Predischarge development in N/sub 2/ and SF/sub 6/ at high gas pressure

The predischarge development in compressed N/sub 2/ (0.1 to 0.6 MPa) and SF/sub 6/ (0.1 to 0.24 MPa) has been investigated. The measurements were performed for approximately homogeneous field distribution with positive DC-voltage of up to 200 kV. Highly sensitive framing of the luminous phenomena was done with a gated microchannel image intensifier. An optical delay line allowed recording of the last 40 ns before the beginning of the voltage collapse at the gap. As about 10/sup 4/ emitted photons could be detected, the first records belong to the late state of the subcritical electron avalanche.<
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