Accelerator Systems
Paper Title Page
MOA2I2
Challenges & Status of HIAF Project and Brief Introduction of Ciads Project in China  
 
  • J.C. Yang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  HIAF (High Intensity heavy ion Accelerator Facility) is a proposed new accelerator facility for advances in the nuclear physics and related research fields in China. The construction of the accelerator complex began in 2018 and is scheduled to be complete by the end of 2025. In the past several years, the prototypes have been developed successfully for these innovative technologies. In this presentation, progress and status of civil engineering and infrastructure construction of HIAF are presented, R&D on critical accelerator techniques and prototypes of core devices are introduced. Accelerator Driven Sub-critical System (ADS) is considered to be the optimum method of converting spent fuel into short-lived isotopes. Currently, ADS is still in the transitional phase from key technologies tackling to systematic and integrated research. As one of the national major science and technology infrastructures, the China initiative Accelerator Driven System (CiADS) will be the world¿s first prototype of ADS facility at megawatt level to explore the safe and proper technology of nuclear waste disposal. The brief introduction of CiADS will be given in this presentation.  
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MOA4I1 Design of a Fixed-Field Accelerating Ring for High Power Applications 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 icon 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
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TUC3I1 Ultra-low Emittance Bunches from Laser Cooled Ion Traps for Intense Focal Points 128
 
  • S.J. Brooks
    BNL, Upton, New York, USA
 
  Laser-cooled ion traps are used to prepare groups of ions in very low temperature states, exhibiting such phenomena as Coulomb crystallization. This corresponds to very small normalized RMS emittances of 10-13–10-12 m, compared to typical accelerator ion sources in the 10-7–10-6 m range. Such bunches could potentially be focused a million times smaller, compensating for the lower number of ions per bunch. Such an ultra-low emittance source could enable high-specific-luminosity colliders where reduced beam current and apertures are needed to produce a given luminosity. Further advances needed to enable such colliders include linear, helical or ring cooling channel designs for increased bunch number or current throughput. Novel high density focal points using only a single bunch also appear possible, where the high density particles collide with themselves. At collider energies ~100 GeV, these approach the nuclear density and offer a way of studying larger quantities of neutron star matter and other custom nuclear matter in the lab.  
slides icon Slides TUC3I1 [167.328 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC3I1  
About • Received ※ 26 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 24 October 2023
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TUC3I2 Shaping High Brightness and Fixed Target Beams with the CERN PSB Charge Exchange Injection 135
 
  • C. Bracco, S.C.P. Albright, F. Asvesta, G.P. Di Giovanni, F. Roncarolo
    CERN, Meyrin, Switzerland
 
  CERN adopted the charge exchange injection technique for the first time in the PS Booster after Long Shutdown 2. This allowed to overcome space charge limitations, tailor high brightness beams for the LHC and deliver high intensity flux of protons to the fixed target experiments. Details on the concept, physics, hardware and diagnostic tools are presented while retracing the exciting steps of the successful commissioning period and the first years of operation with this system. A look to the future is taken by explaining the next stages to achieve the ambitious Luminosity targets foreseen for the HL-LHC era.  
slides icon Slides TUC3I2 [19.053 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC3I2  
About • Received ※ 01 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 24 October 2023
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TUC3I3 Laser Stripping of H⁻ Beam 141
 
  • T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, Y. Liu, A.R. Oguz
    ORNL, Oak Ridge, Tennessee, USA
  • N.J. Evans
    ORNL RAD, Oak Ridge, Tennessee, USA
  • P.K. Saha
    JAEA/J-PARC, Tokai-mura, Japan
 
  Basic principles of laser assisted charge exchange injection for H⁻ ion andH0 beams are presented. Theoretical aspects of electromagnetic interaction of laser with hydrogen atom and H⁻ ions are discussed. Laser excitation, photoionizatio and interaction of atoms and ions with a strong electro-magnetic field are discussed and compared. Different techniques of LACE for stripping of high current stochastic beams are presented. The optimum parameters of LACE are estimated and compared for various ion beam energies. Experimental development of laser stripping at the SNS are reviewed. Future plans of LACE at the SNS and J-PARC are discussed.  
slides icon Slides TUC3I3 [1.790 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC3I3  
About • Received ※ 04 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 01 November 2023
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TUC3C1
Muon Production Target at J-PARC  
 
