A plasma-assisted fine particle classification and identification method has been developed by using a Geisler tube with a coneshape electrode. A particle is charged in plasma, in which its surface is covered with the sheath made of double layer of negative and positive ions. The charged particle flies to the positive electrode under high voltage. The flying mode, however, is influenced by the gravity, the collision of plasma ions with the flying particles and the viscosity of the constituent non-charged gas molecules. The newly-developed classification setup is made with three main parts; the Geisler tube, a powder supplier and an evacuation system. The fine powders such as alumina, silica, silicon carbide were classified under the condition of DC voltage of 500V and the tube current of 30mA at 2.0Torr (2.7×102Pa). It is found from the experiments that the finer particles fall down near the upper side of cone electrode, but the coarser ones fly apart from it and that the grains with different mechanical and physical properties can be identified.
