Power Dependence of Ion Thermal Diffusivity at the Internal Transport Barrier in JT-60U

Yoshiteru SAKAMOTO; Takahiro SUZUKI; Shunsuke IDE; Yoshihiko KOIDE; Hidenobu TAKENAGA; Yutaka KAMADA; Takaaki FUJITA; Tomonori TAKIZUKA; Hiroshi SHIRAI; Takeshi FUKUDA

doi:10.1585/jspf.78.941

Contributed Paper

Power Dependence of Ion Thermal Diffusivity at the Internal Transport Barrier in JT-60U

Yoshiteru SAKAMOTO, Takahiro SUZUKI, Shunsuke IDE, Yoshihiko KOIDE, Hidenobu TAKENAGA, Yutaka KAMADA, Takaaki FUJITA, Tomonori TAKIZUKA, Hiroshi SHIRAI, Takeshi FUKUDA

Author information

Yoshiteru SAKAMOTO
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Takahiro SUZUKI
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Shunsuke IDE
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Yoshihiko KOIDE
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Hidenobu TAKENAGA
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Yutaka KAMADA
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Takaaki FUJITA
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Tomonori TAKIZUKA
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Hiroshi SHIRAI
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,
Takeshi FUKUDA
Naka Fusion Research Establishment, Japan Atomic Energy Research Institute,

Keywords: JT-60U, ion thermal diffusivity, internal transport barrier, weak positive magnetic shear, radial electric field shear

JOURNAL FREE ACCESS

2002 Volume 78 Issue 9 Pages 941-948

DOI https://doi.org/10.1585/jspf.78.941

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Abstract

The formation properties of an internal transport barrier (ITB) were investigated in a weak positive magnetic shear plasma by changing the neutral beam heating power. The ion thermal diffusivity in the core region shows L-mode state, weak ITB, and strong ITB, depending upon the heating power. Two features of ITB formation were experimentally confirmed. Weak ITB was formed in spite of the absence of an apparent transition in an ion temperature profile. On the other hand, strong ITB appeared after an apparent transition from the weak ITB. In addition, the ion thermal diffusivity at the ITB is correlated to the radial electric field shear. In the case of the weak ITB, ion thermal diffusivity decreased gradually with increases in the radial electric field shear. There exists a threshold in the radial electric field shear, which allows for a change in state from that of weak to strong ITBs.

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