Formation of Plasma Structures Due to Local Production of Huge Negative Ions

由于局部产生大量负离子而形成等离子体结构

基本信息

批准号：
09480088
负责人：
HATAKEYAMA Rikizo
金额：
$ 8.77万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09480088/
关键词：
Plasma Huge Ion Local Production Structure Formation Solitary Pulse 孤立波

项目摘要

Huge negative ions are locally produced by introducing "Buckminsterfullerene, C_<60>" particles into a low-temperature potassium plasma column confined by a strong magnetic field. Concerning phenomena parilel to the magnetic-field lines it is experimentally found that a mechanism of reflecting a part of the electrons and ions flowing along the plasma flow exists around the region of negative ion production, and that solitary pulses with negative potential are intermittently excited, propagating downstream at an acoustic speed of the negative ions. This result is also confirmed by means of a one-dimensional electrostatic particle simulation. The plasma becomes unstable for a large rate of negative ion production, being accompanied by a double-layer formation generating the solitary pulse.Concernig phenomena perpendicular to the magnetic-field lines positive inos are experimentally observed to strongly diffuse in the radial direction with a diffusion coefficient ten times larger than that in the absence of negative ion production. Much stronger diffusion of the negative ions is observed around the downstream exit of the region of the negative ion production. As a result, the negative ions are radially localized in the periphery region of the plasma column. A new-type drift-wave instability originating from a combination of positive and negative ions is excited around that region described just above, a radial amplitude profile of which is dominated by the negative ion profile, and which propagates in the direction of the positive-ion diamagnetic drift with the mode number 1 or 2. This drift wave excitation and the radial plasma diffusion are confirmed to be closely related.

通过将“Buckminsterfullerene，C_<60>”颗粒引入强磁场限制的低温钾等离子体柱中，局部产生巨大的负离子。关于与磁场线平行的现象，实验发现在负离子产生区域周围存在反射沿等离子体流流动的电子和离子的一部分的机制，并且间歇地激发具有负电势的孤立脉冲，以负离子的声速向下游传播。这一结果也通过一维静电粒子模拟得到了证实。等离子体因产生大量负离子而变得不稳定，并伴随着产生孤立脉冲的双层形成。实验观察到垂直于磁场线正负离子的现象在径向方向上强烈扩散，并伴有扩散系数比不产生负离子时大十倍。在负离子产生区域的下游出口周围观察到更强的负离子扩散。结果，负离子径向地集中在等离子体柱的外围区域中。源自正离子和负离子组合的新型漂移波不稳定性在上述区域周围被激发，其径向振幅分布由负离子分布主导，并且沿正离子方向传播。模式数为 1 或 2 的离子反磁漂移。这种漂移波激发与径向等离子体扩散密切相关。