Quantitative analysis of agglomerates levitated from particle layers in a strong electric field

Abstract

The electrification, agglomeration, and levitation of particles in a strong electric field were analyzed experimentally and theoretically. Particle layers of glass, alumina, and ferrite were formed on a plate electrode and an external voltage was applied. Microscopic observations of the agglomerates levitated from the particle layers revealed that the number of primary particles constituting an agglomerate is affected by particle diameter and electrical resistance, but not by the applied electric field. The electric field distributions in the system were calculated by considering the charges and geometries of the agglomerates formed on the particle layers. The charges of the agglomerates were obtained experimentally. All forces acting on the agglomerates (i.e., gravitational forces, Coulomb forces, interaction forces between polarized particles, image forces, and gradient forces) were analyzed under different conditions, including various electric field distributions and charges of agglomerates. Furthermore, the critical conditions for the levitation of the agglomerates were evaluated using a force balance.

Light and Thermally Induced Charge Transfer and Ejection of Micro‐/Nanoparticles from Ferroelectric Crystal Surfaces

“…It is well-known that when electric fields are applied between electrodes (normally two parallel plates), different particle-electrode or even particle-particle charge transfer processes may take place. [31][32][33][34][35][36] In the simple case of a conductive particle in contact with one of the electrodes, a net charge is induced in the particle due to the flow of electrons from/to the electrode in search of electrostatic equilibrium (i.e., same electric potential). When the electric fields are sufficiently strong, particles acquire enough charge to lift off from the electrode surface due to Coulombian repulsion, somewhat resembling the ejection reported here.…”

Effective Use of External Electric Field for Charging and Levitation of Particles Under UV Irradiation

“…This is probably due to variations in the electric field. As the thickness of the particle layers increases, the distance between the positively charged surface of the particle layers and the upper electrode decreases; consequently, the electric field strength increases [7]. As shown in Fig.…”

“…In this study, particle motion was calculated assuming that |Ep + En| << |Eex|. Each particle charge qp was estimated by fitting the calculation results based on the equation of motion to the particle trajectory obtained using the high-speed camera [7].…”

Charging and Levitation of Particles Using UV Irradiation and Electric Field

“…In industries such as the electronics, pharmaceutical, and food industries, particle adhesion can lower the quality and productivity of the manufacturing processes [7]. Although gas flow [8][9][10] and vibration [11][12][13] can also be used to remove the particles, the use of an electric field has the added advantages of the ability to control the motion of the charged particles even in stationary fluids, low-pressure environments, and vacuum in a non-contact manner [14][15][16][17][18]. In addition, UV irradiation of the particles enables photoelectric charging regardless of the presence or absence of gases [19][20][21].…”