Charge relaxation process dominates contact charging of a particle in atmospheric conditions

TLDR

The authors propose a new model describing the dominant mechanism of charge generated on a particle during impact or contact with a metal plate. The model attributes impact/contact charging to the residual charge after charge relaxation caused by gaseous discharge in atmospheric conditions, thereby circumventing limitations of the simple condenser model. Experimental results, including equilibrium charges and Ar‑gas breakdown behavior, confirm the model’s predictions, indicating that charge relaxation must be considered for atmospheric impact/contact charging.

Abstract

A new model is proposed for a mechanism dominating the charge generated on a particle due to impact or contact with metal plate. In this model, the impact/contact charging of a particle is determined as the remaining charge by the charge relaxation process due to gaseous discharge in atmospheric conditions; here, some difficulties of the simple condenser model are avoided. The model prediction is in good agreement with the `equilibrium charges` given as the result of impact charging experiments. Furthermore, the impact charging experiments conducted in Ar gas indicated that the impact charging characteristics changed corresponding to the breakdown limit potential of the environmental gas; this was also predicted quantitatively by the model. As a result of the proposal of this new model, hereafter in the case of treating charge generating phenomena due to impact or contact, in atmospheric conditions at least, consideration of the charge relaxation process due to gaseous discharge should be essential.