Modeling the process of charging microparticles in the chamber of an electrostatic injector

Mechanisms of charging microparticles in the area of the electrostatic injector needle are analyzed in the paper. The main attention is paid to the process of charging the conductive particles due to the emission of electrons from its surface under the influence of strong electrostatic field. A mathematical model of contact and contactless charging of particles is described. The results of solving a system of equations describing the dynamics of charging and the motion of the microparticle in the area of the injector charge needle are presented. The values of the relationship between the microparticle’s charge and its mass at the outlet of the electrostatic injector for different diameters of the charging needle and sizes of microparticles are calculated. A comparative analysis of the results of calculating the values of the relationship between the charge of a microparticle and its weight depending on the charging mechanisms and parameters of the microparticles and the charging needle is carried out. The results of calculating the maximum possible values of the relationship between the charge received by the microparticle in the injector and its mass depending on the charging mechanism are presented. The dependence of the values of the relationship between the charge of a particle and its mass on the distance from the needle at the beginning of autoelectronic emission from the particle surface is shown. The values of the relationship between the microparticle’s charge and its mass at the outlet of the electrostatic injector for real initial values of the particle velocities and charges in the charging chamber are calculated.