IPAC2021 - Classification: MC4: Hadron Accelerators / A17 High Intensity Accelerators

Paper	Title	Page
TUPAB196	Achievement of 100-kW Beam Operation in CSNS/RCS	1869
	S.Y. Xu, Y.W. An, J. Chen, L. Huang, M.Y. Huang, Y. Li, S. Wang IHEP, Beijing, People’s Republic of China H.Y. Liu, X.H. Lu IHEP CSNS, Guangdong Province, People’s Republic of China
	The China Spallation Neutron Source (CSNS) is an accelerator-based science facility. CSNS is designed to accelerate proton beam pulses to 1.6 GeV kinetic energy, striking a solid metal target to produce spallation neutrons. CSNS has two major accelerator systems, a linear accelerator (80 MeV Linac) and a 1.6 GeV rapid cycling synchrotron(RCS). The RCS accumulates and accelerates the proton beam to 1.6 GeV and then extracts the beam to the target at the repetition rate of 25 Hz. The Beam commissioning of CSNS/RCS had been started since April 2017. The most important issue in high-power beam commissioning is the beam loss control, as well as the control of induced activities, to meet the requirement of manual maintenance. A series of beam loss optimization work had been done to reduce the uncontrolled beam loss. At the end of February 2020, the CSNS reached the design beam power of 100 kW with very low uncontrolled beam loss.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB196
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 28 August 2021
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TUPAB200	Status of the Electron Lens for Space Charge Compensation in SIS18	1880
	K. Schulte-Urlichs, S. Artikova, D. Ondreka, P.J. Spiller GSI, Darmstadt, Germany P. Apse-Apsitis, I. Steiks Riga Technical University, Riga, Latvia M. Droba, O. Meusel, H. Podlech, K.I. Thoma IAP, Frankfurt am Main, Germany
	At GSI a project has been initiated to investigate the option of space charge compensation (SCC) by use of an electron lens in order to overcome space charge (SC) limits in the synchrotrons SIS18 and SIS100 for the Facility for Antiproton and Ion Research (FAIR). The repeated crossing of resonance lines due to the synchrotron motion in bunched beams is considered one of the main drivers of SC induced beam loss in the synchrotrons. Electron lenses provide a compensation of ion beam SC by virtue of their negative charge interacting with the ions in the overlap region while a time-varying compensation can be achieved by the modulation of the electron beam. In order to demonstrate space charge compensation of bunched ion beams, an electron lens is under development for the application in SIS18. In this contribution, the status of the electron lens design will be reported putting special emphasis on its main components: the RF modulated electron gun, that is being developed within an ARIES collaboration, and the magnet system.
	Poster TUPAB200 [1.869 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB200
About •	paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021
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TUPAB201	Vacuum Tube Operation Tuning for a High Intensity Beam Acceleration in J-PARC RCS	1884
	M. Yamamoto, M. Nomura, H. Okita, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	Tetrode vacuum tubes in the J-PARC RCS are used under a reduced filament voltage condition compared with the rating value to prolong the tube life time. One tube reached the end of life in 2020; it was the first case in the RCS after 60,000 hours operation time. This means the reduced filament voltage works well because the tube has been running beyond an expected life time suggested by the tube manufacturer. However, an electron emission from the filament is decreased by the reduced filament voltage. Although the large amplitude of the anode current is necessary for the high intensity beam acceleration to compensate an wake voltage, a solid-state amplifier to drive a control grid circuit almost reaches the output power limit because of the poor electron emission. We changed the filament voltage reduction rate from 15 % to 5 %; the required power of the solid-state amplifier was fairly reduced, whereas the accelerated beam power was same. We will describe the measurement results of the vacuum tube parameters in terms of the filament voltage tuning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB201
About •	paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 02 September 2021
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TUPAB204	Upgrade of Los Alamos Accelerator Facility as a Fusion Prototypic Neutron Source	1890
