Electrohydrodynamic surface waves of thin oil films generated by needle-plate barrier discharges under argon gas environments

The study of electrohydrodynamically (EHD) induced surface wave phenomena on the surface of dielectric thin oil films under needle-plate barrier discharges for argon gas reduced gas pressure environments has been investigated experimentally, Experiments were conducted in a cloud environmental chamber maintained at gas pressure from 5.1 to 760 Torr. The test system consisted of needle corona electrode gaps, thin mineral oil films, polymer sheet and metal grounded plate. DC (on/off) negative and positive voltages were imposed on needle electrode. Measurements of corona current waveform and surface wave were observed by current transformers and CCD video camera, respectively. Unlike corona discharge in air, Ar discharge will not generate any negative ions, hence only glow corona was observed. The results show that thin oil film started to deform immediately who positive or negative dc voltage was imposed and after voltage was off, and that a formation of depression expanding waves was observed in argon gas when gas pressure was between 11 to 760 Torr for positive applied voltages only.