IPAC2014 - List of Authors (Okamura, K.)

Paper	Title	Page
MOPME068	SiC-JFET Switching Power Supply toward for Induction Ring Accelerators	523
	K. Okamura, K. Takayama, M. Wake, T. Yoshimoto KEK, Ibaraki, Japan R. Sasaki, K. Takaki Iwate university, Morioka, Iwate, Japan K. Takayama, T. Yoshimoto TIT, Yokohama, Japan F. Tamura Nagaoka University of Technology, Nagaoka, Niigata, Japan
	Funding: Japan Science and Technology Agency Grant-In Aid for Scientific Research(s) (KAKENHI No. 24310077) A new induction synchrotron system using an induction cell has been developed and constructed at KEK. In that system, the switching power supply is one of the key devices that realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device. However, series connection gives large complexity and less reliability. Among various switching devices, a SiC-JFET should be a promising candidate because it has ultrafast switching speed and high voltage blocking capability. We have developed a new and original SiC-JFET switching device and a compact switching power supply employing this switching element. Now it is integrated into the induction acceleration system for the KEK-DA. Furthermore we have started development of the next generation of SiC package, which has higher voltage capability (2.4 kV) and 2 in 1 module construction. At the conference, the first experimental demonstration of heavy ion acceleration utilizing the SiC-JFET and the design status of the new device package will be presented. T. Iwashita et al., Phys. Rev. ST-AB 14, 071302 (2011). ** K. Okamura et al., “A Compact Switching Power Supply Utilizing SiC-JFET for The Digital Accelerator ”, in Proc. of IPAC’12, pp 3677-3679.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME068
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WEOAB02	Wide-band Induction Acceleration in the KEK Digital Accelerator	1893
SUSPSNE021	use link to see paper's listing under its alternate paper code
	T. Yoshimoto, X. Liu, K. Takayama TIT, Yokohama, Japan T. Adachi, K. Takayama Sokendai, Ibaraki, Japan T. Adachi, T. Arai, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama, T. Yoshimoto KEK, Ibaraki, Japan H. Asao, Y. Okada NETS, Fuchu-shi, Japan M. Hirose, H. Kobayashi Tokyo City University, Tokyo, Japan
	Induction synchrotron can accelerate any ion species directly to higher energy without a large pre-accelerator, due to its intrinsic nature that there is no frequency band-width limitation below 1 MHz. KEK digital accelerator (DA) is a small scale prototype of fast cycling induction synchrotron. Recently it has been confirmed that heavy ion beams of mass to charge ratio A/Q = 4 are stably accelerated from 200 keV to a few tens of MeV in this accelerator ring, where the revolution frequency changes from82 kHz to 1 MHz. Acceleration and beam confinement are separately realized by pulse voltages generated in induction cells (1 to 1 pulse transformers) driven by the switching power supply (SPS). Everything is simply maneuvered by controlling of gate signals of solid-state switching elements employed in the SPS. For this purpose, the fully programmed acceleration control system based on the FPGA has been developed. In this paper, the wide-band induction acceleration is presented with experimental results. Further possibilities of beam handling in the induction synchrotron, such as super bunch and novel beam handling techniques, are discussed. K.Takayama et al., to be submitted to Phys. Rev. Lett. (2013). ** T.Iwashita et al., Phys. Rev. ST-AB 14, 071301(2011).
	Slides WEOAB02 [8.935 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOAB02
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THPME060	Malfunction, Cause and Recurrence Prevention Measures of J-PARC Slow Extraction	3370
	M. Tomizawa, T. Kimura, H. Nakagawa, K. Okamura KEK, Ibaraki, Japan
	The radiation leakage accident occurred at the J-PARC hadron experimental hall in May 2013 was triggered by a target damage due to an unanticipated short beam pulse from J-PARC main ring. An extremely short beam pulse was produced by a rapid current increase of the quadrupole (EQ) power supply system for a spill feedback. A simulation with the slow extraction process could explain such a short beam pulse generation. The cause of the malfunction has been identified by an intensive investigation of the EQ power supply system performed after the accident. We will show measures to prevent recurrence.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME060
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Paper

