  In this paper we propose new boundary conditions at the hot walls with
thermionic electron emission for two-temperature thermal arc models. In the
derived boundary conditions the walls are assumed to be made from refractory
metals and that the erosion of the wall is small and, therefore, is not taken
into account in the model. In these boundary conditions the plasma sheath
formed at the electrode is considered as the interface between the plasma and
the wall. The derived boundary conditions allow the calculation of the heat
flux to the walls from the plasma and consequently the thermionic electron
current that makes the two temperature thermal model self consistent.
