TUVIR —  MC3 & MC4 Presentations   (12-May-20   09:00—12:00)
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CBETA Beam Results: The First Multi-Turn SRF ERL  
  • K.E. Deitrick
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  CBETA will recirculate multiple beams of different energies in a single accelerator using a SRF cryomodule-based linac and a nonscaling FFA lattice constructed using novel permanent magnets. Electron beams are accelerated making four passes through the cryomodule decelerated in subsequent passes in energy recovery mode. This presentation includes a brief overview of the facility then presents experimental results and comparisons with simulations.  
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Overview of Low Energy Spread Laser Proton Accelerators  
  • X.Q. Yan
    PKU, Beijing, People’s Republic of China
  Laser-driven ion acceleration is a frontier of laser plasma physics which has been developed in recent decades. Energetic ion beam generation in the interaction of laser and matter has unique properties such as high brilliance, compact size, ultrashort duration, and low emittance. These advantages are particularly suitable for many potential applications. The ion acceleration methods like TNSA, RPA and shock acceleration are discussed here. The theories and experiments for monoenergetic proton/ion beams are reviewed in this talk. If laser acceleration is combined with a fully functional beam line, realizing precise manipulation of the proton beams, availability, maintainability and inspectability (RAMI), which paves the way for applications, such as proton therapy, diagnosis of plasma magnetic field (LITP), proton imaging, warm dense matter and so on.  
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Progress in Plasma-Based Accelerators Driven by Particle Beams  
  • S. Corde
    LOA, Palaiseau, France
  Funding: Supported by the European Research Council under the European Union’s Horizon 2020 research and innovation programme (Miniature beam-driven Plasma Accelerators project, Grant Agreement No. 715807).
Plasma wakefield acceleration is a promising concept for a compact particle accelerator with broad range of future applications, such as high energy physics or secondary light sources. Plasma can sustain accelerating fields > 100 GeV/m, driven by intense laser pulses (LWFA) or particle beams (PWFA). The latter one allows to overcome limitations on the accelerating length caused by the speed difference between laser and accelerated beam in LWFA, but requires a dense beam of relativistic particles to drive the wakefield, which are produced by expensive large scale conventional accelerators. Here we report on experimental progress made in PWFA using particle beam drivers from conventional RF accelerators as well as from LWFA. First, we will present results on the successful acceleration of positron beams in a PWFA, and discuss intrinsic limitations, from experimental measurements, theory and simulations. Second, we will show the first demonstration of a PWFA powered by laser-accelerated electron beams, and will discuss new possibilities opened by these results, from the direct optical imaging of the accelerating structure to the generation of bright beams beyond the state of the art.
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Toward High Power Efficiency and High Gradient Dielectric Assist Accelerating Structures  
  • D. Satoh, R. Kuroda, H. Toyokawa
    AIST, Tsukuba, Ibaraki, Japan
  • S. Mori, M. Yoshida
    KEK, Ibaraki, Japan
  A dielectric assist accelerating (DAA) structure, a type of dielectric loaded accelerating structures, is greatly superior in power efficiency compared with the conventional disk-loaded copper structures. The advantage of DAA structure is that it has an extremely high quality (Q0 > 105) factor and a high shunt impedance (Zsh > 600 MOhm/m) at room temperature since the electromagnetic field distribution of the accelerating mode can be controlled by the geometry of its structure to reduce the wall loss on metallic surface. However, in a prototype of a DAA structure, multipactor discharge occurred between the ceramic cells, and high gradient operation has not been achieved. In order to solve this issue while maintaining the high-power efficiency of DAA structure, we have been studying ceramic materials and the surface coating so as to reduce the secondary electron emission coefficient. The structural optimization of the DAA structure for high gradient operation is examined by the cavity simulations. In this conference, the latest results of the simulation study and the experiments of DAA structure are reported.  