	Y.K. Batygin, E.J. Pitcher LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by US DOE under contract 89233218CNA000001 The Fusion Prototypic Neutron Source (FPNS) is considered to be a testbed for scientific understanding of material degradation in future nuclear fusion reactors. The primary mission of FPNS is to provide a damage rate in samples of 8-11 dpa/calendar year with He/dpa ratio of 10 appm in irradiation volume of 50 cubic cm or larger with irradiation temperature 300-1000 deg C and flux gradient less than 20%/cm in the plane of the sample. Los Alamos Neutron Science Center (LANSCE) is an attractive candidate for FPNS project. Accelerator Facility was designed and operated for an extended period as a 0.8-MW Meson Factory. Existing setup of the LANSCE accelerator complex can nearly fulfill requirements of the fusion neutron source station. The primary function of the upgraded accelerator systems is the safe and reliable delivery of a 1.25-mA continuous proton beam current at 800-MeV beam energy from the switchyard to the target assembly to create 1 MW power of proton beam interacting with a solid tungsten target. The present study describes existing accelerator setup and further development required to meet the needs of FPNS project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB204
About •	paper received ※ 14 May 2021 paper accepted ※ 02 June 2021 issue date ※ 21 August 2021
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TUPAB205	Advancement of LANSCE Front End Accelerator Facility	1894
	Y.K. Batygin, D. Gorelov, S.S. Kurennoy, J.W. Lewellen, N.A. Moody, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by US DOE under contract 89233218CNA000001 The LANSCE accelerator started routine operation in 1972 as a high-power facility for fundamental research and national security applications. To reduce long-term operational risk, we propose to develop a new Front End of accelerator facility. It contains 100-keV injector with 3-MeV RFQ, and 6-tanks Drift Tube Linac to accelerate particles up to energy of 100 MeV. The low-energy injector concept includes two independent transports merging H⁺ and H⁻ beams at the entrance of RFQ. Beamlines are aimed to perform preliminary beam bunching in front of accelerator section with subsequent simultaneous acceleration of two different beams in a single RFQ. The paper discusses design topics of new Front End of accelerator facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB205
About •	paper received ※ 12 May 2021 paper accepted ※ 28 May 2021 issue date ※ 14 August 2021
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TUPAB208	FETS-FFA Ring Study	1901
	J.-B. Lagrange, D.J. Kelliher, A.P. Letchford, S. Machida, C.R. Prior, C.T. Rogers STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom S.J. Brooks BNL, Upton, New York, USA C. Brown Brunel University, Middlesex, United Kingdom J. Pasternak STFC/RAL, Chilton, Didcot, Oxon, United Kingdom J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom E. Yamakawa JAI, Egham, Surrey, United Kingdom
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, providing a proton beam with a power of 0.2~MW. Detailed studies are under way for a major upgrade, including the use of Fixed Field alternating gradient Accelerator (FFA). A proof-of-principle FFA ring, called FETS-FFA is planned to investigate the feasibility of this kind of machine for the required MW beam power. This paper discusses the study of the FETS-FFA ring case.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB208
About •	paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 14 August 2021
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TUPAB210	Construction Status of the COMET Experimental Facility	1907
	Y. Fukao, K. Agari, H. Akiyama, E. Hirose, M. Ieiri, Y. Igarashi, M.I. Iio, N. Kamei, Y. Katoh, Y. Komatsu, R. Kurasaki, M. Maki, S. Makimura, S. Mihara, M. Minakawa, Y. Morino, F. Muto, H. Nishiguchi, T. Okamura, K. Sasaki, Y. Sato, S. Sawada, N. Sumi, H. Takahashi, K.H. Tanaka, A. Toyoda, K. Ueno, H. Watanabe, Y. Yamanoi, M.Y. Yoshida KEK, Tsukuba, Japan
	COMET (COherent Muon to Electron Transition) is an experimental project that hunts for a phenomenon of the conversion from the muon to the electron (mu-e conversion). The mu-e conversion violates the lepton flavor universality and its discovery indicates a proof of the physics beyond the standard model of the particle physics. The experiment utilizes a high-intensity primary proton-beam of J-PARC (Japan Proton Accelerator Research Complex). The proton beam is injected to a target about 700mm long to generate a high intensity muon beam so as to accumulate huge statistics and achieve the final goal of a sensitivity of 10^-16. Construction of the experimental facility is underway at a high pace towards an engineering run in 2022 and the first physics run in 2023. In this presentation, we would like to present a current status of the COMET facility construction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB210
