Journal of Plasma and Fusion Research
Print ISSN : 0918-7928
Contributed Paper
Power Dependence of Ion Thermal Diffusivity at the Internal Transport Barrier in JT-60U
Yoshiteru SAKAMOTOTakahiro SUZUKIShunsuke IDEYoshihiko KOIDEHidenobu TAKENAGAYutaka KAMADATakaaki FUJITATomonori TAKIZUKAHiroshi SHIRAITakeshi FUKUDA
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2002 Volume 78 Issue 9 Pages 941-948

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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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© 2002 by The Japan Society of Plasma Science and Nuclear Fusion Research
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