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論文

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:4 パーセンタイル:51.49(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.

論文

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:3 パーセンタイル:53.75(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.

論文

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:43.49(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。

論文

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:1 パーセンタイル:90.16(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.

論文

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:5 パーセンタイル:60.81(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.

論文

An Optical design and accuracy estimation for a JT-60SA edge Thomson scattering diagnostic

東條 寛; 波多江 仰紀; 濱野 隆; 佐久間 猛; 伊丹 潔

Journal of Instrumentation (Internet), 8(12), p.C12025_1 - C12025_13, 2013/12

 パーセンタイル:100(Instruments & Instrumentation)

For collection optics for the edge measurements in a JT-60SA Thomson scattering diagnostic, a compact Petzval-like lens system with smaller lenses (200 mm in diameter) is designed so that the stop position is the middle area of the system, which is effective to miniaturize the lens size. Use of two flat mirrors placed in the middle area enables preventing interferences with the space limit. Generally, the angle ($$phi$$) between the scattering plane determined from the collection optics position and the laser polarization angle should be equal to 90$$^{circ}$$. Otherwise the measured intensity of scattered light decays with $$phi$$. We optimized the angle so that enough intensity is provided for both collection optics positions for the edge and core measurements. It was found that the minimum error in $$T_{rm e}$$ was given at a condition with $$phi=57.2^{circ}$$ for edge optics ($$phi=50.0^{circ}$$ for core optics).

論文

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:7 パーセンタイル:50.65(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.

論文

Optical designs of reflection and refraction collection optics for a JT-60SA core Thomson scattering system

東條 寛; 波多江 仰紀; 濱野 隆; 佐久間 猛; 伊丹 潔

Review of Scientific Instruments, 84(9), p.093506_1 - 093506_8, 2013/09

 被引用回数:2 パーセンタイル:81.3(Instruments & Instrumentation)

Collection optics for the core measurements in a JT-60SA Thomson scattering have been designed. The collection optics will be installed in a limited space and have a wide field of view and a wide dynamic range. Two types of the optics are therefore suggested: refraction and reflection collection optics. The good optical resolutions for the reflection and refraction types are both sufficient for the requirements about the physics study, i.e. 0.3 mm and 0.6 mm, respectively. The efficiencies are also compared. As a result, good measurement accuracy ($$sim$$ 5%) even in high electron temperature ($$<$$ 30 keV) can be expected in the refraction type.

論文

プラズマ磁場閉じ込め装置におけるトムソン散乱計測システムの新展開

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

トムソン散乱計測法は、核融合炉心プラズマの電子温度・密度を測る最も重要な計測の一つである。本解説では、トムソン散乱計測の精度向上や物理的理解の新展開へ資するために、トムソン散乱計測に関する最近の報告を系統的にまとめ、小型装置から大型装置にわたりさまざまな制約・ニーズに応用可能な、先進的なトムソン散乱計測システムのための要素技術を解説する。

論文

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:9 パーセンタイル:44.19(Instruments & Instrumentation)

ITERの周辺トムソン散乱計測装置で用いるYAGレーザー装置の開発の進展について発表する。ITERの計測要求を満たすためには、繰り返し100Hzで出力エネルギー5JのYAGレーザー装置が必要である。これを実現するために、レーザー発振器から出力されるビームを2分岐し、それぞれのビームを口径14mmのレーザーロッド4本で増幅するレーザーシステムを設計し、レーザー増幅器をはじめとする主要機器の製作と、組立てを行った。レーザー増幅器では、フラッシュランプによる強い励起によって、レーザー結晶内で発生するASEやフラッシュランプ光中のレーザー波長と同じ波長の光が増幅率を低下させる原因となるが、サマリウムを添加したガラスを用いたフローチューブで増幅器内のそれらの光を選択的に吸収させることによって、小信号利得が最大2.8倍向上することを明らかにした。結果として、2つのビームラインを同時運転することにより、ITERの要求性能を越える、100Hz,最大7.66Jのレーザー光を発射できるレーザー装置の開発に成功した。

論文

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

 パーセンタイル:100(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.

