Drift velocity measurement of charged particles under corona discharge in an air gap. I

Abstract

It is important to know the velocity of charged particles under an electric field in relation to electrostatic precipitation. These velocities are greatly influenced by corona wind as expressed by W p = W p + μE, where W p = the apparent drift velocity of particles, W e = the velocity of corona wind, μ = the true mobility of particles and E = drift field. A laser Doppler velocimeter is used to measure the velocity of particles without any disturbance. The type of electrode used is a needle and a pair of meshes. Measured particles were dusts and smoke available in the laboratory. Most of the particles which are charged in the vicinity of the needle point are accelerated by the Coulomb force and the corona wind, and pass through a mesh electrode, retaining their velocities in the corona wind between the mesh electrodes. If a drift field exists, particles are accelerated or decelerated in accordance with the polarity of the drift field. We measured the velocity of particles as functions of corona voltage and drift field. As a result, the true mobility of the particles is obtained, from which the effect of the corona wind is removed and the quantity of charge on the particles is estimated.