About •	paper received ※ 17 June 2021 paper accepted ※ 21 June 2021 issue date ※ 13 August 2021
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TUPAB211	The Accelerator System of IFMIF-DONES Multi-MW Facility	1910
	I. Podadera, A. Ibarra, D. Jimenez-Rey, J. Mollá, C. Oliver, D. Regidor, R. Varela, C. de la Morena CIEMAT, Madrid, Spain F. Arbeiter, V. Hauer KIT, Eggenstein-Leopoldshafen, Germany N. Bazin, J. Dumas, L. Seguí CEA-IRFU, Gif-sur-Yvette, France L. Bellan, E. Fagotti, A. Palmieri, A. Pisent INFN/LNL, Legnaro (PD), Italy N. Chauvin, S. Chel, J. Plouin CEA-DRF-IRFU, France G. Duglue, H. Dzitko F4E, Germany W.C. Grabowski, A. Wysocka-Rabin NCBJ, Świerk/Otwock, Poland M. Jaksic, T. Tadic RBI, Zagreb, Croatia W. Królas IFJ-PAN, Kraków, Poland R. López, A. Muñoz, C. Prieto Empresarios Agrupados, Madrid, Spain O. Nomen, M. Sanmartí, F.J. Saura Esteban, B.K. Singh, D. Sánchez-Herranz IREC, Sant Adria del Besos, Spain
	Funding: Work carried out within EUROfusion Consortium and DONES-PreP and received funding from the Euratom research and training programme 2014-2018 & 2019-2020 under grants agreement No. 633053 & 870186 The IFMIF-DONES (DEMO-Oriented Neutron Early Source) facility has passed the preliminary design phase and the detailed design phase is very much advanced. Next step will be the preparation phase for the construction of the facility. The DONES facility aims at developing a database of fusion-like radiation effects on materials to be used in future fusion reactors up to damage levels expected in the EU DEMO. It will be based on an intense neutron source created by an accelerated deuteron beam (125 mA CW, 40 MeV) impinging on a liquid lithium curtain. The DONES Accelerator Systems (AS) will be responsible of delivering this 5 MW D⁺ beam with very high availability. The beam acceleration will be performed by several stages: an ion source and LEBT, an RFQ, a MEBT, an SRF Linac and a HEBT transporting and delivering an optimized profile down to the target. A high power RF system and several ancillaries will ensure the equipment is properly operated. This contribution will report the present status of the AS design, the main challenges faced, the R&D programme to overcome them, and the prospects for the construction and commissioning of the DONES accelerator in Granada (Spain).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB211
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 27 August 2021
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WEXB02	Upgrading J-PARC Accelerator for Hyper Kamiokande Project
	Y. Sato KEK, Ibaraki, Japan
	The Main Ring (MR) of J-PARC has supplied high-intensity proton beams for the T2K long-baseline neutrino oscillation experiment since 2010. The present beam power reaches 515 kW. To observe the CP violation in the lepton sector, more protons need to be delivered to the neutrino target. The project upgrading the beam power to 1.3 MW started in the MR, where hardware upgrades and beam dynamics improvements are scheduled to handle higher repetition and increase protons per pulse. The MR upgrade and the Hyper Kamiokande project, which has recently been approved and started construction, will open up a new phase of leptonic CP violation studies.
	Slides WEXB02 [3.505 MB]
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WEXB08	Beam Losses and Emittance Growth Studies at the Record High Space-Charge in the Booster	2552
	V.D. Shiltsev, J.S. Eldred, V.A. Lebedev, K. Seiya Fermilab, Batavia, Illinois, USA
	Comprehensive studies of high intensity proton beams in the 0.4-8 GeV FNAL Booster synchrotron have revealed interesting nonlinear dynamics of the beam losses and emittance growth at the record high dQ_SC=0.6. We report the results of the studies and directions of further improvements to prepare the Booster to the era of even higher intensity operation with new 0.8 GeV PIP-II linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB08
About •	paper received ※ 24 May 2021 paper accepted ※ 02 July 2021 issue date ※ 17 August 2021
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WEPAB177	Consideration of Triple-Harmonic Operation for the J-PARC RCS	3020
