Fine-particle collection controlled by electrostatic potential configuration in plasmas

Summary form only given, as follows. Summary form only given. The NFP-collector has proved to be quite useful for removal of dust particles levitating in dusty plasmas. The collector is just a simple electrode with hole(s), which is externally biased higher than the floating potential to collect fine particles in plasmas. Fine particles pass through the hole(s) without impinging the electrode surface into the hole(s) of the electrode. This is because the plasma potential is higher than the electrode potential. When fine particles near the electrode are collected, fine particles left away from the electrode approach the electrode in the presence of electric-force balance among fine particles confined by an external potential, being pulled one after another into the electrode. Finally, there is almost no fine particle left in plasmas. When we use a metal plate with an uneven surface for particle levitation, fine particles levitating in the horizontal plane above the plate show a specific spatial distribution, depending on the electrostatic-potential configuration provided by the plate surface Therefore, the spatial distribution of fine particles in the horizontal plane can be controlled by changing the surface shape of the plate for fine-particle levitation. In our experiments, the plate surface is shaped to provide such an electrostatic potential configuration that fine particles are guided to flow toward the NFP-collector In this situation, the NFP-collector can be located at a position far away from the central plasma region, where the disturbance caused by the action of the NFP-collector on the plasma is negligibly small. The surface with ditches is quite effective for this purpose. The results obtained are of crucial importance in various kinds of applications of the NFP-collector.