Study and optimization of lower hybrid wave coupling in advanced scenario plasmas in JET
Study and optimization of lower hybrid wave coupling in advanced scenario plasmas in JET
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DOI：
10.1088/0741-3335/46/2/003
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发表时间：
2004-02
影响因子：
2.2
通讯作者：
V. Ridolfini;A. Ekedahl;S. Erents;J. Mailloux;S. Podda;Y. Sarazin;A. Tuccillo;Efda-Jet contributors
中科院分区：
文献类型：
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作者：
V. Ridolfini;A. Ekedahl;S. Erents;J. Mailloux;S. Podda;Y. Sarazin;A. Tuccillo;Efda-Jet contributors
在对边缘等离子体的H模式特征（即非常低的密度和ELM活动）产生的耦合问题进行系统研究后，JET-EFDA先进方案等离子体中的低混合（LH）波的有源电流驱动获得了成功。与过去相比，LH耦合得到了改善，使LH发射器前方的边缘等离子体更密集、更均匀。从附近的气体管道注入氘代甲烷（CD 4）会使LH发射器前方的密度增加至少1.5倍，高于LH频率的截止值。等离子体形状与LH天线形状的更好匹配使得LH发射器前方的等离子体沿极向角沿着更规则。这两种技术一起允许三个LH格栅的平衡供应，平均反射低于4%，如在先前的L模式操作中那样。CD 4不影响性能，也不污染主血浆，直到目前使用的最大流速，10^{22}{\rm el}\，{\rm s}^{-1} SRC=http：ej.iop.org/images/0741-3335/46/2/003/ppcf169854in001.gif/>，现在它被常规应用于JET（高达4？MW注入时间超过8？s），LHCD的结果非常令人鼓舞。尽管CD 4不适合ITER用于氚滞留，但已经证明了局部安全控制刮除等离子体密度的可能性。
Active current drive with lower hybrid (LH) waves in the advanced scenario plasmas at JET-EFDA was successful after a systematic study of the coupling problems that derive from the H-mode features of the edge plasma, namely very low density and ELM activity. The LH coupling has been improved compared to the past, by making the edge plasma in front of the LH launcher denser and more uniform. Injecting deuterated methane (CD4) from a nearby gas pipe increases the density in front of the LH launcher at least by a factor of 1.5, above the cut-off value for the LH frequency. A better matching of the plasma shape to that of the LH antenna makes the plasma ahead of the LH launcher more regular along the poloidal angle. These two techniques together have permitted a balanced supply of the three LH grills, with an average reflection below 4%, as in the previous L-mode operation. CD4 does not affect the performances nor does it contaminate the main plasma up to the maximum flow rate so far used, 10^{22}{\rm el}\,{\rm s}^{-1} SRC=http://ej.iop.org/images/0741-3335/46/2/003/ppcf169854in001.gif/> and now it is routinely applied in JET (up to 4?MW have been injected for longer than 8?s) with very encouraging results for LHCD. Even though CD4 is not suitable for ITER for tritium retention, the possibility of controlling locally and safely the scrape-off plasma density has been demonstrated.