Observation of three-dimensional motion of the pellet ablatant in the Large Helical Device
Observation of three-dimensional motion of the pellet ablatant in the Large Helical Device
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DOI：
10.1088/0029-5515/51/8/083039
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发表时间：
2011-08-01
期刊：
影响因子：
3.3
通讯作者：
Yamada, H.
中科院分区：
文献类型：
--
作者：
Mishra, J. S.;Sakamoto, R.;Yamada, H.
使用快速摄像机和捆绑光纤的两点立体诊断的应用使得能够在大型螺旋装置中观察颗粒轨迹的三维性质。已经观察到，弹丸轨迹偏离其注入方向，环向和垂直方向取决于切向施加的中性束的方向。环形偏转的大小在顺时针和逆时针中性光束方向上相似，为15-20厘米，偏转速度高达400ms(-1)。相比之下，在垂直方向上观察到了弹道偏转的不对称性。实验结果还表明，在逆时针方向的中性束情况下，弹丸轨迹弯曲的起始半径比等离子体的起始半径更内移。总而言之，这会导致小球在等离子体中穿透较少，在顺时针中性光束的情况下尤为突出。此外，这一事实支持了快离子在大型螺旋装置的弹丸烧蚀过程中发挥重要作用的证据。用快离子单面烧蚀产生的火箭效应解释了弹丸偏转现象。通过考虑磁场结构的几何方面，解释了垂直偏转差异的可能原因。
Application of two-point stereoscopic diagnostics using a fast camera and bundled fibre has enabled the observation of the three-dimensional nature of the pellet trajectory in the Large Helical Device. It has been observed that the pellet trajectory deviates from its injection direction, toroidally and vertically depending on the direction of the tangentially applied neutral beams. The magnitude of the toroidal deviation is similar in the clockwise as well as counter-clockwise neutral beam directions and is of 15-20 cm with a deflection speed of up to 400 ms(-1). In contrast, an asymmetry in trajectory deflection has been observed in the vertical direction. Experimental results also indicate that the starting radius of the pellet trajectory bending in the counter-clockwise neutral beam case is more inward to that of the plasma. Collectively this leads to less penetration of the pellet inside the plasma and is prominent in the case of the clockwise neutral beam. Additionally, this fact supports evidence that the fast ion plays an important role in the pellet ablation process in the Large Helical Device. The pellet deflection is explained by the rocket effect due to unilateral ablation by the fast ions. The possible cause of the difference in the vertical deflection is explained by considering the geometrical aspects of the magnetic field structure.