IPAC2014 - List of Authors (Fuwa, Y.)

Paper	Title	Page
MOPRI010	Laser Ablation Ion Source for the KEK Digital Accelerator	598
	N. Munemoto Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan Y. Fuwa, S. Ikeda, M. Kumaki RIKEN, Saitama, Japan Y. Fuwa Kyoto ICR, Uji, Kyoto, Japan S. Ikeda, K. Takayama TIT, Yokohama, Japan M. Kumaki RISE, Tokyo, Japan M. Okamura BNL, Upton, Long Island, New York, USA S. Takano, K. Takayama KEK, Ibaraki, Japan K. Takayama Sokendai, Ibaraki, Japan
	KEK Digital Accelerator (DA) is a small scale induction synchrotron and operated at 10Hz and recently has succeeded to accelerate gaseous ions. There is a strong demand of fully striped carbon ions because the DA is regarded as the second generation of cancer therapy driver, which does not require an injector and electron stripper. We need a novel carbon ion source providing C⁶⁺ beams, which are directly injected into the DA and accelerated up to required energy. For this purpose, a laser ablation ion source(LAIS) is promising. To obtain high yield C⁶⁺ ions from ablation plasma, the laser irradiation condition has been evaluated and relationship between beam properties of charge spectrum, intensity, and temperature, and carbon target materials were examined. Two laser systems, long pulse (6 ns) and short pulse (170 ps), were employed to irradiate a graphite and amorphous carbon target. The current densities and profile of the generated plasmas in time were measured and charge state distributions were analyzed. In addition we will report a full design integrating this LAIS, the extraction system, the longitudinal chopper system, and the low energy beam transport line. T.Yoshimoto et al., presented in this conference ** N.Munemoto et al., Proceedings of ICIS2013, published in Rev. Sci. Inst.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI010
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TUPRO094	Magnetic Field Evaluation of Multipole Permanent Magnets by Harmonic Coil with Novel Calibration Technique	1259
SUSPSNE097	use link to see paper's listing under its alternate paper code
	R. Kitahara, Y. Fuwa, Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan
	Quadrupole magnets for ILC final focus should be strong enough with the restriction on the external radius to let the disrupted out-going beam pass by, while vibration of the magnetic center has to be highly avoided to keep the nm sized beam focusing stable at the interaction point a few meter downstream from the lens. Gluckstern's 5-ring PMQ singlet seems a good candidate for this point of view. In order to fabricate a good 5-ring singlet, property of each ring has to be good enough. A harmonic coil system, which has 24-bit ADC’s for high resolution, was developed. Current noise level of the system is less than 10^-5, which is supposed to be improved by reducing mechanical vibration of the ball bearings. We demonstrated the evaluation method of coil wire position with magnetic field from pin point magnet, so that the accuracy of the method was comparable to um scale. We measured the prototype 5-ring PMQ singlet and evaluated harmonic components. This result was compared with the data measured at KEK.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO094
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MOPRI011	Control of Plasma Flux with Pulsed Solenoid for Laser Ion Source	601
SUSPSNE027	use link to see paper's listing under its alternate paper code
	S. Ikeda, K. Horioka TIT, Yokohama, Japan Y. Fuwa, S. Ikeda, M. Kumaki RIKEN, Saitama, Japan T. Kanesue, M. Okamura BNL, Upton, Long Island, New York, USA
	We discuss the behavior of laser-ablation plasma spreading through a pulsed solenoidal field to minimize the beam emittance of laser-ablation ion source (LIS). LIS is expected to produce high-flux and low emittance ion beams from various solid materials in vacuum because of the high drift velocity and low temperature of the ablation plasma due to the adiabatic expansion. However, the ion flux level from the ablation plasma into an extraction gap changes within a pulse and then the shape of the sheath boundary changes transiently. Then, the integrated emittance is larger than the stroboscopic emittance at a certain time slice. To prevent the transient effect, we tried to control the plasma flux with a pulsed solenoidal magnetic field. The field is expected to change the direction of the plasma flow like a lens. By changing the magnetic flux density according to the transient flux level of ablation plasma, we can expect to control the plasma flux at the extraction gap. To investigate the controllability of the plasma flow, we measured the plasma flux as a function of parameters of the pulsed magnetic field. We scanned ion probes along the beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Laser Ablation Ion Source for the KEK Digital Accelerator

