STRUCTURE OF 3-D COULOMB CRYSTAL DEPENDING ON OUTER ENVIRONMENT

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Negatively charged fine particles in a plasma are surrounded by positive ions and is crystallized. such a crystal is expected to be applied to the analyses of physical phenomena in a real crystal, however the formation of 3-d structure of the crystal is difficult due to the anisotropic forces by gravity and ion flows. Therefore, under microgravity, a 3-D Coulomb crystal was tried to be formed and the behavior of fine particles were analyzed in this research.Microgravity experiments of fine-particle plasma were carried out by the use of a drop experiment facility and parabolic flights, and fine-particle ordering and behavior have been analyzed in the change of gravitational conditions. Fine particles aligned in radical directions were observed under microgravity, while they were aligned in the vertical direction under gravity. It has been suggested that under gravity the mutual influence between positive ion flow and negative fine particles results in the vertical alignment of fine particles and the vertical flow of ions toward fine particles along with the deformation of plasma. Thus fine particle plasmas are self-organized, so that the method of injection of fine particles should affect the arrangement of fine particles. Although the final goal that is the formation of a 3-D Coulomb crystal in a isotopic force field was not achieved, the new finding should be useful for the development of the research in future.