Composition and transport properties of SF6and their use in a simplified enthalpy flow arc model

The equilibrium composition of SF
6
was calculated for temperatures from 1000 to 45 000°K and for pressures from 1 to 16 atm. The usual thermodynamic functions and transport properties were also computed. Considering the arc column in axially flowing gas as a plasma generator, the power balance and momentum conservation equations are formulated and solved with certain simplifying assumptions. The solution gives the developing flow and electrical parameters as a function of distance along the nozzle. Arc voltages are predicted which agree with available data. Clarification is given on two processes contributing to dielectric recovery: axial sweeping away of the arc channel, and its conductance decay by thermal diffusivity, during the current fall approaching current zero.