Confinement mechanisms in the radiatively improved mode
Confinement mechanisms in the radiatively improved mode
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DOI：
10.1088/0741-3335/41/12b/323
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发表时间：
1999-12
影响因子：
2.2
通讯作者：
M. Tokar;R. Jaspers;H. Koslowski;A. Krämer-Flecken;A. Messiaen;J. Ongena;A A Rogister-A;B. Unterberg;R. Weynants
中科院分区：
文献类型：
--
作者：
M. Tokar;R. Jaspers;H. Koslowski;A. Krämer-Flecken;A. Messiaen;J. Ongena;A A Rogister-A;B. Unterberg;R. Weynants
本文分析了托卡马克装置低约束模反常输运的主要来源--环形离子温度梯度（ITG）不稳定性的特性，以及注入杂质触发辐射改进（RI）模的条件。根据TEXTOR-94的实验数据，我们推断ITG诱导的湍流在等离子体半径的大部分区域中以RI模式淬灭。在这些条件下，耗散俘获电子（DTE）的不稳定性占主导地位的运输。电子密度的峰值，L-RI过渡的最显着的特点之一，是由ITG和DTE不稳定模式的电子流的扩散和对流分量的贡献的差异解释。通过考虑ITG湍流引起的异常等离子体粘性和重新审视的新经典理论的预测，成功地模拟了在具有不平衡中性注入的RI模式中观察到的等离子体环形速度的剪切。
The characteristics of the toroidal ion temperature gradient (ITG) instability, considered as the main source of anomalous transport in the low (L) confinement mode of tokamaks, are analysed for the conditions of the radiatively improved (RI) mode triggered by seeding of impurities. Based on experimental profiles from TEXTOR-94 we deduce that the ITG-induced turbulence is quenched in the RI-mode in a large part of the plasma radius. Under those conditions the dissipative trapped electron (DTE) instability dominates the transport. The peaking of the electron density, one of the most remarkable features of the L-RI transition, is explained by the difference in contributions of ITG and DTE unstable modes to the diffusive and convective components of the electron flow. The shearing of the plasma toroidal velocity observed in the RI-modes with unbalanced neutral injection is successfully modelled by taking into account both the anomalous plasma viscosity due to ITG-turbulence and predictions of the revisited neoclassical theory.