598

N. Munemoto
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama, Japan
Y. Fuwa, S. Ikeda, M. Kumaki
RIKEN, Saitama, Japan
Y. Fuwa
Kyoto ICR, Uji, Kyoto, Japan
S. Ikeda, K. Takayama
TIT, Yokohama, Japan
M. Kumaki
RISE, Tokyo, Japan
M. Okamura
BNL, Upton, Long Island, New York, USA
S. Takano, K. Takayama
KEK, Ibaraki, Japan
K. Takayama
Sokendai, Ibaraki, Japan

KEK Digital Accelerator (DA) is a small scale induction synchrotron and operated at 10Hz and recently has succeeded to accelerate gaseous ions*. There is a strong demand of fully striped carbon ions because the DA is regarded as the second generation of cancer therapy driver, which does not require an injector and electron stripper. We need a novel carbon ion source providing C⁶⁺ beams, which are directly injected into the DA and accelerated up to required energy. For this purpose, a laser ablation ion source(LAIS) is promising**. To obtain high yield C⁶⁺ ions from ablation plasma, the laser irradiation condition has been evaluated and relationship between beam properties of charge spectrum, intensity, and temperature, and carbon target materials were examined. Two laser systems, long pulse (6 ns) and short pulse (170 ps), were employed to irradiate a graphite and amorphous carbon target. The current densities and profile of the generated plasmas in time were measured and charge state distributions were analyzed. In addition we will report a full design integrating this LAIS, the extraction system, the longitudinal chopper system, and the low energy beam transport line.
* T.Yoshimoto et al., presented in this conference
** N.Munemoto et al., Proceedings of ICIS2013, published in Rev. Sci. Inst.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI010

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

TUPRO094

Magnetic Field Evaluation of Multipole Permanent Magnets by Harmonic Coil with Novel Calibration Technique

1259

SUSPSNE097

use link to see paper's listing under its alternate paper code

R. Kitahara, Y. Fuwa, Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan

Quadrupole magnets for ILC final focus should be strong enough with the restriction on the external radius to let the disrupted out-going beam pass by, while vibration of the magnetic center has to be highly avoided to keep the nm sized beam focusing stable at the interaction point a few meter downstream from the lens. Gluckstern's 5-ring PMQ singlet seems a good candidate for this point of view. In order to fabricate a good 5-ring singlet, property of each ring has to be good enough. A harmonic coil system, which has 24-bit ADC’s for high resolution, was developed. Current noise level of the system is less than 10^-5, which is supposed to be improved by reducing mechanical vibration of the ball bearings. We demonstrated the evaluation method of coil wire position with magnetic field from pin point magnet, so that the accuracy of the method was comparable to um scale. We measured the prototype 5-ring PMQ singlet and evaluated harmonic components. This result was compared with the data measured at KEK.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO094

Export •

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

MOPRI011

Control of Plasma Flux with Pulsed Solenoid for Laser Ion Source

601

SUSPSNE027

use link to see paper's listing under its alternate paper code

S. Ikeda, K. Horioka
TIT, Yokohama, Japan
Y. Fuwa, S. Ikeda, M. Kumaki
RIKEN, Saitama, Japan
T. Kanesue, M. Okamura
BNL, Upton, Long Island, New York, USA

We discuss the behavior of laser-ablation plasma spreading through a pulsed solenoidal field to minimize the beam emittance of laser-ablation ion source (LIS). LIS is expected to produce high-flux and low emittance ion beams from various solid materials in vacuum because of the high drift velocity and low temperature of the ablation plasma due to the adiabatic expansion. However, the ion flux level from the ablation plasma into an extraction gap changes within a pulse and then the shape of the sheath boundary changes transiently. Then, the integrated emittance is larger than the stroboscopic emittance at a certain time slice. To prevent the transient effect, we tried to control the plasma flux with a pulsed solenoidal magnetic field. The field is expected to change the direction of the plasma flow like a lens. By changing the magnetic flux density according to the transient flux level of ablation plasma, we can expect to control the plasma flux at the extraction gap. To investigate the controllability of the plasma flow, we measured the plasma flux as a function of parameters of the pulsed magnetic field. We scanned ion probes along the beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI011

Export •

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