Measurement of electrostatic potential fluctuation using heavy ion beam probe in large helical device.
Heavy ion beam probe (HIBP) for large helical device (LHD) has been improved to measure the potential fluctuation in high-temperature plasmas. The spatial resolution is improved to about 10 mm by controlling the focus of a probe beam. The HIBP is applied to measure the potential fluctuation in plasmas where the rotational transform is controlled by electron cyclotron current drive. The fluctuations whose frequencies change with the time constant of a few hundreds of milliseconds and that with a constant frequency are observed. The characteristics of the latter fluctuation are similar to those of the geodesic acoustic mode oscillation. The spatial profiles of the fluctuations are also obtained.
Ido
Takeshi
T
National Institute for Fusion Science, Gifu 509-5292, Japan.
Shimizu
Akihiro
A
Nishiura
Masaki
M
Nakano
Haruhisa
H
Ohshima
Shinsuke
S
Kato
Shinji
S
Hamada
Yasuji
Y
Yoshimura
Yasuo
Y
Kubo
Shin
S
Shimozuma
Takashi
T
Igami
Hiroe
H
Takahashi
Hiromi
H
Toi
Kazuo
K
Watanabe
Fumitake
F