Résumé:
In this paper, a microscopic approach for the calculation of partial and total
power dissipation from energy losses by collisions is considered and applied
in the case of N2O low pressure RF discharges. This approach is based on a
Monte Carlo technique in a particle model permitting sampling of the
energy deposited by different inelastic electron–N2O collisions. The
calculated power densities presented in this paper are in good agreement
with the experimental results and those obtained by the classical
macroscopic formula based on spatio-temporal integration of the product of
current density and electrical field. This microscopic approach presents,
however, a major advantage in comparison with the classical method (which
only offers the possibility to calculate the global power dissipation) by
making possible the calculation of all the power density terms, thereby
permitting one to examine the relative contribution of each collision process
in the power dissipation. Its application to N2O electronegative discharges,
at 503K gas temperature, several RF voltages and two different gas
pressures shows how the power is dissipated through electron–gas
processes. The power density variation is found to be proportional to the
electron density variation brought about by the changes in attachment (i.e.
e +N2O → N2 + O−), detachment (i.e. NO− + N2O → NO+N2O + e) and
ionization (i.e. e + N2O → N2O+ + 2e) processes. The role of each of these
processes is fully studied with our particle model in order to explain the
dissipated power variation.
