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The paper presents the measurement and computation of the corona onset voltages, electric field and ion current density profiles of a new "Tri-electrode system" intended for electrostatic separation applications. Unlike the well-known "dual cylinder-wire electrode system", the new system utilizes an extra adjustable wire in order to provide the means for a more efficient ion charging current; necessary for separation of different granular mixtures. An experimental setup is constructed to model the present multi-electrode arrangement. The measurements are carried out for wire diameters between 0.3-1.0 µm and for different geometrical parameters. Without resorting to the commonly used Deutch's assumption, a computational scheme is developed to solve the corona equations and to compute the associated ionized field quantities of the system. Mapping of the ion flow field patterns demonstrates the impact of this assumption on the solution's accuracy. The computed results were found to be in good agreement with experiments. The configuration offers a more efficient charging process and separation in comparison with earlier separators' designs.

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This paper concerns the influence of moving an auxiliary limiting cylinder in X-

The paper presents the computation and measurement of electric field, in both electrostatic as well as ionized case, for dual electrode system intended for electrostatic applications. The Keywords: corona discharge, dual electrode system, linear biased probe, electric field.Copyright © 2016 Institute of Advanced Engineering and Science. All rights reserved. IntroductionThe corona discharge employed in electrostatic approaches is useful in many applications such as dust precipitation, powder spraying, or granular mixtures separation by utilizing the electric forces exerted on such charged particles [1][2][3][4][5][6]. The region in which the electric forces act is widening by using a non-ionizing electrode with an ionizing electrode, dual electrode, resulting in the so called the corona-electrostatic field [7]. Several types and shapes of electrodes have been carried out experimentally to study these corona electrostatic fields, but they were very complex and expensive due to the presence of many parameters involving such fields [3,4]. Besides, there was another trend to simulate the phenomena of corona charging and particle motion in electric fields in the presence of space charge by numerical model [4][5][6][7].Accurate calculations and measurements of such fields are one of the major problems facing the designers of such electrostatic applications. Several analytical techniques have been applied by using different numerical models for such situations based on techniques such as the charge simulation method (CSM), finite differences (FDM), finite element (FEM), and the integrated method of finite element and the method of characteristics (MOC) [7][8][9][10][11][12]. Although various computational tools are developed for electric field calculations, none of them is mutable enough to be employed for the analysis of more complicated electric field configurations.Many experiments had been carried out to measure the electric field in the presence of the ionic space charge field, but they are very complicated to get accurate measurements. The biased current probe is one of the procedures to measure the ionized electric field introduced by Tassiker [13] and then developed by selim and waters [14]. It consists of a linear biased probe and a rectangular collecting plate surrounded by a bias plates at voltage V b . The operation of the linear biased probe is as follows [15]:1. During corona discharge, the collector probe collects the current resulting from this discharge (I o ) when no bias voltage is applied to the bias plates.2. This current (I o ) is reduced to I when the bias voltage V b is applied to bias plates such that it produces a biased field that opposes the original unknown field E, so: