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Development of laser beam injection system for the Edge Thomson Scattering (ETS) in ITER

谷塚 英一; 波多江 仰紀; 水藤 哲*; 小原 美由紀*; 萩田 浩二*; 井上 和典*; Bassan, M.*; Walsh, M.*; 伊丹 潔

Journal of Instrumentation (Internet), 11(1), p.C01006_1 - C01006_12, 2016/01

 被引用回数:6 パーセンタイル:32.38(Instruments & Instrumentation)

In the ITER Edge Thomson Scattering, the penetration in the port plug allows the laser beams to be injected into the plasma. The penetration has to be as small as possible to reduce neutron streaming from the plasma-side. In ITER, multiple laser systems are needed for high availability of Thomson scattering diagnostics. A new type of beam combiner was developed to obtain collinear, i.e. smallest footprint because of the common path, and fixed polarization from multiple laser beams using a rotating half-wave-plate. The rotating half-wave-plate method does not induce misalignment even if the rotating mechanism defects. The combined beam is injected into plasma and is absorbed at the beam dump. The beam alignment system was designed to hit the laser beam onto the center of the beam dump. The beam position at the beam dump head is monitored by multiple alignment laser beams which are collinear with the diagnostic YAG laser beam and an imaging system installed outside the diagnostic port.


Enhancement of resistance against high energy laser pulse injection with chevron beam dump

谷塚 英一; 波多江 仰紀; Bassan, M.*; Vayakis, G.*; Walsh, M.*; 伊丹 潔

Fusion Engineering and Design, 100, p.461 - 467, 2015/11

 被引用回数:6 パーセンタイル:47.56(Nuclear Science & Technology)

This paper reports our recent developments on the laser beam dump for the Edge Thomson Scattering System in ITER. The laser-induced damage on the beam dump surface is one of the most severe issues of the beam dump development to be overcome. In order to resolve the damage issue, a new type of beam dump called the chevron beam dump was proposed recently. This paper aims to verify the key concept of the chevron beam dump design. The laser irradiation tests onto flat-mirror-molybdenum sample were carried out. It was clarified that the absorbed energy density of the laser pulses should be the correct figure of the laser-induced damage. Therefore, the concept of the chevron beam dump, that minimizes the absorbed laser energy density per unit area, was validated experimentally. It was concluded that the chevron beam dump enables us to extend its lifetime drastically relative to conventional beam dumps.


Development of instrumentation and control systems for the ITER diagnostic systems in JADA

山本 剛史; 橋本 慰登*; 北澤 真一; 谷塚 英一; 波多江 仰紀; 杉江 達夫; 小川 宏明; 竹内 正樹; 河野 康則; 伊丹 潔

Fusion Engineering and Design, 96-97, p.1012 - 1016, 2015/10

 被引用回数:4 パーセンタイル:34.71(Nuclear Science & Technology)

日本国内機関では、ITER計画において6種類のプラズマ計測装置の調達を担当している。原子力機構では、ITER標準ソフトウェアを用いて、統括制御機能、シーケンス制御管理機能及びデータ収集機能を含むITER計測装置用計装制御システムを開発した。統括制御機能は、センサーの健全性検査、計測条件の設定及び計測条件間の一貫性検査といった計測のための内部処理を管理する。我々は、Python言語を用いてフローチャートからEPICS(Experimental Physics and Industrial Control System)のコードを生成するツール及びシーケンス制御管理機能を開発した。EPICSは、運転手順のトリガー及び進行を示すために使用される。シーケンス制御管理機能は、EPICSを用いてプラント状態の変化を監視することにより、運転手順の進行を管理する。EPICSと運転手順の関連付けは、上記ツールにより自動的に行われる。我々は、熱電対計測システムに関して、上記の計装制御システムの性能を検証した。また、さらに複雑な計測装置向けに本設計を適用していく予定である。


Signal evaluations using singular value decomposition for Thomson scattering diagnostics

東條 寛; 山田 一博*; 安原 亮*; 谷塚 英一; 舟場 久芳*; 波多江 仰紀; 林 浩*; 伊丹 潔

Review of Scientific Instruments, 85(11), p.11D865_1 - 11D865_3, 2014/11

 被引用回数:2 パーセンタイル:11.64(Instruments & Instrumentation)

