IPAC2014 - List of Authors (Umemori, K.)

Paper	Title	Page
MOPRO084	Recent Development and Operational Status of PF-Ring and PF-AR	286
	T. Honda, M. Adachi, S. Asaoka, K. Haga, K. Harada, Y. Honda, M. Izawa, T. Kageyama, Y. Kamiya, Y. Kobayashi, K. Marutsuka, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, M. Ono, T. Ozaki, H. Sagehashi, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, M. Shimada, K. Shinoe, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Ma. Yoshida, S.I. Yoshimoto KEK, Ibaraki, Japan
	Update of the first-generation undulators installed in 1980s is pushed forward at PF-Ring, a 2.5-GeV SR source of KEK, taking advantage of the expanded straight sections reconstructed in 2005. New undulators have been designed as elliptically polarizing undulators each has 6 magnetic arrays to obtain various polarization states, not only circular polarization but also linear (horizontal and vertical) polarization. Three undulators will be installed in FY2013 and FY2014 for BL02, BL13 and BL28. For BL02, the longest straight section of about 9 m, the new undulator will be installed in tandem with the existing planar undulator, in order to cover the wide photon energy range from 15 eV to 2 keV. At PF-AR, a 6.5-GeV SR source, a new direct beam transport (BT) line from the injector LINAC is under construction. Super KEKB which shares the injector LINAC with PF-Ring and PF-AR will be commissioned at the end of FY2014. The full-energy continuous injection of PF-AR will be available as a simultaneous injection with the 7-GeV HER, the 4-GeV LER and PF-Ring not so later than the commissioning of Super KEKB.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO084
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MOPRO109	Beam Loss Studies for the KEK Compact-ERL	349
	O. Tanaka, T. Furuya, K. Harada, N. Nakamura, H. Sakai, M. Shimada, K. Umemori KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan
	Beam losses due to eﬀects of Touschek, residual gas, intra-beam scattering, and field emission were studied for the KEK compact Energy Recovery Linac (cERL), which is now under commissioning. By studying the beam losses of cERL, we can better understand the loss mechanisms, estimate the beam loss rates, and localize potentially dangerous areas of the beamline for the future 3GeV ERL project. The goal is to achieve a safety low-emittance and high-current beams operation which can help contribute to the beam loss study under 3GeV ERL project. We used existing and modiﬁed ELEGANT routine to perform the simulations. We also developed a MATLAB data analysis algorithm to handle the large amount of information that is outputted from the program. The data obtained then compared with the theoretical estimation to judge the computation’s accuracy.
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MOPRO110	Present Status of the Compact ERL at KEK	353
	N. Nakamura, M. Adachi, S. Adachi, M. Akemoto, D.A. Arakawa, S. Asaoka, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, S. Sasaki, K. Satoh, M. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan R. Hajima, S. Matsuba, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma JAEA, Ibaraki-ken, Japan J.G. Hwang KNU, Deagu, Republic of Korea M. Kuriki Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan
	The Compact Energy Recovery Linac (cERL) project is ongoing at KEK in order to demonstrate excellent ERL performance as a future light source. The cERL injector was already constructed with its diagnostic beamline and successfully commissioned from April to June in 2013. In the next step, the cERL recirculation loop with a main superconducting linac and merger and dump sections has been constructed and its commissioning is scheduled to start in December 2013. Significant progress is expected by the IPAC14 conference date. In this presentation, we will describe the present status of the cERL including future developments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO110
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TUPRI092	Improvement of the Position Monitor using White Light Interferometer for Measuring Precise Movement of Compact ERL Superconducting Cavities in Cryomodule	1787
	H. Sakai, K. Enami, T. Furuya, M. Satoh, K. Shinoe, K. Umemori KEK, Ibaraki, Japan T. Aoto, K. Hayashi, K. Kanzaki Tokyo Seimitsu Co. Ltd, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	Alignment of superconducting cavities is one of the important issues for linear collider and/or future light source like ERL and X-FEL. To measure the cavity displacement under cooling to liquid He temperature more precisely, we newly developed the position monitor by using white light interferometer. This monitor is based on the measurement of the interference of light between the measurement target and the reference point. It can measure the position from the outside of the cryomodule. We applied this monitor to the main linac cryomodule of Compact ERL (cERL) and successfully measured the displacement during 2K cooling with the resolution of 10um. However, some drift come from outer temperature and humidity were observed. In this paper, we describe the upgraded version of this monitor to suppress these drift for cERL beam operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI092
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WEPME073	Performance of RF System for Compact-ERL Main Linac at KEK	2450
	T. Miura, M. Akemoto, A. Akiyama, D.A. Arakawa, S. Fukuda, H. Honma, H. Katagiri, T. Matsumoto, H. Matsushita, S. Michizono, H. Nakajima, K. Nakao, F. Qiu, H. Sakai, T. Shidara, T. Takenaka, K. Umemori, Y. Yano KEK, Ibaraki, Japan
	The construction of compact ERL in the first stage has been completed in the end of 2013. The rf commissioning in main-linac has been started. The main-linac consists of two nine-cell cavities. The loaded Q is high, ~10⁷. As the rf power sources, a solid state power amplifier and an inductive output tube (IOT) has been used for two cavities, respectively. The RF field and tuner have been successfully controlled by using micro-TCA digital feedback board. This paper reports about the RF commissioning and the performance.
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WEPRI022	In-house Production of a Large-Grain Single-Cell Cavity at Cavity Fabrication Facility and Results of Performance Tests	2519
