Radial profiles of gas density have been measured in positive and negative SF6 coronas at 101.3 kPa using optical interferometry. The results show that, in DC SF6 coronas, the electrical power input is confined to a small volume around the point electrode and energy transfer by the corona wind efficiently dissipates the heat generated there throughout the discharge chamber. Consequently, temperature rises and neutral species density changes throughout the chamber are relatively small. The gas density profiles reveal a thin channel of reduced density extending well out into the discharge gap towards the plane electrode and regions of increased density in the outer regions of the discharge chamber. This is consistent with the idea of a corona-driven circulation of gas around the discharge chamber. [References: 20]
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