Influence of pressure and discharge voltage on spectral intensities in a pulsed nitrogen discharge supersonic free-jet

The effects of the pressure and discharge voltage on the spectral intensities of the second positive and first negative systems were studied in a pulsed nitrogen discharge supersonic free-jet. The results show that a stabilized discharge condition was reached when the vacuum chamber pressure increased to 100 Pa. Both N(2)(C(3)Pi(u)) and N(2)(+)(B(2)Sigma(+)(u)) states were highly populated at a pressure of 100 Pa to 130 Pa. The active state N(2) (C(3)Pi(u))could be selectively populated at a low pressure of 10 Pa and a discharge voltage of 4500 V. Different populating mechanisms under the experimental conditions for N(2)(C(3)Pi(u)) and N(2)(+)(B(2)Sigma(+)(u)) states were proposed to account for the experimental results.