ROLE OF DIFFUSION IN CONDUCTION IN DIELECTRIC FLUIDS

The role of diffusion in the steady conduction process in dielectric fluids is developed. The relation of initial conditions to the mode of conduction is discussed and necessary conditions for the space-charge-limited mode are established. A generalized voltage-current characteristic for the space-charge-limited mode and for a diffusion controlled mode is obtained and properties of the charge density, field, body force, and potential profiles calculated. Certain constraints on integration constants are obtained together with their implications for material and process parameters. The constraints enable us to derive an equation for the volume charge density at a surface of the fluid. For the space-charge-limited mode, aside from material parameters, this is found to be proportional to the two-thirds power of the current density and independent of the thickness of the fluid.