IPAC2022 - List of Authors (Tamura, F.)

Paper	Title	Page
TUPOTK052	Influence of a Positive Grid Biasing on RF System in J-PARC RCS	1336
	M. Yamamoto, M. Nomura, H. Okita, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-mura, Japan K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	In order to accelerate a high intensity beam in the RCS, a large amplitude of the anode current is provided by a tube amplifier to compensate a heavy beam loading. Tetrode vacuum tubes are used in the RCS, and the control grid voltage enters into a positive region to feed such a large current. The positive grid biasing affects the waveform of the control grid voltage; it is deformed due to the induced control grid current under the condition of the multi-harmonic rf driving. Furthermore, the DC bias voltage drop on the control grid is observed because of the exceeding the ability for the control grid power supply. We describe the influence of the positive grid biasing in the RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK052
About •	Received ※ 06 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 24 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEOYGD1	Recent Results of Beam Loss Mitigation and Extremely Low Beam Loss Operation of J-PARC RCS	1616
	P.K. Saha, H. Harada, T. Nakanoya, K. Okabe, H. Okita, Y. Shobuda, F. Tamura, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Hotchi KEK, Tokai, Ibaraki, Japan
	In the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex), multi-turn charge-exchange injection of H⁻ by using a thin stripper foil is performed to achieve high-intensity proton beam of 1 MW. The beam loss at 1 MW has already been well controlled, but for further minimizing both uncontrolled and controlled beam losses caused by the foil scattering of the circulating beam, recently we have implemented a lower vertical injection beam size and installed a corresponding smaller size stripper foil. A smaller foil gives a significant reduction of the foil scattering uncontrolled beam loss at the injection area, while an optimization of the vertical transverse painting area matching with a smaller beam size further gives an extremely reduction of the beam loss at the collimator section. The corresponding residual radiation at the recent operation with 700 kW beam power was also measured to extremely reduced.
	Slides WEOYGD1 [1.161 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOYGD1
About •	Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 24 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOTK004	Status and Upgrade Plan of the MR Ring RF Systems in J-PARC	2031
	K. Hasegawa, K. Hara, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan M. Nomura, H. Okita, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	The J-PARC Main Ring (MR) is a high intensity proton accelerator and delivers 30 GeV proton beams for the long-base line neutrino experiment and the hadron experiments. At present, the beam intensity supplied to the neutrino experiment reached 520 kW with a cycle time of 2.48 s. Toward the design beam power of 750 kW and future goal of 1.3 MW, we chose shortening the MR operation cycle. Accelerating time is shortened in order to shorten the cycle, so a high accelerating voltage is required. Therefore, it is necessary to upgrade the RF systems. This RF upgrade expands the current nine RF systems to a total of thirteen. We are planning to fabricate four RF power sources and add four additional cavities that are recombined with existing cavities. The present status and upgrade plan of the MR RF systems are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK004
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 07 July 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

FROXSP1	20-Year Collaboration on Synchrotron RF Between CERN and J-PARC	3130
	C. Ohmori J-PARC, KEK & JAEA, Ibaraki-ken, Japan M. Brucoli, M. Brugger, H. Damerau, S. Danzeca, M.M. Paoluzzi, C. Rossi CERN, Meyrin, Switzerland K. Hasegawa, Y. Morita, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan H. Okita, M.J. Shirakata, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	KEK/J-PARC and CERN started the collaboration on the RF systems of Low Energy Ion Ring to use magnetic alloy loaded cavities in 2002 for heavy ion collision program at LHC. It was an exchange of our expertise on the wideband cavities and high-power solid-state amplifiers. This paper summarizes the 20-year collaboration which includes many synchrotrons of both facilities: J-PARC Rapid Cycling Synchrotron and Main Ring, CERN Proton Synchrotron, PS Booster, Antiproton Decelerator, Extra Low Energy Antiproton ring and MedAustron. By the improvements of cavity core using the magnetic annealing, field gradient of cavity and compactness were improved to fit the requirements for LHC Injector Upgrade (LIU)program. Radiation-hard and compact high-power solid-state amplifiers were also developed for LIU and future accelerator improvements.
	Slides FROXSP1 [8.210 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXSP1
About •	Received ※ 07 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 19 June 2022 — Issue date ※ 25 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOTK051	Design Studies on a High-Power Wide-Band RF Combiner for Consolidation of the Driver Amplifier of the J-PARC RCS	1333
	H. Okita, K. Hara, K. Hasegawa, M. Nomura, T. Shimada, F. Tamura, M. Yamamoto KEK/JAEA, Ibaraki-Ken, Japan C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Ibaraki, Japan M.M. Paoluzzi CERN, Meyrin, Switzerland
	A power upgrade of the existing 8 kW solid-state driver amplifier is required for the acceleration of high intensity proton beams in the J-PARC 3 GeV rapid cycling synchrotron (RCS). The development of a 25 kW amplifier with gallium nitride (GaN) HEMTs and based on 6.4 kW modules is ongoing. The combiner is a key component to achieve such a high output power over the wide bandwidth required for multi-harmonic rf operation. This paper presents a preliminary design of the combiner. The circuit simulation setup and results, including the realistic magnetic core characteristics and frequency response of the cables are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK051
About •	Received ※ 18 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 14 June 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Influence of a Positive Grid Biasing on RF System in J-PARC RCS