	H. Okita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Furusawa, Y. Sugiyama KEK, Tokai, Ibaraki, Japan K. Hara, K. Hasegawa, M. Nomura, C. Ohmori, T. Shimada, F. Tamura, M. Yamamoto, M. Yoshii KEK/JAEA, Ibaraki-Ken, Japan
	The wideband magnetic alloy (MA) cavities are employed in the J-PARC RCS. The dual-harmonic operation, in which each MA cavity is driven by superposition of the fundamental accelerating voltage and the second harmonic voltage, significantly improves the bunching factor and is indispensable for acceleration of the high intensity beams. The original LLRF control system was replaced with the new system in 2019, which can control the amplitudes of the higher harmonics as well as the fundamental and second harmonics. Therefore we consider to use additionally the third harmonic voltage for further improvement of the bunching factor during acceleration. By the triple-harmonic operation, the flat RF bucket can be realized with a higher synchronous phase and improvement of the bunching factor is expected. In this presentation, we describe the longitudinal simulation studies of the triple-harmonic operation. Also the preliminary test results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB177
About •	paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 19 August 2021
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WEPAB178	Non-Adiabatic Longitudinal Bunch Manipulation at Flattop of the J-PARC MR	3023
	F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	The J-PARC MR delivers the high-intensity proton beams for the neutrino experiment. Eight bunches of high peak current are extracted by the extraction kickers, therefore the neutrino beam has a similar time structure. The new Intermediate Water Cherenkov Detector (IWCD) will be constructed for the future neutrino experiment and a low peak time structure is desired by the IWCD. Thus, we consider bunch manipulation at flattop of the MR for reducing the peak current. The manipulation requires a longer repetition period to extend the flattop. This reduces the output beam power. The manipulation should be quickly done to minimize the loss of the beam power. Also, the beam gap must be kept for the rise time of the extraction kicker. We propose a non-adiabatic bunch manipulation using the multiharmonic rf voltage. By using the neighbor harmonic of the accelerating harmonic, the first and eighth bunches can be decelerated and accelerated, respectively. After a certain period, the rf phase is flipped to pi for debunching. Thanks to the initial deceleration and acceleration, the beam gap for the kickers is kept. We present the concept and the longitudinal simulation result.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB178
About •	paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 28 August 2021
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WEPAB179	Recent Status of J-PARC Rapid Cycling Synchrotron	3027
	K. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The 3 GeV rapid cycling synchrotron (RCS) at the Ja-pan Proton Accelerator Research Complex (J-PARC) provides more than 500 kW beams to the Material and Life Science Facility (MLF) and Main Ring (MR). In such a high-intensity hadron accelerator, even losing less than 0.1% of the beam can cause many problems. Such lost protons can cause serious radio-activation and accelerator component malfunctions. Therefore, we have been continuing a beam study to achieve high-power operation. In addition, we have also improved and maintained the accelerator components to enable stable operation. This paper reports the status of the J-PARC RCS over the last two years.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB179
About •	paper received ※ 13 May 2021 paper accepted ※ 25 June 2021 issue date ※ 22 August 2021
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THXX02	High Power Proton Sources for Neutrino Science
	E. Pozdeyev Fermilab, Batavia, Illinois, USA
	Neutrinos can hold keys to fundamental physics questions such as the origin of matter, the relationship between nature’s forces, formation of the most extreme objects in galaxies, and how we come to exist at all. Accelerator-based neutrino facilities provide platforms that enable comprehensive studies of neutrinos and their properties. In this paper, we discuss high-power proton accelerators for neutrino science and describe their parameters, features, and critical technologies.
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Paper

