Extension of the nonlocal approach to evaluate the electron velocity distribution

The method of the nonlocal approach is used to describe the spatially dependent electron kinetics in an inert gas dc column plasma taking into account the space charge confinement. The historical concept of the method, the applied simplification of the electron kinetic equation, and the specifications about its validity are critically discussed. The accuracy of the results are evaluated by means of detailed comparisons with a strict solution of the relevant kinetic equation based on the two-term approximation. An extension of the method is deduced to estimate the anisotropic part of the electron velocity distribution which allows an approximate description of the electron particle and power fluxes. These estimations are used for a consistent treatment of the spatially resolved electron power balance in the column plasma.