High-voltage Pulse Corona Discharge In N <sub> 2 </ Sub>, N <sub> 2 </ Sub> + The O <sub> 2 </ Sub> Plasma Molecular Beam Mass Spectrometry Diagnostic Study

Positive ions from the near-cathode region in wire-plate highvoltage pulsed corona discharge induced N2 and N2-02 plasma were characterized using a molecular beam mass spectrometer (MBMS) under severe electromagnetic interference. The experimental results show that, 1) the electromagnetic interference caused by high-voltage pulsed (in nanosecond scale) discharge can be dismissed by improving the grounding and shielding of the instrument, and the signal-to-noise ratio can be enhanced through signal accumulation using a digital oscilloscope. 2) in the high voltage pulsed corona N2 plasma, the N~ current is 2-8 times greater than that of N2~ at N2 pressure of (5-25) >( 133Pa, peak voltage of 4-10kV and repetition rate of 10-70Hz. The nitrogen ion signals rise with increasing peak voltage and repetition rate of pulsed discharge, but exhibit a clear peak over the N2 pressure range studied. 3) in the high voltage pulsed corona N2+02 plasma, the N~ current is 1-10 times greater than that of N~ or O~, the N2~ current is approximately equal to that of 0~ at mixed gas (20% ~2 and 80% N2) pressure of(5-25) X l33Pa, peak voltage of 4-10kV and repetition rate of 10-100Hz. The N~, N2~ and Q~ signals rise with increasing peak voltage and repetition rate of pulsed discharge, also show a clear peak over the mixed gas pressure range studied. A kinetic simulation of N~ and N2~ created by the high voltage pulsed corona in N2 plasma is presented. Good agreement exists between the results of simulations and the experimental data.