  • M.S. Matoba
    KEK, Tokai, Ibaraki, Japan
 
  The Muon Science Facility (MUSE) at the Japan Proton Accelerator Research Complex (J-PARC MLF) generates intense pulsed muon beams (3 GeV, 25 Hz, up to 0.33 mA), which are used to study various elementary particle and material life. A muon production target is installed on the proton beamline between the 3 GeV synchrotron and the neutron target. The target is made of high-purity isotropic graphite IG-430U (Toyo Tanso), which is exposed to a strong radiation environment and heats up to high temperatures during beam irradiation. In 2014, the fixed target was replaced by a rotating target, which is now operating smoothly at 800 kW. The ring-shaped graphite, 250 mm in inner diameter, 350 mm in outer diameter, and 20 mm thick, is divided into three sections to prevent failure due to thermal stress caused by thermal imbalance. By introducing a solid lubricant made from tungsten disulfide, we have achieved a long life of the rotating support under high heat, high radiation, and vacuum, which is expected to be about ten years. In the presentation, the current status of the target development and monitoring system will be reported.  
slides icon Slides TUC3C1 [2.721 MB]  
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TUC3C2
Challenging of Muon Acceleration for Muon Colliders  
 
  • K. Yonehara
    Fermilab, Batavia, Illinois, USA
 
  The US HEP community presents a high interest on multi-TeV muon colliders in the last P5 meetings which will perform as a Higgs factory to characterize a Higgs boson in high precision. Besides, it will be a discovery machine to reveal various mysteries in high energy particle physics and cosmology. Because muons are tertiary particles and are decayed with a finite lifetime, a novel muon acceleration technology is required. In this presentation, I will show the identified challenge in the muon acceleration and demonstrate the new technology what we have researched and developed, and discuss a strategic plan and milestone for the future R&D.  
slides icon Slides TUC3C2 [1.925 MB]  
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TUC4I1 A Kicker Impedance Reduction Scheme with Diode Stack and Resistor at the RCS in J-PARC 162
 
  • Y. Shobuda, H. Harada, P.K. Saha, T. Takayanagi, F. Tamura, T. Togashi, Y. Watanabe, K. Yamamoto, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  At the 3-GeV Rapid Cycling Synchrotron (RCS) within the Japan Proton Accelerator Research Complex (J-PARC), kicker impedance causes beam instability. A 1-MW beam with a large emittance can be delivered to the Material and Life Science Experimental Facility (MLF) by suppressing beam instabilities without the need for a transverse feedback system¿simply by turning off the sextuple magnets. However, we require other high-intensity and high-quality beams with smaller emittances for the Main Ring (MR). To address this, we proposed a scheme for suppressing the kicker impedance using a diode stack and resistors, which effectively reduces beam instability. Importantly, these devices have a negligible effect on the extracted beam from the RCS.  
slides icon Slides TUC4I1 [2.713 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4I1  
About • Received ※ 26 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023
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TUC4I2 Development of an Impedance Model for the ISIS Synchrotron and Predictions for the Head-Tail Instability 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 icon 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
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TUC4C1 Beam Coupling Impedance of the Main Extraction Kickers in the CERN PS 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 icon 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
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TUC4C2 Mitigating Collimation Impedance and Improving Halo Cleaning with New Optics and Settings Strategy of the HL-LHC Betatron Collimation System 183
 
  • B. Lindström, R. Bruce, X. Buffat, R. De Maria, L. Giacomel, P.D. Hermes, D. Mirarchi, N. Mounet, T.H.B. Persson, S. Redaelli, R. Tomás García, F.F. Van der Veken, A. Wegscheider
    CERN, Meyrin, Switzerland
 
  Funding: Work supported by the HL-LHC project
With High Luminosity Large Hadron Collider (HL-LHC) beam intensities, there are concerns that the beam losses in the dispersion suppressors around the betatron cleaning insertion might exceed the quench limits. Furthermore, to maximize the beam lifetime it is important to reduce the impedance as much as possible. The collimators constitute one of the main sources of impedance in HL-LHC, given the need to operate with small collimator gaps. To improve this, a new optics was developed which increases the beta function in the collimation area, as well as the single pass dispersion from the primary collimators to the downstream shower absorbers. Other possible improvements from orbit bumps, to further enhance the locally generated dispersion, and from asymmetric collimator settings were also studied. The new solutions were partially tested with 6.8 TeV beams at the LHC in a dedicated machine experiment in 2022. In this paper, the new performance is reviewed and prospects for future operational deployment are discussed.
 
