Bubble instabilities and transition to streamers in liquid dielectrics

The paper deals with the dynamics of a bubble initiated in the vicinity of an electrode in a liquid dielectric gap submitted to an electric field, and to the conditions leading to the generation of a streamer at its interface. By taking into account the surface tension of the bubble and the electrical charge that it carries, we establish a mathematical expression describing the shape of the bubble and allowing to analyze its deformation in function of the experimental conditions. The frequency of the disturbances at the interface is studied and the zone at which the local electric field is the highest is determined. It is shown that according to this frequency then to the value of the local electric field, different structures can be generated. An example of the topology of the disturbed interface is given and discussed