	T. Kubo, Y. Ajima, H. Inoue, K. Umemori, Y. Watanabe, M. Yamanaka KEK, Ibaraki, Japan
	We studied electron beam welding (EBW) conditions for large grain Nb, and fabricated a single cell cavity in Cavity Fabrication Facility (CFF), KEK. Vertical-test results of the cavity made from large grain Nb are also presented.
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WEPRI025	Studies of Fabrication Procedure of 9-cell SRF Cavity for ILC Mass-production at KEK.	2528
	T. Saeki, Y. Ajima, K. Enami, H. Hayano, H. Inoue, E. Kako, S. Kato, S. Koike, T. Kubo, S. Noguchi, M. Satoh, M. Sawabe, T. Shishido, A. Terashima, N. Toge, K. Ueno, K. Umemori, K. Watanabe, Y. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, M. Yamanaka, K. Yokoya KEK, Ibaraki, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan N. Kawabata, H. Nakamura, K. Nohara, M. Shinohara SPS, Funabashi-shi, Japan F. Yasuda The University of Tokyo, Institute of Physics, Tokyo, Japan
	We had been constructing a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deep-drawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the studies on the fabrication of 9-cell cavity for International Linear Collier (ILC) using this facility. The studies are focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We already finished the fabrication of two 9-cell cavities in this facility. This article reports the current status of the studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI025
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WEPRI026	Mechanical Vibration Search of Compact ERL Main Linac Superconducting Cavities in Cryomodule	2531
	M. Satoh, K. Enami, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, K. Shinoe, K. Umemori KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	In 2014, we will start the beam operation in Compact ERL(cERL) by using main linac cryomodule, which contained the two 9-cell cavities. In principle, thanks to the mechanism of energy recovery, the input power of main linac of cERL is very small even if the beam current will be higher than 100mA. Therefore, the coupling is very weak. However, this coupling is perfectly not matched to the unloaded Q-value of the superconducting cavity like 1x10¹⁰. The minimum input power will be restricted by the cavity detuning due to the microphonics from the cryomodule itself. We designed the lower loaded Q-valued of (1-4)x10⁷ to reduce the effect of the michrophonics from the expected outer disturbance At present, we successfully suppressed the michrophonics to meet our requirement. However we found the enhancement of the detuning angle when we did not optimize the feedback loop of LLRF. This enhancement will be expected coming from the mechanical resonance frequencies of cavity and/or cryomodule. In this paper, we reported the correlation between the measured microphincs spectrum with LLRF in a beam operation and the results of the measured resonance frequencies spectrum at the test bench.
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WEPRI027	Performance Evaluation of ERL Main Linac Tuner	2534
	K. Enami, D.A. Arakawa, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, M. Satoh, K. Shinoe, K. Umemori KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	cERL project is now progressing. We are carrying on R&D for cERLmain linac consisted of 1.3GHz superconductive cavity. We evaluate slide jack tuner, which is component part of cryomodule. A slide jack tuner has 2 mechanism to tune frequency. One is slide jack mechanism that tunes roughly and the other is piezo mechanism that tunes finely. We carried out basic experiment and cold experiment. We finally confirmed that slide jack tuning system can tuning to target frequency 1.3GHz.
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WEPRI028	Operation Status of Compact ERL Main Linac Cryomodule	2537
	K. Umemori, K. Enami, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, M. Satoh, K. Shinoe KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	We have developed a main linac cryomodule, in which two nine-cell HOM damped SRF cavities were mounted, for the Compact ERL (cERL) project in Japan. The main linac cryomodule is operated by a 2K refrigerator system, whose cooling ability is 80W. RF power is fed to each cavity from an IOT or a solid state amplifier. Amplitude and phase of RF stabilization is done by using a digital LLRF system. Cavity resonant frequency is controlled by using mechanical and piezo tuners. Before beam operation, performance test of the cryomodule has been carried out. Generally the cryomodule works well, but heavy field emission is rather problem. After construction of cERL circulation ring, we have a plan to do first beam operation with energy recovery mode, in this winter. Electron beam are accelerated up to 20 MeV. Heavy heat load to 2K Helium, caused by field emission, restrict cavity operation voltage. We report about a series of performance tests and a first experiment from beam operation.
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THPRI045	Development of a 1.3-GHz Buncher Cavity for the Compact ERL	3866
	T. Takahashi, Y. Honda, T. Miura, T. Miyajima, H. Sakai, S. Sakanaka, K. Shinoe, T. Uchiyama, K. Umemori, M. Yamamoto KEK, Ibaraki, Japan
	In a high-brightness injector of the Compact ERL (cERL), a 1.3-GHz buncher cavity is used to compress the electron bunches which are produced at a 500-kV photocathode DC electron gun. An rf voltage required is about 130 kV. To elongate the lifetime of the photocathode of the DC gun which is located beside the buncher cavity, an extremely-low pressure of about 10^-9 Pa is required in the buncher cavity under operating conditions. In order to achieve such low pressures, we have developed a normal-conducting cavity which included several measures to reduce the outgas from the cavity components, together with careful rf designs to avoid any problems due to multipactor discharges or to other problems. With the developed cavity, we achieved a vacuum pressure of about 2·10^-9 Pa under rf operations at an rf voltage of about 100 kV. The buncher cavity was installed in the cERL, and it worked very well; we could demonstrate to compress the bunch length from 10 ps (FWHM) to 0.5 ps (rms) using the buncher cavity.
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Paper

