NEGATIVE ELECTRON-MOBILITY IN A DECAYING PLASMA

The electron energy distribution function and the corresponding plasma parameters are studied numerically in a decaying Ar-NF3 plasma in the presence of an external electric field. It is shown that, in this pla sma, a steady state energy distribution is established. The shape of t he distribution function changes qualitatively when the electric field strength exceeds a certain threshold value. In this case, a so-called inverse distribution function forms and the electron mobility (the el ectron drift velocity) rapidly decreases and becomes negative. This ef fect is explained in terms of the specific energy dependence of the cr oss section for electron attachment to NF3 molecules. The possibility of experimental observation of negative electron mobility in a decayin g plasma is discussed.