A Global (volume averaged) Model (GM) conceived for modeling of discharges fed by N2O and by N2 / O2 mixtures including 4:1 [N2]:[O2] air-like ones, is applied to plasma discharges and to electric propulsion devices in case of pure N2O and of N2 / O2 feeding. The main results obtained by this model allowing to characterize the central “core” region part of Helicon Thrusters (HelT) are presented and discussed. Functioning is restricted in a rather low pressure region, of 3 mTorr up to 30 mTorr. The absorbed power in the “core” region introduced here is varying from 25 W up to 1000 W. Note that both pressure and power ranges have been here enlarged in comparison with previous values treating an Ar fed HelT which spanned only a 2 mTorr to 10 mTorr region for the pressure and 25 W to 150 W for the absorbed power. Various types of thrusters are examined on the basis of Functioning Diagrams (FD) and the plasma composition is given by Plasma Components Composition (PCC) results.