論文

Fatal damages due to breakdown on a diagnostic mirror located outside the vaccum vessel in JT-60U

梶田 信*; 波多江 仰紀; 佐久間 猛; 高村 秀一*; 大野 哲靖*; 伊丹 潔

Plasma and Fusion Research (Internet), 7(Sp.1), p.2405121_1 - 2405121_4, 2012/09

Recently, enhancement of the initiation of arcing on divertor surfaces has been pointed out due to the surface morphology change and transient heat loads, such as ELMs and disruptions. Inside the vacuum vessel, it seems that the arcing has been frequently observed, and the existences are more or less recognized. However, it is likely that arcing or breakdown phenomena take place not only inside the vessel, but also outside the vessel. In this study, we will report that a diagnostic mirror in JT-60U, which was located outside the vacuum vessel, for Thomson scattering measurement optics in JT-60U has been seriously damaged by some discharge phenomena. Because the damages were so fatal that the mirror had to be replaced after the breakdown. Details of the characteristics of the damage are revealed from the observation of the trails. Furthermore, the mechanism to cause the damages is discussed based on the observation. Many fine trails were found on the surface. The trails could be categorized into two different types with respect to the trail width. It is thought that surface discharge was initiated on the mirror. The mechanisms to lead the damages were discussed based on the observation. This study issues warning on the components to be installed in ITER and future fusion devices both inside and outside the vacuum vessel.

論文

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:81.78(Instruments & Instrumentation)

ITERの周辺トムソン散乱計測では、散乱光を分光するために、干渉フィルター式ポリクロメータ分光器を使用する。トムソン散乱計測は、信号が微弱であるため、集光から分光までの間の損失を低減し、信号強度を増大させることが重要な課題である。従来のポリクロメータ分光器では、干渉フィルターを用いて特定の波長成分を取り出し、残りの成分を次の干渉フィルターで再び特定の波長成分とその他に分けることを繰り返して分光を行っており、干渉フィルターでの多数回の反射が必要であった。反射回数の低減による信号強度増大のため、干渉フィルターで分離した透過・反射光それぞれを再び干渉フィルターで透過・反射させる分岐型の分光器を提案した。信号光のフィルターへの入射角を10度以下程度にすることにより、ITERの周辺トムソン散乱計測装置に適用できる性能を持った分光器が製作できる可能性を示した。

論文

Principle of an in-situ relative calibration method using a double-pass beam for Thomson scattering diagnostics

東條 寛; 波多江 仰紀; 伊丹 潔

Journal of Instrumentation (Internet), 7(5), p.C05004_1 - C05004_11, 2012/05

 被引用回数:10 パーセンタイル:40.95(Instruments & Instrumentation)

This paper presents detailed principles of an in-situ relative calibration method that determine electron temperature ($$T_{rm e}$$) without using optical relative transmissivity and then provide the optical relative transmissivity. The method requires a double-pass scattering system and signal ratio between the two signals from the forward and back scattering in each spectral channel. Statistical simulation results indicates the method suppress a systematic error in $$T_{rm e}$$ without considering chromatic degradation in optical components due to radiation effect. In this new method, scattering angle ($$theta$$) and $$T_{rm e}$$ are important parameters to evaluate the feasibility. It is found that the method is useful in a range of $$theta > 105^{circ}$$ at $$T_{rm e}$$=10 keV. The statistical error tends to decrease in high $$T_{rm e}$$ measurements regime.

論文

Demonstration of in-situ relative calibration method for a Thomson scattering diagnostic on TST-2

東條 寛; 江尻 晶*; 平塚 淳一*; 山口 隆史*; 高瀬 雄一*; 伊丹 潔; 波多江 仰紀

Journal of Instrumentation (Internet), 7(4), p.P04005_1 - P04005_11, 2012/04

 被引用回数:2 パーセンタイル:81.78(Instruments & Instrumentation)

This paper presents experimental results of an in-situ calibration method for Thomson scattering diagnostics in the TST-2 spherical tokamak. Usage of a double-pass scattering configuration enables finding the ratio of the output signal from the first (back scattering) pass to that from the second (forward scattering) pass, which can be treated as an independent function of electron temperature. The temperature from this new method shows a good agreement with that obtained by a standard method (single pass). Relative sensitivities among spectral channels can be then obtained from the method without accessing the machines. The sensitivities from this new method correspond to the values obtained from direct measurements within 5% except for a spectral channel with a wide band-pass range. These results demonstrate feasibility of this new in-situ calibration method, which can be applied to Thomson scattering diagnostics in severe radiation condition.

