Dynamic properties of crystallized fine-particle vortices

结晶细颗粒涡的动态特性

基本信息

批准号：
11480105
负责人：
IIZUKA Satoru
金额：
$ 7.68万
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：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The effects of potential structure and vertical magnetic field on the vortex formation of fine particles are investigated in dc and rf discharge plasmas experimentally.First, we investigate the formation mechanism of fine-particle vortex driven by inhomogeneous potential profile provided by a small plate electrode biased negatively that is placed on a levitation electrode. It is observed that the appearance of vortex phenomena depends on the number of fine particles constituting the fine-particle cloud. The particles are accelerated near the edge of the small electrode. The rotation speed of the vortex varies in radial direction and a shear flow appears with increasing the particle number. On the other hand, when the small electrode potential becomes positive, the fine particles change their flow direction towards the edges of the small electrode. If a cylindrical electrode is used instead of the plate, then the fine particles are absorbed into the cylindrical electrode. This technique is used for fine-particle removal from the dusty plasma.Secondary, we have investigated the driving mechanism of a rotational motion of fine-particle cloud in the presence of vertical magnetic field. We find that changing either density or potential profile in radial direction controls the rotational direction. The ion drag force due to the ion flow in ion-diamagnetic direction takes an important role of the rotation. We also observe a spin motion of fine particle. It is found that the spin axis turns to the magnetic field direction with increasing the magnetic field.

通过实验研究了直流和射频放电等离子体中电势结构和垂直磁场对细颗粒涡旋形成的影响。首先，我们研究了由偏置小板电极提供的不均匀电势分布驱动细颗粒涡旋的形成机制。负极放置在悬浮电极上。据观察，涡旋现象的出现取决于构成细颗粒云的细颗粒的数量。粒子在小电极边缘附近加速。涡旋的转速沿径向变化，随着颗粒数的增加，出现剪切流。另一方面，当小电极电位变为正时，细颗粒改变其流动方向朝向小电极的边缘。如果使用圆柱形电极代替板，则细颗粒被吸收到圆柱形电极中。该技术用于从尘埃等离子体中去除细颗粒。其次，我们研究了垂直磁场下细颗粒云旋转运动的驱动机制。我们发现改变径向方向的密度或电势分布可以控制旋转方向。由于离子反磁方向上的离子流而产生的离子拖曳力对旋转起着重要作用。我们还观察到细粒子的自旋运动。发现随着磁场的增加，自旋轴转向磁场方向。