Development of a Heavy Ion Bearn Probe for Measuring Electrostatic Potential Profile and Its Fluctua

• 作 者: TakeshiI DO Akihiro SHIMIZU Masaki NISHIURA Haruhisa NAKANO Shinji KATO Shinsuke OHSHIMA Yasuo YOSHIMURA Shin KUBO Takashi SHIMOZUMA HiroeI GAMI Hiromi TAKAHASHI Kazuo TOI Fumitake WATANABE Kazumichi
• 机 构: National Institute for Fusion Science,the LHD Experiment Group,
• 出 处: Plasma Science and Technology
• 发表日期: 2009年04期
• 关键词: accelerator Probe helical rotational tandem termine reversed heating representat

A heavy ion beam probe (HIBP) using a 3-MV tandem accelerator has been installedon large helical device (LHD). Electrostatic potential in core plasma can be measured under thetoroidal magnetic field strength of up to 3 T. By using the HIBP, the transition of potentialprofiles from electron-root to ion-root is observed in core plasmas during ramp-up of the electrondensity. Potential fluctuations are also measured electron cyclotron current drive (ECCD). Twokind of characteristic fluctuations are observed. One is a reversed-shear-induced Alfven eigenmode(RSAE), whose frequency varies during the evolution of the rotational transform profile, and theother is with a constant geodeisc acoustic mode (GAM) frequency.

A heavy ion beam probe (HIBP) using a 3-MV tandem accelerator has been installed on a large helical device (LHD). Electrostatic potential in core plasma can be measured under the toroidal magnetic field strength of up to 3 T. By using the HIBP, the transition of potentialprofiles from electron-root to ion-root is observed in core plasmas during ramp-up of the electrondensity. Potential fluctuations are also measured electron cyclotron current drive (ECCD). Twokind of characteristic fluctuations are observed. -induced Alfven eigenmode (RSAE), whose frequency varies during the evolution of the rotational transform profile, and theother is with constant geodeisc acoustic mode (GAM) frequency.