Luminescence in air on a rough LiNbO3 surface. The movie was taken with a 10× optical magnification and shows how the luminescence pattern is affected by the surface roughness. We can observe the formation of radial streamers that bridge the central toroidal plasma with a plasma ring located approximately at 500μm from the jet impinging site. The streamers are seen to interact collectively and to give a visual perception of rotation, resembling the streamers seen in plasma balls.

Effect of high electric potential on the plasma stability and viability. The movie was taken from the impinging side and shows that the application of a 50-kV potential between the wafer and the nozzle, either positive or negative, leaves the plasma structure unaffected. The luminescence was generated in a mixed atmosphere of air and helium. Secondary streamers are seen that bridge the nozzle to the wafer away from the luminescent structure at the jet impingement site. They are not connected and do not interfere with this latter phenomenon.