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Study on Structural Change of Coulomb Crystals in Plasmas

等离子体中库仑晶体结构变化的研究

基本信息

批准号：
09680464
负责人：
HAYASHI Yasuaki
金额：
$ 2.18万
依托单位：
Kyoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
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

项目摘要

Structural change of Coulomb crystals, which were formed by growing carbon particles in a methane plasma, have been analyzed with the use of 2 CCD video cameras and Mie-scattering ellipsometry. Three dimensional structures of the crystals were observed from the top and the side at the same time and at the same position. As a result, it has been understood that the structure was three-dimensional like face-centered or body-centered for smaller particles (1.2-1.5 mu m) while two-dimensional of simple hexagonal one for larger particles (>1.8 mu m). It has bee also found that the three-dimensional crystal once became in the liquid phase before changing to two-dimensional one and that transition to three-dimensional structure occurred from the lower region while the particle alignment , 1. e., transition to two-dimensional one from the upper.The three-dimensional structure of a three-dimensional Coulomb crystal was precisely analyzed and proved to be strictly face-centered orthorohmbic. It was understood that the structure was formed from the slip of (111) plane of a face-centered cubic structure and the reconstruction of particles for minimum Coulomb energy in the plane.The force of aligning particles in the direction perpendicular to an electrode in the two-dimensional Coulomb crystal was investigated by the application of radiation pressure or photophoretic force of laser light and the decrease of particle density. Consequently it has been found that the particle alignment is caused by the resultant of an attractive and the Coulomb repulsive forces.

本文用双CCD摄像机和米氏椭圆偏振仪分析了在甲烷等离子体中生长碳颗粒所形成的库仑晶体的结构变化。从顶部和侧面同时在同一位置观察晶体的三维结构。结果，可以理解，对于较小的颗粒（1.2-1.5 μ m），结构是三维的，如面心或体心，而对于较大的颗粒（>1.8 μ m），结构是二维的，如简单的六边形。还发现，三维晶体在变为二维晶体之前曾经变为液相，并且在颗粒排列1.例如，精确地分析了三维库仑晶体的三维结构，证明了它是严格面心正交的。该结构是由面心立方结构的（111）面的滑移和粒子在该面内库仑能量最小时的重构形成的，通过施加激光的辐射压力或电泳力以及粒子密度的降低，研究了二维库仑晶体中粒子在垂直于电极方向上的取向力。因此，它已被发现，粒子的排列是由一个吸引力和库仑排斥力的合力。