IPAC2014 - List of Keywords (induction)

Paper	Title	Other Keywords	Page
MOPME068	SiC-JFET Switching Power Supply toward for Induction Ring Accelerators	acceleration, ion, extraction, injection	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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TUPRO085	Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators	undulator, cryogenics, permanent-magnet, polarization	1238
	F.-J. Börgermann, C. Brombacher, K. Üstüner Vacuumschmelze GmbH & Co. KG, Hanau, Germany
	The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO085
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WEOAB02	Wide-band Induction Acceleration in the KEK Digital Accelerator	acceleration, ion, synchrotron, experiment	1893
	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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WEPRI069	Reproducibility of High-Q SRF Cavities by High Temperature Heat Treatment	cavity, vacuum, SRF, niobium	2651
	P. Dhakal, G. Ciovati, P. Kneisel, G.R. Myneni JLab, Newport News, Virginia, USA
	Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 Recent work on high-temperature (> 600 °C) heat treatment of ingot Nb cavities in a customized vacuum furnace for several hours showed the possibility of achieving Q0-values of up to ~5×10¹⁰ at 2.0 K, 1.5 GHz and accelerating gradients of ~20 MV/m. This contribution presents results on further studies of the heat treatment process to produce cavities with high Q0 values for continuous-wave accelerator application. Single-cell cavities of different Nb purity have been processed through few cycles of heat-treatments and chemical etching. Measurements of Q0 as a function of temperature at low RF field and of Q0 as a function of the RF field at or below 2.0 K have been made after each treatment. Measurements by TOF-SIMS of the impurities’ depth profiles were made on samples heat treated with the cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI069
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THPME131	A Multi-conductor Transmission Line Model for the BPMs	pick-up, impedance, beam-transport, framework	3550
	T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	We have developed an accurate and efficient analysis method with a multi-conductor transmission line model for beam position monitors (BPMs). This method combines the two-dimensional electrostatic analysis including beams in the transverse plane and the transmission line analysis in the longitudinal direction. The loads are also included in the boundary condition of the transmission line analysis. Calculation of 2D electrostatic fields can be easily performed with the boundary element method. The BPM response to a beam is compared with that to a stretched wire.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME131
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Paper

Title

Other Keywords

Page

MOPME068

SiC-JFET Switching Power Supply toward for Induction Ring Accelerators

acceleration, ion, extraction, injection

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)

TUPRO085

Properties, Options and Limitations of PrFeB-magnets for Cryogenic Undulators

undulator, cryogenics, permanent-magnet, polarization

1238

F.-J. Börgermann, C. Brombacher, K. Üstüner
Vacuumschmelze GmbH & Co. KG, Hanau, Germany

The gap induction and thus the K-factor of permanent magnet undulators may be increased by cooling them to cryogenic temperatures. The use of NdFeB-magnets in cryogenic undulators, however, is limited to temperatures above 140 K due to the spin-reorientation transition (SRT) which leads to a reduction of the magnetization level. A further increase of the gap induction in undulators may be achieved by use of PrFeB-magnets at even lower temperatures, as this alloy does not show the SRT phenomenon. Although the effects are well known, up to now only a few undulator prototypes were built using this class of material since the coercivity of ternary PrFeB-magnets is not sufficient to minimize the risk of partial demagnetization when the undulator structure is kept at room temperature. This problem can be solved by applying actual technologies like grain-boundary diffusion in order to achieve coercivities exceeding 20 kOe at RT without sacrificing the high remanence Br of about 1.6 T at 77 K. We will provide actual data of the magnet performance achieved and show up the technological limitations in building PrFeB-based CPMU’s.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO085

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

WEOAB02

Wide-band Induction Acceleration in the KEK Digital Accelerator

acceleration, ion, synchrotron, experiment

1893

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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WEPRI069

Reproducibility of High-Q SRF Cavities by High Temperature Heat Treatment

cavity, vacuum, SRF, niobium

2651

P. Dhakal, G. Ciovati, P. Kneisel, G.R. Myneni
JLab, Newport News, Virginia, USA

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Recent work on high-temperature (> 600 °C) heat treatment of ingot Nb cavities in a customized vacuum furnace for several hours showed the possibility of achieving Q0-values of up to ~5×10¹⁰ at 2.0 K, 1.5 GHz and accelerating gradients of ~20 MV/m. This contribution presents results on further studies of the heat treatment process to produce cavities with high Q0 values for continuous-wave accelerator application. Single-cell cavities of different Nb purity have been processed through few cycles of heat-treatments and chemical etching. Measurements of Q0 as a function of temperature at low RF field and of Q0 as a function of the RF field at or below 2.0 K have been made after each treatment. Measurements by TOF-SIMS of the impurities’ depth profiles were made on samples heat treated with the cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI069

Export •

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

THPME131

A Multi-conductor Transmission Line Model for the BPMs

pick-up, impedance, beam-transport, framework

3550

T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

We have developed an accurate and efficient analysis method with a multi-conductor transmission line model for beam position monitors (BPMs). This method combines the two-dimensional electrostatic analysis including beams in the transverse plane and the transmission line analysis in the longitudinal direction. The loads are also included in the boundary condition of the transmission line analysis. Calculation of 2D electrostatic fields can be easily performed with the boundary element method. The BPM response to a beam is compared with that to a stretched wire.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME131

Export •

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