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Energy Spread Control in Plasma Wakefield Accelerators  
  • R.T.P. D’Arcy
    DESY, Hamburg, Germany
  In order to apply plasma wakefield accelerators for free electron lasers and/or colliders it is mandatory to reduce the beam energy spread from the many-percent-level down to 0.1% without affecting the beam emittance. Recently such reduction has been observed in particle-driven plasma-wakefield accelerators. The correlated energy spread is reduced by using the interaction of the electron bunch with its wakefields generated in the plasma. This contribution reviews the working principle of such a dechirper and the experimental observations in the different test facilities. A view on future directions and various ideas and concepts is presented.  
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TUVIR06 Review of Required Proof-Of-Principle-Experiments Towards a Muon Collider 16
  • A. Variola
    INFN/LNF, Frascati, Italy
  The HEP scientific community is, at present, exploring different scenario concerning the post LHC era. In fact, after the Higgs boson discovery, the future facility will require not only to improve the LHC and HL-LHC physics programs but also to continue the search for phenomena beyond the Standard Model into an extended energy domain. In this framework ideas and proposals, together with the results obtained in accelerator research, introduce a scenario where the feasibility of a multi-TeV muon collider should be explored. This article will describe the advantages provided by the muon collider scheme. The proposed schemes will be shortly illustrated. The very important recent results obtained in proof-of-principle experiments will be subsequently described. Finally, for each scheme, the future possible directions for proof-of-principle experiments to demonstrate the muon collider feasibility will be presented.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2020-TUVIR06  
About • paper received ※ 31 May 2020       paper accepted ※ 12 June 2020       issue date ※ 23 October 2020  
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Terahertz-Driven Acceleration of a Relativistic Electron Beam  
  • M.T. Hibberd, V. Georgiadis, D.M. Graham
    The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
  • R.B. Appleby, E.J.H. Smith
    UMAN, Manchester, United Kingdom
  • G. Burt, O.J. Finlay, A.L. Healy, S.P. Jamison, D. Lake
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.K. Jones, T.H. Pacey, Y.M. Saveliev, E.W. Snedden, D.A. Walsh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  Funding: Science and Technology Facilities Council (STFC)
Terahertz (THz) pulses are emerging as unique driving sources for next-generation particle accelerators, offering unprecedented control over the energy-time phase-space of a particle bunch compared with conventional radio-frequency technology. Acceleration, compression and streaking have all been demonstrated with low energy electrons* but operation at relativistic energies remains limited. Here, we report on the first demonstration of phase-velocity matched acceleration of a relativistic electron beam in a THz-driven linear accelerator**, confirmed through frequency-tuning of the THz source. Operating in the highest beam energy (35 MeV) and charge (60 pC) regimes reported to date, we use narrowband THz pulses centered at 0.4 THz to drive collinear THz-electron interaction in a dielectric-lined waveguide. We exploit multi-cycle energy modulation of a chirped 6 ps electron bunch to extract the often-inaccessible longitudinal phase-space distribution, highlighting the potential for THz-driven bunch diagnostics. We also show injection-time-dependent preferential energy gain/loss for 2 ps bunches, demonstrating a route to whole-bunch acceleration of sub-ps relativistic electron beams.
*D. Zhang et al. Nat. Photonics 12, 336 (2018).
**M.T. Hibberd et al. arXiv:1908.04055.
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A Compact High Repetition Rate Free-Electron Laser Based on the Advanced Wakefield Accelerator Technology  
  • A. Zholents, D.S. Doran, W.G. Jansma, M. Kasa, A. Nassiri, J.G. Power, S. Sorsher, K.J. Suthar, E. Trakhtenberg, G.J. Waldschmidt, J.Z. Xu
    ANL, Lemont, Illinois, USA
  • S. Baturin, P. Piot, W.H. Tan
    Northern Illinois University, DeKalb, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
  Funding: Supported by a U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357.