論文

First measurement of electron temperature from signal ratios in a double-pass Thomson scattering system

東條 寛; 江尻 晶*; 平塚 淳一*; 山口 隆史*; 高瀬 雄一*; 伊丹 潔; 波多江 仰紀

Review of Scientific Instruments, 83(2), p.023507_1 - 023507_4, 2012/02

 被引用回数:8 パーセンタイル:48.08(Instruments & Instrumentation)

This paper presents a experimental demonstration to determine electron temperature ($$T_{rm e}$$) with unknown spectral sensitivity (transmissivity) in a Thomson scattering system. In this method, a double-pass scattering configuration is used and the scattered lights from each pass (with different scattering angles) are measured separately. $$T_{rm e}$$ can be determined from the ratio of the signal intensities without a real chromatic dependence in the sensitivity. This method was applied to the TST-2 Thomson scattering system. As a result, $$T_{rm e}$$ measured from the ratio ($$T_{rm e,r}$$) and $$T_{rm e}$$ measured from a standard method ($$T_{rm e,s}$$) showed a good agreement with $$langle |T_{rm e,r}$-T_${rm e,s}$|/T_${rm e,s}$ rangle = 7.3%.

論文

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:5 パーセンタイル:68.87(Physics, Fluids & Plasmas)

2つの異なる方向から測定したトムソン散乱スペクトルを用いることにより、非等方電子温度を局所計測できる。特に、レーザービーム伝搬方向とトムソン散乱の方向がなす角の2等分線に磁力線が平行又は垂直なとき、磁力線に対してそれぞれ垂直及び平行方向の電子温度を反映したトムソン散乱スペクトルが得られる。磁場がこのような方向を向いていることに加え、ダブルパストムソン散乱計測装置のように、2つのトムソン散乱角の和が180度である場合が理想的な配置であり、磁力線に平行及び垂直方向の電子温度を同時に計測することができる。また、磁場の向きが理想的な方向から20度程度ずれても十分な測定精度が期待される。

論文

Measurements of carbon dust property in experiment and post-campaign sampling on JT-60U Tokamak

朝倉 伸幸; 林 孝夫; 芦川 直子*; 波多江 仰紀; 仲野 友英

Fusion Science and Technology, 60(4), p.1572 - 1575, 2011/11

 被引用回数:5 パーセンタイル:50.9(Nuclear Science & Technology)

JT-60Uにおける実験中及び実験終了後に容器内で収集されたダスト粒子の測定結果を発表する。レーザー散乱によりダスト粒子からの散乱光の分布測定し、プラズマ放電中は周辺部で多くのダストが昇華されることを明らかにした。散乱光強度からダスト粒子の大きさを評価した。さらに、実験期間後に収集されたダストの分析結果から、特にダイバータ下の排気経路部分に多くのダストが蓄積され、粒子の大きさや形状の特性も定量的に評価を行い水素同位体の蓄積量の評価を行った。堆積したダストに蓄積される水素同位体量を、ダスト内部及び表面に蓄積される場合について推定評価を行った。

論文

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

 パーセンタイル:100(Nuclear Science & Technology)

ITERにおいて日本が調達するポロイダル偏向計測装置の設計の一環として、中性子輸送モンテカルロコード(MCNP)を用いた中性子解析を行い、運転時における核発熱量を評価した。その結果、水平ポート内に設置される光学ミラーのうち、第2ミラーの核発熱量は、第1ミラーと同程度であることがわかった。これは、同一ポート内に周辺トムソン散乱計測システムやLIDARシステムが設置されることでポロイダル偏光計の光学系のスペースが制限されるために、十分な迷路構造をもった光路が確保できないことや、第2ミラーの設置位置がプラズマに近い場所に配置せざるを得ないことが原因と考えられる。一方で、水平ポート前面に設置されるブランケット遮蔽モジュールが十分な中性子遮蔽性能を有していれば、光学ミラーの核発熱量は効率的に低減できることがわかった。また、ポロイダル偏光計の光学ミラーが設置される上部ポートの上部に配置されるポロイダル磁場コイルの核発熱量を評価した。その結果、中性子遮蔽材が十分に設置された場合、コイルの核発熱量は上限値である1mW/ccに比べて2桁以上小さくなることがわかった。

論文

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

 パーセンタイル:100(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.

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