IBIC2012 - List of Keywords (bunching)

Paper	Title	Other Keywords	Page
MOPA08	Various Usages of Wall Current Monitors for Commissioning of RF Systems in J-PARC Synchrotrons	cavity, impedance, controls, synchrotron	63
	F. Tamura, M. Nomura, A. Schnase, T. Shimada, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan K. Hara, K. Hasegawa, C. Ohmori, M. Toda, M. Yoshii KEK, Tokai, Ibaraki, Japan
	Wall current monitors (WCM) for rf system commissioning are installed in the J-PARC synchrotrons, the RCS and the MR. The WCM signals are used as the input of the beam loading compensation system, and also used diagnosis to adjust the rf system parameters. Since the rf and beam frequency is in the range of a few MHz, direct measurement of the WCM signals is possible. For the diagnosis, the WCM signals are taken by an oscilloscope with the revolution clock signal generated by the LLRF control system, and slices of the WCM waveform with lengths of the revolution periods are generated. By stacking the slices, one can get a mountain plot, which shows motions of bunches and variations of the bunch shapes. Also, time variations of the bunching factor, which are important for acceleration of high intensity proton beams, are obtained. The harmonic analysis is performed on the WCM signal and the cavity voltage monitor signal. By using complex amplitudes of them, one can calculate the impedance seen by the beam. In this presentation, we show examples of the analyses described above. The rf parameters for high intensity beams have been successfully adjusted by using these analyses.

MOPA26	Performance and Upgrade of BPMs at the J-PARC MR	proton, quadrupole, alignment, operation	107
	T. Toyama, Y. Hashimoto J-PARC, KEK & JAEA, Ibaraki-ken, Japan K. Hanamura Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan S. Hatakeyama JAEA/J-PARC, Tokai-mura, Japan M. Okada, M. Tejima KEK, Ibaraki, Japan
	Since recovery from the great earthquake 2011.3.11, proton beam, more than 10¹⁴ ppp, is accelerated up to 30 GeV at the J-PARC MR. The BPMs were originally designed with the external capacitors. The aim was to improve the position response in wider frequencies and to get an adequate output voltage at the design intensity, 4x10¹³ ppb. It was modified, however, not to have the capacitors. Therefore we have sufficient signal intensity from low intensity beams of the initial beam commissioning, but too large from the design intensity beam. The processing circuits (BPMC) have to accommodate those output signals from high intensity beams. We are adding the attenuator-LPFs just before the BPMC. This paper will describe these additional attenuator-LPFs. In connection with the MR collimator upgrade, some BPMs are re-allocated. This process is also reported.

Paper

Title

Other Keywords

Page

MOPA08

Various Usages of Wall Current Monitors for Commissioning of RF Systems in J-PARC Synchrotrons

cavity, impedance, controls, synchrotron

63

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

Wall current monitors (WCM) for rf system commissioning are installed in the J-PARC synchrotrons, the RCS and the MR. The WCM signals are used as the input of the beam loading compensation system, and also used diagnosis to adjust the rf system parameters. Since the rf and beam frequency is in the range of a few MHz, direct measurement of the WCM signals is possible. For the diagnosis, the WCM signals are taken by an oscilloscope with the revolution clock signal generated by the LLRF control system, and slices of the WCM waveform with lengths of the revolution periods are generated. By stacking the slices, one can get a mountain plot, which shows motions of bunches and variations of the bunch shapes. Also, time variations of the bunching factor, which are important for acceleration of high intensity proton beams, are obtained. The harmonic analysis is performed on the WCM signal and the cavity voltage monitor signal. By using complex amplitudes of them, one can calculate the impedance seen by the beam. In this presentation, we show examples of the analyses described above. The rf parameters for high intensity beams have been successfully adjusted by using these analyses.

MOPA26

Performance and Upgrade of BPMs at the J-PARC MR

proton, quadrupole, alignment, operation

107

T. Toyama, Y. Hashimoto
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
K. Hanamura
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
S. Hatakeyama
JAEA/J-PARC, Tokai-mura, Japan
M. Okada, M. Tejima
KEK, Ibaraki, Japan

Since recovery from the great earthquake 2011.3.11, proton beam, more than 10¹⁴ ppp, is accelerated up to 30 GeV at the J-PARC MR. The BPMs were originally designed with the external capacitors. The aim was to improve the position response in wider frequencies and to get an adequate output voltage at the design intensity, 4x10¹³ ppb. It was modified, however, not to have the capacitors. Therefore we have sufficient signal intensity from low intensity beams of the initial beam commissioning, but too large from the design intensity beam. The processing circuits (BPMC) have to accommodate those output signals from high intensity beams. We are adding the attenuator-LPFs just before the BPMC. This paper will describe these additional attenuator-LPFs. In connection with the MR collimator upgrade, some BPMs are re-allocated. This process is also reported.