IPAC2019 - List of Authors (Okamura, K.)

Paper	Title	Page
WEPMP007	Current Status of Slow Extraction from J-PARC Main Ring	2311
	R. Muto, Y. Arakaki, T. Kimura, S. Murasugi, M. Okada, K. Okamura, T. Shimogawa, Y. Shirakabe, M. Tomizawa, T. Toyama, E. Yanaoka KEK, Ibaraki, Japan A. Matsumura Nihon Advanced Technology Co., Ltd, Ibaraki, Nakagun, Tokaimura, 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. The slow extraction (SX) from the MR has unique characteristics that can be used to obtain a low beam loss rate. A dynamic bump scheme under achromatic condition drastically reduces beam hit rate on the septa devices. We have attained 50 kW SX operation at 5.2s cycle in current physics run. Slow extraction efficiency has been achieved to be very high, 99.5%. A beam instability during debunching with beam loss can be suppressed by a unique RF phase offset technique at MR injection. A spill duty factor indicating a uniformity for time structure of the extracted beam is typically 50%, which can be obtained by a feedback system using fast response quadrupoles, applying transverse RF field and so on. Future plans to improve present SX performances will be introduced.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP007
About •	paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPMP008	A Consideration on the Transfer Function Between RQ Field and Slow Extraction Spill in the Main Ring of J-Parc	2315
	K. Okamura, Y. Arakaki, S. Murasugi, R. Muto, Y. Shirakabe, M. Tomizawa, E. Yanaoka KEK, Ibaraki, Japan T. Kimura J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	A 30 GeV proton beam accelerated in the J-PARC Main Ring (MR) is slowly extracted by the third integer reso-nant extraction and delivered to the hadron experimental facility. Increasing the duty of beam spill is one of the important issues in the slow extraction system. In the MR, the spill feedback system utilizing a digital signal processor (DSP) combined with EQ and RQ magnet is used to smooth the spill, where EQ defines a rough out-line of the slow extraction shape and RQ is used for the ripple cancelling. In this study, frequency domain charac-teristics between the current of RQ magnet and the beam spill was investigated by driving the RQ magnet with sinusoidal current, so that the transfer function from the current of RQ magnet to the spill signal is delivered.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP008
About •	paper received ※ 15 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)

WEPMP010	8 Gev Slow Extraction Beam Test for Muon to Electron Conversion Search Experiment at J-PARC	2322
	M. Tomizawa, Y. Arakaki, Y. Fukao, Y. Hashimoto, Y. Igarashi, T. Kimura, S. Mihara, M. Moritsu, S. Murasugi, R. Muto, H. Nishiguchi, K. Okamura, Y. Shirakabe, K. Ueno, E. Yanaoka KEK, Ibaraki, Japan Y. Fujii Monash University, Faculty of Science, Clayton, Victoria, Australia F. Tamura JAEA/J-PARC, Tokai-mura, Japan
	A muon to electron conversion search experiment (COMET) planned at J-PARC needs 8 GeV bunched proton beams with a continuous 1 MHz pulse structure. In this experiment, an intensity ratio of the residual to the main pulsed beam, which is expressed as extinction, should be less than the level of 10^-10. In RUN78 (Jan. to Feb., 2018), we have succeeded in slow extraction of 8 GeV protons with 7.3×1012 ppp, satisfies the COMET phase-I requirement, and the extinction derived from a timing measurement of secondary particles from the target shows a promising result. A mechanism to explain the measured extinction will be also described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP010
About •	paper received ※ 01 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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FRXXPLM3	Development of a Pulsed Power Supply Utilizing 13 kV Class SiC-MOSFET	4364
	K. Okamura, F. Naito, K. Takayama KEK, Ibaraki, Japan K. Fukuda, H. Kitai, K. Sakamoto AIST, Tsukuba, Ibaraki, Japan T. Kaito Chiba Institute of Technology, Narashino, Chiba, Japan D. Kumamoto Nagaoka University of Technology, Nagaoka, Niigata, Japan S. Lim, A. Tokuchi Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan
	Funding: A part of this work has been implemented under a joint research project of Tsukuba Power Electronics Constellation (TPEC). To resolve the drawback of conventional thyratron switches, development of a semiconductor high voltage switch utilizing a 13 kV class SiC-MOSFET developed by Tsukuba Power Electronics Constellations (TPEC) is proceeding. At first, the device evaluation test was carried out with a resistive load circuit. With the conditions of drain voltage of 10 kV and load resistance of 1 kΩ, turn on loss Eon, turn off loss Eoff, rise time Tr and fall time Tf were 1.7 mJ, 1.1 mJ, 64 ns, and 75 ns, respectively. As to gate charge characteristics, required electric charge to increase gate source voltage from 0 V to 20 V was about 80 nC. Thereafter, the 2s-12p switch array was designed and assembled, where 12 MOSFETs are equally aligned on a circle shaped circuit board and two circuit boards are stacked in series. A 14 kV-490 A-5 us pulse with a rise time of 430 ns in the long pulse mode and a 18 kV-318 A-1 us pulse with a rise time of 289 ns in the short pulse mode were successfully demonstrated. This switch will be installed as a turn-off switch for the injec-tion ES kicker in the KEK-DA.
	Slides FRXXPLM3 [5.088 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLM3
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

