Effect of edge neutrals on the low-to-high confinement transition threshold in the DIII-D tokamak
Effect of edge neutrals on the low-to-high confinement transition threshold in the DIII-D tokamak
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DOI：
10.1063/1.872949
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发表时间：
1998-06
影响因子：
2.2
通讯作者：
B. Carreras;L. Owen;R. Maingi;P. Mioduszewski;T. Carlstrom;R. Groebner
中科院分区：
文献类型：
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作者：
B. Carreras;L. Owen;R. Maingi;P. Mioduszewski;T. Carlstrom;R. Groebner
为了研究边缘中性粒子对低到高约束跃迁阈值的影响，分析了宽范围的等离子体放电。这些放电随气体的抽吸和泵送速率、X点的位置和线平均密度而变化。结果表明，在刮除层（SOL）的中性密度（或中性压力）的测定可以给出一个误导性的指示中性人口内的分界线。溶胶中中性粒子密度的增加会导致等离子体密度的增加，这反过来又会增加中性粒子的不透明度，并导致中性粒子渗透减少。在恒定磁场下，跃迁功率除以密度似乎是测量中性粒子效应的单个参数的函数。根据该分析，无法唯一识别此参数。例如，它可以是中性分布的径向衰减长度或在约r/a = 0.95处的电荷交换阻尼率。类似的相关性之间存在这些中性para.
To study the effect of edge neutrals on the low-to-high confinement transition threshold, a broad range of plasma discharges has been analyzed. These discharges vary by gas puffing and pumping rates, position of the X point, and line-averaged density. It is shown that the determination of the neutral density (or neutral pressure) in the scrape-off layer (SOL) can give a misleading indication of the neutral population inside the separatrix. An increase of neutral density in the SOL creates an increase of plasma density that, in turn, increases the opacity to the neutrals and results in reduced neutral penetration. At a constant magnetic field, the transition power divided by the density appears to be a function of a single parameter measuring the neutrals effect. From this analysis, this parameter cannot be uniquely identified. For instance, it may be the radial decay length of the neutral profile or the charge-exchange damping rate at about r/a≈0.95. A similar correlation exists between these neutral para...