Significant progress has been made at ANL in the design of a hard x-ray facility based on the array of compact free-electron lasers (FELs). Each FEL uses a dedicated compact collinear wakefield accelerator (CWA) delivering 5-GeV electron bunches with up to 50-kHz repetition rate. The CWA uses a cylindrical copper structure with a 2-mm ID and fine corrugations on the wall. It causes a 10-nC "drive" bunch to radiate an electromagnetic field with a field amplitude ~ 100 MV/m acting on a ~ 0.3-nC "witness" bunch trailing behind. The entire accelerator will span a few tens of meters and will contain almost identical ~ 0.5-m-long accelerator modules. The accelerator module includes a 4-cm-long transition section with an output coupler, a notch filter, an integrated offset monitor, bellows, pumping and water-cooling ports. All CWAs share a 1-GeV superconducting linac for production of asymmetrically shaped drive bunches with a high repetition rate. The design of this accelerator is nearing completion and will be presented. Plans for the prototyping and "cold" testing of the accelerator module will be discussed, and first results of the test with the electron beam will be presented.
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Outcome of the Horizon 2020 Design Study EuPRAXIA for a European Plasma Accelerator Facility  
  • A. Specka
    LLR, Palaiseau, France
  • R.W. Aßmann, A.R. Maier, A. Martinez de la Ossa, J. Osterhoff, P.A. Walker, M.K. Weikum
    DESY, Hamburg, Germany
  • A. Chancé, P.A.P. Nghiem
    CEA-IRFU, Gif-sur-Yvette, France
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • M.-E. Couprie
    SOLEIL, Gif-sur-Yvette, France
  • B. Cros
    CNRS LPGP Univ Paris Sud, Orsay, France
  • G. Dattoli
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • N. Delerue
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • U. Dorda
    SCK•CEN, Mol, Belgium
  • M. Ferrario, A. Mostacci, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • L.A. Gizzi
    INO-CNR, Pisa, Italy
  • B. Hidding, C.P. Welsch, G.X. Xia
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • B. Hidding, D.A. Jaroszynski, Z.M. Sheng
    USTRAT/SUPA, Glasgow, United Kingdom
  • A.R. Maier
    University of Hamburg, Hamburg, Germany
  • V. Malka
    Weizmann Institute of Science, Physics, Rehovot, Israel
  • F. Mathieu
    LULI, Palaiseau, France
  • A. Mostacci
    Sapienza University of Rome, Rome, Italy
  • Z. Najmudin
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • R. Pattathil
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • L.O. Silva
    Instituto Superior Tecnico, Lisbon, Portugal
  • R. Walczak
    JAI, Oxford, United Kingdom
  • R. Walczak
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • G.X. Xia
    The University of Manchester, Manchester, United Kingdom
  Funding: This work was supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782.
Although plasma accelerators can sustain unmatched accelerating gradients - up to three orders of magnitude beyond what RF-based machines reach - their performance and use in applications is still limited by beam quality, in particular a large inherent energy spread. With the aim to demonstrate user readiness, the EuPRAXIA design study has, since 2015, developed various concepts and techniques to improve electron beam quality, increase machine stability, and study possible applications of plasma accelerators. Consisting of a consortium of 41 laboratories from Europe, Asia and the US, the EuPRAXIA project thus presents the first design of a dedicated multi-GeV electron accelerator research infrastructure based on plasma accelerator technology. This presentation explains some of the technical innovations proposed in the EuPRAXIA design and highlights the general facility concept as well as the possible role of the project within the accelerator landscape.
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Status of the Construction and Commissioning of ESS  
  • M. Eshraqi
    ESS, Lund, Sweden
  The ESS linac under construction will deliver beam at 2 GeV with an unprecedented 5 MW average power. The commissioning of the Normal Conducting Drift Tube linac should be completed by the first quarter of 2020. The status of the commissioning and of the construction of ESS will be reported. The plans and challenges towards operation of the ESS will be described and reviewed.  
