Speaker
Prof.
Mizuki Sakamoto
(Plasma Research Center, University of Tsukuba)
Description
In GAMMA 10/PDX, studies on the boundary plasma and plasma surface interaction have been done using the end region making best use of the tandem mirror device. The features of GAMMA 10/PDX for the boundary plasma and PSI studies are the following: (1) high ion temperature of the plasma exposed to the D-module (i.e. a few hundreds eV), (2) high magnetic field (0.15 $\sim$ 1.5 T), (3) large plasma size (0.1 $\sim$ 0.3 m), (4) low background pressure in the vacuum vessel and (5) high controllability of the plasma exposure since plasma heating systems of ECH, ICH and NBI are equipped. Noted that ion energy of the plasma is distributed, meaning that condition of PSI is equivalent to that of the torus plasma from a viewpoint of hydrogen recycling.
The divertor simulation experimental module (D-module) has been installed in the west end region. The D-module consists of a rectangular box (0.5 m square and 0.7 m in length) with an inlet aperture at the front panel and a V-shaped target inside the box. Tungsten target plates with the thickness of 0.2 mm are attached on the V-shaped base made of Cu. The target size is 0.3 m in width and 0.35 m in length. The open-angle of the V-shaped base can remotely be changed from 15 degrees to 80 degrees. The sheath electric heaters are attached on the backside of the Cu base to control the target temperature ($T_\textrm{target}$) up to 573 K. Besides, additional hydrogen gas can be supplied into the D-module.
The V-shaped tungsten target in the D-module is exposed to the end loss plasma. The effect of additional hydrogen gas supply into the D-module on the recycling is investigated. The density roll-over due to the additional gas supply has clearly been observed, indicating that the plasma near the target is detached. The dependence of the H${\alpha}$ and H${\beta}$ line intensities on the neutral pressure suggests that molecular activated recombination (MAR) occurred near the corner of the V-shaped target. When the $T_\textrm{target}$ was increased upto 573 K shot by shot in another experiment, it is found that the intensities of balmer lines inside the V-shaped target and the electron density increased with increase in $T_\textrm{target}$, indicating that the recycling was enhanced due to increase in the target temperature.
Primary author
Prof.
Mizuki Sakamoto
(Plasma Research Center, University of Tsukuba)
Co-authors
Mr
Akihiro Terakado
(Plasma Research Center, University of Tsukuba)
Dr
Junko Kohagura
(Plasma Research Center, University of Tsukuba)
Dr
Kazuya Ichimura
(Plasma Research Center, University of Tsukuba)
Dr
Kensuke Oki
(Graduate School of Electrical and Electronic Engineering, Chiba University)
Mr
Kunpei Nojiri
(Plasma Research Center, University of Tsukuba)
Prof.
Makoto Ichimura
(Plasma Research Center, University of Tsukuba)
Dr
Masakatsu Fukumoto
(National Institute for Quantum and Radiological Science and Technology)
Dr
Masayuki Yoshikawa
(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)
Peer reviewing
Paper
Paper files:
