Effect of two-temperature electron distribution on the Bohm sheath criterion

The effect of two-temperature electron distribution on the Bohm sheath criterion is studied in a collisionless sheath layer in contact with a perfectly absorbing wall. A modified Maxwell-Boltzmann model is used for the electron distribution functions, which considers the effect that the electrons above the sheath potential energy do not reflect back into the plasma. The present model shows that the Bohm velocity at the sheath edge is much more independent of the hotter species than what was understood previously with a simple Maxwell-Boltzmann electron model.