UNSLASSIFIED For particles subjected to electrostatic and gravitational forces, the velocity is the vector sum of the velocities given bv (2) and 3) corrected by equation (1). IIe Laws Governing the Chargingof Particles Particles may acquire charges by passing shrough a region containing ions of a piven sign either by diffusion or field charging. In the former, the mechaniam is one of impingement of the particles with the ions due to the kinetic energy of the gas, whereas in the latter the impingement is assisted by the energy imparted by the electrostatic field. (a) For diffusion charging, the equation given by White d KT qs (; z] in G+ WaGNo eft 2 XT (5) gives the number of electronic charges which will be acquired by & particle of diameter ad. (b) For field charging, Pauthenier has given the following equation as modified by Dallavale fer a cylindrical electrostatic precipitator. Ge = jie? ko - 1 d? £ ——r ‘|3S Vasa . Tet Le E <r 1 Trt ey (6 Although others have asgaumed that the particle will acquire the eum of the charges piven by both methods, it is felt that. con- sidering the mechanisms involved, the particle charge will be given by the preater of the two effects. In any case, this gives a more conservative result. (c) Electrical considerations of the charger. Pauthenier has shown thet the potential distribution in a cylindgfr with central co-axial wire changes from logarithmic to a linear function as the corona current increases from zero, except for a small region around the wire. Under these conditions the field intensity will be given by 2i E & k 2 ~/ we -.02e UNCLASSIFIED