IPAC2017 - List of Authors (Toyama, T.)

Paper	Title	Page
MOPAB069	Measurement of Transverse Multipole Moments of the Proton Beam in the J-PARC MR	274
	T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan A. Ichikawa, A. Minamino, K.G. Nakamura, Y. Nakanishi, T. Nakaya, W. Uno Kyoto University, Kyoto, Japan T. Koseki, H. Kuboki, M. Okada KEK, Ibaraki, Japan
	Funding: This work was partially supported by MEXT/JSPS KAKENHI Grant Numbers 25105002 and 16H06288. Transverse multipole moments (quadrupole and more) of the beam may give important informations of the beam such as beam sizes, nonlinear resonances and so on. However higher moments are difficult to measure because signal-to-noise-ratio becomes smaller proportional to the n-th order of the beam-radius-to-vacuum-duct-radius ratio. In order to increase the SNR and to extend the multipole order, we developed and installed a 16 electrode beam monitor in the J-PARC MR, which consists of guard-potential-separated 16 striplines. The calibration method, beam test results will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB069
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TUOAB3	Development of Wide Dynamic Range Beam Loss Monitor System for the J-PARC Main Ring	1248
	K. Satou, N. Kamikubota, T. Toyama, S. Yamada J-PARC, KEK & JAEA, Ibaraki-ken, Japan S.Y. Yoshida Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan
	The new beam loss monitor (BLM) system now in operation at the main ring of J-PARC consists of an isolated front-end current to voltage converter, a VME-based 24 bit ADC system. A dual detector system employs a proportional-type gas chamber (PBLM) and an air-filled ionization chamber (AIC). The system shows a wide dynamic range of 160 dB. It can detect the low level signal that would arise in the case of the detection of residual dose in the ring itself after the beam has been turned off as well as an event such as high level beam loss at the collimators. The signal rise time of the waveform obtained is 17 us which fast enough to meet the speed requirement of the Machine Protection System (MPS); which is that the MPS should dump the beam within 100 us when the beam loss signal exceeds the reference levels set in the ADC system.
	Slides TUOAB3 [2.692 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOAB3
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WEPIK014	Coupled Bunch Instability and Its Cure at J-PARC RCS	2946
	Y. Shobuda, H. Harada, H. Hotchi, P.K. Saha, T. Takayanagi, F. Tamura, N. Tani, T. Togashi, Y. Watanabe, K. Yamamoto, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan Y.H. Chin, Y. Irie, T. Toyama KEK, Tokai, Ibaraki, Japan
	The RCS at J-PARC is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Nevertheless, we have recently succeeded to accelerate a 1-MW equivalent beam by making maximum use of the space charge effect on the beam instabilities. In this report, we explain the manipulation to suppress the beam instability, at first. Then, we discuss some issues to suppress the beam instabilities for beams with much smaller transverse emittance, as well as the present status of our efforts to reduce the kicker impedance toward the realization of the higher beam power at the RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK014
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WEPIK074	Twiss Parameter Measurement and Application to Space Charge Dynamics	3101
	K. Ohmi, S. Igarashi, T. Toyama KEK, Tokai, Ibaraki, Japan H. Harada, S. Hatakeyama JAEA/J-PARC, Tokai-mura, Japan N. Kuroo UTTAC, Tsukuba, Ibaraki, Japan Y. Sato J-PARC, KEK & JAEA, Ibaraki-ken, Japan R. Tomás, A. Wegscheider CERN, Geneva, Switzerland
	We are looking for feasible and quantitative method to evaluate space charge induced beam loss in J-PARC MR. One possible way is space charge simulation and theory based on measured Twiss parameter. Twiss parameter measurement using turn-by-turn monitors is presented. Resonance strengths of lattice magnets and space charge force are estimated by the measured Twiss parameters. Emittance growth and beam loss under the resonance strengths are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK074
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THPVA010	Electron Cloud Simulations for the Main Ring of J-PARC	4436
	B. Yee-Rendón, R. Muto, K. Ohmi, K. Satou, M. Tomizawa, T. Toyama KEK, Ibaraki, Japan
	The simulation of beam instabilities is a helpful tool to evaluate potential threats against the machine protection of the high intensity beams. At Main Ring (MR) of J-PARC, signals related to the electron cloud have been observed during the slow beam extraction mode. Hence, several studies were conducted to investigate the mechanism that produces it, the results confirmed a strong dependence on the beam intensity and the bunch structure in the formation of the electron cloud, however, the precise explanation of its trigger conditions remains incomplete. To shed light on the problem, electron cloud simulations were done using an updated version of the computational model developed from previous works at KEK. The code employed the signals of the measurements to reproduce the events seen during the surveys.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA010
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Paper

