1 - Nuclear Sciences and Applications - IAEA

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5
5 — ECH
IAEA-CN-50/A-VTI-7 427
(a)
ECH
r- ^
(b)
0.3 0.4 0.5 0.6 0.3 r 0.4 i 0.5 i 0.6
FIG. 4. Time variations ofm = 2 magnetic island position and width (above) and m = 2 mode amplitude
(below) at two values of toroidal magnetic field: (a) BT = 29.5 kG, (b) BT = 31.6 kG. Duration
of heating and resonance zone position are shown by black lines.
t(s)
0.2 0.4 0.6 0.8 1.0
FIG. 5. Relationship between magnetic island width and m — 2 mode amplitude.
the result of the measurement. This conclusion seems to be important for understanding
the role of the magnetic islands in the plasma energy balance and does not seem
to be evident a priori. Indeed, the magnetic island width in theory is defined as the
maximum distance between the separatrices limiting the island, i.e. as a magnetic
structure characteristic, and the result of our measurement by the method of synchronous
plasma radiation detection yields the width of the region where the electron
temperature is equalized, i.e. the width of the region with enhanced heat conduction.
The agreement between theoretical and experimental values of W means that
enhanced electron heat conduction prevails just in the region that is limited by the
magnetic island separatrices.