HB2016 - Table of Session: TUC2 (Working Group C

Paper	Title	Page
TUPM5X01	Injection Painting Improvements in the J-PARC RCS	299
	S. Kato, K. Horino, H. Hotchi, M. Kinsho, K. Okabe, P.K. Saha, Y. Shobuda, T. Takayanagi, T. Tobita, T. Ueno JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Harada JAEA, Ibaraki-ken, Japan
	In the J-PARC 3GeV RCS, the injection painting is essential method for the reduction of the space charge force. In this method, the H⁻ beam from Linac is arranged on the large phase space area of the ring orbit during multiple turns. To implement this method, painting magnets form the time variable beam orbit. Therefore, the precise output current control of the magnet power supply is required. Because the power supply controlled by mainly feedforward signal is operated, we developed the iterative tuning method for the optimum feedforward parameter determination. As a result, we could reduce the tracking error of the current compared to before. Furthermore, to improve the accuracy of the painting area size, we applied the output readjustment additionally. Because the current monitor value of the power supply was different from the actual magnetic field due to the delay in the circuit and the leakage field, we corrected the tracking of the current based on the measured painting area size determined by the analysis of the measured COD. As a result, we achieved the precise injection painting. This talk presents these improvement results of the injection painting in the RCS.
	Slides TUPM5X01 [4.122 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUPM5X01
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPM6X01	H⁻ Charge Exchange Injection Issues at High Power	304
	M.A. Plum ORNL, Oak Ridge, Tennessee, USA
	At low beam powers H− charge exchange injection into a storage ring or synchrotron is relatively simple. A thin stripper foil removes the two “convoy” electrons from the H− particle and the newly-created proton begins to circulate around the ring. At high beam powers there are complications due to the heat created in the stripper foil, the power in the H⁰ excited states, and the power in the convoy electrons. The charge-exchanged beam power at the Oak Ridge Spallation Neutron Source is the highest in the world. Although the SNS ring was carefully designed to operate at this level there have been surprises, primarily involving the convoy electrons. Examples include damage to the foil brackets due to reflected convoy electrons and damage to the electron collector due to the primary convoy electrons. The SNS Second Target Station project calls for doubling the beam power and thus placing even more stress on the charge-exchange-injection beam-line components. In this presentation we will compare charge-exchange-injection designs at high-power facilities around the world, discuss lessons learned, and describe the future plans at SNS.
	Slides TUPM6X01 [10.929 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUPM6X01
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPM7X01	An Experimental Plan for 400 MeV H⁻ Stripping to Proton by Using Only Lasers in the J-PARC RCS	310
	P.K. Saha, H. Harada, S. Kato, M. Kinsho JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie, I. Yamane KEK, Ibaraki, Japan
	The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC is gradually approaching to the design operation with 1 MW beam power. Studies are ongoing for further higher beam power of 1.5 MW. The injection and extraction energy of RCS is 0.4 and 3 GeV, respectively. Lifetime of the stripper foil is the highest concern beyond 1 MW beam power. We have also already started detail studies of H⁻ stripping to protons by using lasers. However, in order to avoid high magnetic field required in the process of laser-assisted H⁻ stripping to protons, especially for lower H⁻ energies, we are studying the possibilities of using only laser system for 400 MeV H⁻ beam in the RCS. The method is a three step process, similar to that of SNS but lasers are used instead of high field magnets in the 1st (H⁻ to H⁰) and 3rd step (H0* to p). A Nd:YAG laser can be properly used for both 1st and 3rd steps, where commercially available powerful Excimer laser will be used an H⁰ excitation in the 2nd step. Although detail R&D studies are necessary to reach to the ultimate goal, we plan to carry out an experiment in 2017. A detail of the present method, experimental schedule and the expected outcome will be presented.
	Slides TUPM7X01 [3.316 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUPM7X01
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPM8X01	First results of laser-assisted H⁻ stripping of a 10 us, 1 GeV beam at the SNS accelerator
	S.M. Cousineau ORNL, Oak Ridge, Tennessee, USA
	Laser-assisted H⁻ stripping has been successfully performed for a 10 us, 1 GeV H⁻ beam at the SNS accelerator. Here we discuss the configuration of the experiment, the associated challenges, and the final results including stripping efficiencies and parameter sensitivities.
	Slides TUPM8X01 [8.208 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Injection Painting Improvements in the J-PARC RCS