Title

Page

Achievement of 100-kW Beam Operation in CSNS/RCS

1869

S.Y. Xu, Y.W. An, J. Chen, L. Huang, M.Y. Huang, Y. Li, S. Wang
IHEP, Beijing, People’s Republic of China
H.Y. Liu, X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China

The China Spallation Neutron Source (CSNS) is an accelerator-based science facility. CSNS is designed to accelerate proton beam pulses to 1.6 GeV kinetic energy, striking a solid metal target to produce spallation neutrons. CSNS has two major accelerator systems, a linear accelerator (80 MeV Linac) and a 1.6 GeV rapid cycling synchrotron(RCS). The RCS accumulates and accelerates the proton beam to 1.6 GeV and then extracts the beam to the target at the repetition rate of 25 Hz. The Beam commissioning of CSNS/RCS had been started since April 2017. The most important issue in high-power beam commissioning is the beam loss control, as well as the control of induced activities, to meet the requirement of manual maintenance. A series of beam loss optimization work had been done to reduce the uncontrolled beam loss. At the end of February 2020, the CSNS reached the design beam power of 100 kW with very low uncontrolled beam loss.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB196

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 28 August 2021

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TUPAB200

Status of the Electron Lens for Space Charge Compensation in SIS18

1880

K. Schulte-Urlichs, S. Artikova, D. Ondreka, P.J. Spiller
GSI, Darmstadt, Germany
P. Apse-Apsitis, I. Steiks
Riga Technical University, Riga, Latvia
M. Droba, O. Meusel, H. Podlech, K.I. Thoma
IAP, Frankfurt am Main, Germany

At GSI a project has been initiated to investigate the option of space charge compensation (SCC) by use of an electron lens in order to overcome space charge (SC) limits in the synchrotrons SIS18 and SIS100 for the Facility for Antiproton and Ion Research (FAIR). The repeated crossing of resonance lines due to the synchrotron motion in bunched beams is considered one of the main drivers of SC induced beam loss in the synchrotrons. Electron lenses provide a compensation of ion beam SC by virtue of their negative charge interacting with the ions in the overlap region while a time-varying compensation can be achieved by the modulation of the electron beam. In order to demonstrate space charge compensation of bunched ion beams, an electron lens is under development for the application in SIS18. In this contribution, the status of the electron lens design will be reported putting special emphasis on its main components: the RF modulated electron gun, that is being developed within an ARIES collaboration, and the magnet system.

Poster TUPAB200 [1.869 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB200

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paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 17 August 2021

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TUPAB201

Vacuum Tube Operation Tuning for a High Intensity Beam Acceleration in J-PARC RCS

1884

M. Yamamoto, M. Nomura, H. Okita, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

Tetrode vacuum tubes in the J-PARC RCS are used under a reduced filament voltage condition compared with the rating value to prolong the tube life time. One tube reached the end of life in 2020; it was the first case in the RCS after 60,000 hours operation time. This means the reduced filament voltage works well because the tube has been running beyond an expected life time suggested by the tube manufacturer. However, an electron emission from the filament is decreased by the reduced filament voltage. Although the large amplitude of the anode current is necessary for the high intensity beam acceleration to compensate an wake voltage, a solid-state amplifier to drive a control grid circuit almost reaches the output power limit because of the poor electron emission. We changed the filament voltage reduction rate from 15 % to 5 %; the required power of the solid-state amplifier was fairly reduced, whereas the accelerated beam power was same. We will describe the measurement results of the vacuum tube parameters in terms of the filament voltage tuning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB201

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paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 02 September 2021

