Fluctuation-driven transport in the DIII-D boundary
Fluctuation-driven transport in the DIII-D boundary
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DOI：
10.1088/0741-3335/44/6/308
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发表时间：
2002-05
影响因子：
2.2
通讯作者：
D. Rudakov;J. Boedo;R. Moyer;S. Krasheninnikov;A. Leonard;M. Mahdavi;G. Mckee;G. Porter;P. Stangeby;J. Watkins;W. West;D. Whyte;G. Antar
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文献类型：
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作者：
D. Rudakov;J. Boedo;R. Moyer;S. Krasheninnikov;A. Leonard;M. Mahdavi;G. Mckee;G. Porter;P. Stangeby;J. Watkins;W. West;D. Whyte;G. Antar
在DIII-D托卡马克装置上，利用快速往复式朗缪尔探针阵列研究了边缘和刮削层等离子体中的跨场涨落驱动输运，并对涨落驱动的粒子和热通量进行了局部测量。两种不同的非扩散机制，可以大大有助于跨场运输的SOL的高密度放电的确定和比较。其中第一个涉及间歇性的运输事件，在等离子体分界线和SOL中观察到。L模和无ELM的H模中的阵发具有定性相似的特征。在高密度H模式中观察到的低振幅ELMs产生于SOL周期，交叉场传输增强到L模式水平，并具有类似于L模式的间歇性事件。间歇性输运事件与由于E×B漂移而导致的等离子体细丝穿过SOL传播的概念是一致的。在SOL中的运输的间歇性字符也是在协议的非线性数值模拟的预测与强加的驱动通量。另一种类型的非扩散输运通常出现在具有延长的ELM自由周期的高密度H模式中，其中分界线附近的输运由准相干模式驱动超过L模式水平的粒子和/或热通量主导。这些模式可以通过在ELM之间提供颗粒和/或热排出而发挥重要作用。
Cross-field fluctuation-driven transport is studied in edge and scrape-off layer (SOL) plasmas in the DIII-D tokamak using a fast reciprocating Langmuir probe array allowing local measurements of the fluctuation-driven particle and heat fluxes. Two different non-diffusive mechanisms that can contribute strongly to the cross-field transport in the SOL of high-density discharges are identified and compared. The first of these involves intermittent transport events that are observed at the plasma separatrix and in the SOL. Intermittence has qualitatively similar character in L-mode and ELM-free H-mode. Low-amplitude ELMs observed in high-density H-mode produce in the SOL periods with cross-field transport enhanced to L-mode levels and featuring intermittent events similar to those in L-mode. The intermittent transport events are compatible with the concept of plasma filaments propagating across the SOL due to E×B drifts. The intermittent character of the transport in the SOL is also in agreement with predictions of the non-linear numerical simulations performed with an imposed driving flux. Another type of non-diffusive transport is often seen in high-density H-modes with prolonged ELM-free periods, where the transport near the separatrix is dominated by quasi-coherent modes driving particle and/or heat fluxes exceeding L-mode levels. These modes may play an important role by providing particle and/or heat exhaust between ELMs.