-collapse-induced vertical displacement event in high tokamak disruption
-collapse-induced vertical displacement event in high tokamak disruption
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DOI：
10.1088/0741-3335/38/10/007
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发表时间：
1996-10
影响因子：
2.2
通讯作者：
Y. Nakamura;R. Yoshino;N. Pomphrey;S. Jardin
中科院分区：
文献类型：
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作者：
Y. Nakamura;R. Yoshino;N. Pomphrey;S. Jardin
利用托卡马克模拟程序，在一个垂直伸长的高阻壳托卡马克装置中，发现了由强坍缩引起的极快垂直位移事件（VDE）。虽然在VDE演化过程中没有观察到等离子体电流猝灭，但所观察到的VDE增长速率几乎是通常位置不稳定性增长速率的5倍，而等离子体电流猝灭已被证明是相对低的托卡马克中VDE的主要原因（中村Y等，1996 Nucl. Fusion 36 643）。崩塌诱导VDE的基本机制被澄清为，除了由于稳定性指数降低而导致的显着不稳定之外，还由于磁场衰减n指数的大幅度突然下降而导致位置不稳定性的强烈增强。由塌陷引起的磁轴的径向偏移在电阻壳上感应出涡电流，并且这些涡电流产生n指数的大的退化。它指出，壳的几何特征的VDE动力学，VDE率强烈依赖于崩溃的大小和崩溃发生前的平衡的n-指数。JT-60 U型真空室具有防止电子束诱发的VDE的能力。
Extremely fast vertical displacement events (VDEs) induced by a strong collapse were found in a vertically elongated , high tokamak with a resistive shell through computer simulations using the tokamak simulation code. Although the plasma current quench which has been shown to be the prime cause of VDEs in a relatively low tokamak (Nakamura Y et al 1996 Nucl. Fusion 36 643), was not observed during the VDE evolution, the observed growth rate of VDEs was almost five times faster than the growth rate of the usual positional instability . The essential mechanism of the -collapse-induced VDE was clarified to be the intense enhancement of positional instability due to a large and sudden degradation of the magnetic field decay n-index in addition to the significant destabilization due to a reduction in the stability index . The radial shift of the magnetic axis caused by the collapse induces eddy currents on the resistive shell, and these eddy currents produce a large degradation of the n-index. It is pointed out that the shell geometry characterizes the VDE dynamics, and that the VDE rate depends strongly both on the magnitude of the collapse and the n-index of the equilibria just before the collapse occurs. The JT-60U vacuum vessel is shown to possess the capability of preventing -collapse-induced VDEs.