Title

Page

Recent Development and Operational Status of PF-Ring and PF-AR

286

T. Honda, M. Adachi, S. Asaoka, K. Haga, K. Harada, Y. Honda, M. Izawa, T. Kageyama, Y. Kamiya, Y. Kobayashi, K. Marutsuka, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, T. Nogami, T. Obina, M. Ono, T. Ozaki, H. Sagehashi, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, M. Shimada, K. Shinoe, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Ma. Yoshida, S.I. Yoshimoto
KEK, Ibaraki, Japan

Update of the first-generation undulators installed in 1980s is pushed forward at PF-Ring, a 2.5-GeV SR source of KEK, taking advantage of the expanded straight sections reconstructed in 2005. New undulators have been designed as elliptically polarizing undulators each has 6 magnetic arrays to obtain various polarization states, not only circular polarization but also linear (horizontal and vertical) polarization. Three undulators will be installed in FY2013 and FY2014 for BL02, BL13 and BL28. For BL02, the longest straight section of about 9 m, the new undulator will be installed in tandem with the existing planar undulator, in order to cover the wide photon energy range from 15 eV to 2 keV. At PF-AR, a 6.5-GeV SR source, a new direct beam transport (BT) line from the injector LINAC is under construction. Super KEKB which shares the injector LINAC with PF-Ring and PF-AR will be commissioned at the end of FY2014. The full-energy continuous injection of PF-AR will be available as a simultaneous injection with the 7-GeV HER, the 4-GeV LER and PF-Ring not so later than the commissioning of Super KEKB.

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MOPRO109

Beam Loss Studies for the KEK Compact-ERL

349

O. Tanaka, T. Furuya, K. Harada, N. Nakamura, H. Sakai, M. Shimada, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan

Beam losses due to eﬀects of Touschek, residual gas, intra-beam scattering, and field emission were studied for the KEK compact Energy Recovery Linac (cERL), which is now under commissioning. By studying the beam losses of cERL, we can better understand the loss mechanisms, estimate the beam loss rates, and localize potentially dangerous areas of the beamline for the future 3GeV ERL project. The goal is to achieve a safety low-emittance and high-current beams operation which can help contribute to the beam loss study under 3GeV ERL project. We used existing and modiﬁed ELEGANT routine to perform the simulations. We also developed a MATLAB data analysis algorithm to handle the large amount of information that is outputted from the program. The data obtained then compared with the theoretical estimation to judge the computation’s accuracy.