slides icon Slides TUC4C2 [2.222 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-TUC4C2  
About • Received ※ 01 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 28 October 2023
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WEC3I1 Self-Consistent Injection Painting for Space Charge Mitigation 258
 
  • N.J. Evans, V.S. Morozov
    ORNL RAD, Oak Ridge, Tennessee, USA
  • T.V. Gorlov, A.M. Hoover
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: This work was conducted at UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy, with partial funding provided by Field Work Proposal ORNL-ERKCS41.
I will present results of experiments at the Spallation Neutron Source to implement a method of phase space painting we refer to as ¿eigenpainting¿, in which beam is injected along one eigenvector of the transfer matrix of a ring with full coupling.  The method and resultant distribution were initially proposed by Danilov almost to linearize the space charge force, minimizing space charge tune spread. In the theoretically ideal case this so-called Danilov distribution has uniform charge distribution, elliptical envelope in real-space, and a vanishing 4D transverse emittance. Such a beam can be maintained throughout injection. The Danilov distribution has implications for increasing beam intensity beyond the conventional space charge limit through a reduction of both tune spread and shift, and increasing collider performance. This talk will present current limits on beam quality, and details of the preparation of the optics in the SNS accumulator ring, including the installation of new solenoid magnets. The status of experiments to improve beam quality and characterize the interesting dynamical implications of the defining features of the Danilov distribution will also be discussed.
 
slides icon Slides WEC3I1 [2.687 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC3I1  
About • Received ※ 28 September 2023 — Revised ※ 10 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 23 October 2023
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WEC3I2 Mitigation of Space Charge Effects in RHIC and Its Injectors 264
 
  • V. Schoefer, C.J. Gardner, K. Hock, H. Huang, K. Zeno
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
The RHIC collider physics program, in particular its polarized proton and low energy heavy ion components, present unique challenges for maintaining collider performance in the presence of space charge effects. Polarized beam performance is especially sensitive to emittance increases, since they decrease both the luminosity and polarization. Operation of the collider with gold beams at sub-injection energies (down to 3.85 GeV/n Au) with space charge tune shifts up to 0.1 required special care to optimize both the ion lifetime and its interaction with the electron-beam cooler. We describe the operational experience in these modes and some of the mitigation efforts.
 
slides icon Slides WEC3I2 [10.503 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC3I2  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 14 October 2023
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WEC3C1 Beyond 1-MW Scenario in J-Parc Rapid-Cycling Synchrotron 270
 
  • K. Yamamoto, T. Morishita, K. Moriya, H. Okita, P.K. Saha, Y. Shobuda, F. Tamura, I. Yamada, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The 3-GeV rapid cycling synchrotron at the Ja-pan Pro-ton Accelerator Research Complex was designed to provid 1-MW proton beams to the Material and Life Sci-ence Experimental Facility and Main Ring. Thanks to the improvement works of the accelerator system, we success-fully accelerate 1-MW beam with quite small beam loss. Currently, the beam power of RCS is limited by the lack of anode current in the RF cavity system rather than the beam loss. Recently we developed a new acceleration cavity that can accelerate a beam with less anode current. This new cavity enables us not only to reduce require-ment of the anode power supply but also to accelerate more than 1-MW beam. We have started to consider the way to achieve beyond 1-MW beam acceleration. So far, it is expected that up to 1.5-MW beam can be accelerated after replacement of the RF cavity. We have also contin-ued study to achieve more than 2 MW beam in J-PARC RCS.  
slides icon Slides WEC3C1 [2.787 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC3C1  
About • Received ※ 25 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 26 October 2023
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WEC3C2 High Energy Cooling 274
 
  • V.A. Lebedev
    Fermilab, Batavia, Illinois, USA
 
  The paper considers methods of particle cooling applicable to beam cooling in high energy hadron colliders at the collision energy. Presently, there are two major methods of the cooling the electron cooling and stochastic cooling. The later, in application to colliders, requires exceptionally large frequency band of cooling system. Presently two methods are considered. They are the optical stochastic cooling (OSC) and the coherent electron cooling (CEC). OSC and CEC are essentially extensions of microwave stochastic cooling, operating in 1-10 GHz frequency range, to the optical frequencies enabling bands up to 30-300 THz. The OSC uses undulators as a pickup and a kicker, and an optical amplifier for signal amplification, while the CEC uses an electron beam for all these functions. We discuss major limitations, advantages and disadvantages of electron and stochastic cooling systems.  
slides icon Slides WEC3C2 [1.054 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC3C2  
About • Received ※ 26 September 2023 — Revised ※ 06 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 30 October 2023
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WEC3C3 Simulations and Measurements of Betatron and Off-momentum Cleaning Performance in the Energy Ramp at the LHC 279
 