Current Status of Slow Extraction from J-PARC Main Ring

2311

R. Muto, Y. Arakaki, T. Kimura, S. Murasugi, M. Okada, K. Okamura, T. Shimogawa, Y. Shirakabe, M. Tomizawa, T. Toyama, E. Yanaoka
KEK, Ibaraki, Japan
A. Matsumura
Nihon Advanced Technology Co., Ltd, Ibaraki, Nakagun, Tokaimura, 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. The slow extraction (SX) from the MR has unique characteristics that can be used to obtain a low beam loss rate. A dynamic bump scheme under achromatic condition drastically reduces beam hit rate on the septa devices. We have attained 50 kW SX operation at 5.2s cycle in current physics run. Slow extraction efficiency has been achieved to be very high, 99.5%. A beam instability during debunching with beam loss can be suppressed by a unique RF phase offset technique at MR injection. A spill duty factor indicating a uniformity for time structure of the extracted beam is typically 50%, which can be obtained by a feedback system using fast response quadrupoles, applying transverse RF field and so on. Future plans to improve present SX performances will be introduced.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP007

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)

WEPMP008

A Consideration on the Transfer Function Between RQ Field and Slow Extraction Spill in the Main Ring of J-Parc

2315

K. Okamura, Y. Arakaki, S. Murasugi, R. Muto, Y. Shirakabe, M. Tomizawa, E. Yanaoka
KEK, Ibaraki, Japan
T. Kimura
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

A 30 GeV proton beam accelerated in the J-PARC Main Ring (MR) is slowly extracted by the third integer reso-nant extraction and delivered to the hadron experimental facility. Increasing the duty of beam spill is one of the important issues in the slow extraction system. In the MR, the spill feedback system utilizing a digital signal processor (DSP) combined with EQ and RQ magnet is used to smooth the spill, where EQ defines a rough out-line of the slow extraction shape and RQ is used for the ripple cancelling. In this study, frequency domain charac-teristics between the current of RQ magnet and the beam spill was investigated by driving the RQ magnet with sinusoidal current, so that the transfer function from the current of RQ magnet to the spill signal is delivered.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP008

About •

paper received ※ 15 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)

WEPMP010

8 Gev Slow Extraction Beam Test for Muon to Electron Conversion Search Experiment at J-PARC

2322

M. Tomizawa, Y. Arakaki, Y. Fukao, Y. Hashimoto, Y. Igarashi, T. Kimura, S. Mihara, M. Moritsu, S. Murasugi, R. Muto, H. Nishiguchi, K. Okamura, Y. Shirakabe, K. Ueno, E. Yanaoka
KEK, Ibaraki, Japan
Y. Fujii
Monash University, Faculty of Science, Clayton, Victoria, Australia
F. Tamura
JAEA/J-PARC, Tokai-mura, Japan

A muon to electron conversion search experiment (COMET) planned at J-PARC needs 8 GeV bunched proton beams with a continuous 1 MHz pulse structure. In this experiment, an intensity ratio of the residual to the main pulsed beam, which is expressed as extinction, should be less than the level of 10^-10. In RUN78 (Jan. to Feb., 2018), we have succeeded in slow extraction of 8 GeV protons with 7.3×1012 ppp, satisfies the COMET phase-I requirement, and the extinction derived from a timing measurement of secondary particles from the target shows a promising result. A mechanism to explain the measured extinction will be also described in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP010

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)

FRXXPLM3

Development of a Pulsed Power Supply Utilizing 13 kV Class SiC-MOSFET

4364

K. Okamura, F. Naito, K. Takayama
KEK, Ibaraki, Japan
K. Fukuda, H. Kitai, K. Sakamoto
AIST, Tsukuba, Ibaraki, Japan
T. Kaito
Chiba Institute of Technology, Narashino, Chiba, Japan
D. Kumamoto
Nagaoka University of Technology, Nagaoka, Niigata, Japan
S. Lim, A. Tokuchi
Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan

Funding: A part of this work has been implemented under a joint research project of Tsukuba Power Electronics Constellation (TPEC).
To resolve the drawback of conventional thyratron switches, development of a semiconductor high voltage switch utilizing a 13 kV class SiC-MOSFET developed by Tsukuba Power Electronics Constellations (TPEC) is proceeding. At first, the device evaluation test was carried out with a resistive load circuit. With the conditions of drain voltage of 10 kV and load resistance of 1 kΩ, turn on loss Eon, turn off loss Eoff, rise time Tr and fall time Tf were 1.7 mJ, 1.1 mJ, 64 ns, and 75 ns, respectively. As to gate charge characteristics, required electric charge to increase gate source voltage from 0 V to 20 V was about 80 nC. Thereafter, the 2s-12p switch array was designed and assembled, where 12 MOSFETs are equally aligned on a circle shaped circuit board and two circuit boards are stacked in series. A 14 kV-490 A-5 us pulse with a rise time of 430 ns in the long pulse mode and a 18 kV-318 A-1 us pulse with a rise time of 289 ns in the short pulse mode were successfully demonstrated. This switch will be installed as a turn-off switch for the injec-tion ES kicker in the KEK-DA.

Slides FRXXPLM3 [5.088 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLM3

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)