Electrical conduction in water revisited: Roles of field-enhanced dissociation and a reaction-based boundary condition

A one-dimensional formulation for the current density-electric field (J-E) characteristic for pure water has been developed which includes a self-consistent boundary condition, the auto-dissociation process, and electro-chemical kinetics at the electrodes. Our model results in a relatively simple form for the J-E characteristic. The predictions are shown to be in agreement with experimental data. The resulting J-E characteristics have an initial linear shape, followed by a super-linear increase. A saturating behavior is predicted based on the details of field-dependent variations in electro-chemical kinetic rates. Strong auto-dissociation would finally cause non-linear increases at much higher applied voltages. Based on the present theory, pertinent suggestions for improving the performance of water-based gaps for pulsed power applications have been made. These include water circulation, employing surface coatings, and optical/laser excitation at the electrodes.