  • N. Triantafyllou, R. Bruce, M. D’Andrea, K.A. Dewhurst, B. Lindström, D. Mirarchi, S. Redaelli, F.F. Van der Veken
    CERN, Meyrin, Switzerland
 
  The Large Hadron Collider (LHC) is equipped with a multistage collimation system that protects the machine against unavoidable beam losses at large betatron and energy offsets at all stages of operation. Dedicated validations and an understanding in simulations of the collimation performance are crucial for the energy ramp from 450 GeV to 6.8 TeV because complex changes of optics and orbit take place in this phase. Indeed, the betatron functions are reduced in all experiments for an efficient setup of the collisions at top energy. In this paper, simulations of the betatron and off-momentum cleaning during the energy ramp are presented. A particular focus is given to the off-momentum losses at the start of the ramp. The simulation results are benchmarked against experimental data, demonstrating the accuracy of the newly developed tools used for the simulations.  
slides icon Slides WEC3C3 [1.641 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC3C3  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 19 October 2023
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WEC4I1 RF Systems of J-PARC Proton Synchrotrons for High-Intensity Longitudinal Beam Optimization and Handling 305
 
  • F. Tamura, R. Miyakoshi, M. Nomura, H. Okita, T. Shimada, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  • K. Hara, K. Hasegawa, C. Ohmori, K. Seiya, Y. Sugiyama, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
 
  The application of magnetic alloy (MA) cores to the accelerating rf cavities in high intensity proton synchrotrons was pioneered for the J-PARC synchrotrons, the RCS and MR. The MA loaded cavities can generate high accelerating voltages. The wideband frequency response of the MA cavity enables the frequency sweep to follow the velocity change of protons without the tuning loop. The dual harmonic operation, where a single cavity is driven by the superposition of the fundamental and second harmonic rf voltages, is indispensable for the longitudinal bunch shaping to alleviate the space charge effects in the RCS. These advantages of the MA cavity are also disadvantages when looking at them from a different perspective. Since the wake voltage consists of several harmonics, which can cause bucket distortion or coupled-bunch instabilities, the beam loading compensation must be multiharmonic. The operation of tubes in the final stage amplifier is not trivial when accelerating very high intensity beams; the output current is high and the anode voltageis also multiharmonic. We summarize our effort against these issues in the operation of the RCS and MR for more than 10 years.  
slides icon Slides WEC4I1 [6.932 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I1  
About • Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 29 October 2023
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WEC4I2 Development of Dual-harmonic RF System for CSNS-II 312
 
  • X. Li, X. Li, W. Long, W.J. Wu, C.L. Zhang
    IHEP, Beijing, People’s Republic of China
  • Y. Liu
    DNSC, Dongguan, People’s Republic of China
  • B. Wu
    IHEP CSNS, Guangdong Province, People’s Republic of China
 
  The upgrade of the China Spallation Neutron Source (CSNS-II) encompasses the development of a dual har-monic RF system for the Rapid Cycling Synchrotron (RCS). The objective of this system is to achieve a maxi-mum second harmonic voltage of 100 kV. To meet this requirement, a high gradient cavity is being used in place of the traditional ferrite loaded cavity. Magnetic alloy (MA) loaded cavities, which can attain very high field gradients, have demonstrated their suitability for high-intensity proton synchrotrons. As a result, designing an RF system with MA-loaded cavities has emerged as a primary focus. Over the past decade, substantial ad-vancements have been made in the development of MA-loaded cavities at CSNS. This paper provides an overview of the RF system that incorporates the MA-loaded cavity and presents the high-power test results of the system.  
slides icon Slides WEC4I2 [6.449 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I2  
About • Received ※ 28 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 22 October 2023
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WEC4C1 Magnetic Alloy Loaded Cavities in J-PARC and CERN 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 icon 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
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WEC4C2 Multiharmonic Buncher for the Isolde Superconducting Recoil Separator Project 321
 
