HB2014 - List of Authors (Tamura, F.)

Paper

Title

Page

High Gradient RF System for Upgrade of J-PARC

162

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

Magnetic alloy cavities are successfully used for J-PARC synchrotrons. These cavities generate much higher RF voltage than ordinary ferrite-loaded cavities. The MR (Main Ring) upgrade project aims to deliver the beam power of 750 kW to the neutrino experiment. It includes replacements of all RF cavities for high repetition rate of about 1 Hz. By the replacements, the total acceleration voltage will be doubled, while power supplies and amplifiers remain the same. The key issue is the development of a high gradient RF system using high impedance magnetic alloy, FT3L. A dedicated production system for the FT3L cores with 80 cm diameter was assembled in the J-PARC and demonstrated that we can produce material with two times higher muQf product compared to the cores used for present cavities. The first 5-cell FT3L cavity was assembled and the status of high power test is reported.

THO1LR02

Recent Commissioning of High-Intensity Proton Beams in J-PARC Main Ring

Y. Sato, T. Koseki, J. Takano, S. Yamada, N. Yamamoto
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
H. Harada, M.J. Shirakata, F. Tamura
JAEA/J-PARC, Tokai-mura, Japan
S. Igarashi
KEK, Ibaraki, Japan

In the J-PARC, the main ring (MR) provides high power proton beams of 240 kW (1.24·10¹⁴ protons per pulse) to the neutrino experiment. The linac energy was upgraded from 181 MeV to 400 MeV in 2013, and its current is going to be from 30 mA to 50 mA in 2014. If the beam losses are minimized and localized in the MR, the MR will have the capability to provide over 300 kW after the upstream upgrades. Based on the upgrades and improvements of the 3-50BT and the MR in 2013 and 2014, following approaches have been tested and commissioned: 2nd harmonic RFs under the faster rise-up time improvement of the injection kickers, to increase bunching factor; intra-bunch feed-back system and chromaticity patterned correction, to suppress instability; intra-bunch feed-back, tail and reflection improvement of the injection kickers, and 6D matching between the 3-50BT and the MR, to reduce injection losses; achromatic tuning at the collimator section of the 3-50BT to cut beam halo effectively; collimator upgrades, aperture enlargement at dispersion peaks, and momentum spread control, to localize beam losses in the collimator section; new operation point survey.

Slides THO1LR02 [2.553 MB]

THO3AB02

Dynamic Correction of Extraction Beam Displacement by Field Ringing of Extraction Pulsed Kicker Magnets in the J-PARC 3-GeV RCS

389

H. Harada, H. Hotchi, S.I. Meigo, P.K. Saha, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The 3-GeV rapid cycling synchrotron (RCS) of J-PARC is designed for a high-intensity output beam power of 1MW. The RCS is extracted two bunches by using eight pulsed kicker and three DC septum magnets with 25Hz repetition. The extracted beam is simultaneously delivered to the material and life science experimental facility (MLF) as well as the 50-GeV main ring synchrotron (MR). The kicker magnets have the ringing of flat-top field and the ringing causes the position displacement. The displacement is big issue because it causes an emittance growth of the extracted beam directly. In the beam tuning, we performed a timing scan of each kicker magnet by using a shorter pulse beam in order to understand the characteristics of ringing field. We then carefully optimized the trigger timings of each kicker for the ringing compensation. We have successfully compensated the extracted beam displacements to (min., max.) = (1.1 mm, +0.6 mm) as compared to (14 mm, +10 mm) with no ringing compensation. The procedure for ringing compensation and experimental results are reported in this paper.

Paper	Title	Page
TUO1AB01	High Gradient RF System for Upgrade of J-PARC	162
	C. Ohmori, K. Hara, K. Hasegawa, M. Toda, M. Yoshii KEK, Tokai, Ibaraki, Japan M. Nomura, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan A. Schnase GSI, Darmstadt, Germany
	Magnetic alloy cavities are successfully used for J-PARC synchrotrons. These cavities generate much higher RF voltage than ordinary ferrite-loaded cavities. The MR (Main Ring) upgrade project aims to deliver the beam power of 750 kW to the neutrino experiment. It includes replacements of all RF cavities for high repetition rate of about 1 Hz. By the replacements, the total acceleration voltage will be doubled, while power supplies and amplifiers remain the same. The key issue is the development of a high gradient RF system using high impedance magnetic alloy, FT3L. A dedicated production system for the FT3L cores with 80 cm diameter was assembled in the J-PARC and demonstrated that we can produce material with two times higher muQf product compared to the cores used for present cavities. The first 5-cell FT3L cavity was assembled and the status of high power test is reported.

THO1LR02	Recent Commissioning of High-Intensity Proton Beams in J-PARC Main Ring
	Y. Sato, T. Koseki, J. Takano, S. Yamada, N. Yamamoto J-PARC, KEK & JAEA, Ibaraki-ken, Japan H. Harada, M.J. Shirakata, F. Tamura JAEA/J-PARC, Tokai-mura, Japan S. Igarashi KEK, Ibaraki, Japan
	In the J-PARC, the main ring (MR) provides high power proton beams of 240 kW (1.24·10¹⁴ protons per pulse) to the neutrino experiment. The linac energy was upgraded from 181 MeV to 400 MeV in 2013, and its current is going to be from 30 mA to 50 mA in 2014. If the beam losses are minimized and localized in the MR, the MR will have the capability to provide over 300 kW after the upstream upgrades. Based on the upgrades and improvements of the 3-50BT and the MR in 2013 and 2014, following approaches have been tested and commissioned: 2nd harmonic RFs under the faster rise-up time improvement of the injection kickers, to increase bunching factor; intra-bunch feed-back system and chromaticity patterned correction, to suppress instability; intra-bunch feed-back, tail and reflection improvement of the injection kickers, and 6D matching between the 3-50BT and the MR, to reduce injection losses; achromatic tuning at the collimator section of the 3-50BT to cut beam halo effectively; collimator upgrades, aperture enlargement at dispersion peaks, and momentum spread control, to localize beam losses in the collimator section; new operation point survey.
	Slides THO1LR02 [2.553 MB]

THO3AB02	Dynamic Correction of Extraction Beam Displacement by Field Ringing of Extraction Pulsed Kicker Magnets in the J-PARC 3-GeV RCS	389
	H. Harada, H. Hotchi, S.I. Meigo, P.K. Saha, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The 3-GeV rapid cycling synchrotron (RCS) of J-PARC is designed for a high-intensity output beam power of 1MW. The RCS is extracted two bunches by using eight pulsed kicker and three DC septum magnets with 25Hz repetition. The extracted beam is simultaneously delivered to the material and life science experimental facility (MLF) as well as the 50-GeV main ring synchrotron (MR). The kicker magnets have the ringing of flat-top field and the ringing causes the position displacement. The displacement is big issue because it causes an emittance growth of the extracted beam directly. In the beam tuning, we performed a timing scan of each kicker magnet by using a shorter pulse beam in order to understand the characteristics of ringing field. We then carefully optimized the trigger timings of each kicker for the ringing compensation. We have successfully compensated the extracted beam displacements to (min., max.) = (1.1 mm, +0.6 mm) as compared to (14 mm, +10 mm) with no ringing compensation. The procedure for ringing compensation and experimental results are reported in this paper.