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TUPAB204

Upgrade of Los Alamos Accelerator Facility as a Fusion Prototypic Neutron Source

1890

Y.K. Batygin, E.J. Pitcher
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract 89233218CNA000001
The Fusion Prototypic Neutron Source (FPNS) is considered to be a testbed for scientific understanding of material degradation in future nuclear fusion reactors. The primary mission of FPNS is to provide a damage rate in samples of 8-11 dpa/calendar year with He/dpa ratio of 10 appm in irradiation volume of 50 cubic cm or larger with irradiation temperature 300-1000 deg C and flux gradient less than 20%/cm in the plane of the sample. Los Alamos Neutron Science Center (LANSCE) is an attractive candidate for FPNS project. Accelerator Facility was designed and operated for an extended period as a 0.8-MW Meson Factory. Existing setup of the LANSCE accelerator complex can nearly fulfill requirements of the fusion neutron source station. The primary function of the upgraded accelerator systems is the safe and reliable delivery of a 1.25-mA continuous proton beam current at 800-MeV beam energy from the switchyard to the target assembly to create 1 MW power of proton beam interacting with a solid tungsten target. The present study describes existing accelerator setup and further development required to meet the needs of FPNS project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB204

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paper received ※ 14 May 2021 paper accepted ※ 02 June 2021 issue date ※ 21 August 2021

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TUPAB205

Advancement of LANSCE Front End Accelerator Facility

1894

Y.K. Batygin, D. Gorelov, S.S. Kurennoy, J.W. Lewellen, N.A. Moody, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by US DOE under contract 89233218CNA000001
The LANSCE accelerator started routine operation in 1972 as a high-power facility for fundamental research and national security applications. To reduce long-term operational risk, we propose to develop a new Front End of accelerator facility. It contains 100-keV injector with 3-MeV RFQ, and 6-tanks Drift Tube Linac to accelerate particles up to energy of 100 MeV. The low-energy injector concept includes two independent transports merging H⁺ and H⁻ beams at the entrance of RFQ. Beamlines are aimed to perform preliminary beam bunching in front of accelerator section with subsequent simultaneous acceleration of two different beams in a single RFQ. The paper discusses design topics of new Front End of accelerator facility.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB205

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paper received ※ 12 May 2021 paper accepted ※ 28 May 2021 issue date ※ 14 August 2021

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TUPAB208

FETS-FFA Ring Study

1901

J.-B. Lagrange, D.J. Kelliher, A.P. Letchford, S. Machida, C.R. Prior, C.T. Rogers
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
S.J. Brooks
BNL, Upton, New York, USA
C. Brown
Brunel University, Middlesex, United Kingdom
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
E. Yamakawa
JAI, Egham, Surrey, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK, providing a proton beam with a power of 0.2~MW. Detailed studies are under way for a major upgrade, including the use of Fixed Field alternating gradient Accelerator (FFA). A proof-of-principle FFA ring, called FETS-FFA is planned to investigate the feasibility of this kind of machine for the required MW beam power. This paper discusses the study of the FETS-FFA ring case.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB208

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paper received ※ 19 May 2021 paper accepted ※ 08 July 2021 issue date ※ 14 August 2021

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TUPAB210

Construction Status of the COMET Experimental Facility

1907

Y. Fukao, K. Agari, H. Akiyama, E. Hirose, M. Ieiri, Y. Igarashi, M.I. Iio, N. Kamei, Y. Katoh, Y. Komatsu, R. Kurasaki, M. Maki, S. Makimura, S. Mihara, M. Minakawa, Y. Morino, F. Muto, H. Nishiguchi, T. Okamura, K. Sasaki, Y. Sato, S. Sawada, N. Sumi, H. Takahashi, K.H. Tanaka, A. Toyoda, K. Ueno, H. Watanabe, Y. Yamanoi, M.Y. Yoshida
KEK, Tsukuba, Japan

COMET (COherent Muon to Electron Transition) is an experimental project that hunts for a phenomenon of the conversion from the muon to the electron (mu-e conversion). The mu-e conversion violates the lepton flavor universality and its discovery indicates a proof of the physics beyond the standard model of the particle physics. The experiment utilizes a high-intensity primary proton-beam of J-PARC (Japan Proton Accelerator Research Complex). The proton beam is injected to a target about 700mm long to generate a high intensity muon beam so as to accumulate huge statistics and achieve the final goal of a sensitivity of 10^-16. Construction of the experimental facility is underway at a high pace towards an engineering run in 2022 and the first physics run in 2023. In this presentation, we would like to present a current status of the COMET facility construction.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB210

