The electron energy-loss factor in a low-pressure discharge in an alkali-metal vapor

A study has been made of the mean proportion of the energy lost by an electron in one collision in a positive discharge column for the vapors of sodium, potassium, rubidium, and cesium at $E/n_a = (2-20)\cdot 10^{-15} V\cdot cm^2$. The measured and calculated energy-loss factors agree satisfactorily. The main energy loss is due to inelastic collisions between electrons and atoms in the ground state and first excited one.