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The effect of plasma shape variation (in particular, the variation of the upper and lower triangularity "d") on edge localized modes (ELMs) and H-mode pedestal properties in ASDEX Upgrade is reported here. Strongly shaped plasmas (high "d") show an increased edge pressure gradient and, without external gas puff, type-I ELMs generally have larger losses and lower frequency than in plasmas with low "d". The average ELM power loss is a constant fraction of the total loss power, independent of triangularity. The width of the steep electron temperature and pressure gradient zone remains essentially constant at low "d" while at high "d" it shows a variation inconsistent with a poloidal gyroradius scaling. The edge pressure gradient and the pedestal pressure scales strongly with plasma current and triangularity. In type-I ELM H-modes, the pedestal pressure is directly related to the global stored plasma energy, independent of plasma shape.

Additional information

Authors: SUTTROP W ET AL, Max-Planck Institut f³r Plasmaphysik, EURATOM Association, Garching bei M³nchen (DE)
Bibliographic Reference: Article: Plasma Physics Controlled Fusion, Vol. 42 (2000) pp. A97-A102
Availability: Plasma Physics Controlled Fusion (Journal)
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