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paper received ※ 17 June 2021 paper accepted ※ 21 June 2021 issue date ※ 13 August 2021

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TUPAB211

The Accelerator System of IFMIF-DONES Multi-MW Facility

1910

I. Podadera, A. Ibarra, D. Jimenez-Rey, J. Mollá, C. Oliver, D. Regidor, R. Varela, C. de la Morena
CIEMAT, Madrid, Spain
F. Arbeiter, V. Hauer
KIT, Eggenstein-Leopoldshafen, Germany
N. Bazin, J. Dumas, L. Seguí
CEA-IRFU, Gif-sur-Yvette, France
L. Bellan, E. Fagotti, A. Palmieri, A. Pisent
INFN/LNL, Legnaro (PD), Italy
N. Chauvin, S. Chel, J. Plouin
CEA-DRF-IRFU, France
G. Duglue, H. Dzitko
F4E, Germany
W.C. Grabowski, A. Wysocka-Rabin
NCBJ, Świerk/Otwock, Poland
M. Jaksic, T. Tadic
RBI, Zagreb, Croatia
W. Królas
IFJ-PAN, Kraków, Poland
R. López, A. Muñoz, C. Prieto
Empresarios Agrupados, Madrid, Spain
O. Nomen, M. Sanmartí, F.J. Saura Esteban, B.K. Singh, D. Sánchez-Herranz
IREC, Sant Adria del Besos, Spain

Funding: Work carried out within EUROfusion Consortium and DONES-PreP and received funding from the Euratom research and training programme 2014-2018 & 2019-2020 under grants agreement No. 633053 & 870186
The IFMIF-DONES (DEMO-Oriented Neutron Early Source) facility has passed the preliminary design phase and the detailed design phase is very much advanced. Next step will be the preparation phase for the construction of the facility. The DONES facility aims at developing a database of fusion-like radiation effects on materials to be used in future fusion reactors up to damage levels expected in the EU DEMO. It will be based on an intense neutron source created by an accelerated deuteron beam (125 mA CW, 40 MeV) impinging on a liquid lithium curtain. The DONES Accelerator Systems (AS) will be responsible of delivering this 5 MW D⁺ beam with very high availability. The beam acceleration will be performed by several stages: an ion source and LEBT, an RFQ, a MEBT, an SRF Linac and a HEBT transporting and delivering an optimized profile down to the target. A high power RF system and several ancillaries will ensure the equipment is properly operated. This contribution will report the present status of the AS design, the main challenges faced, the R&D programme to overcome them, and the prospects for the construction and commissioning of the DONES accelerator in Granada (Spain).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB211

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 27 August 2021

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WEXB02

Upgrading J-PARC Accelerator for Hyper Kamiokande Project

Y. Sato
KEK, Ibaraki, Japan

The Main Ring (MR) of J-PARC has supplied high-intensity proton beams for the T2K long-baseline neutrino oscillation experiment since 2010. The present beam power reaches 515 kW. To observe the CP violation in the lepton sector, more protons need to be delivered to the neutrino target. The project upgrading the beam power to 1.3 MW started in the MR, where hardware upgrades and beam dynamics improvements are scheduled to handle higher repetition and increase protons per pulse. The MR upgrade and the Hyper Kamiokande project, which has recently been approved and started construction, will open up a new phase of leptonic CP violation studies.