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TUVIR11 IFMIF/EVEDA RFQ Beam Commissioning at Nominal 125 mA Deuteron Beam in Pulsed Mode 21
  • F. Grespan, L. Bellan, M. Comunian, E. Fagotti, A. Palmieri, F. Scantamburlo
    INFN/LNL, Legnaro (PD), Italy
  • T. Akagi, Y. Hirata, K. Kondo, Y. Shimosaki, T. Shinya, M. Sugimoto
    QST, Aomori, Japan
  • B. Bolzon, N. Chauvin, J. Marroncle
    CEA-IRFU, Gif-sur-Yvette, France
  • P. Cara
    IFMIF/EVEDA, Rokkasho, Japan
  • H. Dzitko, A. Jokinen, I.M. Moya
    F4E, Germany
  • D. Jimenez-Rey, I. Podadera
    CIEMAT, Madrid, Spain
  • A. Marqueta
    Fusion for Energy, Garching, Germany
  • Á. Rodríguez Páramo
    ESS Bilbao, Zamudio, Spain
  In summer 2019 the IFMIF/EVEDA Radio Frequency Quadrupole (RFQ) accelerated its nominal 125 mA deuteron beam current up to 5 MeV, with 90% transmission for pulses of 1 ms at 1Hz. The Linear IFMIF Prototype Accelerator (LIPAc) is a high intensity deuteron linear accelerator; it is the demonstrator of the International Fusion Material Irradiation Facility (IFMIF). In particular the RFQ is the longest and most powerful ever operated. An intense campaign of measurements have been performed in Rokkasho to characterize several performances of this complex machine: transmission, emittances, energy spectrum and beam loading. The history and the results of the commissioning until this important project milestone are here described. An overview of the activities planned to reach CW operation is also presented.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2020-TUVIR11  
About • paper received ※ 31 May 2020       paper accepted ※ 17 August 2020       issue date ※ 09 October 2020  
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Spiral2 Project Status  
  • P. Dolegieviez, R. Ferdinand
    GANIL, Caen, France
  The commissioning of the SPIRAL2 facility at GANIL is running well. A first proton beam was accelerated up to the nominal energy (33 MeV, 200µA) by the superconducting LINAC in November 2019. This paper describes the status of the SPIRAL2 facility following the authorization given by the French Nuclear Safety authority in July 2019 : cryomodule qualifications, conditioning of the superconducting cavities, safety system tests, beam commissioning and first beam sent to the Neutron For Science (NFS) experimental area. The short term objectives are finally presented.  
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Status Report on a Low Energy High Intensity High Charge State Heavy Ion Accelerator Facility at Imp  
  • L.T. Sun, W.P. Dou, X. Fang, J.W. Guo, Y.H. Guo, Y. He, X. Jin, L. Jing, J.Q. Li, L.B. Li, X.J. Liu, L. Lu, W. Lu, H.Y. Ma, W. Ma, Y.M. Ma, L.B. Shi, L.P. Sun, F.F. Wang, Z.J. Wang, B.M. Wu, W. Wu, X.B. Xu, Y. Yang, Y.H. Zhai, B. Zhang, P. Zhang, W.H. Zhang, X.Z. Zhang, Z.L. Zhang, Z.M. Zhang, B. Zhao, H.W. Zhao, T.M. Zhu
    IMP/CAS, Lanzhou, People’s Republic of China
  Funding: This work was supported the NSFC (Contract no. 11427904).
A Low Energy heavy ion Accelerator Facility LEAF has been built at IMP. Aiming to prototype the room temperature front end of High Intensity Heavy Ion Accelerator Facility (HIAF)* and also serve as a stand-along operation facility for multi-discipline physics researches using high intensity low energy heavy ion beams, LEAF can accelerate high intensity ion beams of M/q=2~7 up to 0.7 MeV/u, typically >1 emA U34+. The LEAF 81.25 MHz 4-vane RFQ** has been fully commissioned to its design power. Machine study with the ion beams of M/Q=2~7 has been completed, and the typical transmission efficiency of the RFQ can reach 97%. An acceleration efficiency of 85% for heavy ion beams can be made with a multi-harmonic buncher (MHB). With a superconducting ECR ion source, highly charged uranium ion beams are available that enables the successful acceleration of high intensity uranium ion beams with LEAF. This paper will present the design and preliminary commissioning results of the facility, and future plan of an IH type DTL to tune the output energy will also be discussed.
* J. C. Yang, et al., Nucl. Instrum. Methods Phys. Res., Sect. B 317, 263 (2013).