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MOPRO110

Present Status of the Compact ERL at KEK

353

N. Nakamura, M. Adachi, S. Adachi, M. Akemoto, D.A. Arakawa, S. Asaoka, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, S. Sasaki, K. Satoh, M. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
R. Hajima, S. Matsuba, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
JAEA, Ibaraki-ken, Japan
J.G. Hwang
KNU, Deagu, Republic of Korea
M. Kuriki
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
Y. Seimiya
HU/AdSM, Higashi-Hiroshima, Japan

The Compact Energy Recovery Linac (cERL) project is ongoing at KEK in order to demonstrate excellent ERL performance as a future light source. The cERL injector was already constructed with its diagnostic beamline and successfully commissioned from April to June in 2013. In the next step, the cERL recirculation loop with a main superconducting linac and merger and dump sections has been constructed and its commissioning is scheduled to start in December 2013. Significant progress is expected by the IPAC14 conference date. In this presentation, we will describe the present status of the cERL including future developments.

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TUPRI092

Improvement of the Position Monitor using White Light Interferometer for Measuring Precise Movement of Compact ERL Superconducting Cavities in Cryomodule

1787

H. Sakai, K. Enami, T. Furuya, M. Satoh, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
T. Aoto, K. Hayashi, K. Kanzaki
Tokyo Seimitsu Co. Ltd, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

Alignment of superconducting cavities is one of the important issues for linear collider and/or future light source like ERL and X-FEL. To measure the cavity displacement under cooling to liquid He temperature more precisely, we newly developed the position monitor by using white light interferometer. This monitor is based on the measurement of the interference of light between the measurement target and the reference point. It can measure the position from the outside of the cryomodule. We applied this monitor to the main linac cryomodule of Compact ERL (cERL) and successfully measured the displacement during 2K cooling with the resolution of 10um. However, some drift come from outer temperature and humidity were observed. In this paper, we describe the upgraded version of this monitor to suppress these drift for cERL beam operation.

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WEPME073

Performance of RF System for Compact-ERL Main Linac at KEK

2450

T. Miura, M. Akemoto, A. Akiyama, D.A. Arakawa, S. Fukuda, H. Honma, H. Katagiri, T. Matsumoto, H. Matsushita, S. Michizono, H. Nakajima, K. Nakao, F. Qiu, H. Sakai, T. Shidara, T. Takenaka, K. Umemori, Y. Yano
KEK, Ibaraki, Japan

The construction of compact ERL in the first stage has been completed in the end of 2013. The rf commissioning in main-linac has been started. The main-linac consists of two nine-cell cavities. The loaded Q is high, ~10⁷. As the rf power sources, a solid state power amplifier and an inductive output tube (IOT) has been used for two cavities, respectively. The RF field and tuner have been successfully controlled by using micro-TCA digital feedback board. This paper reports about the RF commissioning and the performance.

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WEPRI022

In-house Production of a Large-Grain Single-Cell Cavity at Cavity Fabrication Facility and Results of Performance Tests

2519

T. Kubo, Y. Ajima, H. Inoue, K. Umemori, Y. Watanabe, M. Yamanaka
KEK, Ibaraki, Japan

We studied electron beam welding (EBW) conditions for large grain Nb, and fabricated a single cell cavity in Cavity Fabrication Facility (CFF), KEK. Vertical-test results of the cavity made from large grain Nb are also presented.

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WEPRI025

Studies of Fabrication Procedure of 9-cell SRF Cavity for ILC Mass-production at KEK.

2528

T. Saeki, Y. Ajima, K. Enami, H. Hayano, H. Inoue, E. Kako, S. Kato, S. Koike, T. Kubo, S. Noguchi, M. Satoh, M. Sawabe, T. Shishido, A. Terashima, N. Toge, K. Ueno, K. Umemori, K. Watanabe, Y. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, M. Yamanaka, K. Yokoya
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
N. Kawabata, H. Nakamura, K. Nohara, M. Shinohara
SPS, Funabashi-shi, Japan
F. Yasuda
The University of Tokyo, Institute of Physics, Tokyo, Japan

We had been constructing a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deep-drawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the studies on the fabrication of 9-cell cavity for International Linear Collier (ILC) using this facility. The studies are focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We already finished the fabrication of two 9-cell cavities in this facility. This article reports the current status of the studies.

