IPAC2014 - List of Authors (Miura, T.)

Paper	Title	Page
MOPRO001	Upgrade Status of Injector LINAC for SuperKEKB	59
	T. Miura, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, R. Ichimiya, N. Iida, M. Ikeda, E. Kadokura, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takenaka, M. Tanaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	The SuperKEKB collider is under construction to achieve 40-times higher luminosity than that of previous KEKB collider. The injector LINAC should provide high-intensity and low-emittance beams of 7-GeV electron and 4-GeV positron for SuperKEKB based on a nano-beam scheme. A photocathode RF-gun for low emittance electron beam has been already installed and the commissioning has started. The construction of positron capture section using a flux-concentrator and the dumping ring for low emittance positron beam is in progress. The simultaneous top-up injections to four storage-rings including photon factories is also required. In the upstream of dumping ring, the compatible optics between positron and electron has been designed. In the downstream of dumping ring, RF phase, focusing, and steering magnets will be switched by pulse to pulse against each beam-mode for optimising beam-transportation. This paper describes recent upgrade status toward the SuperKEKB.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO001
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

MOPRI003	Positron Yield Optimization by Adjusting the Components Offset and Orientation	576
	L. Zang, M. Akemoto, S. Fukuda, K. Furukawa, T. Higo, N. Iida, K. Kakihara, T. Kamitani, T. Miura, F. Miyahara, Y. Ogawa, H. Someya, T. Takatomi, K. Yokoyama KEK, Ibaraki, Japan S. Ushimoto Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
	In order to keep high luminosity beam collision condition at SuperKEKB, low emittance electron/positron injection and flexible pulse-to-pulse switching of these beam modes are essential requirements. While a primary electron beam strikes on a target to generate positrons, an injection electron beam passes through a small hole besides the target. Since the injection electron orbit should be on axis to avoid emittance growth, the target and the flux concentrator for positron focusing have a few millimeters offset from the axis. This offset positron generation gives significant degradation in the positron yield. In this paper, we will discuss positron yield improvement by proper orientation of the cut-in slit of the flux concentrator which yields un-symmetric field distribution and primary electron incident point. With particle tracking simulation taking three dimensional field distribution into account, an ideal positron trajectory giving optimum yield was found.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPRI004	SuperKEKB Positron Source Construction Status	579
	T. Kamitani, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, N. Iida, M. Ikeda, E. Kadokura, H. Kaji, K. Kakihara, H. Katagiri, M. Kikuchi, H. Koiso, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, M. Sato, T. Shidara, A. Shirakawa, M. Suetake, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	The KEKB positron source is under the upgrade for SuperKEKB. The previous positron production target and capture section have been removed and the new system is constructed at a location forty meters upstream to have sufficient energy margin for beam injection to the newly introduced damping ring. A flux concentrator is introduced in the new capture section to make an adiabatic matching system. Large aperture (30mm in diameter) S-band accelerating structures are introduced in the capture section and in the subsequent accelerator module to enlarge the transverse phase space acceptance. The beam focusing system of quadrupoles is also upgraded for a comparable beam acceptance to that of the capture section. This paper reports on the status of the SuperKEKB positron source construction and the preliminary positron beam commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI004
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPME072	Performance of the Digital LLRF System at the cERL	2447
	F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura KEK, Ibaraki, Japan
	A digital low-level radio frequency (LLRF) system has been developed and evaluated at compact Energy Recovery Linac (cERL) in High Energy Accelerator Research Organization (KEK), Japan. A total of three two-cell cavities were installed for the injector, and two nine-cell cavities were installed for the main linac. The required RF stabilities for these cavities are 0.1% rms in amplitude and 0.1° rms in phase. To satisfy these requirements, we survey feedback parameters such as the proportional and integral (PI) gains. Furthermore, we evaluated the beam energy fluctuation due to the vector-sum controlling error between the cavities injectors 2 and 3. Finally, we present the performance of the LLRF system that was realized in the beam commissioning. This paper describes the current status of the LLRF system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME072
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME073
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI026
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI027
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI028
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI045
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Upgrade Status of Injector LINAC for SuperKEKB