** W. Ma, et al., Nucl. Instrum. Methods Phys. Res., Sect. A 847, 130 (2017).
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TUVIR14 The SIS100 RF Systems - Updates and Recent Progress 26
  • J.S. Schmidt, R. Balß, M. Frey, P. Hülsmann, H. Klingbeil, H.G. König, U. Laier, D.E.M. Lens, A. Stuhl
    GSI, Darmstadt, Germany
  Within the FAIR (Facility for Antiproton and Ion Research) accelerator complex, the SIS100 synchrotron will provide high intensity proton to heavy ion beams to the various beam lines and storage rings. This paper presents the recent progress of the SIS100 overall RF system in its preparation towards installation. The RF system is split into four separate sub-systems with a significant number of RF stations. Each RF station consists of a ferrite or MA loaded cavity, a tetrode-based power amplifier, a switching mode power supply unit and various analogue or digital LLRF components for feedback and feedforward control. Fourteen ferrite cavities will generate the accelerating field, while nine cavities loaded with magnetic alloy ring cores are used for bunch compression. The barrier bucket system, which is used to apply a pre-compression of the beam, as well as the longitudinal feedback system for stabilization of beam oscillations will be realized by in total four cavities of the same type.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2020-TUVIR14  
About • paper received ※ 03 June 2020       paper accepted ※ 11 June 2020       issue date ※ 10 August 2020  
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TUVIR15 Long-Term Beam Position and Angle Stabilities for the J-Parc Main Ring Slow Extraction 31
  • M. Tomizawa, Y. Arakaki, T. Kimura, Y. Komatsu, S. Murasugi, R. Muto, K. Okamura, Y. Shirakabe, E. Yanaoka
    KEK, Ibaraki, Japan
  A 30 GeV proton beam accelerated in the J-PARC Main Ring (MR) is slowly extracted by the third integer resonant extraction and delivered to the hadron experimental hall. One of the critical issues in slow extraction of a high intensity proton beam is an inevitable beam loss caused by the extraction process at septum devices. A unique dynamic bump scheme for the slow extraction has been applied to reduce the beam loss. We have achieved 51 kW stable operation at 5.2s cycle in the recent physics run. The extraction efficiency is very high, typically 99.5%. However, the dynamic bump scheme is sensitive to the beam orbit angle at the first electrostatic septum (ESS1). The orbit angle of the dynamic bump must be sometimes readjusted to keep such a high efficiency. In future, diffusers and/or a silicon bend crystal, which are more sensitive to the orbit angle fluctuation, would be introduced to achieve a further high slow extraction efficiency. A long-term stability of the beam position and angle at the ESS1 has been investigated. We observed the fluctuations synchronized with tides and estimated to be due to tunnel expansion.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2020-TUVIR15  
About • paper received ※ 09 June 2020       paper accepted ※ 11 June 2020       issue date ※ 30 July 2020  
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Demonstration of Superconducting RF Linac Flexibility for High Power Linacs  
  • C.C. Peters, G.D. Johns
    ORNL RAD, Oak Ridge, Tennessee, USA
  • S.-H. Kim, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy.
Future high-power Superconducting Radio Frequency (SRF) Linacs may need to operate with strict limits on beam trip durations on the order of a few seconds. In order to provide the desired beam powers, these linacs will require significant numbers of SRF cavities which increases the probability of beam trips. The SRF linac at the Spallation Neutron Source (SNS) is currently operating with 81 SRF cavities to provide 1 GeV protons for neutron production. The typical SRF cavity trip rate is approximately 2-3 trips per week each with a recovery time on the order of a few minutes. Occasionally an SRF cavity cannot be recovered and downstream cavities must be re-phased in order to recover the beam energy. Downtime for this type of event is on the order of 30 minutes. As part of a controlled test, it has been demonstrated that after an SRF cavity trip high-power production-quality beam can be recovered automatically without operator intervention in only a few seconds.
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Status of the Raon Heavy Ion Accelerator Project  
  • M. Kwon
    IBS, Daejeon, Republic of Korea
  The RAON heavy ion superconducting linac project is under way in Korea. The RAON consists of the 200 MeV/u superconducting linac delivering 400 kW of beam power to various targets to promote cutting edge science researches. The installation the accelerator components has started in May 2019. It aims to achieve the first beam by the end of 2021. The current status of the project will be presented.  
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