Speaker
Dr
Masayuki Yoshikawa
(University of Tsukuba)
Description
Divertor magnetic field configuration has been utilized to protect the nuclear fusion reactor from high heat flow from fusion plasmas. The reduction of the heat load to the divertor plate by promoting the radiation cooling is an important subject to form the detached plasma [1-3].
GAMMA 10/PDX consists of central-cell, anchor-cell, plug/barrier-cell and end-cell. Plasma heating devices, such as neutral beam injection (NBI), electron cyclotron resonance heating (ECRH) and ion cyclotron range of frequency (ICRF) have been installed. In GAMMA 10/PDX, ICRF wave heating is used to make high-temperature hydrogen plasma and high heat flux plasma flow is generated at the end-cell by making use of the open magnetic field. The divertor simulation experimental module (D-module) has been installed in the west end-cell. A V-shaped target plate made of tungsten is mounted in this module. The angle of V-shaped target plate can be varied from 15 to 80 degree. Several gas injection ports have been installed in D-module in order to investigate radiation cooling by injecting impurity gases. There are several spectrometers installed at end-cell and plug/barrier-cell.
The purpose of this study is to analyze the mechanism of radiation cooling, formation of detached plasma and the impurity transport. In the experiment, various types of gases (Argon, Xenon, Neon, Nitrogen and Hydrogen) have been injected into D-module. In this experiment, the emission spectra of impurity particles were measured by using spectrometers under several conditions, such as changing the gas throughput and gas injection timing. It is found that increasing the quantity of neon and nitrogen gas injection, the emission spectra of neon continued to rise. However, in the case of nitrogen, the emission intensity was saturated at the plug/barrier-cell. The effect of barrier-ECH injection on impurity transport also investigated from the comparison of the spectral measurements in the end-cell and plug/barrier-cell. Time evolution of specific emission spectra shows the reduction of the impurity transport.
In this paper, detailed results of spectral measurements in gas injection experiments are presented. Discussion on the behavior of the impurity transport and on the change of the electron temperature and density will be also described.
References:
[1] Y. Nakashima et al., Trans. Fus. Sci. Technol 68, 28 (2015).
[2] K. Shimizu et al., Trans. Fus. Sci. Technol 68, 130 (2015).
[3] Y. HOSODA et al., Plasma Fusion Res. 9, 3402087 (2014).
Primary author
Mr
Takayuki Yokodo
(Plasma Research Center, University of Tsukuba)
Co-authors
Mr
Kazuma Fukui
(Plasma Research Center, University of Tsukuba)
Mr
Kazuya Ichimura
(Plasma Research Center, University of Tsukuba)
Keita Shimizu
(Plasma Research Center, University of Tsukuba)
Mr
MD SHAHINUL ISLAM
(Plasma Research Center, University of Tsukuba)
Masato Ohuchi
(Plasma Research Center, University of Tsukuba)
Dr
Masayuki Yoshikawa
(University of Tsukuba)
Mr
Md. Maidul Islam
(Plasma Research Center, University of Tsukuba)
Prof.
Mizuki Sakamoto
(Plasma Research Center, University of Tsukuba)
Dr
Naomichi Ezumi
(Plasma Research Center, University of Tsukuba)
Prof.
Tsuyoshi Imai
(Plasma Research Center, University of Tsukuba)
Prof.
Yousuke Nakashima
(Plasma Research Center, University of Tsukuba)