  • J.L. Muñoz, I. Bustinduy, P.J. González, A. Kaftoosian, L.C. Medina, S. Varnasseri
    ESS Bilbao, Zamudio, Spain
  • I. Martel
    University of Huelva, Huelva, Spain
 
  Funding: This work has been supported by the European Union ¿NextGenerationEU program
The ISOLDE Superconducting Recoil Separator (ISRS) is a proposal of building a very compact separator ring as an instrument in the HIE-ISOLDE facility. The injection of the HIE-ISOLDE beam into this ring requires a more compact bunch structure, so a Multi-Harmonic Buncher device is proposed for this task. The MHB will operate at a frequency of 10.128 MHz, which is a 10% of the linac frequency, and would be installed before the RFQ. The MHB is desgined as a two electrodes system, and the MHB signal, composed for the first four harmonics of the fundamental frequency, is fed into the electrodes that are connected to the central conductor of a coaxial waveguides. The full design of the MHB is presented, including electromagnetic optimization of the electrode shape, optimization of the weights of each of the harmonic contribution, mechanical and thermal design of the structure. The RF generation and electronics to power up the device are also presented. A solution that generates directly the composed signal andis then amplified by a solid state power amplifier is also presented in this contribution.
 
slides icon Slides WEC4C2 [4.165 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4C2  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 09 October 2023 — Issued ※ 27 October 2023
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THBP01 ESS-Bilbao RFQ Power Coupler: Design, Simulations and Tests 433
 
  • I. Bustinduy, A. Conde, D. Fernández-Cañoto, N. Garmendia, P.J. González, G. Harper, A. Kaftoosian, J. Martin, J.L. Muñoz
    ESS Bilbao, Zamudio, Spain
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  ESS-Bilbao RFQ power coupler is presented. The RFQ operates at 352.2 MHz and will accelerate the 32 mA proton beam extracted from the ion source up to 3.0MeV. The RFQ will complete the ESS-Bilbao injector, that can be used by the ARGITU neutron source or as a stand-alone facility. The machining of the RFQ is finished, and vacuum tests as well as low power RF measurements have been carried out. The presented power coupler is a first iteration of the device, designed to be of easier and faster manufacturing than what might be needed for future upgrades of the linac. The coupler does not have active cooling and no brazing has been needed to assemble it. It can operate at the RF power required by the RFQ but at lower duty cycles. The dielectric window is made of polymeric material, so it can withhold the assembly using vacuum seals and bolts. Design and manufacturing issues are reported in the paper, as well as the RF tests that have been carried out at medium power. Multipacting calculations compared to measured values during conditioning are also reported. High power tests of the coupler have also been performed in the ISIS-FETS RFQ and are also described here.  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP01  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 11 October 2023 — Issued ※ 28 October 2023
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THBP02 FFA Magnet for Pulsed High Power Proton Driver 436
 
  • J.-B. Lagrange, C.W. Jolly, D.J. Kelliher, A.P. Letchford, S. Machida, I. Rodríguez, C.T. Rogers, J.D. Speed
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • S.J. Brooks
    BNL, Upton, New York, USA
  • T.-J. Kuo
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
 
  Fixed Field Alternating gradient (FFA) accelerator is considered as a proton driver for the next generation spallation neutron source (ISIS-II). To demonstrate its suitability for high intensity operation, an FFA proton prototype ring is planned at RAL, called FETS-FFA. The main magnets are a critical part of the machine, and several characteristics of these magnets require attention, such as doublet spiral structure, essential operational flexibility in terms of machine optics and control of the fringe field extent from the nonlinear optics point of view. This paper will discuss the design of the prototype magnet for FETS-FFA ring.  
poster icon Poster THBP02 [5.871 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP02  
About • Received ※ 02 October 2023 — Revised ※ 08 October 2023 — Accepted ※ 12 October 2023 — Issued ※ 23 October 2023
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THBP03 ESS-Bilbao RFQ Static Tuning Algorithm and Simulation 440
 
  • J.L. Muñoz, I. Bustinduy, A. Conde, N. Garmendia, P.J. González, J. Martin, V. Toyos
    ESS Bilbao, Zamudio, Spain
 