Title

Page

Measurement of Transverse Multipole Moments of the Proton Beam in the J-PARC MR

274

T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
A. Ichikawa, A. Minamino, K.G. Nakamura, Y. Nakanishi, T. Nakaya, W. Uno
Kyoto University, Kyoto, Japan
T. Koseki, H. Kuboki, M. Okada
KEK, Ibaraki, Japan

Funding: This work was partially supported by MEXT/JSPS KAKENHI Grant Numbers 25105002 and 16H06288.
Transverse multipole moments (quadrupole and more) of the beam may give important informations of the beam such as beam sizes, nonlinear resonances and so on. However higher moments are difficult to measure because signal-to-noise-ratio becomes smaller proportional to the n-th order of the beam-radius-to-vacuum-duct-radius ratio. In order to increase the SNR and to extend the multipole order, we developed and installed a 16 electrode beam monitor in the J-PARC MR, which consists of guard-potential-separated 16 striplines. The calibration method, beam test results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB069

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TUOAB3

Development of Wide Dynamic Range Beam Loss Monitor System for the J-PARC Main Ring

1248

K. Satou, N. Kamikubota, T. Toyama, S. Yamada
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
S.Y. Yoshida
Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan

The new beam loss monitor (BLM) system now in operation at the main ring of J-PARC consists of an isolated front-end current to voltage converter, a VME-based 24 bit ADC system. A dual detector system employs a proportional-type gas chamber (PBLM) and an air-filled ionization chamber (AIC). The system shows a wide dynamic range of 160 dB. It can detect the low level signal that would arise in the case of the detection of residual dose in the ring itself after the beam has been turned off as well as an event such as high level beam loss at the collimators. The signal rise time of the waveform obtained is 17 us which fast enough to meet the speed requirement of the Machine Protection System (MPS); which is that the MPS should dump the beam within 100 us when the beam loss signal exceeds the reference levels set in the ADC system.

Slides TUOAB3 [2.692 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOAB3

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

WEPIK014

Coupled Bunch Instability and Its Cure at J-PARC RCS

2946

Y. Shobuda, H. Harada, H. Hotchi, P.K. Saha, T. Takayanagi, F. Tamura, N. Tani, T. Togashi, Y. Watanabe, K. Yamamoto, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan
Y.H. Chin, Y. Irie, T. Toyama
KEK, Tokai, Ibaraki, Japan

The RCS at J-PARC is a kicker-impedance dominant machine, which violates the impedance budget from a classical viewpoint. Nevertheless, we have recently succeeded to accelerate a 1-MW equivalent beam by making maximum use of the space charge effect on the beam instabilities. In this report, we explain the manipulation to suppress the beam instability, at first. Then, we discuss some issues to suppress the beam instabilities for beams with much smaller transverse emittance, as well as the present status of our efforts to reduce the kicker impedance toward the realization of the higher beam power at the RCS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK014

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

WEPIK074

Twiss Parameter Measurement and Application to Space Charge Dynamics

3101

K. Ohmi, S. Igarashi, T. Toyama
KEK, Tokai, Ibaraki, Japan
H. Harada, S. Hatakeyama
JAEA/J-PARC, Tokai-mura, Japan
N. Kuroo
UTTAC, Tsukuba, Ibaraki, Japan
Y. Sato
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
R. Tomás, A. Wegscheider
CERN, Geneva, Switzerland

We are looking for feasible and quantitative method to evaluate space charge induced beam loss in J-PARC MR. One possible way is space charge simulation and theory based on measured Twiss parameter. Twiss parameter measurement using turn-by-turn monitors is presented. Resonance strengths of lattice magnets and space charge force are estimated by the measured Twiss parameters. Emittance growth and beam loss under the resonance strengths are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK074

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

THPVA010

Electron Cloud Simulations for the Main Ring of J-PARC

4436

B. Yee-Rendón, R. Muto, K. Ohmi, K. Satou, M. Tomizawa, T. Toyama
KEK, Ibaraki, Japan

The simulation of beam instabilities is a helpful tool to evaluate potential threats against the machine protection of the high intensity beams. At Main Ring (MR) of J-PARC, signals related to the electron cloud have been observed during the slow beam extraction mode. Hence, several studies were conducted to investigate the mechanism that produces it, the results confirmed a strong dependence on the beam intensity and the bunch structure in the formation of the electron cloud, however, the precise explanation of its trigger conditions remains incomplete. To shed light on the problem, electron cloud simulations were done using an updated version of the computational model developed from previous works at KEK. The code employed the signals of the measurements to reproduce the events seen during the surveys.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA010

Export •

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