IPAC2011 - List of Authors (Ezura, E.)

Paper

Title

Page

Condition of MA Cut Cores in the RF Cavities of J-PARC Main Ring after Several Years of Operation

107

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

J-PARC 3 GeV RCS and 50 GeV Synchrotron (MR) employ RF cavities loaded with Magnetic Alloy (MA) cores to generate a high field gradient. The RF cavities in RCS use MA un-cut cores. On the other hand, the RF cavities in MR employ MA cut cores to increase the Q-value from 0.6 to 26. We observed the impedance reductions of all MR RF cavities during several years operation. Opening the RF cavities, we found that the impedance reductions were resulting from corrosion on the cut and polished surfaces of MA cores. Before installation of the RF cavities, we had 1000 and 2000 hours long tests at a test stand. We didn't observe the impedance reduction related to the corrosion on the MA core cut surfaces at the test stand. The only difference between the test stand and MR is the quality of cooling water. The MR cooling water contains copper ions for example from copper hollow conductors of the main magnets. We report the influence of the copper ions to the corrosion on the MA core cut surface. We also show plans how to solve the issue of MA core cut surface corrosion.

MOPS008

Simulation of Longitudinal Emittance Control in J-PARC RCS for 400 MeV Injection

607

M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-mura, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
KEK, Tokai, Ibaraki, Japan

The injection energy upgrade of the J-PARC RCS from 181 MeV to 400 MeV is scheduled, this is necessary to achieve the design beam intensity. The high intensity beam is delivered to the MR, and the space charge effect at the MR injection should be alleviated by optimizing the longitudinal beam emittance at RCS extraction. This is realized by matching the shape of the beam emittance between the RCS and the MR. We describe the results of particle tracking simulation with the longitudinal emittance control during the whole acceleration period of the RCS.

WEPS010

Acceleration of High Intensity Proton Beams in the J-PARC Synchrotrons

2502

M. Yoshii
KEK/JAEA, Ibaraki-Ken, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, K. Takata, M. Toda
KEK, Tokai, Ibaraki, Japan
T. Minamikawa
University of Fukui, Fukui, Japan
M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

The J-PARC accelerator complex consists of the linac, the 3GeV rapid cycling synchrotron (RCS) and the 50GeV main synchrotron (MR). These synchrotrons are the first MW-class proton accelerators which employ the high electric field gradient magnetic alloy (MA) loaded RF cavities. The beam commissioning was started in October 2007 for RCS and in May 2008 for MR. High intensity beam operation studies and user runs have been performed, while carefully controlling and minimizing the beam loss. The cycle to cycle beam operation is reproducible and quite stable, because of the stable linac beam energy and the reproducible bending field in both synchrotrons. The MA loaded RF systems and the full digital LLRF also guarantee the stable longitudinal particle motion and precise beam transfer synchronization from RCS to the MLF user facility as well as to the MR. A high intensity proton beam of 2.5·10¹³ ppp is accelerated in RCS. And in MR, a beam intensity up to ~100 Tera ppp was obtained.　We summarize the RF systems and the longitudinal parameters in both rings.

THOBB02

High Gradient Magnetic Alloy Cavities for J-PARC Upgrade

2885

C. Ohmori, O. Araoka, E. Ezura, K. Hara, K. Hasegawa, A. Koda, Y. Makida, Y. Miyake, R. Muto, K. Nishiyama, T. Ogitsu, H. Ohhata, K. Shimomura, A. Takagi, K. Takata, K.H. Tanaka, M. Toda, M. Yoshii
KEK, Tokai, Ibaraki, Japan
T. Minamikawa
University of Fukui, Fukui, Japan
M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

Magnetic alloy cavities are used for both MR and RCS synchrotrons. Both cavity systems operate successfully and they generate a higher voltage than could be achieved by an ordinary ferrite cavity system. For the future upgrade of J-PARC, a higher RF voltage is needed. A new RF cavity system using the material, FT3L, is designed to achieve this higher field gradient. A large production system using an old cyclotron magnet was constructed to anneal 85-cm size FT3L cores in the J-PARC Hadron Experiment Hall. The muSR (Muon Spin Rotation/Relaxation/Resonance) Experiments were also carried out to study the magnetic alloy. The status of development on the J-PARC site and a new RF system design will be reported.

