  We investigate the existence of the electric field reversal in the negative
glow of a dc discharge, its location, the width of the well trapping the
electrons, the slow electrons scattering time, and as well the trapping time.
Based on a stress-energy tensor analysis we show the inherent instability of
the well. We suggest that the Fermi mechanism is a possible process for pumping
out electrons from the through, and linking this phenomena with electrostatic
plasma instabilities. A power law distribution function for trapped electrons
is also obtained. Analytical expressions are derived which can be used to
calculate these characteristics from geometrical dimensions and the operational
parameters of the discharge.
