IPAC2011 - List of Authors (Takagi, A.)

Paper

Title

Page

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.

WEOBA02

KEK Digital Accelerator and its Beam Commissioning

1920

K. Takayama, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, T. Kawakubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake
KEK, Ibaraki, Japan
T. Adachi, K.W. Leo
Sokendai, Ibaraki, Japan
K. Okazaki
Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan

The digital accelerator (DA), which is a small-scale induction synchrotron no requiring a high-energy injector accelerator and capable of providing a wide variety of ions, has been constructed at KEK*. Since the last winter beam commissioning has been carried out. Preliminary results of the beam commissioning experiment as well as the accelerator itself will be presented at the conference. The KEK-DA consists of a 200 kV high voltage terminal, in which an ECRIS is embedded, 15 m long LEBT, electro-static injection kicker, and a 10 Hz rapid cycle synchrotron, which is the recycle use of the former 500 MeV Booster synchrotron. An ion pulse, which is chopped in 5 μs by the newly developed Marx generator driven chopper**, is guided through the LEBT and injected by the electrostatic kicker, which is turned off before the injected ion pulse completes the first turn. Then the ion pulse is captured with a pair of barrier voltages and accelerated with the induction acceleration voltage through a full acceleration period. Beam commissioning has been started with a He¹⁺ ion beam of 50 micro-ampere. Beam commissioning of other ions such as C, N, O, Ne, and Ar will be expected.
* T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011.
** T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, these proceedings.

Slides WEOBA02 [4.268 MB]

WEPS025

First Beam Experiments at ISIS with a Low Output-impedance Second Harmonic Cavity

2538

Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi, T. Oki, A. Takagi
KEK, Ibaraki, Japan
D. Bayley, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.C. Dooling, D. Horan, R. Kustom
ANL, Argonne, USA
M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

A Low Output-Impedance (LOI) rf drive, which may be suitable for future high intensity accelerator applications, has been developed jointly by ANL, ISIS and KEK for an ISIS synchrotron second harmonic cavity. The cavity is ferrite-loaded, and is driven by a high-power triode (240 kW plate dissipation) with a plate-to-grid feedback circuit. The impedance is designed to be 20~30 ohms over a 2-6 MHz frequency range. Beam induced voltage has been measured with the ISIS beam, and compared with that calculated from the designed output impedance.

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]

THPS037

Performance Characteristics of HBC-foils by 650 KeV H⁻ and DC High Intensity Ion Beam Irradiation

3502

I. Sugai, Y. Irie, H. Kawakami, M. Oyaizu, A. Takagi, Y. Takeda
KEK, Ibaraki, Japan
M. Kinsho, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Newly developed Hybrid type Boron mixed Carbon stripper foils (HBC-stripper foil) are extensively used for not only J-PARC, for but also LANL-PSR since September of 2007. In order to know further characteristics of the HBC-stripper foils, we measured following parameters; foil lifetimes, thickness reduction, uniformity before and after beam irradiation and foil shrinkage, using 3.2 MeV Ne⁺ DC beam from TIT-Van de Grraff and 650 keV DC proton beam at KEK Cock-Croft accelerators, which are almost the same energy deposition as well as the J-PARC. We also investigated sputtering yield by hydrogen ion beam, thermal conductivity, weight change in heating and density of the HBC-stripper foils. We compared these values with other tested carbon stripper foils such as commercially available carbon foils (CM-foil), synthetic diamond (DM-foil) and nano-tube carbon foils (NTC-foil). Through these experiments, the　HBC-stripper foils showed superior performance characteristics, in especially, on the lifetime at temperature higher than 1800K compared with other tested CM-, DM- and NTC-foils.

Paper	Title	Page
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.

WEOBA02	KEK Digital Accelerator and its Beam Commissioning	1920
	K. Takayama, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, T. Kawakubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake KEK, Ibaraki, Japan T. Adachi, K.W. Leo Sokendai, Ibaraki, Japan K. Okazaki Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture, Japan
	The digital accelerator (DA), which is a small-scale induction synchrotron no requiring a high-energy injector accelerator and capable of providing a wide variety of ions, has been constructed at KEK. Since the last winter beam commissioning has been carried out. Preliminary results of the beam commissioning experiment as well as the accelerator itself will be presented at the conference. The KEK-DA consists of a 200 kV high voltage terminal, in which an ECRIS is embedded, 15 m long LEBT, electro-static injection kicker, and a 10 Hz rapid cycle synchrotron, which is the recycle use of the former 500 MeV Booster synchrotron. An ion pulse, which is chopped in 5 μs by the newly developed Marx generator driven chopper, is guided through the LEBT and injected by the electrostatic kicker, which is turned off before the injected ion pulse completes the first turn. Then the ion pulse is captured with a pair of barrier voltages and accelerated with the induction acceleration voltage through a full acceleration period. Beam commissioning has been started with a He¹⁺ ion beam of 50 micro-ampere. Beam commissioning of other ions such as C, N, O, Ne, and Ar will be expected. T. Iwashita et al., “KEK Digital Accelerator”, Phys. Rev. ST-AB, published in 2011. ** T.Adachi et al., “A Solid-State Marx Generator Driven Einzel Lens Chopper”, these proceedings.
	Slides WEOBA02 [4.268 MB]

WEPS025	First Beam Experiments at ISIS with a Low Output-impedance Second Harmonic Cavity	2538
	Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi, T. Oki, A. Takagi KEK, Ibaraki, Japan D. Bayley, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom J.C. Dooling, D. Horan, R. Kustom ANL, Argonne, USA M.E. Middendorf ORNL RAD, Oak Ridge, Tennessee, USA
	A Low Output-Impedance (LOI) rf drive, which may be suitable for future high intensity accelerator applications, has been developed jointly by ANL, ISIS and KEK for an ISIS synchrotron second harmonic cavity. The cavity is ferrite-loaded, and is driven by a high-power triode (240 kW plate dissipation) with a plate-to-grid feedback circuit. The impedance is designed to be 20~30 ohms over a 2-6 MHz frequency range. Beam induced voltage has been measured with the ISIS beam, and compared with that calculated from the designed output impedance.

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]

THPS037	Performance Characteristics of HBC-foils by 650 KeV H⁻ and DC High Intensity Ion Beam Irradiation	3502
	I. Sugai, Y. Irie, H. Kawakami, M. Oyaizu, A. Takagi, Y. Takeda KEK, Ibaraki, Japan M. Kinsho, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Newly developed Hybrid type Boron mixed Carbon stripper foils (HBC-stripper foil) are extensively used for not only J-PARC, for but also LANL-PSR since September of 2007. In order to know further characteristics of the HBC-stripper foils, we measured following parameters; foil lifetimes, thickness reduction, uniformity before and after beam irradiation and foil shrinkage, using 3.2 MeV Ne⁺ DC beam from TIT-Van de Grraff and 650 keV DC proton beam at KEK Cock-Croft accelerators, which are almost the same energy deposition as well as the J-PARC. We also investigated sputtering yield by hydrogen ion beam, thermal conductivity, weight change in heating and density of the HBC-stripper foils. We compared these values with other tested carbon stripper foils such as commercially available carbon foils (CM-foil), synthetic diamond (DM-foil) and nano-tube carbon foils (NTC-foil). Through these experiments, the　HBC-stripper foils showed superior performance characteristics, in especially, on the lifetime at temperature higher than 1800K compared with other tested CM-, DM- and NTC-foils.