CHARGED PLUMES DUE TO ION INJECTION IN AN INSULATING LIQUID IN BLADE-PLANE OR POINT-PLANE GEOMETRIES

When applying a high enough potential difference to a blade or a point opposite a plane in an insulating liquid, an injection of ions is pro duced in that liquid. The Coulomb force due to the action of the elect ric field on the space charge, plays a role analogous to buoyancy in t hermal convection. It induces a convection which takes the form of a c harged plume going from blade to plane. Following what has been done i n the thermal case, simple models in geometries with planar or axial s ymmetry are presented which give the width and the characteristic velo city of these plumes in both laminar and turbulent cases. We report al so on a preliminary flow visualization in blade-plane geometry using S chlieren observation technique. This experiment suggests the plume is laminar.