Microscopics of toner transfer across a gap

The electric field transfer of charged toner particles across a gap has been investigated. Distributions in size and charge of spherical particles, as well as random placement, are allowed for in a computer simulation. The approximation of a semi-infinite slab model of toner on a substrate is used to derive some general trends. While a complete model would require consideration of nonspherical toner, polarization, and Van der Waals forces, the approach described here is in semi-quantitative agreement with visual observations and measurements of toner mass transfer as a function of field.