  The ESS-Bilbao RFQ operates at 352.2 MHz. The machining of the four RFQ segments has finished and the assembly and tuning operations will follow shorly. The static tuning and field flatness are provided by an array of 60 plunger tuners, distributed along the 3.2 meters length of the structure. There are four tuners per segment per quadrant, except for one of the segments where the ports are used by the power couplers. A bead-pull setup will provide the measurements of the field profiles, that will be collected in a matrix built up with the contributions of individual tuners. The conventional approach of inverting the matrix to get the optimum tuners distribution is explored, as well as additional optimization method. Particularly, a genetic optimization algorithm provides a very succesful tuning of the RFQ. The solution provided by this approach will be used as the initial configuration of the tuners before the bead-pull measurements are carried out. Additionally, static and dynamic tuning of the RFQ is studied by high performance computing simulations of the RFQ. The analysis of the in-house computational electromagnetics suite used for these tasks is also discussed in this paper.  
poster icon Poster THBP03 [2.285 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP03  
About • Received ※ 29 September 2023 — Revised ※ 08 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 28 October 2023
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THBP04 Machine Protection System for the Proposed TATTOOS Beamline at HIPA 443
 
  • J. Snuverink, P. Bucher, R. Eichler, M. Hartmann, D.C. Kiselev, D. Reggiani, E. Zimoch
    PSI, Villigen PSI, Switzerland
 
  IMPACT (Isotope and Muon Production with Advanced Cyclotron and Target Technology) is a proposed upgrade project for the High Intensity Proton Accelerator (HIPA) at the Paul Scherrer Institute (PSI). As part of IMPACT, a new radioisotope target station, TATTOOS (Targeted Alpha Tumour Therapy and Other Oncological Solutions) is planned. The TATTOOS beamline and target will be located near the UCN (Ultra Cold Neutron source) target area, branching off from the main UCN beamline. In particular, the 590 MeV proton beamline is designed to operate at a beam intensity of 100 ¿A (60 kW), requiring a continuous splitting of the main beam by an electrostatic splitter. The philosophy of the machine protection system (MPS) for the TATTOOS beamline will not differ significantly from the one already implemented for HIPA. However, it is particularly important for TATTOOS to avoid damage to the target due to irregular beam conditions. We will show the diagnostic systems involved and how the requirements of the machine protection system can be met. Emergency scenarios and protective measures are also discussed.  
poster icon Poster THBP04 [3.228 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP04  
About • Received ※ 01 October 2023 — Revised ※ 03 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 21 October 2023
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THBP05 CERN SPS Dilution Kicker Vacuum Pressure Behaviour under Unprecedented Beam Brightness 447
 
  • F.M. Velotti, M.J. Barnes, W. Bartmann, H. Bartosik, E. Carlier, G. Favia, I. Karpov, K.S.B. Li, N. Magnin, L. Mether, V. Senaj, P. Van Trappen, C. Zannini
    CERN, Meyrin, Switzerland
 
  The Super Proton Synchrotron (SPS) is the second largest synchrotron at CERN and produces high-brightness beams for the Large Hadron Collider (LHC). Recently, the dilution kicker (MKDH) of the SPS beam dump system (SBDS) has demonstrated unanticipated behaviour under high beam brightness conditions. During the 2022 and 2023 beam commissioning, the MKDH, which is routinely pulsed at high voltage, was subjected to intensities of up to 288 bunches of 2·1011 protons per bunch and bunch lengths as low as 1.5 ns. Under these conditions, all the SPS kickers and septa exhibited a rapid vacuum pressure rise and a significant temperature increase with the MKDH playing the dominant effect in restricting the maximum line density that can be attained. This paper presents the results of the collected data, emphasizes the dependence on beam parameters, and introduces a probabilistic model to illustrate the effect of MKDH conditioning observed to forecast the pressure behaviour. Finally, potential countermeasures and outlook are discussed.  
poster icon Poster THBP05 [1.913 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-THBP05  
About • Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 19 October 2023
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FRA2I3 Summary of the Working Group C on Accelerator Systems 670
 
  • S. Machida
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • H. Huang
    BNL, Upton, New York, USA
  • P.K. Saha
    JAEA/J-PARC, Tokai-mura, Japan
 
  This is a summary of the presentations and discussions of the Accelerator System working group at the 68th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams.  
slides icon Slides FRA2I3 [0.262 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-HB2023-FRA2I3  
About • Received ※ 22 November 2023 — Accepted ※ 29 November 2023 — Issued ※ 15 December 2023  
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