IPAC2019 - List of Authors (Igarashi, S.)

Paper	Title	Page
MOYPLM1	Challenges to Higher Beam Power in J-PARC: Achieved Performance and Future Prospects	6
	S. Igarashi KEK, Ibaraki, Japan
	J-PARC is a world leading intensity frontier accelerator facility, consisting of a 400-MeV H⁻ linac, a 3-GeV Rapid Cycling Synchrotron (RCS) and a 30-GeV slow cycling Main Ring synchrotron (MR). The RCS delivered a 500 kW beam (4.2·10¹³ particles per pulse (ppp)) to the Material and Life science experimental Facility (MLF) in April of 2018, The design power of 1 MW will be delivered in the next few years. Construction of a second target station (2TS) of the MLF with beam power upgraded to 1.5 MW is now under discussion. The MR delivers proton beam to a long-baseline neutrino oscillation experiment, T2K, by fast extraction (FX) and to the hadron experimental facility by slow extraction (SX). For the FX, the maximum beam power is 475 kW and 2.5·10¹⁴ ppp, the world highest ppp in synchrotrons, and for the SX 51 kW and 5.5·10¹³ ppp with an extremely high extraction efficiency of 99.5 %. To achieve 1.3 MW beam power for the neutrino experiment, upgrades to allow operation with a higher repetition rate are planned. The talk will review recent progress of J-PARC facility by highlighting technical challenges toward higher beam power together with future prospects.
	Slides MOYPLM1 [9.193 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOYPLM1
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPGW036	Studies on Coherent Multi-Bunch Tune Shifts with Different Bunch Spacing at the J-PARC Main Ring	167
	A. Kobayashi, S. Igarashi, Y. Sato, T. Shimogawa, Y. Sugiyama, T. Toyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	At a high-power proton synchrotron, betatron tune shifts induced by space charge effects cause beam loss which limits the beam intensity. To achieve further high beam intensity at the main ring of the Japan Proton Accelerator Research Complex, precise control of the tune shift is indispensable. When carrying out multi-bunch measurements, we observed that the dependence of the tune shift intensity on the number of bunches follow opposite slope trends for the horizontal and vertical directions. The influence of the bunch spacing was also observed. We report on a simplified tune shift model reconstruction for understanding the origin of these phenomena and present a correction of the tune shifts for reducing beam loss up to 30 %.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW036
About •	paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPGW039	Multi-Ribbon Profile Monitor for High Power Proton Beam at J-PARC MR Abort Line	2561
SUSPFO044	use link to see paper's listing under its alternate paper code
	K. Sato The University of Tokyo, Graduate School of Science, Tokyo, Japan E. Hamada, Y. Hashimoto, S. Igarashi, T. Koseki, Y. Sato KEK, Ibaraki, Japan
	Japan Proton Accelerator Research Complex (J-PARC) Main Ring (MR), the world-class high intensity proton synchrotron, provides proton beam to two experimental facilities with two extraction modes: Fast extraction (FX) and Slow extraction (SX). The number of protons per pulse (ppp) in MR recorded the world highest value of 2.6×10¹⁴ in the FX mode. Now we are planning to increase the ppp further up to 3.3×10¹⁴ in near future. The beam profile is one of the most important parameters to discuss the high intensity beam dynamics in MR. Monitors using multi-wires / ribbons are effective to measure the beam profile with good accuracy and wide dynamic range. However, they cause significant beam losses by interactions with high-intensity circulating beam in synchrotrons. Recently, we installed new multi-ribbon profile monitor (MRPM) in an abort line in MR. The abort line is one of the extracted beam lines of the FX system. It has a quadrupole doublet which is called Abort Q and transports extracted beam to a beam dump. The FX system can extract the circulating beam in MR with an arbitrary energy. Performing the single-pass measurement with MRPM and changing the transfer matrix by sweeping field strength of Abort Q, the emittance of the extracted beam can be measured. In this paper, we present the design, manufacturing, and results of the first beam test of newly installed MRPM system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW039
About •	paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPTS024	Tune Shifts and Optics Modulations in the High Intensity Operation at J-PARC MR	3148
SUSPFO051	use link to see paper's listing under its alternate paper code
	T.Y. Yasui The University of Tokyo, Graduate School of Science, Tokyo, Japan S. Igarashi, T. Koseki, K. Ohmi, Y. Sato, K. Satou KEK, Ibaraki, Japan
	Funding: This study is supported by the MEXT program "Advanced Leading Graduate Course for Photon Science (ALPS)" J-PARC Main Ring (MR) is the intensity-frontier proton accelerator. The beam intensity of 2.6×10¹⁴ protons per pulse has been achieved for the current user operation. In this high-intensity operation, the tune spread caused by the space-charge is one of the main reasons for beam loss. The modulation of the betatron function and the tune shift were simulated with a PIC algorithm calculation code. The simulation results showed that the space-charge effects were dominant in small particle action, and the sextupole fields effects were dominant in large particle action. Because sextupole strength is large in MR, sextupole fields induce substantial tune shifts. At the benchmark of the space-charge simulation, the simulation results matched the analytical space-charge calculations performed without sextupoles. It was found that the betatron function was modulated at most 6% by the space-charge effects and at most 8% by the effects of sextupoles in J-PARC MR. These effects to the injection beam optics matching and to the beam aperture will be investigated. K. Ohmi et al., "Study of Halo Formation in J-PARC MR", Proceedings of the 22nd Particle Accelerator Conf. (PAC’07), Albuquerque, NM, USA, Jun. 2007, paper THPAN040, pp. 3318-3320.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS024
About •	paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Challenges to Higher Beam Power in J-PARC: Achieved Performance and Future Prospects

