IPAC2015 - List of Authors (Harada, H.)

Paper	Title	Page
MOPWA058	Measurement Results of the Impedance of the RF-cavity at the RCS in J-PARC	255
	Y. Shobuda, H. Harada, H. Hotchi JAEA/J-PARC, Tokai-mura, Japan
	The kicker impedance dominates at the RCS in J-PARC. Recently, we observe beam instabilities, which are not explained by the kicker. As a candidate causing the beam instability, the impedance of the RF-cavity is measured. The longitudinal impedance is measured by stretching a single-wire inside the cavity. On the other hand, the measurement of the transverse impedance is done by horizontally shifting the single-wire, due to the accuracy problem. The measured impedance is too low to explain the beam instability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA058
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MOPTY003	Measurement of Momentum Spread of the Injection Beam with Longitudinal Tomography Method in the J-PARC RCS	944
	M. Yoshimoto, H. Harada, H. Hotchi, M. Kinsho, P.K. Saha, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the J-PARC RCS, the beam tuning toward the design output beam power of 1MW were started after the completing of the beam energy and beam current upgrades in the LINAC. One of the important issues to achieve the 1MW beam operation is the optimization of the injection beam from the LINAC. Due to the longitudinal beam tuning in the LINAC, the momentum spread of the injected beam into the RCS was measured with the longitudinal tomography method. Our longitudinal tomography tool had been developed using the simple algorithm with the Convolution Back-Projection (CBP) method for the beam storage mode of the RCS. Accordingly, we improved this tool to expand into the acceleration mode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY003
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THPF043	Preliminary Studies of Laser-assisted H⁻ Stripping at 400 MeV	3795
	P.K. Saha, H. Harada, M. Kinsho, T. Maruta, K. Okabe, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T.V. Gorlov ORNL, Oak Ridge, Tennessee, USA Y. Irie KEK, Ibaraki, Japan
	Conventional H⁻ stripping injection by using solid stripper foils in high intensity accelerators has many limitations concerning foil scattering beam losses, short lifetime of the foil including unexpected and rapid foil failure due to overheating of the foil. It is not only an issue for reliable machine operation but also for facility maintenance. In the 3-GeV RCS of J-PARC, the residual radiation level is extremely high not only near the injection area but also the used foil itself including the foil holder even at the present operation with one third of the designed 1 MW beam power. As an alternate method, later-assisted stripping of 1 GeV H⁻ beam has been intensively studied at SNS in Oak Ridge. The preparation for the next experiment is underway to demonstrate a three orders of magnitude improvement as compared to the earlier experiment. It is important to extend these studies for the lower H⁻ beam energies. In the same framework as in the SNS, laser stripping for the J-PARC H⁻ beam energy of 400 MeV has been studied in the present work. The real challenges and feasibilities at this lower energy are discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF043
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Measurement Results of the Impedance of the RF-cavity at the RCS in J-PARC

255

Y. Shobuda, H. Harada, H. Hotchi
JAEA/J-PARC, Tokai-mura, Japan

The kicker impedance dominates at the RCS in J-PARC. Recently, we observe beam instabilities, which are not explained by the kicker. As a candidate causing the beam instability, the impedance of the RF-cavity is measured. The longitudinal impedance is measured by stretching a single-wire inside the cavity. On the other hand, the measurement of the transverse impedance is done by horizontally shifting the single-wire, due to the accuracy problem. The measured impedance is too low to explain the beam instability.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA058

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPTY003

Measurement of Momentum Spread of the Injection Beam with Longitudinal Tomography Method in the J-PARC RCS

944

M. Yoshimoto, H. Harada, H. Hotchi, M. Kinsho, P.K. Saha, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the J-PARC RCS, the beam tuning toward the design output beam power of 1MW were started after the completing of the beam energy and beam current upgrades in the LINAC. One of the important issues to achieve the 1MW beam operation is the optimization of the injection beam from the LINAC. Due to the longitudinal beam tuning in the LINAC, the momentum spread of the injected beam into the RCS was measured with the longitudinal tomography method. Our longitudinal tomography tool had been developed using the simple algorithm with the Convolution Back-Projection (CBP) method for the beam storage mode of the RCS. Accordingly, we improved this tool to expand into the acceleration mode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY003

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THPF043

Preliminary Studies of Laser-assisted H⁻ Stripping at 400 MeV

3795

P.K. Saha, H. Harada, M. Kinsho, T. Maruta, K. Okabe, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T.V. Gorlov
ORNL, Oak Ridge, Tennessee, USA
Y. Irie
KEK, Ibaraki, Japan

Conventional H⁻ stripping injection by using solid stripper foils in high intensity accelerators has many limitations concerning foil scattering beam losses, short lifetime of the foil including unexpected and rapid foil failure due to overheating of the foil. It is not only an issue for reliable machine operation but also for facility maintenance. In the 3-GeV RCS of J-PARC, the residual radiation level is extremely high not only near the injection area but also the used foil itself including the foil holder even at the present operation with one third of the designed 1 MW beam power. As an alternate method, later-assisted stripping of 1 GeV H⁻ beam has been intensively studied at SNS in Oak Ridge. The preparation for the next experiment is underway to demonstrate a three orders of magnitude improvement as compared to the earlier experiment. It is important to extend these studies for the lower H⁻ beam energies. In the same framework as in the SNS, laser stripping for the J-PARC H⁻ beam energy of 400 MeV has been studied in the present work. The real challenges and feasibilities at this lower energy are discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)