Slides THOBB02 [2.729 MB]

Paper	Title	Page
MOPC019	Condition of MA Cut Cores in the RF Cavities of J-PARC Main Ring after Several Years of Operation	107
	M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan E. Ezura, K. Hasegawa, K. Takata KEK, Tokai, Ibaraki, Japan K. Hara, C. Ohmori, M. Toda, M. Yoshii KEK/JAEA, Ibaraki-Ken, Japan T. Sato, M. Yamamoto JAEA, Ibaraki-ken, Japan
	J-PARC 3 GeV RCS and 50 GeV Synchrotron (MR) employ RF cavities loaded with Magnetic Alloy (MA) cores to generate a high field gradient. The RF cavities in RCS use MA un-cut cores. On the other hand, the RF cavities in MR employ MA cut cores to increase the Q-value from 0.6 to 26. We observed the impedance reductions of all MR RF cavities during several years operation. Opening the RF cavities, we found that the impedance reductions were resulting from corrosion on the cut and polished surfaces of MA cores. Before installation of the RF cavities, we had 1000 and 2000 hours long tests at a test stand. We didn't observe the impedance reduction related to the corrosion on the MA core cut surfaces at the test stand. The only difference between the test stand and MR is the quality of cooling water. The MR cooling water contains copper ions for example from copper hollow conductors of the main magnets. We report the influence of the copper ions to the corrosion on the MA core cut surface. We also show plans how to solve the issue of MA core cut surface corrosion.

MOPS008	Simulation of Longitudinal Emittance Control in J-PARC RCS for 400 MeV Injection	607
	M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-mura, Japan E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii KEK, Tokai, Ibaraki, Japan
	The injection energy upgrade of the J-PARC RCS from 181 MeV to 400 MeV is scheduled, this is necessary to achieve the design beam intensity. The high intensity beam is delivered to the MR, and the space charge effect at the MR injection should be alleviated by optimizing the longitudinal beam emittance at RCS extraction. This is realized by matching the shape of the beam emittance between the RCS and the MR. We describe the results of particle tracking simulation with the longitudinal emittance control during the whole acceleration period of the RCS.

WEPS010	Acceleration of High Intensity Proton Beams in the J-PARC Synchrotrons	2502
	M. Yoshii KEK/JAEA, Ibaraki-Ken, Japan E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, K. Takata, M. Toda KEK, Tokai, Ibaraki, Japan T. Minamikawa University of Fukui, Fukui, Japan M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	The J-PARC accelerator complex consists of the linac, the 3GeV rapid cycling synchrotron (RCS) and the 50GeV main synchrotron (MR). These synchrotrons are the first MW-class proton accelerators which employ the high electric field gradient magnetic alloy (MA) loaded RF cavities. The beam commissioning was started in October 2007 for RCS and in May 2008 for MR. High intensity beam operation studies and user runs have been performed, while carefully controlling and minimizing the beam loss. The cycle to cycle beam operation is reproducible and quite stable, because of the stable linac beam energy and the reproducible bending field in both synchrotrons. The MA loaded RF systems and the full digital LLRF also guarantee the stable longitudinal particle motion and precise beam transfer synchronization from RCS to the MLF user facility as well as to the MR. A high intensity proton beam of 2.5·10¹³ ppp is accelerated in RCS. And in MR, a beam intensity up to ~100 Tera ppp was obtained.　We summarize the RF systems and the longitudinal parameters in both rings.

THOBB02	High Gradient Magnetic Alloy Cavities for J-PARC Upgrade	2885
	C. Ohmori, O. Araoka, E. Ezura, K. Hara, K. Hasegawa, A. Koda, Y. Makida, Y. Miyake, R. Muto, K. Nishiyama, T. Ogitsu, H. Ohhata, K. Shimomura, A. Takagi, K. Takata, K.H. Tanaka, M. Toda, M. Yoshii KEK, Tokai, Ibaraki, Japan T. Minamikawa University of Fukui, Fukui, Japan M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	Magnetic alloy cavities are used for both MR and RCS synchrotrons. Both cavity systems operate successfully and they generate a higher voltage than could be achieved by an ordinary ferrite cavity system. For the future upgrade of J-PARC, a higher RF voltage is needed. A new RF cavity system using the material, FT3L, is designed to achieve this higher field gradient. A large production system using an old cyclotron magnet was constructed to anneal 85-cm size FT3L cores in the J-PARC Hadron Experiment Hall. The muSR (Muon Spin Rotation/Relaxation/Resonance) Experiments were also carried out to study the magnetic alloy. The status of development on the J-PARC site and a new RF system design will be reported.
	Slides THOBB02 [2.729 MB]