IPAC2014 - List of Authors (Shobuda, Y.)

Paper	Title	Page
TUPRI051	Comparison between Measurements and Orbit Code Simulations for Beam Instabilities due to Kicker Impedance in the 3-GeV RCS of J-PARC	1683
	P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The transverse impedance of the extraction kicker magnets is the most dominant beam instability source in the 3-GeV Rapid Cycling Synchrotron of J-PARC. The instability occurs when chromaticity is fully corrected during acceleration but on the other hand no instabilities are observed for a full chromatic correction only at the injection energy even for a beam power up to 500 kW. However, the situation may change for a beam power of 1 MW and also for the upgraded injection beam energy from the present 181 MeV to the 400 MeV, as space charge effect in the non-relativistic region is believed to suppress the growth rate of beam instability. In order to study the kicker impedance in detail, recently we have introduced measured time dependent impedance source in the ORBIT simulation code in a realistic manner. The ORBIT code itself has also been well upgraded and given realistic features for application to synchrotrons. We have also carried out a systematic experimental study for a maximum beam power of 500 kW. In this paper, a detail comparison between measurements and corresponding simulations including 1 MW simulation results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI051
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THOAA03	Transverse Intra-bunch Feedback in the J-PARC MR	2786
SUSPSNE086	use link to see paper's listing under its alternate paper code
	K. Nakamura Kyoto University, Kyoto, Japan Y.H. Chin, T. Obina, M. Okada, M. Tobiyama KEK, Ibaraki, Japan T. Koseki, T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	We will report the development of a new broadband (bandwidth of around 100MHz) feedback system for suppression of intra-bunch oscillations and reduction of particle losses at the J-PARC Main Ring (MR). A new BPM has been designed based on the exponential coupler stripline type (the diameter of 134 mm and the length of 300 mm) and it is now under fabrication. In this BPM system, the frequency characteristics are corrected using the equalizer as bunch signals are differentiated. The design detail and the performance of the new BPM as well as preparation of newly installed exciter and power amplifiers will be presented. We will also report beam test results of head-tail mode suppression at 3 GeV with the bunch length of 150-250 ns.
	Slides THOAA03 [1.149 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOAA03
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Comparison between Measurements and Orbit Code Simulations for Beam Instabilities due to Kicker Impedance in the 3-GeV RCS of J-PARC

1683

P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The transverse impedance of the extraction kicker magnets is the most dominant beam instability source in the 3-GeV Rapid Cycling Synchrotron of J-PARC. The instability occurs when chromaticity is fully corrected during acceleration but on the other hand no instabilities are observed for a full chromatic correction only at the injection energy even for a beam power up to 500 kW. However, the situation may change for a beam power of 1 MW and also for the upgraded injection beam energy from the present 181 MeV to the 400 MeV, as space charge effect in the non-relativistic region is believed to suppress the growth rate of beam instability. In order to study the kicker impedance in detail, recently we have introduced measured time dependent impedance source in the ORBIT simulation code in a realistic manner. The ORBIT code itself has also been well upgraded and given realistic features for application to synchrotrons. We have also carried out a systematic experimental study for a maximum beam power of 500 kW. In this paper, a detail comparison between measurements and corresponding simulations including 1 MW simulation results are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI051

Export •

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

THOAA03

Transverse Intra-bunch Feedback in the J-PARC MR

2786

SUSPSNE086

use link to see paper's listing under its alternate paper code

K. Nakamura
Kyoto University, Kyoto, Japan
Y.H. Chin, T. Obina, M. Okada, M. Tobiyama
KEK, Ibaraki, Japan
T. Koseki, T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

We will report the development of a new broadband (bandwidth of around 100MHz) feedback system for suppression of intra-bunch oscillations and reduction of particle losses at the J-PARC Main Ring (MR). A new BPM has been designed based on the exponential coupler stripline type (the diameter of 134 mm and the length of 300 mm) and it is now under fabrication. In this BPM system, the frequency characteristics are corrected using the equalizer as bunch signals are differentiated. The design detail and the performance of the new BPM as well as preparation of newly installed exciter and power amplifiers will be presented. We will also report beam test results of head-tail mode suppression at 3 GeV with the bunch length of 150-250 ns.

Slides THOAA03 [1.149 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOAA03

Export •

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