Abstract
The effect of plasma shape variation (in particular, variation ofthe upper and lower triangularity δ) on edge localizedmodes (ELMs) and H-mode pedestal properties in ASDEX Upgrade isreported here. Strongly shaped plasmas (high δ) show anincreased edge pressure gradient and, without external gaspuff, type-I ELMs generally have larger losses and lowerfrequency than in plasmas with low δ. With external gaspuff, ELM losses at high δ are reduced and in the samerange as found for low δ. The average ELM power loss is aconstant fraction of the total loss power, independent oftriangularity. The width of the steep electron temperature andpressure gradient zone remains essentially constant at lowδ while at high δ it shows a variationinconsistent with a poloidal gyroradius scaling. The edgepressure gradient and the pedestal pressure scales strongly withplasma current and triangularity. In type-I ELM H-modes, thepedestal pressure is directly related to the global storedplasma energy, independent of plasma shape.
Published Version
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