Valuations of Charging Efficiency and Critical Gap for Electron Tunnelling under Contact Electrification Model

The electrification mechanism during particle fluidization is complex, and developing a reliable contact electrification model requires addressing many issues, especially the valuations of the charging efficiency and the critical gap for the electron tunnelling. This work aims to utilize the modelling of the simplest normal contact electrification between insulator particle and metal surface as an attempt to explore methods for the valuations of the critical gap and charging efficiency. A contact electrification model is developed based on the condenser model. The appropriate expressions for the contact potential difference and charge relaxation are discussed by reviewing previous works; the valuations of critical gap and charging efficiency are implemented by analyzing the effect of initial charge and impact velocity on the transferred charge. The model is validated by the published experimental results, and accurately predicts the electrification during the normal collision of the insulator particle on the metal surface.