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WEPRI026

Mechanical Vibration Search of Compact ERL Main Linac Superconducting Cavities in Cryomodule

2531

M. Satoh, K. Enami, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

In 2014, we will start the beam operation in Compact ERL(cERL) by using main linac cryomodule, which contained the two 9-cell cavities. In principle, thanks to the mechanism of energy recovery, the input power of main linac of cERL is very small even if the beam current will be higher than 100mA. Therefore, the coupling is very weak. However, this coupling is perfectly not matched to the unloaded Q-value of the superconducting cavity like 1x10¹⁰. The minimum input power will be restricted by the cavity detuning due to the microphonics from the cryomodule itself. We designed the lower loaded Q-valued of (1-4)x10⁷ to reduce the effect of the michrophonics from the expected outer disturbance At present, we successfully suppressed the michrophonics to meet our requirement. However we found the enhancement of the detuning angle when we did not optimize the feedback loop of LLRF. This enhancement will be expected coming from the mechanical resonance frequencies of cavity and/or cryomodule. In this paper, we reported the correlation between the measured microphincs spectrum with LLRF in a beam operation and the results of the measured resonance frequencies spectrum at the test bench.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI026

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WEPRI027

Performance Evaluation of ERL Main Linac Tuner

2534

K. Enami, D.A. Arakawa, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, M. Satoh, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

cERL project is now progressing. We are carrying on R&D for cERLmain linac consisted of 1.3GHz superconductive cavity. We evaluate slide jack tuner, which is component part of cryomodule. A slide jack tuner has 2 mechanism to tune frequency. One is slide jack mechanism that tunes roughly and the other is piezo mechanism that tunes finely. We carried out basic experiment and cold experiment. We finally confirmed that slide jack tuning system can tuning to target frequency 1.3GHz.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI027

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WEPRI028

Operation Status of Compact ERL Main Linac Cryomodule

2537

K. Umemori, K. Enami, T. Furuya, S. Michizono, T. Miura, F. Qiu, H. Sakai, M. Satoh, K. Shinoe
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

We have developed a main linac cryomodule, in which two nine-cell HOM damped SRF cavities were mounted, for the Compact ERL (cERL) project in Japan. The main linac cryomodule is operated by a 2K refrigerator system, whose cooling ability is 80W. RF power is fed to each cavity from an IOT or a solid state amplifier. Amplitude and phase of RF stabilization is done by using a digital LLRF system. Cavity resonant frequency is controlled by using mechanical and piezo tuners. Before beam operation, performance test of the cryomodule has been carried out. Generally the cryomodule works well, but heavy field emission is rather problem. After construction of cERL circulation ring, we have a plan to do first beam operation with energy recovery mode, in this winter. Electron beam are accelerated up to 20 MeV. Heavy heat load to 2K Helium, caused by field emission, restrict cavity operation voltage. We report about a series of performance tests and a first experiment from beam operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI028

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THPRI045

Development of a 1.3-GHz Buncher Cavity for the Compact ERL

3866

T. Takahashi, Y. Honda, T. Miura, T. Miyajima, H. Sakai, S. Sakanaka, K. Shinoe, T. Uchiyama, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan

In a high-brightness injector of the Compact ERL (cERL), a 1.3-GHz buncher cavity is used to compress the electron bunches which are produced at a 500-kV photocathode DC electron gun. An rf voltage required is about 130 kV. To elongate the lifetime of the photocathode of the DC gun which is located beside the buncher cavity, an extremely-low pressure of about 10^-9 Pa is required in the buncher cavity under operating conditions. In order to achieve such low pressures, we have developed a normal-conducting cavity which included several measures to reduce the outgas from the cavity components, together with careful rf designs to avoid any problems due to multipactor discharges or to other problems. With the developed cavity, we achieved a vacuum pressure of about 2·10^-9 Pa under rf operations at an rf voltage of about 100 kV. The buncher cavity was installed in the cERL, and it worked very well; we could demonstrate to compress the bunch length from 10 ps (FWHM) to 0.5 ps (rms) using the buncher cavity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI045

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