[en] The discharge in an electron-beam-sustainer atmospheric pressure CO₂ laser is investigated. An arbitrary two-dimensional geometry is employed in calculating the electric field. The conductivity is a function of the local electric field, the loss rate, and the ionization rate, the third of which is proportional to the energy deposition by high-energy electrons. The predicted discharge nonuniformities are compared with experimental results. Experimental evidence indicates that the discharge is recombination dominated. (U.S.)