标题： Alcator C-Mod 脉冲边缘层在欧姆和高约束模式等离子体中的间歇性波动 显示英文标题

标题： Intermittent fluctuations in the Alcator C-Mod scrape-off layer for ohmic and high confinement mode plasmas

摘要： 在Alcator C-Mod托卡马克装置的边缘层中，通过气体喷射成像数据分析了欧姆和高约束模式下的等离子体涨落。 在所有研究的情况下，从单一空间分辨视图中观察到的发射时间序列主要由大振幅爆发主导，这些爆发归因于类似blob的丝状结构径向向外和环向移动。 欧姆等离子体和无边缘局域模及增强D-α高约束模式等离子体的涨落统计表现出显著的相似性。 条件平均波形呈双侧指数形状，具有相似的时间尺度和不对称性，而爆发振幅以及它们之间的等待时间呈指数分布。 所有这些约束模式的概率密度函数和频率功率谱密度都是自相似的。 这些结果强有力地支持了一个随机模型，该模型将边缘层中的等离子体涨落描述为不相关指数脉冲的叠加。 该模型的预测与欧姆和高约束模式等离子体的实验测量结果高度一致。 因此，该随机模型为预测磁约束聚变等离子体中的波动引起的等离子体-壁相互作用提供了一个有价值的工具。 显示英文摘要

摘要： Plasma fluctuations in the scrape-off layer of the Alcator C-Mod tokamak in ohmic and high confinement modes have been analyzed using gas puff imaging data. In all cases investigated, the time series of emission from a single spatially-resolved view into the gas puff are dominated by large-amplitude bursts, attributed to blob-like filament structures moving radially outwards and poloidally. There is a remarkable similarity of the fluctuation statistics in ohmic plasmas and in edge localized mode-free and enhanced D-alpha high confinement mode plasmas. Conditionally averaged wave forms have a two-sided exponential shape with comparable temporal scales and asymmetry, while the burst amplitudes and the waiting times between them are exponentially distributed. The probability density functions and the frequency power spectral densities are self-similar for all these confinement modes. These results are strong evidence in support of a stochastic model describing the plasma fluctuations in the scrape-off layer as a super-position of uncorrelated exponential pulses. Predictions of this model are in excellent agreement with experimental measurements in both ohmic and high confinement mode plasmas. The stochastic model thus provides a valuable tool for predicting fluctuation-induced plasma-wall interactions in magnetically confined fusion plasmas.