STUDY OF THE DECOMPOSITION OF SF6 UNDER DC NEGATIVE POLARITY CORONA DISCHARGES (POINT-TO-PLANE GEOMETRY) - INFLUENCE OF THE METAL CONSTITUTING THE PLANE ELECTRODE

SF6 samples (P(SF6) = 100 or 200 kPa) were submitted to point-to-plane dc negative polarity corona discharges in the presence of water [concentration = 2000 ppm(v) (parts per million by volume)] or without the addition of water. The stable gaseous byproducts formed, (SO2F2, SOF2, and S2F10) were assayed by gas-phase chromatography. The variation of their yields against the charge transported (up to 10 C) was studied for two metals (aluminum and stainless steel) constituting the plane electrode, at various values of the SF6 pressure, the water content, the gap spacing (2.5 and 8 mm), and the discharge current [12 less-than-or-equal-to IBAR (muA) less-than-or-equal-to 25]. The results indicate an important effect of the metal constituting the plane electrode and of the moisture conditions, particularly on the production of SOF2 and S2F10.