The peculiar variation of breakdown voltage
vb with pressure p in compressed SF6 due to coronastabilization
of the applied field is well pronounced in
rod to plane gaps, Fig. (1). In this paper, the spacecharge
mo&ed field has been calculated and a
simple criterion based on the gapminimumfieldis
proposed for breakdown in the rising straight part of
the vb-p characteristic . This calls at first for
assessment of the corona onset voltage. For pressures
greater than the critical pressure breakdown occurs
without any preceding corona discharges and the
breakdown voltage is theoretically predicted. The
calculated corona-onset V, and breakdown voltages
agreed with those measured experimentally within f
10 Yo.