Effect of plasma-wall separation on the stability of resistive wall modes in the JT-60U tokamak
Effect of plasma-wall separation on the stability of resistive wall modes in the JT-60U tokamak
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DOI：
10.1088/0741-3335/49/1/007
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发表时间：
2006
影响因子：
2.2
通讯作者：
G. Matsunaga;M. Takechi;G. Kurita;T. Ozeki;Y. Kamada
中科院分区：
文献类型：
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作者：
G. Matsunaga;M. Takechi;G. Kurita;T. Ozeki;Y. Kamada
为了研究等离子体-壁分离对电阻壁模稳定性的影响，我们在JT-60 U欧姆等离子体中进行了电流驱动的电阻壁模实验。在实验中，等离子体被放置在外壁附近，并且等离子体电流斜升以便使电流驱动的RWM不稳定。一个明确的m/n = 3/1模式结构的不稳定性观察之前的热崩溃。这种不稳定性的增长时间约为10 ms，这是JT-60 U壁的趋肤时间的数量级。因此，不稳定性已被确定为电流驱动的RWM。系统地改变了等离子体-壁面间距，发现生长速率对壁面位置有很强的依赖性。因此，随着等离子体壁分离的减小，生长速率变小。此外，所观察到的增长率进行了比较与AEOLUS-FT代码，这是基于电阻MHD方程与电阻壁，和模型的RWM色散关系。所观察到的增长率对壁的位置的依赖性是在定性与这些数值结果。
To clarify the effect of the plasma-wall separation on the stability of the resistive wall modes (RWM), we have performed current-driven RWM experiments in the JT-60U ohmic plasmas. In the experiment, the plasma was placed near the outer wall, and the plasma current was ramped up so as to destabilize the current-driven RWM. An instability with a clear m/n = 3/1 mode structure was observed just before a thermal collapse. The growth time of this instability is about 10 ms, which is of the order of the skin time of the JT-60U wall. Therefore, the instability has been identified as a current-driven RWM. The plasma-wall separation was systematically changed, and it is found that the growth rates have strong dependence on the wall position. Thus, the growth rates became smaller with decreasing the plasma-wall separation. Additionally, the observed growth rates have been compared with the AEOLUS-FT code, which is based on the resistive MHD equations with a resistive wall, and the model of the RWM dispersion relation. The dependence of the observed growth rate on the wall position is in qualitative agreement with these numerical results.