HB2023 - List of Authors (Ohmori, C.)

Paper	Title	Page
WEC4I1	RF Systems of J-PARC Proton Synchrotrons for High-Intensity Longitudinal Beam Optimization and Handling	305
	F. Tamura, R. Miyakoshi, M. Nomura, H. Okita, T. Shimada, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan K. Hara, K. Hasegawa, C. Ohmori, K. Seiya, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	The application of magnetic alloy (MA) cores to the accelerating rf cavities in high intensity proton synchrotrons was pioneered for the J-PARC synchrotrons, the RCS and MR. The MA loaded cavities can generate high accelerating voltages. The wideband frequency response of the MA cavity enables the frequency sweep to follow the velocity change of protons without the tuning loop. The dual harmonic operation, where a single cavity is driven by the superposition of the fundamental and second harmonic rf voltages, is indispensable for the longitudinal bunch shaping to alleviate the space charge effects in the RCS. These advantages of the MA cavity are also disadvantages when looking at them from a different perspective. Since the wake voltage consists of several harmonics, which can cause bucket distortion or coupled-bunch instabilities, the beam loading compensation must be multiharmonic. The operation of tubes in the final stage amplifier is not trivial when accelerating very high intensity beams; the output current is high and the anode voltageis also multiharmonic. We summarize our effort against these issues in the operation of the RCS and MR for more than 10 years.
	Slides WEC4I1 [6.932 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I1
About •	Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 29 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEC4C1	Magnetic Alloy Loaded Cavities in J-PARC and CERN	316
	C. Ohmori KEK, Ibaraki, Japan M.M. Paoluzzi CERN, Meyrin, Switzerland
	Funding: This work was supported by JSPS KAKENHI Grant Number 19KK0078 and 18K11930. Magnetic Alloy loaded cavities have been used in seven synchrotrons in J-PARC and CERN. In this paper, we will review variety of the cavity technologies to satisfy the requirements for the beam acceleration, deceleration, manipulation and instability damping. This paper also contains improvements of cavity cores by magnetic annealing scheme, quality control of cores during production, the cooling methods of magnetic alloy cores: direct water cooling and indirect one using copper discs, control of cavity bandwidths from broad to narrow bands, and the ways to drive RF cavities by tube and rad-hard solid-state amplifiers.
	Slides WEC4C1 [3.371 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4C1
About •	Received ※ 04 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

RF Systems of J-PARC Proton Synchrotrons for High-Intensity Longitudinal Beam Optimization and Handling

305

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

The application of magnetic alloy (MA) cores to the accelerating rf cavities in high intensity proton synchrotrons was pioneered for the J-PARC synchrotrons, the RCS and MR. The MA loaded cavities can generate high accelerating voltages. The wideband frequency response of the MA cavity enables the frequency sweep to follow the velocity change of protons without the tuning loop. The dual harmonic operation, where a single cavity is driven by the superposition of the fundamental and second harmonic rf voltages, is indispensable for the longitudinal bunch shaping to alleviate the space charge effects in the RCS. These advantages of the MA cavity are also disadvantages when looking at them from a different perspective. Since the wake voltage consists of several harmonics, which can cause bucket distortion or coupled-bunch instabilities, the beam loading compensation must be multiharmonic. The operation of tubes in the final stage amplifier is not trivial when accelerating very high intensity beams; the output current is high and the anode voltageis also multiharmonic. We summarize our effort against these issues in the operation of the RCS and MR for more than 10 years.

Slides WEC4I1 [6.932 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4I1

About •

Received ※ 29 September 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 29 October 2023

Cite •

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

WEC4C1

Magnetic Alloy Loaded Cavities in J-PARC and CERN

316

C. Ohmori
KEK, Ibaraki, Japan
M.M. Paoluzzi
CERN, Meyrin, Switzerland

Funding: This work was supported by JSPS KAKENHI Grant Number 19KK0078 and 18K11930.
Magnetic Alloy loaded cavities have been used in seven synchrotrons in J-PARC and CERN. In this paper, we will review variety of the cavity technologies to satisfy the requirements for the beam acceleration, deceleration, manipulation and instability damping. This paper also contains improvements of cavity cores by magnetic annealing scheme, quality control of cores during production, the cooling methods of magnetic alloy cores: direct water cooling and indirect one using copper discs, control of cavity bandwidths from broad to narrow bands, and the ways to drive RF cavities by tube and rad-hard solid-state amplifiers.

Slides WEC4C1 [3.371 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-HB2023-WEC4C1

About •

Received ※ 04 October 2023 — Revised ※ 07 October 2023 — Accepted ※ 10 October 2023 — Issued ※ 10 October 2023

Cite •

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