IPAC2019 - List of Authors (Sugiyama, Y.)

Paper	Title	Page
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
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TUPTS035	Vacuum Tube Operation Analysis for 1.2 MW Beam Acceleration in J-PARC RCS	2017
	M. Yamamoto, M. Nomura, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-mura, Japan M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	The J-PARC RCS has successfully accelerated 1 MW proton beam, matching the designed beam power. Therefore, we have considered acceleration beyond the designed beam power, with the next target being 1.2 MW. An issue for 1.2 MW beam acceleration is the rf system. The present anode power supply is limited by its output current, and the vacuum tube amplifier suffers from an unbalance of the anode voltage swing, arising from the combination of multi-harmonic rf driving and push-pull operation. We have investigated the mitigation of the maximum anode currents and unbalanced tubes by choosing appropriate circuit parameters of the rf cavity with the tube amplifier. We describe the analysis results of the vacuum tube operation for 1.2 MW beam acceleration in the RCS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS035
About •	paper received ※ 14 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)

WEPRB026	Simulations of Beam Loading Compensation in a Wideband Accelerating Cavity Using a Circuit Simulator Including a LLRF Feedback Control	2863
	F. Tamura, M. Nomura, T. Shimada, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	Magnetic alloy cavities are employed in the J-PARC RCS to generate high accelerating voltages. The cavity, which is driven by a vacuum tube amplifier, has a wideband frequency response and the beam loading in the cavity is multiharmonic. Therefore, the tube must generate a multiharmonic output current. An LTspice circuit model is developed to analyze the vacuum tube operation and the compensation of the multiharmonic beam loading. The model includes the cavity, tube amplifier, beam current, and LLRF feedback control. The feedback control consists of the I/Q demodulator including low pass filters, PI control, and I/Q modulator. In this presentation, we present the implementation of the LLRF functions in the LTspice simulations. The preliminary simulation results are also presented. The simulations fairly agree with the beam test results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB026
About •	paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

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)

TUPTS035

Vacuum Tube Operation Analysis for 1.2 MW Beam Acceleration in J-PARC RCS

2017

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

The J-PARC RCS has successfully accelerated 1 MW proton beam, matching the designed beam power. Therefore, we have considered acceleration beyond the designed beam power, with the next target being 1.2 MW. An issue for 1.2 MW beam acceleration is the rf system. The present anode power supply is limited by its output current, and the vacuum tube amplifier suffers from an unbalance of the anode voltage swing, arising from the combination of multi-harmonic rf driving and push-pull operation. We have investigated the mitigation of the maximum anode currents and unbalanced tubes by choosing appropriate circuit parameters of the rf cavity with the tube amplifier. We describe the analysis results of the vacuum tube operation for 1.2 MW beam acceleration in the RCS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS035

About •

paper received ※ 14 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)

WEPRB026

Simulations of Beam Loading Compensation in a Wideband Accelerating Cavity Using a Circuit Simulator Including a LLRF Feedback Control

2863

F. Tamura, M. Nomura, T. Shimada, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

Magnetic alloy cavities are employed in the J-PARC RCS to generate high accelerating voltages. The cavity, which is driven by a vacuum tube amplifier, has a wideband frequency response and the beam loading in the cavity is multiharmonic. Therefore, the tube must generate a multiharmonic output current. An LTspice circuit model is developed to analyze the vacuum tube operation and the compensation of the multiharmonic beam loading. The model includes the cavity, tube amplifier, beam current, and LLRF feedback control. The feedback control consists of the I/Q demodulator including low pass filters, PI control, and I/Q modulator. In this presentation, we present the implementation of the LLRF functions in the LTspice simulations. The preliminary simulation results are also presented. The simulations fairly agree with the beam test results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB026

About •

paper received ※ 23 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

Export •

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