In incoherent Thomson scattering diagnostics, stray light of the incident laser, which is frequently generated at the vacuum windows, also causes wrong evaluations of the signal intensities. Because the laser goes through the vacuum windows many times in a double-pass (or multi-pass) scattering system, complicate temporal structures can be seen in the output signals. In this paper, Singular Value Decomposition (SVD) is applied to the output signals in a Thomson scattering diagnostic on Large Helical Device (LHD). The analyzed data were all measured signals for each one spectral channel over one plasma shot. Some noises were filtered and Te was evaluated within good accuracies especially in the second pass (forward scattering). We compared the errors in Te (0.8 - 1.3 keV) from the noise-filtered and from non-filtered data. Use of the filtered data enables suppressing the error in Te measured from the second pass by a factor of $$sim$$ 0.5 at the most.


Progresses in development of the ITER edge Thomson scattering system

谷塚 英一; Bassan, M.*; 波多江 仰紀; 石川 正男; 嶋田 恭彦; Vayakis, G.*; Walsh, M.*; Scannell, R.*; Huxford, R.*; Bilkova, P.*; et al.

Journal of Instrumentation (Internet), 8(12), p.C12001_1 - C12001_10, 2013/12

 被引用回数:12 パーセンタイル:50.93(Instruments & Instrumentation)

In ITER, the edge Thomson scattering system (ETS) is one of the primary diagnostic systems for measuring electron temperature and electron density profiles of edge plasma. In order to provide a high throughput of scattered light against a low throughput of neutron and $$gamma$$ ray from plasma, collection optics with a labyrinthine optical path in the port plug was designed. A combination of in-situ calibration (using two lasers with different wavelengths) and periodic calibration (using a super-continuum light source illuminating shutter rear-plate covered with a diffusive material) would provide accurate measurements in ITER against the degradation of spectral transmissivity due to the harsh radiation environment and sputtering/contamination of the first mirror. Specifications of subsystems were determined from assessments of measurement error. It was confirmed that the ETS will work in ITER with the specifications achieved by present technologies.


Chevron beam dump for ITER edge Thomson scattering system

谷塚 英一; 波多江 仰紀; Vayakis, G.*; Bassan, M.*; 伊丹 潔

Review of Scientific Instruments, 84(10), p.103503_1 - 103503_6, 2013/10

 被引用回数:10 パーセンタイル:45.48(Instruments & Instrumentation)

This paper contains the design of the beam dump for the ITER Edge Thomson Scattering (ETS) System and mainly concerns its lifetime under the harsh thermal and electromagnetic loads as well as tight space allocation. The lifetime was estimated from the multi-pulse laser-induced damage threshold. In order to extend its lifetime, the structure of the beam dump was optimized. A number of bent sheets aligned parallel in the beam dump form a shape called a chevron which enables it to avoid the concentration of the incident laser pulse energy. The chevron beam dump is expected to withstand thermal loads due to nuclear heating, radiation from the plasma and numerous incident laser pulses throughout the entire ITER project. Structural analysis was also carried out in case of electromagnetic loads during a disruption. Induced stress is significantly less than the yield strength. Therefore, it is expected that the chevron beam dump will work under the ITER's environment.



波多江 仰紀; 吉田 英次*; 谷塚 英一

プラズマ・核融合学会誌, 88(10), p.555 - 574, 2012/10



Development of a YAG laser system for the edge Thomson scattering system in ITER

波多江 仰紀; 谷塚 英一; 林 利光; 吉田 英次*; 小野 武博; 草間 義紀

Review of Scientific Instruments, 83(10), p.10E344_1 - 10E344_3, 2012/10

 被引用回数:14 パーセンタイル:53.09(Instruments & Instrumentation)



Anisotropic electron temperature measurements without knowing the spectral transmissivity for a JT-60SA Thomson scattering diagnostic

東條 寛; 波多江 仰紀; 谷塚 英一; 伊丹 潔

Review of Scientific Instruments, 83(10), p.10E346_1 - 10E346_3, 2012/10

 被引用回数:0 パーセンタイル:0.01(Instruments & Instrumentation)

This paper focuses on a method to measure $$T_{rm e}$$ without knowing transmissivity using Thomson scattering diagnostic with a double-pass scattering configuration. Effect of installation errors about the scattering angle to accuracy in $$T_{rm e}$$ is discussed. Application of this method to measure anisotropic $$T_{rm e}$$, i.e. $$T_{rm e}$$ about the parallel ($$T_{rm e ||}$$) and perpendicular ($$T_{rm e perp}$$) directions for the magnetic field, is proposed. Although large statistical errors are expected because of correspondences between the scattered spectra from the first and second pass, stable accuracy appears in the area with $$T_{rm e perp}/T_{rm e ||} > 0.5$$ in the core measurements of JT-60SA.


