Measurements of the atomic nitrogen population produced by a microwave electron cyclotron resonance plasma

The atomic nitrogen population produced from a microwave electron cyclotron resonance plasma and a microwave plasma has been measured using the nitric oxide gas titration technique for pressures between 0.005 and 0.5 Torr. For 15 W microwave power the atomic nitrogen production efficiency is observed to reach a maximum of 12% at 0.006 Torr. The pressure dependence of atomic nitrogen production efficiency and concentration are found to fall by one order at the pressure where particle mean free path exceeds apparatus dimensions (0.015 Torr). The shift has been attributed to changing electron temperature.