The dielectric response of water in high electric fields: equilibrium water thickness and the field distribution

Adsorption and reaction of water at metal surfaces can be strongly influenced by high surface electric fields. A numerical model, which includes a field-dependent relative permittivity of water, has been developed to predict the equilibrium thickness of the condensed water layer and its effect on the field distribution around a field emitter tip. Thin water layers weaken the field at the tip surface while thick layers concentrate it. When the water becomes sufficiently thick, the field at the tip surface becomes greater than the field at a clean tip surface for the same applied potential.