Polychromator for the edge Thomson scattering system in ITER

谷塚 英一; 波多江 仰紀; 藤江 大二郎*; 黒川 敦雄*; 草間 義紀

Review of Scientific Instruments, 83(10), p.10E328_1 - 10E328_3, 2012/07

 被引用回数:2 パーセンタイル:12.67(Instruments & Instrumentation)



Principles for local measurement of the anisotropic electron temperature of plasma using incoherent Thomson scattering

谷塚 英一; 波多江 仰紀; 草間 義紀

Nuclear Fusion, 51(12), p.123004_1 - 123004_4, 2011/12

 被引用回数:9 パーセンタイル:38.66(Physics, Fluids & Plasmas)



Neutronic analysis of the ITER poloidal polarimeter

石川 正男; 河野 康則; 今澤 良太; 佐藤 聡; Vayakis, G.*; Bertalot, L.*; 谷塚 英一; 波多江 仰紀; 近藤 貴; 草間 義紀

Fusion Engineering and Design, 86(6-8), p.1286 - 1289, 2011/10

 被引用回数:1 パーセンタイル:10.89(Nuclear Science & Technology)



Plasma boundary and first-wall diagnostics in ITER

Pitcher, C. S.*; Andrew, P.*; Barnsley, R.*; Bertalot, L.*; Counsell, G. G.*; Encheva, A.*; Feder, R. E.*; 波多江 仰紀; Johnson, D. W.*; Kim, J.*; et al.

Journal of Nuclear Materials, 415(Suppl.1), p.S1127 - S1132, 2011/08

 被引用回数:0 パーセンタイル:0.01(Materials Science, Multidisciplinary)

ITER plasma boundary and first-wall diagnostics are summarized in terms of their physical implementation and physics motivation. The challenge of extracting diagnostic signals while maintaining nuclear shielding is discussed, as well as the problems associated with high levels of erosion and redeposition.


Conceptual design of the collection optics for the edge Thomson scattering system in ITER

谷塚 英一; 波多江 仰紀; 水藤 哲*; 相田 善行*; 草間 義紀

Review of Scientific Instruments, 81(10), p.10D541_1 - 10D541_4, 2010/10

 被引用回数:6 パーセンタイル:31.42(Instruments & Instrumentation)

The difficulty in the edge Thomson scattering (TS) diagnostic in ITER is caused by the neutron and $$gamma$$-ray irradiation. The vacuum window shall not directly face to a plasma. The TS light is relayed through the relaying optics with labyrinth, and collected to the optical fiber bundles. The total transmissivity of the TS light from a plasma to the optical fiber is approximately 30%. An electron density of 2$$times10^{19}$$ $$rm{m}^{-3}$$ is enough to measure electron temperature and electron density within a 10% and 5% margin of error, respectively, with 5 mm of the spatial resolution. The super-Gaussian beam is the ideal laser profile for the laser injection optics to avoid the break-down of filling gas at the calibration of the spectral transmissivity.


A Self-calibration method for the edge Thomson scattering diagnostic in ITER

谷塚 英一; 波多江 仰紀; 草間 義紀

Journal of Plasma and Fusion Research SERIES, Vol.9, p.12 - 17, 2010/08

Calibration of spectral transmissivity of the collection and transmission optics is one of the most crucial issues in Thomson scattering diagnostic system. In ITER, since the vacuum vessel will be radioactivated, it will not be easy to calibrate the spectral transmissivity nearby the vacuum vessel. By injecting additional calibration laser and fitting both of two Thomson scattering lights, one can obtain electron temperature $$T_{e}$$ and relative transmissivity of each spectral channel of polychromator from Thomson scattering signal itself. As a calibration laser, Ruby laser is a promissing candidate because wavelength of it is desirable not to differ from both of main laser and lower limit of observation so much. Even when spectral transmissivity is unknown, $$T_{e}$$ will be obtained with less than 10 % of accuracy, which is a requirement of edge $$T_{e}$$ measurement in ITER.


