Thermal bubble motion in liquid nitrogen under nonuniform electric fields

This paper describes an experimental study into the influence of a non-uniform electric field on bubble motion and behavior in liquid nitrogen. The electric field effect on bubble motion as it rises due to buoyancy within applied dc electric fields is quantitatively investigated using a rod-plane gap. Thermal bubble motion and bubble collision with the plane electrode processes were observed in these experiments. The experimental results show that dc non-uniform electric fields have an obvious effect on bubble behavior; bubbles move closer to the plane electrode away from a higher field region to a lower one, irrespective of electric field direction. A model based on analysis of the forces acting on the bubble has been developed. This set of differential equations describes the motion of a spherical bubble in the rod-plane gap with voltage and can be solved numerically to determine bubble trajectory. Compared to experimental data, the theoretical prediction is in very good agreement.