28aA02 GAMMA10におけるダイバータ模擬プラズマの特性評価 Characterization of divertor simulation plasma in GAMMA 10 大木健輔，坂本瑞樹，中嶋洋輔，赤羽泰央，長塚優，野原涼，吉川基輝， 小波蔵純子，吉川正志，細井克洋，武田寿人，市村和也，市村真，今井剛 K. Oki, M. Sakamoto, Y. Nakashima, Y. Akabane, Y. Nagatsuka, R. Nohara, M. Yoshikawa, J. Kohagura, M. Yoshikawa, K. Hosoi, H. Takeda, K. Ichimura, M. Ichimura, and T. Imai 筑波大学プラズマ研究センター Plasma Research Center, University of Tsukuba In the tandem mirror device GAMMA 10/PDX, divertor simulation experiments have been promoted using an end region [1, 2]. Recently, a divertor simulation experimental module (D-module) has newly been installed at the end region. A variety of experiments about divertor physics and plasma-wall interaction (PWI) can be carried out using the D-module, which consists of a stainless-steel rectangular chamber (500×480 mm, 700 mm in length) with an inlet with diameter of 200 mm and two tungsten plates (350×300×0.2 mm) composing V-shape with their open-angle from 15 to 80 degrees. A gas injection system is prepared for radiation cooling and detachment studies. At the back of the D-module, an exhaust door for pumping is attached and its clearance is adjustable. The divertor simulation plasmas near the V-shaped target plate are characterized by measurement of electron temperature and density using Langmuir probes and spectrometers in order to study divertor physics and PWI. The Langmuir probes are installed at 13 locations on the upper target plate. Because effective ion temperature is as high as 200 to 400 eV in the GAMMA 10/PDX end region, finite ion temperature effect is taken into account in estimation of electron density from the ion saturation current . He gas is also injected to estimate the electron temperature and density from the He I line intensity ratios using a collisional-radiative model . A viewing field of the spectrometer for the He I lines is at 150 mm away from the corner of the V-shaped target (on axis). Figure 1 shows dependence of electron temperature and density measured using the Langmuir probe on the open-angle of the V-shaped target. These dependence is considered to be related to PWI such as recycling. This figure also shows the results without and with an additional ICRF. With the additional ICRF, the electron temperature decreases and the density increases. In the mirror-confined core plasma (central region), diamagnetism decreases by ~ 50 % and line-averaged density increases by ~ 50 % due to the additional ICRF. Therefore, the electron temperature and density near the V-shaped target change according to the core plasma parameters. In this presentation, we will also show results measured using the spectrometer, along with change in the plasma parameters near the V-shaped target by the gas injection for radiation cooling and so on. Fig. 1. Electron temperature Te and density ne measured using the Langmuir probe.  Y. Nakashima, et al., Fusion Engineering and Design 85 (2010) 956.  Y. Nakashima, et al., Journal of Nuclear Materials 415 (2011) S996.  A. Tsushima and S. Kabaya, Journal of the Physical Society of Japan 67 (1998) 2315.  M. Goto, Journal of Quantitative Spectroscopy & Radiative Transfer 76 (2003) 331.
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