Measurement of Electron Temperature of Divertor Plasma

近年来，电子伯恩斯坦波(EBW)在等离子体加热和等离子体诊断中得到了广泛的研究，因为在EBW中，即使是低密度和/或低温的等离子体也是黑体。本研究旨在探讨偏滤器等离子体电子温度测量的可能性。由于电子束焊接是一种静电波，必须将其转换为电磁波才能从等离子体中发出。在切向方向，在电子回旋谐振层中产生的电子束在上混合谐振层中转换为X模，在截止层中将X模转换为O模。然后O模从等离子体中发出，最后到达切向天线。在本研究中，在铲运机真空室中安装了切向天线。在这一年，一个远程控制设备，以连接欧洲经委会测量系统。因此，EBW接收器和ECA接收器可以在等离子发射之间切换，EBW数据通常不需要占用特殊的机器时间。LHD实验的季节通常从9月份开始，经过新年假期，在明年2月份结束。在这一年中，电子束焊接数据被用于各种条件，如增加电子密度、深穿透弹丸注入和浅穿透弹丸注入。结果表明，当等离子体边缘电子密度梯度较大时，切向天线接收到较大的辐射，而基波ECES信号很小。频谱取决于电子密度分布。这些现象既不能用欧洲经委会的多重反映解释，也不能用欧洲经委会的折射解释。因此，这可能是电子束辐射。由于京都大学正在开发用于LHD的EBW光线跟踪程序，筑波大学正在开发用于切向的全波程序，因此，人们有望很快对目前的EBW实验结果有进一步的了解。

Recently plasma heating and plasma diagnostics using the electron Bernstein wave (EBW) have been intensively investigated, since plasma is black body for EBW even if it is low density and/or low temperature. Present research is aimed to investigate possibility of the electron temperature measurement of divertor plasma. Since EBW is an electrostatic wave, it has to be converted to a electromagnetic wave in order to go out from the plasma. In the tangential direction, EBW, which is generated in the electron cyclotron resonance layer, is converted to the X-mode in the upper-hybrid resonance layer, and the X-mode is converted to the O-mode at the cut-off layer. Then the O-mode goes out from the plasma, and finally it reaches the tangential antenna. In the present research, a tangential antenna has been installed in the LHD vacuum vessel. In this year, a remote controlled device in order to connect the ECE measurement system. So, the EBW receiver and the ECE receiver can be switched between plasma shots, EBW data have been often taken without taking special machine time. The season of LHD experiment starts in September, passes new year holidays and finishes in next February, usually. In this year, EBW data have been taken for various conditions, such as ramping-up electron density, deeply penetrating pellet injection and shallow penetrating pellet injection. As the result, when the electron density gradient is large at the plasma edge, a large emission is received with tangential antenna while fundamental ECE signal is very small. The frequency spectrum depends on the electron density profile. These phenomena cannot be explained by the multi-reflection nor the refraction of ECE. So, it may be EBW emission. Since, an EBW ray tracing code for LHD is under development in Kyoto University, and a full wave code for tangential direction is being developed in Tsukuba University, further understanding is expected for the present EBW experimental result, soon.