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Observation of divertor and core radiation in JT-60U by means of bolometric imaging

ボロメータイメージング法によるJT-60Uダイバータ及びコアプラズマ放射の観測

Peterson, B. J.*; 木島 滋; Parchamy, H.*; 金子 昌司*; 大森 俊道*; Seo, D. C.*; 芦川 直子*; 助川 篤彦; JT-60チーム

Peterson, B. J.*; Konoshima, Shigeru; Parchamy, H.*; Kaneko, Masashi*; Omori, Toshimichi*; Seo, D. C.*; Ashikawa, Naoko*; Sukegawa, Atsuhiko; JT-60 Team

核融合科学研究所との研究協力としてJT-60Uで実施している「核燃焼トカマク実験用イメージング・ボロメータの開発」に関する最新の研究成果を報告する。この計測法は、プラズマの放射をピンホールを介して薄膜に投影し、その結果生じる薄膜上の温度変化を赤外カメラの画像として測定する方法である。接線方向に広角の視野を持つ所から、ダイバータを含む全ポロイダル断面のトーラス1/4周にわたる広い範囲の観測が可能である。昨年開始した予備試験では高加熱入力の重水素放電時に赤外カメラの誤動作が発生したため、中性子,$$gamma$$線並びに漏洩磁場に対する遮蔽をさらに強化し、併せて画像信号伝送系の改造を行った。この改造により、強磁場で高パワー加熱の重水素放電での測定が可能となり、赤外カメラのデータから薄膜上に写影された放射強度を1秒間に30コマの映像として観測できるようになった。不純物を入射して放射損失を過大にした時のプラズマ崩壊の様子を視覚的に捉える、など幾つかの初期結果を得た。感度較性,2次元放射パワー分布の算出など測定・検討結果を報告する。

Diagnosis of the radiation from both the divertor and core plasma regions is a key issue for the study of impurities resulting from plasma-surface interaction in existing magnetic plasma confinement experiments and future fusion reactors. An infrared imaging video bolometer has been designed, fabricated and installed on the JT-60U tokamak. This diagnostic utilizes an IR camera to image the temperature change of a thin foil which is exposed to plasma radiation through an aperture resulting in an image of the incident plasma radiation absorbed by the foil. In the 2004-2005 experimental campaign intitial data was taken which was limited to 8-bit analog video data from ohmic and hydrogen neutral beam discharges due to inadequate shielding. The semitangential, wide-angle view of the plasma covers the entire poloidal cross-section and the divertor extending over 90 degrees toroidally. This preliminary data showed a strong radiation zone from the divertor that moved up into the core plasma as the discharge terminated in agreement with the data from the resistive bolometer arrays. For the current campaign we have upgraded the system by improving the shielding against neutrons, $$gamma$$ and magnetic field. This has enabled operation of the camera during high magnetic field and some high power deuterium neutral beam discharges. We also improved the triggering and data transmission system to acquire 14-bit digital data. This will allow processing of the IR camera data to produce images of the radiation brightness at the foil which can be viewed as a movie with a frame rate of 30 fps. This data is used to study the toroidal uniformity of the radiation from the divertor in JT-60U.

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パーセンタイル:31.65

分野:Materials Science, Multidisciplinary

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