The behavior of spherical particle under uniform electric field in silicone oil

The motion of an impurity particle in liquefied plastic is simulated with a spherical conductive particle in silicone oil. When the electrostatic force acting on the particle is high enough, the up-and-down motion of a particle is carefully observed with a high-speed camera. This motion is classified into four stages: settling on the lower electrode, moving upward, settling on the upper electrode and moving downward. It was found that the particle velocity is decelerated before reaching the counter electrode. Such deceleration could be explained by damper action of silicone oil layer between the particle and the electrode. After the particle contacts the counter electrode, it stays on the electrode for a while. This settling time on the both electrodes is much longer than the estimated from charge exchange time. The settling phenomenon could be explained by the effect of the flow induced by particle motion. There is a difference between actual particle velocity and calculated one. The comparison of the theoretical estimation with experimental results revealed that the charge acquired by a particle could be a half of the theoretical induction charge