Development of prototype YAG laser amplifier for the edge Thomson scattering system in ITER

波多江 仰紀; 林 利光; 谷塚 英一; 梶田 信*; 吉田 英次*; 藤田 尚徳*; 中塚 正大*; 矢作 鎌一*; 信夫 克也*; 小野 武博; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.253 - 258, 2010/08

An edge Thomson scattering system for ITER is a diagnostic system which measures electron temperature and density at the peripheral region in the plasma (r/a $$>$$ 0.85). Required measurement ranges for the electron temperature and density are 50 eV $$<$$ T$$_{e}$$ $$<$$ 10 keV and 5$$times$$10$$^{18}$$ $$<$$ n$$_{e}$$ $$<$$ 3$$times$$10$$^{20}$$ m$$^{-3}$$, respectively. The spatial and the temporal resolutions are 5 mm and 10 ms, respectively. A high-energy (5 J) and high repetition-rate (100 Hz) Q-switch Nd:YAG laser system is necessary to satisfy measurement requirements above. We have been developing the YAG laser system for ITER. We have developed a prototype high-power laser amplifier. Since the laser efficiency of solid-state laser is low in generally ($$sim$$ 2%), heat removal from the amplifier is crucial. In the amplifier design, we carried out heat analysis to optimize the cooling design. To realize 5 J of output energy, more than 1.6 J of energy needs to be extracted from one laser rod. In the initial laser amplification test, the extracted energy was limited $$sim$$1.4 J by a lateral depumping effect. We have changed a cooling flow tube for the laser rod made by borosilicate glass to samarium-doped glass in order to deplete an infrared light emission. The Sm-doped flow tube was successfully suppressed the lateral depumping, and consequently the extracted energy reached up to 1.76 J. We have obtained a prospect of the real laser amplifier production from the results.


Progress in ITER diagnostics development in Japan

河野 康則; 岩前 敦; 小川 宏明; 杉江 達夫; 波多江 仰紀; 谷塚 英一; 近藤 貴; 石川 正男; 佐藤 和義; 林 利光; et al.

no journal, , 



In-situ calibration of the spectral transmissivity of Thomson scattering measurements

谷塚 英一

no journal, , 

Calibration of the spectral transmissivity is one of the most crusial issues for the Thomson scattering system in ITER plasmas. However, since the vacuum vessel will be radioactivated, it is very hard to calibrate by conventional methods that uses a known light source at the measurement point. In addition, the calibration needs to be carried out frequently because the deterioration of the transmissivity will occur due to the neutron and $$gamma$$-ray irradiation. Availability of the $$it{in}$$-$$it{situ}$$ calibration method by injecting 2 lasers has been investigated. It depends on the combination of the spectrometor, wavelengths of the 2 lasers, electron temperature $$T_{e}$$ and electron density $$n_{e}$$ at the calibration. If we assume the edge Thomson scattering system in ITER, the ruby laser is promising, and 1.5 keV of $$T_{e}$$ and $$3times 10^{19}$$ $$rm{m}^{-3}$$ of $$n_{e}$$ is enough to calibrate the spectral transmissivity.


Progress in ITER diagnostics development in Japan

河野 康則; 近藤 貴; 石川 正男; 小川 宏明; 岩前 敦; 杉江 達夫; 佐藤 和義; 波多江 仰紀; 谷塚 英一; 林 利光; et al.

no journal, , 




草間 義紀; 河野 康則; 杉江 達夫; 近藤 貴; 小川 宏明; 波多江 仰紀; 佐藤 和義; 鈴木 哲; 林 利光; 小野 武博; et al.

no journal, , 

ITERの計測装置は、2007年の設計レビューによる見直し、調達分担の再調整を経て、2009年6月のITER理事会において決定された。日本は、中性子束測定・核融合出力評価のためのマイクロフィッションチェンバー, プラズマ周辺部の電子温度・密度を測定する周辺トムソン散乱計測装置、プラズマコア部の電流密度・安全係数を評価するポロイダル偏光計、ダイバータ部の水素同位体と不純物を測定するダイバータ不純物モニター、ダイバータターゲットの温度・入熱を評価するダイバータ赤外サーモグラフィー、ダイバータ熱電対の6つの計測装置を調達する。原子力機構は、日本の国内機関として、これらの計測装置の開発を進めてきた。現在は、調達準備の最終段階として、機器の設計と試作試験を進めている。これらの活動の現状と今後の計画を述べる。

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