59

T. Miura, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, R. Ichimiya, N. Iida, M. Ikeda, E. Kadokura, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takenaka, M. Tanaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

The SuperKEKB collider is under construction to achieve 40-times higher luminosity than that of previous KEKB collider. The injector LINAC should provide high-intensity and low-emittance beams of 7-GeV electron and 4-GeV positron for SuperKEKB based on a nano-beam scheme. A photocathode RF-gun for low emittance electron beam has been already installed and the commissioning has started. The construction of positron capture section using a flux-concentrator and the dumping ring for low emittance positron beam is in progress. The simultaneous top-up injections to four storage-rings including photon factories is also required. In the upstream of dumping ring, the compatible optics between positron and electron has been designed. In the downstream of dumping ring, RF phase, focusing, and steering magnets will be switched by pulse to pulse against each beam-mode for optimising beam-transportation. This paper describes recent upgrade status toward the SuperKEKB.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO001

Export •

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

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

Export •

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

MOPRI003

Positron Yield Optimization by Adjusting the Components Offset and Orientation

576

L. Zang, M. Akemoto, S. Fukuda, K. Furukawa, T. Higo, N. Iida, K. Kakihara, T. Kamitani, T. Miura, F. Miyahara, Y. Ogawa, H. Someya, T. Takatomi, K. Yokoyama
KEK, Ibaraki, Japan
S. Ushimoto
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

In order to keep high luminosity beam collision condition at SuperKEKB, low emittance electron/positron injection and flexible pulse-to-pulse switching of these beam modes are essential requirements. While a primary electron beam strikes on a target to generate positrons, an injection electron beam passes through a small hole besides the target. Since the injection electron orbit should be on axis to avoid emittance growth, the target and the flux concentrator for positron focusing have a few millimeters offset from the axis. This offset positron generation gives significant degradation in the positron yield. In this paper, we will discuss positron yield improvement by proper orientation of the cut-in slit of the flux concentrator which yields un-symmetric field distribution and primary electron incident point. With particle tracking simulation taking three dimensional field distribution into account, an ideal positron trajectory giving optimum yield was found.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI003

Export •

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

MOPRI004

SuperKEKB Positron Source Construction Status

579

T. Kamitani, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, N. Iida, M. Ikeda, E. Kadokura, H. Kaji, K. Kakihara, H. Katagiri, M. Kikuchi, H. Koiso, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, M. Sato, T. Shidara, A. Shirakawa, M. Suetake, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

The KEKB positron source is under the upgrade for SuperKEKB. The previous positron production target and capture section have been removed and the new system is constructed at a location forty meters upstream to have sufficient energy margin for beam injection to the newly introduced damping ring. A flux concentrator is introduced in the new capture section to make an adiabatic matching system. Large aperture (30mm in diameter) S-band accelerating structures are introduced in the capture section and in the subsequent accelerator module to enlarge the transverse phase space acceptance. The beam focusing system of quadrupoles is also upgraded for a comparable beam acceptance to that of the capture section. This paper reports on the status of the SuperKEKB positron source construction and the preliminary positron beam commissioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI004

Export •

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

WEPME072

Performance of the Digital LLRF System at the cERL

2447

F. Qiu, D.A. Arakawa, H. Katagiri, T. Matsumoto, S. Michizono, T. Miura
KEK, Ibaraki, Japan

A digital low-level radio frequency (LLRF) system has been developed and evaluated at compact Energy Recovery Linac (cERL) in High Energy Accelerator Research Organization (KEK), Japan. A total of three two-cell cavities were installed for the injector, and two nine-cell cavities were installed for the main linac. The required RF stabilities for these cavities are 0.1% rms in amplitude and 0.1° rms in phase. To satisfy these requirements, we survey feedback parameters such as the proportional and integral (PI) gains. Furthermore, we evaluated the beam energy fluctuation due to the vector-sum controlling error between the cavities injectors 2 and 3. Finally, we present the performance of the LLRF system that was realized in the beam commissioning. This paper describes the current status of the LLRF system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME072

Export •

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

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME073

Export •

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

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.

DOI •

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

Export •

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

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.

DOI •

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

Export •

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

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.

DOI •

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

Export •

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

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.

DOI •

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

Export •

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