Presentation Gamma ray irradiation effect on optical elements of ITER diverter impurity monitor

Sin-iti, KITAZAWA  ,  YOKOZUKA, Tomohiro  ,  小川, 宏明  ,  丸山, 敏征  ,  田中, 優  ,  及川, 聡洋

ITER divertor impurity monitor (DIM) is a diagnostic system that directly observes light from nuclear fusion plasma in the range of 200-1000 nm. Since DIM observes wide range from infrared to ultraviolet with single optical system, high optical performance such as spatial resolution and aberration is required for optical elements. In addition, it must be highly robustness against external environments such as toughness, temperature, humidity, vibration, magnetic field. Because of its high radiation environment, it is necessary to use a component with high radiation resistance. In this study, the optical elements of the DIM installed in the interspaces and the port cells were investigated, because the gamma ray irradiation effects on those elements are greatly dominant for their robustness. Irradiation experiments were conducted at Gamma-ray irradiation facilities at QST, Takasaki. The dose rates were 0.1 to 10 kGy / h, taking into account the actual rate at ITER and the time required for the experiment. For the glass materials, quartz (SiO2) and fluorite (CaF2) pair lenses which were designed to be installed in interspace as relay lenses in the preliminary design were evaluated. We also conducted irradiation experiments on glass materials used for spectroscopes installed in port cells. For these experimental results, we obtain information necessary for proceeding the design of ITER DIM.
The 27th International Toki Conference on Plasma and Fusion Research & The 13th Asia Pacific Plasma Theory Conference

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