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arXiv physics/0410208physics.plasm-ph
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CASTOR托卡马克刮除层中对流单体的形成

Formation of convective cells in the scrape-off layer of the CASTOR tokamak

J. Stockel, P. Devynck, J. Gunn, E. Martines, G. Bonhomme, G. Van Oost, M. Hron, J. Adamek, J. Brotankova, R. Dejarnac, I. Duran, T. Gorler, T. Hansen, R. Panek… 展开作者

J. Stockel, P. Devynck, J. Gunn, E. Martines, G. Bonhomme, G. Van Oost, M. Hron, J. Adamek, J. Brotankova, R. Dejarnac, I. Duran, T. Gorler, T. Hansen, R. Panek, P. Stejskal, V. Svoboda, F. Zacek

摘要:

理解托卡马克中的刮削层(SOL)物理需要具有足够的时间和空间分辨率的诊断。本文介绍了在CASTOR托卡马克(R=40 cm,a = 6 cm)的SOL中,用124个朗缪尔探针环环绕整个极向截面进行的实验结果。单独的探头测量的浮动电位的离子饱和电流的空间分辨率高达3毫米。实验是在一个特定的磁性配置,其特征在于由一个长的并联连接长度在SOL,L_par ~ q2 piR。我们报告的测量放电,其中的边缘电场被修改通过插入一个偏置的电极到边缘等离子体。特别地,如果偏置电极位于SOL内部,则观察到复杂的图像。浮动电位的极向分布在偏置时似乎是强烈不均匀的。在特定的极向角处观察到电势峰值。这被解释为一个偏置的磁通管的形成,它从电极发出沿着磁场线和蛇绕环q倍。在SOL中产生的电场是2维的,具有径向以及极向分量。结果表明,极向电场E_pol使边缘等离子体径向对流,这是由于E_pol x B_T随其符号向内或向外漂移所致。对流粒子通量比波动引起的通量大两个数量级,因此占主导地位。

英文摘要:

Understanding of the scrape-off layer (SOL) physics in tokamaks requires diagnostics with sufficient temporal and spatial resolution. This contribution describes results of experiments performed in the SOL of the CASTOR tokamak (R=40 cm, a = 6 cm) by means of a ring of 124 Langmuir probes surrounding the whole poloidal cross section. The individual probes measure either the ion saturation current of the floating potential with the spatial resolution up to 3 mm. Experiments are performed in a particular magnetic configuration, characterized by a long parallel connection length in the SOL, L_par ~q2piR. We report on measurements in discharges, where the edge electric field is modified by inserting a biased electrode into the edge plasma. In particular, a complex picture is observed, if the biased electrode is located inside the SOL. The poloidal distribution of the floating potential appears to be strongly non-uniform at biasing. The peaks of potential are observed at particular poloidal angles. This is interpreted as formation of a biased flux tube, which emanates from the electrode along the magnetic field lines and snakes q times around the torus. The resulting electric field in the SOL is 2-dimensional, having the radial as well as the poloidal component. It is demonstrated that the poloidal electric field E_pol convects the edge plasma radially due to the E_pol x B_T drift either inward or outward depending on its sign. The convective particle flux is by two orders of magnitude larger than the fluctuation-induced one and consequently dominates.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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