299

S. Kato, K. Horino, H. Hotchi, M. Kinsho, K. Okabe, P.K. Saha, Y. Shobuda, T. Takayanagi, T. Tobita, T. Ueno
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
H. Harada
JAEA, Ibaraki-ken, Japan

In the J-PARC 3GeV RCS, the injection painting is essential method for the reduction of the space charge force. In this method, the H⁻ beam from Linac is arranged on the large phase space area of the ring orbit during multiple turns. To implement this method, painting magnets form the time variable beam orbit. Therefore, the precise output current control of the magnet power supply is required. Because the power supply controlled by mainly feedforward signal is operated, we developed the iterative tuning method for the optimum feedforward parameter determination. As a result, we could reduce the tracking error of the current compared to before. Furthermore, to improve the accuracy of the painting area size, we applied the output readjustment additionally. Because the current monitor value of the power supply was different from the actual magnetic field due to the delay in the circuit and the leakage field, we corrected the tracking of the current based on the measured painting area size determined by the analysis of the measured COD. As a result, we achieved the precise injection painting. This talk presents these improvement results of the injection painting in the RCS.

Slides TUPM5X01 [4.122 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUPM5X01

Export •

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

TUPM6X01

H⁻ Charge Exchange Injection Issues at High Power

304

M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

At low beam powers H− charge exchange injection into a storage ring or synchrotron is relatively simple. A thin stripper foil removes the two “convoy” electrons from the H− particle and the newly-created proton begins to circulate around the ring. At high beam powers there are complications due to the heat created in the stripper foil, the power in the H⁰ excited states, and the power in the convoy electrons. The charge-exchanged beam power at the Oak Ridge Spallation Neutron Source is the highest in the world. Although the SNS ring was carefully designed to operate at this level there have been surprises, primarily involving the convoy electrons. Examples include damage to the foil brackets due to reflected convoy electrons and damage to the electron collector due to the primary convoy electrons. The SNS Second Target Station project calls for doubling the beam power and thus placing even more stress on the charge-exchange-injection beam-line components. In this presentation we will compare charge-exchange-injection designs at high-power facilities around the world, discuss lessons learned, and describe the future plans at SNS.

Slides TUPM6X01 [10.929 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUPM6X01

Export •

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

TUPM7X01

An Experimental Plan for 400 MeV H⁻ Stripping to Proton by Using Only Lasers in the J-PARC RCS

310

P.K. Saha, H. Harada, S. Kato, M. Kinsho
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie, I. Yamane
KEK, Ibaraki, Japan

The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC is gradually approaching to the design operation with 1 MW beam power. Studies are ongoing for further higher beam power of 1.5 MW. The injection and extraction energy of RCS is 0.4 and 3 GeV, respectively. Lifetime of the stripper foil is the highest concern beyond 1 MW beam power. We have also already started detail studies of H⁻ stripping to protons by using lasers. However, in order to avoid high magnetic field required in the process of laser-assisted H⁻ stripping to protons, especially for lower H⁻ energies, we are studying the possibilities of using only laser system for 400 MeV H⁻ beam in the RCS. The method is a three step process, similar to that of SNS but lasers are used instead of high field magnets in the 1st (H⁻ to H⁰) and 3rd step (H0* to p). A Nd:YAG laser can be properly used for both 1st and 3rd steps, where commercially available powerful Excimer laser will be used an H⁰ excitation in the 2nd step. Although detail R&D studies are necessary to reach to the ultimate goal, we plan to carry out an experiment in 2017. A detail of the present method, experimental schedule and the expected outcome will be presented.

Slides TUPM7X01 [3.316 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-HB2016-TUPM7X01

Export •

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

TUPM8X01

First results of laser-assisted H⁻ stripping of a 10 us, 1 GeV beam at the SNS accelerator

S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA

Laser-assisted H⁻ stripping has been successfully performed for a 10 us, 1 GeV H⁻ beam at the SNS accelerator. Here we discuss the configuration of the experiment, the associated challenges, and the final results including stripping efficiencies and parameter sensitivities.

Slides TUPM8X01 [8.208 MB]

Export •

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