Title

Page

SiC-JFET Switching Power Supply toward for Induction Ring Accelerators

523

K. Okamura, K. Takayama, M. Wake, T. Yoshimoto
KEK, Ibaraki, Japan
R. Sasaki, K. Takaki
Iwate university, Morioka, Iwate, Japan
K. Takayama, T. Yoshimoto
TIT, Yokohama, Japan
F. Tamura
Nagaoka University of Technology, Nagaoka, Niigata, Japan

Funding: Japan Science and Technology Agency Grant-In Aid for Scientific Research(s) (KAKENHI No. 24310077)
A new induction synchrotron system using an induction cell has been developed and constructed at KEK*. In that system, the switching power supply is one of the key devices that realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device. However, series connection gives large complexity and less reliability. Among various switching devices, a SiC-JFET should be a promising candidate because it has ultrafast switching speed and high voltage blocking capability. We have developed a new and original SiC-JFET switching device and a compact switching power supply employing this switching element**. Now it is integrated into the induction acceleration system for the KEK-DA. Furthermore we have started development of the next generation of SiC package, which has higher voltage capability (2.4 kV) and 2 in 1 module construction. At the conference, the first experimental demonstration of heavy ion acceleration utilizing the SiC-JFET and the design status of the new device package will be presented.
* T. Iwashita et al., Phys. Rev. ST-AB 14, 071302 (2011).
** K. Okamura et al., “A Compact Switching Power Supply Utilizing SiC-JFET for The Digital Accelerator ”, in Proc. of IPAC’12, pp 3677-3679.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPME068

Export •

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

WEOAB02

Wide-band Induction Acceleration in the KEK Digital Accelerator

1893

SUSPSNE021

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

T. Yoshimoto, X. Liu, K. Takayama
TIT, Yokohama, Japan
T. Adachi, K. Takayama
Sokendai, Ibaraki, Japan
T. Adachi, T. Arai, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama, T. Yoshimoto
KEK, Ibaraki, Japan
H. Asao, Y. Okada
NETS, Fuchu-shi, Japan
M. Hirose, H. Kobayashi
Tokyo City University, Tokyo, Japan

Induction synchrotron can accelerate any ion species directly to higher energy without a large pre-accelerator, due to its intrinsic nature that there is no frequency band-width limitation below 1 MHz. KEK digital accelerator (DA) is a small scale prototype of fast cycling induction synchrotron. Recently it has been confirmed that heavy ion beams of mass to charge ratio A/Q = 4 are stably accelerated from 200 keV to a few tens of MeV in this accelerator ring*, where the revolution frequency changes from82 kHz to 1 MHz. Acceleration and beam confinement are separately realized by pulse voltages generated in induction cells (1 to 1 pulse transformers) driven by the switching power supply (SPS)**. Everything is simply maneuvered by controlling of gate signals of solid-state switching elements employed in the SPS. For this purpose, the fully programmed acceleration control system based on the FPGA has been developed. In this paper, the wide-band induction acceleration is presented with experimental results. Further possibilities of beam handling in the induction synchrotron, such as super bunch and novel beam handling techniques, are discussed.
* K.Takayama et al., to be submitted to Phys. Rev. Lett. (2013).
** T.Iwashita et al., Phys. Rev. ST-AB 14, 071301(2011).

Slides WEOAB02 [8.935 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEOAB02

Export •

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

THPME060

Malfunction, Cause and Recurrence Prevention Measures of J-PARC Slow Extraction

3370

M. Tomizawa, T. Kimura, H. Nakagawa, K. Okamura
KEK, Ibaraki, Japan

The radiation leakage accident occurred at the J-PARC hadron experimental hall in May 2013 was triggered by a target damage due to an unanticipated short beam pulse from J-PARC main ring. An extremely short beam pulse was produced by a rapid current increase of the quadrupole (EQ) power supply system for a spill feedback. A simulation with the slow extraction process could explain such a short beam pulse generation. The cause of the malfunction has been identified by an intensive investigation of the EQ power supply system performed after the accident. We will show measures to prevent recurrence.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME060

Export •

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