6

S. Igarashi
KEK, Ibaraki, Japan

J-PARC is a world leading intensity frontier accelerator facility, consisting of a 400-MeV H⁻ linac, a 3-GeV Rapid Cycling Synchrotron (RCS) and a 30-GeV slow cycling Main Ring synchrotron (MR). The RCS delivered a 500 kW beam (4.2·10¹³ particles per pulse (ppp)) to the Material and Life science experimental Facility (MLF) in April of 2018, The design power of 1 MW will be delivered in the next few years. Construction of a second target station (2TS) of the MLF with beam power upgraded to 1.5 MW is now under discussion. The MR delivers proton beam to a long-baseline neutrino oscillation experiment, T2K, by fast extraction (FX) and to the hadron experimental facility by slow extraction (SX). For the FX, the maximum beam power is 475 kW and 2.5·10¹⁴ ppp, the world highest ppp in synchrotrons, and for the SX 51 kW and 5.5·10¹³ ppp with an extremely high extraction efficiency of 99.5 %. To achieve 1.3 MW beam power for the neutrino experiment, upgrades to allow operation with a higher repetition rate are planned. The talk will review recent progress of J-PARC facility by highlighting technical challenges toward higher beam power together with future prospects.

Slides MOYPLM1 [9.193 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOYPLM1

About •

paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

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

MOPGW036

Studies on Coherent Multi-Bunch Tune Shifts with Different Bunch Spacing at the J-PARC Main Ring

167

A. Kobayashi, S. Igarashi, Y. Sato, T. Shimogawa, Y. Sugiyama, T. Toyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

At a high-power proton synchrotron, betatron tune shifts induced by space charge effects cause beam loss which limits the beam intensity. To achieve further high beam intensity at the main ring of the Japan Proton Accelerator Research Complex, precise control of the tune shift is indispensable. When carrying out multi-bunch measurements, we observed that the dependence of the tune shift intensity on the number of bunches follow opposite slope trends for the horizontal and vertical directions. The influence of the bunch spacing was also observed. We report on a simplified tune shift model reconstruction for understanding the origin of these phenomena and present a correction of the tune shifts for reducing beam loss up to 30 %.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW036

About •

paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

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

WEPGW039

Multi-Ribbon Profile Monitor for High Power Proton Beam at J-PARC MR Abort Line

2561

SUSPFO044

use link to see paper's listing under its alternate paper code

K. Sato
The University of Tokyo, Graduate School of Science, Tokyo, Japan
E. Hamada, Y. Hashimoto, S. Igarashi, T. Koseki, Y. Sato
KEK, Ibaraki, Japan

Japan Proton Accelerator Research Complex (J-PARC) Main Ring (MR), the world-class high intensity proton synchrotron, provides proton beam to two experimental facilities with two extraction modes: Fast extraction (FX) and Slow extraction (SX). The number of protons per pulse (ppp) in MR recorded the world highest value of 2.6×10¹⁴ in the FX mode. Now we are planning to increase the ppp further up to 3.3×10¹⁴ in near future. The beam profile is one of the most important parameters to discuss the high intensity beam dynamics in MR. Monitors using multi-wires / ribbons are effective to measure the beam profile with good accuracy and wide dynamic range. However, they cause significant beam losses by interactions with high-intensity circulating beam in synchrotrons. Recently, we installed new multi-ribbon profile monitor (MRPM) in an abort line in MR. The abort line is one of the extracted beam lines of the FX system. It has a quadrupole doublet which is called Abort Q and transports extracted beam to a beam dump. The FX system can extract the circulating beam in MR with an arbitrary energy. Performing the single-pass measurement with MRPM and changing the transfer matrix by sweeping field strength of Abort Q, the emittance of the extracted beam can be measured. In this paper, we present the design, manufacturing, and results of the first beam test of newly installed MRPM system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW039

About •

paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

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

WEPTS024

Tune Shifts and Optics Modulations in the High Intensity Operation at J-PARC MR

3148

SUSPFO051

use link to see paper's listing under its alternate paper code

T.Y. Yasui
The University of Tokyo, Graduate School of Science, Tokyo, Japan
S. Igarashi, T. Koseki, K. Ohmi, Y. Sato, K. Satou
KEK, Ibaraki, Japan

Funding: This study is supported by the MEXT program "Advanced Leading Graduate Course for Photon Science (ALPS)"
J-PARC Main Ring (MR) is the intensity-frontier proton accelerator. The beam intensity of 2.6×10¹⁴ protons per pulse has been achieved for the current user operation. In this high-intensity operation, the tune spread caused by the space-charge is one of the main reasons for beam loss. The modulation of the betatron function and the tune shift were simulated with a PIC algorithm calculation code*. The simulation results showed that the space-charge effects were dominant in small particle action, and the sextupole fields effects were dominant in large particle action. Because sextupole strength is large in MR, sextupole fields induce substantial tune shifts. At the benchmark of the space-charge simulation, the simulation results matched the analytical space-charge calculations performed without sextupoles. It was found that the betatron function was modulated at most 6% by the space-charge effects and at most 8% by the effects of sextupoles in J-PARC MR. These effects to the injection beam optics matching and to the beam aperture will be investigated.
* K. Ohmi et al., "Study of Halo Formation in J-PARC MR", Proceedings of the 22nd Particle Accelerator Conf. (PAC’07), Albuquerque, NM, USA, Jun. 2007, paper THPAN040, pp. 3318-3320.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS024

About •

paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

Export •

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