Identification of plasma-edge-related operational regime boundaries and the effect of edge instability on confinement in ASDEX Upgrade
Identification of plasma-edge-related operational regime boundaries and the effect of edge instability on confinement in ASDEX Upgrade
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DOI：
10.1088/0741-3335/39/12/008
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发表时间：
1997-12
影响因子：
2.2
通讯作者：
W. Suttrop;M. Kaufmann;H. Blank;B. Brüsehaber;K. Lackner;V. Mertens;H. Murmann;J. Neuhauser;F. Ryter;H. Salzmann;J. Schweinzer;J. Stober;H. Zohm
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文献类型：
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作者：
W. Suttrop;M. Kaufmann;H. Blank;B. Brüsehaber;K. Lackner;V. Mertens;H. Murmann;J. Neuhauser;F. Ryter;H. Salzmann;J. Schweinzer;J. Stober;H. Zohm
研究了ASDEX升级托卡马克在L模到H模转变、不同类型的边缘局域模式(ELM)和密度极限时的局域边缘参数。找到了边界电子温度的标度律，它描述了具有有利离子漂移方向的充氢放电的H模阈值。稳定运行的区域被理想的气球极限附近的I型ELMS和避免等离子体边缘热不稳定所必需的最低温度所限制。使用III型ELMS的静态操作会对边缘温度施加上限。在所研究的整个边界密度范围内，L模和H模都是可达的。在I型Elmy H模中，发现了全局约束与边缘压力梯度的关系，这种关系与ITER-92P和ITER-93H Elmy H模标度所预测的有利密度相关性的丧失有关。在高密度下，在边缘压力梯度低于理想气球极限的H模中，例如在带有杂质种子辐射的III型Elmy H模中，实现了更好的约束。
Local edge parameters on the ASDEX Upgrade tokamak are investigated at the L-mode to H-mode transition, during phases with various types of edge-localized modes (ELMs), and at the density limit. A scaling law for the boundary electron temperature, , is found which describes the H-mode threshold for deuterium-puffed discharges with favourable ion -drift direction. The region of stable operation is bounded by type I ELMs near the ideal ballooning limit and by a minimum temperature necessary to avoid thermal instability of the plasma edge. Stationary operation with type III ELMs imposes an upper limit on the edge temperature. Within the entire range of boundary densities investigated , both L-mode and H-mode are found to be accessible. During type I ELMy H-mode, a relation of global confinement with the edge pressure gradient is found which is connected with a loss of the favourable density dependence predicted by the ITER-92P and ITER-93H ELMy H-mode scalings. At high density, better confinement is achieved in H-modes with an edge pressure gradient below the ideal ballooning limit, e.g. during type III ELMy H-mode with impurity-seeded radiation.