying a 3 TeV center-of-mass muon collider ring, as well as a possible next stage at 10 TeV. Muons being 200 times heavier than electrons, limitations from synchrotron radiation are mostly suppressed, but the muon decay drives the accelerator chain design. After the muon and anti-muon bunches are produced and 6D cooled, a series of Linac, recirculating Linac and Rapid Cycling Synchrotron (RCS) quickly accelerate the bunches before the collider ring. A large number of RF cavities are required in the RCS to ensure that over 90% of the muons survive in each ring. The effects of cavities higher-order modes on transverse coherent stability have been looked at in detail, including the one of a bunch offset in the cavities, along with possible mitigation measures. In the collider ring, the decay of high-energy muons is a challenge for heat load management and radiation shielding. A tungsten liner would protect the superconducting magnet from decay products. Impedance and related beam stability have been investigated to identify the minimum vacuum chamber radius and transverse damper properties required for stable beams.

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP17

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Received ※ 29 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 01 November 2023

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THBP36

Study of the Performance of the CERN Proton Synchrotron Internal Dump

simulation, beam-losses, proton, vacuum

555

T. Pugnat, L.S. Esposito, M. Giovannozzi, C. Hernalsteens, A. Huschauer, S. Niang
CERN, Meyrin, Switzerland
D. Domange, E. Gnacadja, R. Tesse
ULB, Bruxelles, Belgium

In the framework of the LHC Injector Upgrade project, a new internal dump for the CERN Proton Synchrotron (PS) has been designed, installed, and successfully commissioned. This device is meant to move rapidly into the beam and stop charged particles over several turns to provide protection to the PS hardware against beam-induced damage. The performance of the dump should ensure efficient use throughout the PS energy range, i.e. from injection at 2 GeV (kinetic energy) to flat top at 26 GeV (total energy). In this paper, detailed numerical simulations are presented, carried out with a combination of sophisticated beam dynamics and beam-matter interaction codes, assessing the behaviour of stopped or scattered particles. The results of these numerical simulations are compared with the data collected during the routine operation of the PS and its internal dump.

Poster THBP36 [0.609 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP36

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Received ※ 26 September 2023 — Revised ※ 05 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 28 October 2023

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THBP38

Two-Dimensional Longitudinal Painting at Injection into the CERN PS Booster

injection, linac, target, emittance

563

S.C.P. Albright, F. Asvesta, B. Bielawski, C. Bracco, P.K. Skowroński, R. Wegner
CERN, Meyrin, Switzerland

To inject highest beam intensities at the transfer from Linac4 into the four rings of the PS Booster (PSB) at CERN, protons must be accumulated during up to 148 turns in total. With the conventional, fixed chopping pattern this process results in an approximately rectangular distribution in the longitudinal phase space. As the bucket shape in the PSB does not correspond to this distribution, the process leads to longitudinal mismatch, contributing to emittance growth and reduced transmission. The field in the last accelerating cavity of Linac4 can be modulated, which leads to fine corrections of the extracted beam energy. At the same time, the chopping pattern can be varied. Combining both allows injecting a near uniform longitudinal distribution whose boundary corresponds to an iso-Hamiltonian contour of the RF bucket, hence significantly reducing mismatch. In an operational context, the longitudinal painting must be controlled in a way that allows easy intensity variation, and can even require different painting configurations for each of the four PSB rings. This contribution presents the first demonstration of longitudinal painting in the PSB, and its impact on beam performance.

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP38

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Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 24 October 2023

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THBP42

Longitudinal Loss of Landau Damping in Double Harmonic RF Systems below Transition Energy

damping, impedance, space-charge, proton

575

L. Intelisano, H. Damerau, I. Karpov
CERN, Meyrin, Switzerland

Landau damping plays a crucial role in ensuring single-bunch stability in hadron synchrotrons. In the longitudinal plane, loss of Landau damping (LLD) occurs when a coherent mode of oscillation moves out of the incoherent synchrotron frequency band. The LLD threshold is studied for a purely inductive impedance below transition energy, specifically considering the common case of double harmonic RF systems operating in counter-phase at the bunch position. The additional focusing force due to beam-induced voltage distorts the potential well, ultimately collapsing the bucket. The limiting conditions for a binomial particle distribution are calculated. Furthermore, the contribution focuses on the configuration of the higher-harmonic RF system at four times the fundamental RF frequency operating in phase. In this case, the LLD threshold shows a non-monotonic behavior with a zero threshold where the derivative of the synchrotron frequency distribution is positive. The findings are obtained employing semi-analytical calculations using the MELODY code.

Poster THBP42 [1.710 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP42

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Received ※ 30 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 14 October 2023

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THBP47

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

impedance, simulation, coupling, 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]

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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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THBP59

Tomographic Longitudinal Phase Space Reconstruction of Bunch Compression at ISIS

proton, simulation, operation, extraction

625

B.S. Kyle, H.V. Cavanagh, A. Seville, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is an 800 MeV, high intensity, rapid-cycling synchrotron (RCS) used as a driver for a spallation neutron and muon spectroscopy (¿SR) facility. The intensity-limited beam and RCS operation at ISIS poses significant challenges, with non-adiabatic acceleration and space charge forces resulting in distortions to the Hamiltonian longitudinal dynamics. Effective modelling of the machine and benchmarking of models with beam measurements is essential both to improving machine performance, and to the development of the proposed ISIS II facility. The tomographic principle is a well-established tool for the reconstruction of the longitudinal phase space (LPS) of synchrotron beams. Is it operationally desirable for the ISIS accelerator to provide longitudinally compressed proton beams for ¿SR instrumentation. A new bunch compression scheme has been developed and validated using tomography. A reconstruction of the LPS of the ISIS high-intensity proton beam is presented, along with accompanying benchmarking measurements and beam physics simulations.

Poster THBP59 [0.907 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP59

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Received ※ 01 October 2023 — Revised ※ 09 October 2023 — Accepted ※ 20 October 2023 — Issued ※ 25 October 2023

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