1336

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

In order to accelerate a high intensity beam in the RCS, a large amplitude of the anode current is provided by a tube amplifier to compensate a heavy beam loading. Tetrode vacuum tubes are used in the RCS, and the control grid voltage enters into a positive region to feed such a large current. The positive grid biasing affects the waveform of the control grid voltage; it is deformed due to the induced control grid current under the condition of the multi-harmonic rf driving. Furthermore, the DC bias voltage drop on the control grid is observed because of the exceeding the ability for the control grid power supply. We describe the influence of the positive grid biasing in the RCS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK052

About •

Received ※ 06 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 24 June 2022

Cite •

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

WEOYGD1

Recent Results of Beam Loss Mitigation and Extremely Low Beam Loss Operation of J-PARC RCS

1616

P.K. Saha, H. Harada, T. Nakanoya, K. Okabe, H. Okita, Y. Shobuda, F. Tamura, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
H. Hotchi
KEK, Tokai, Ibaraki, Japan

In the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex), multi-turn charge-exchange injection of H⁻ by using a thin stripper foil is performed to achieve high-intensity proton beam of 1 MW. The beam loss at 1 MW has already been well controlled, but for further minimizing both uncontrolled and controlled beam losses caused by the foil scattering of the circulating beam, recently we have implemented a lower vertical injection beam size and installed a corresponding smaller size stripper foil. A smaller foil gives a significant reduction of the foil scattering uncontrolled beam loss at the injection area, while an optimization of the vertical transverse painting area matching with a smaller beam size further gives an extremely reduction of the beam loss at the collimator section. The corresponding residual radiation at the recent operation with 700 kW beam power was also measured to extremely reduced.

Slides WEOYGD1 [1.161 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOYGD1

About •

Received ※ 20 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 24 June 2022

Cite •

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

WEPOTK004

Status and Upgrade Plan of the MR Ring RF Systems in J-PARC

2031

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

The J-PARC Main Ring (MR) is a high intensity proton accelerator and delivers 30 GeV proton beams for the long-base line neutrino experiment and the hadron experiments. At present, the beam intensity supplied to the neutrino experiment reached 520 kW with a cycle time of 2.48 s. Toward the design beam power of 750 kW and future goal of 1.3 MW, we chose shortening the MR operation cycle. Accelerating time is shortened in order to shorten the cycle, so a high accelerating voltage is required. Therefore, it is necessary to upgrade the RF systems. This RF upgrade expands the current nine RF systems to a total of thirteen. We are planning to fabricate four RF power sources and add four additional cavities that are recombined with existing cavities. The present status and upgrade plan of the MR RF systems are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK004

About •

Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 07 July 2022

Cite •

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

FROXSP1

20-Year Collaboration on Synchrotron RF Between CERN and J-PARC

3130

C. Ohmori
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
M. Brucoli, M. Brugger, H. Damerau, S. Danzeca, M.M. Paoluzzi, C. Rossi
CERN, Meyrin, Switzerland
K. Hasegawa, Y. Morita, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan
H. Okita, M.J. Shirakata, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

KEK/J-PARC and CERN started the collaboration on the RF systems of Low Energy Ion Ring to use magnetic alloy loaded cavities in 2002 for heavy ion collision program at LHC. It was an exchange of our expertise on the wideband cavities and high-power solid-state amplifiers. This paper summarizes the 20-year collaboration which includes many synchrotrons of both facilities: J-PARC Rapid Cycling Synchrotron and Main Ring, CERN Proton Synchrotron, PS Booster, Antiproton Decelerator, Extra Low Energy Antiproton ring and MedAustron. By the improvements of cavity core using the magnetic annealing, field gradient of cavity and compactness were improved to fit the requirements for LHC Injector Upgrade (LIU)program. Radiation-hard and compact high-power solid-state amplifiers were also developed for LIU and future accelerator improvements.

Slides FROXSP1 [8.210 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-FROXSP1

About •

Received ※ 07 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 19 June 2022 — Issue date ※ 25 June 2022

Cite •

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

TUPOTK051

Design Studies on a High-Power Wide-Band RF Combiner for Consolidation of the Driver Amplifier of the J-PARC RCS

1333

H. Okita, K. Hara, K. Hasegawa, M. Nomura, T. Shimada, F. Tamura, M. Yamamoto
KEK/JAEA, Ibaraki-Ken, Japan
C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Ibaraki, Japan
M.M. Paoluzzi
CERN, Meyrin, Switzerland

A power upgrade of the existing 8 kW solid-state driver amplifier is required for the acceleration of high intensity proton beams in the J-PARC 3 GeV rapid cycling synchrotron (RCS). The development of a 25 kW amplifier with gallium nitride (GaN) HEMTs and based on 6.4 kW modules is ongoing. The combiner is a key component to achieve such a high output power over the wide bandwidth required for multi-harmonic rf operation. This paper presents a preliminary design of the combiner. The circuit simulation setup and results, including the realistic magnetic core characteristics and frequency response of the cables are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK051

About •

Received ※ 18 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 14 June 2022

Cite •

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