Effect of plasma shape variation on ELMs and H-mode pedestal properties in ASDEX Upgrade
2000; IOP Publishing; Volume: 42; Issue: 5A Linguagem: Inglês
10.1088/0741-3335/42/5a/308
ISSN1361-6587
AutoresW. Suttrop, O. Gruber, B. Kurzan, H. Murmann, R. Neu, J. Schweinzer, J. Stöber, W. Treutterer, the ASDEX Upgrade Team,
Tópico(s)Particle accelerators and beam dynamics
ResumoThe effect of plasma shape variation (in particular, variation of the upper and lower triangularity δ) on edge localized modes (ELMs) and H-mode pedestal properties in ASDEX Upgrade is reported here. Strongly shaped plasmas (high δ) 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 δ. With external gas puff, ELM losses at high δ are reduced and in the same range as found for low δ. 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 δ while at high δ 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.
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