The nonequilibrium behavior of electron swarms in nonuniform fields in SF6

The behavior of electron swarms in nonuniform electric fields in SF₆ has been analyzed by Monte Carlo simulation. Decreasing and increasing electric field configurations have been studied. The spatial variations of the electron mean energy, drift velocity, and ionization and attachment coefficients are calculated for different field slopes and compared with the values calculated assuming equilibrium field conditions. It is found that the nonequilibrium behavior depends on the ratio of the field slope to pressure, and not on the field slope alone. The mean energy and drift velocity are almost the same as the equilibrium values, while the ionization and attachment coefficients show significant nonequilibrium features. The electron and ion distributions along the uniformly decreasing and increasing fields have also been studied