Molecular Nitrogen Vibrational Temperature in an Inductively Coupled Plasma

Using a technique applied previously to the vibrationally excited molecular nitrogen (N^*₂) in the region of daytime and nighttime aurora, the emission intensity of the N₂ second positive band system in an inductively coupled plasma (ICP) was analysed and the vibrational temperature of nitrogen molecules in the ICP is thus determined. The result shows that the vibrational temperature increases with the increase of the neutral gas pressure from 0.04Pa to 10Pa, then decreases with the further increase of the pressure from 10Pa to 100Pa. Also, this is explained by using the Boltzmann relation between the vibrational temperature and the concentration of the vibrationally excited N^*₂(X¹Σ⁺_g) molecules.