NEGATIVE DIFFERENTIAL CONDUCTIVITY OF ELECTRONS IN HE-XE MIXTURES

The drift velocity of electrons in He-Xe mixtures is calculated using the two-term expansion of the electron energy distribution function in Legendre polynomials. Collisions of electrons with ground-state and e xcited atoms are considered, together with Coulomb collisions. The cal culations are performed under conditions when negative differential co nductivity of electrons occurs. It is shown that concurrent effects of Coulomb collisions and of electron collisions with excited Xe atoms e xtend the region of parameters in the He-Xe mixtures where negative di fferential conductivity takes place.