Slides WEXB02 [3.505 MB]

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WEXB08

Beam Losses and Emittance Growth Studies at the Record High Space-Charge in the Booster

2552

V.D. Shiltsev, J.S. Eldred, V.A. Lebedev, K. Seiya
Fermilab, Batavia, Illinois, USA

Comprehensive studies of high intensity proton beams in the 0.4-8 GeV FNAL Booster synchrotron have revealed interesting nonlinear dynamics of the beam losses and emittance growth at the record high dQ_SC=0.6. We report the results of the studies and directions of further improvements to prepare the Booster to the era of even higher intensity operation with new 0.8 GeV PIP-II linac.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB08

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paper received ※ 24 May 2021 paper accepted ※ 02 July 2021 issue date ※ 17 August 2021

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WEPAB177

Consideration of Triple-Harmonic Operation for the J-PARC RCS

3020

H. Okita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Furusawa, Y. Sugiyama
KEK, Tokai, Ibaraki, Japan
K. Hara, K. Hasegawa, M. Nomura, C. Ohmori, T. Shimada, F. Tamura, M. Yamamoto, M. Yoshii
KEK/JAEA, Ibaraki-Ken, Japan

The wideband magnetic alloy (MA) cavities are employed in the J-PARC RCS. The dual-harmonic operation, in which each MA cavity is driven by superposition of the fundamental accelerating voltage and the second harmonic voltage, significantly improves the bunching factor and is indispensable for acceleration of the high intensity beams. The original LLRF control system was replaced with the new system in 2019, which can control the amplitudes of the higher harmonics as well as the fundamental and second harmonics. Therefore we consider to use additionally the third harmonic voltage for further improvement of the bunching factor during acceleration. By the triple-harmonic operation, the flat RF bucket can be realized with a higher synchronous phase and improvement of the bunching factor is expected. In this presentation, we describe the longitudinal simulation studies of the triple-harmonic operation. Also the preliminary test results are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB177

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paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 19 August 2021

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WEPAB178

Non-Adiabatic Longitudinal Bunch Manipulation at Flattop of the J-PARC MR

3023

F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

The J-PARC MR delivers the high-intensity proton beams for the neutrino experiment. Eight bunches of high peak current are extracted by the extraction kickers, therefore the neutrino beam has a similar time structure. The new Intermediate Water Cherenkov Detector (IWCD) will be constructed for the future neutrino experiment and a low peak time structure is desired by the IWCD. Thus, we consider bunch manipulation at flattop of the MR for reducing the peak current. The manipulation requires a longer repetition period to extend the flattop. This reduces the output beam power. The manipulation should be quickly done to minimize the loss of the beam power. Also, the beam gap must be kept for the rise time of the extraction kicker. We propose a non-adiabatic bunch manipulation using the multiharmonic rf voltage. By using the neighbor harmonic of the accelerating harmonic, the first and eighth bunches can be decelerated and accelerated, respectively. After a certain period, the rf phase is flipped to pi for debunching. Thanks to the initial deceleration and acceleration, the beam gap for the kickers is kept. We present the concept and the longitudinal simulation result.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB178

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paper received ※ 17 May 2021 paper accepted ※ 25 June 2021 issue date ※ 28 August 2021

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WEPAB179

Recent Status of J-PARC Rapid Cycling Synchrotron

3027

K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The 3 GeV rapid cycling synchrotron (RCS) at the Ja-pan Proton Accelerator Research Complex (J-PARC) provides more than 500 kW beams to the Material and Life Science Facility (MLF) and Main Ring (MR). In such a high-intensity hadron accelerator, even losing less than 0.1% of the beam can cause many problems. Such lost protons can cause serious radio-activation and accelerator component malfunctions. Therefore, we have been continuing a beam study to achieve high-power operation. In addition, we have also improved and maintained the accelerator components to enable stable operation. This paper reports the status of the J-PARC RCS over the last two years.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB179

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paper received ※ 13 May 2021 paper accepted ※ 25 June 2021 issue date ※ 22 August 2021

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THXX02

High Power Proton Sources for Neutrino Science

E. Pozdeyev
Fermilab, Batavia, Illinois, USA

Neutrinos can hold keys to fundamental physics questions such as the origin of matter, the relationship between nature’s forces, formation of the most extreme objects in galaxies, and how we come to exist at all. Accelerator-based neutrino facilities provide platforms that enable comprehensive studies of neutrinos and their properties. In this paper, we discuss high-power proton accelerators for neutrino science and describe their parameters, features, and critical technologies.

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