Electron swarm coefficients and the limiting field strength of SF6–N2O mixtures

The electron drift velocities and the effective ionization coefficients have been measured with a pulsed Townsend apparatus for the SF 6 –N 2 O mixtures (1–75% SF 6 ) over the combined density-normalized electric field strength, E / N , from 130 to 420 Td (1 Townsend = 10 −17 V cm 2 ). Strong electron detachment effects have been observed for gas pressure mixtures above 1 Torr due mostly to NO − , arising as a dissociation product of N 2 O. In contrast, the influence of detachment due to the negative ions from SF 6 is shown to be very small. It has been found that the limiting electric field strength, E / N lim , of the SF 6 –N 2 O mixture is slightly superior (25–5%) to that of SF 6 –N 2 for SF 6 amounts of 0–50%, respectively.