HB2014 - List of Authors (Shobuda, Y.)

Paper

Title

Page

Resonance Structures in the Impedance of a Ceramic Break and the Measured Results

74

Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y.H. Chin, K. Takata
KEK, Tokai, Ibaraki, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Recently, we have developed a new theory to evaluate longitudinal and transverse impedances of any size of ceramic break sandwiched between metal chambers. The theory successfully reproduces the resonance structures in the impedance due to trapped modes inside the ceramic break. The comparisons between the theoretical and the simulation results such as ABCI and CST Studio show excellent agreements, indicating that they can be used as a good benchmark test for accuracy of simulation codes. To demonstrate the existence of such resonances, the transverse impedance of the ceramic break is measured using the wire-method. The measurement results reproduce the simulations well. The theory is particularly useful for the evaluation of the impedance of the ceramic break with titanium nitride coating.

THO2AB02

The Kicker Impedance and its Effect on the RCS in J-PARC

369

Y. Shobuda, P.K. Saha, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan
Y.H. Chin, Y. Irie
KEK, Ibaraki, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Measurements demonstrate that the kicker impedance dominates along the RCS. Based on a newly developed theory, the impedance is measured by observing the beam-induced voltages at the ends of power cable of the kicker. Toward one mega-watt goal, it is essential to take advantage of tune manipulations and the space charge damping effect. A reduction scheme of the kicker impedance is proposed to pursue the ultimate goal at the RCS.

Slides THO2AB02 [9.113 MB]

THO3AB01

Performance of Transverse Intra-Bunch Feedback System at J-PAC MR

384

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

A new broadband (~100 MHz) feedback system has been developed for suppression of intra-bunch oscillations and reduction of particle losses at the J-PARC Main Ring (MR). A new BPM has been designed and fabricated, based on Linnecar’s exponential coupler stripline type, for a flatter and wider frequency response. The design and performance of the new BPM as well as preparation of a newly installed exciter and power amplifier is presented. We also report beam test results of suppression of horizontal intra-bunch oscillations at 3 GeV with the bunch length of 150-200 ns.

Slides THO3AB01 [6.245 MB]

Paper	Title	Page
MOPAB23	Resonance Structures in the Impedance of a Ceramic Break and the Measured Results	74
	Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y.H. Chin, K. Takata KEK, Tokai, Ibaraki, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Recently, we have developed a new theory to evaluate longitudinal and transverse impedances of any size of ceramic break sandwiched between metal chambers. The theory successfully reproduces the resonance structures in the impedance due to trapped modes inside the ceramic break. The comparisons between the theoretical and the simulation results such as ABCI and CST Studio show excellent agreements, indicating that they can be used as a good benchmark test for accuracy of simulation codes. To demonstrate the existence of such resonances, the transverse impedance of the ceramic break is measured using the wire-method. The measurement results reproduce the simulations well. The theory is particularly useful for the evaluation of the impedance of the ceramic break with titanium nitride coating.

THO2AB02	The Kicker Impedance and its Effect on the RCS in J-PARC	369
	Y. Shobuda, P.K. Saha, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan Y.H. Chin, Y. Irie KEK, Ibaraki, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Measurements demonstrate that the kicker impedance dominates along the RCS. Based on a newly developed theory, the impedance is measured by observing the beam-induced voltages at the ends of power cable of the kicker. Toward one mega-watt goal, it is essential to take advantage of tune manipulations and the space charge damping effect. A reduction scheme of the kicker impedance is proposed to pursue the ultimate goal at the RCS.
	Slides THO2AB02 [9.113 MB]

THO3AB01	Performance of Transverse Intra-Bunch Feedback System at J-PAC MR	384
	Y.H. Chin, T. Obina, M. Okada, M. Tobiyama, T. Toyama KEK, Ibaraki, Japan K.G. Nakamura Kyoto University, Kyoto, Japan Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	A new broadband (~100 MHz) feedback system has been developed for suppression of intra-bunch oscillations and reduction of particle losses at the J-PARC Main Ring (MR). A new BPM has been designed and fabricated, based on Linnecar’s exponential coupler stripline type, for a flatter and wider frequency response. The design and performance of the new BPM as well as preparation of a newly installed exciter and power amplifier is presented. We also report beam test results of suppression of horizontal intra-bunch oscillations at 3 GeV with the bunch length of 150-200 ns.
	Slides THO3AB01 [6.245 MB]