Spatial distribution measurement of electron temperature and density of inductively coupled nitrogen plasma by tomographic optical emission spectroscopy

The 2-D horizontal distribution of electron temperature and density of nitrogen inductively coupled plasma (ICP) was estimated by optical emission spectroscopy with tomographic method. The electron density was determined from the electron temperature and the degree of dissociation, compared to the results of the calculation program that takes into account the excitation kinetics of atoms and molecules. Based on the molecular processes in N2 plasma, the electron density was obtained from the density ratio of the B and C states, which are electronically excited states of the nitrogen molecule, whereas the degree of dissociation of the nitrogen molecule was obtained by actinometry method using argon as actinometer. The results show a strong positive correlation between the electron density and the degree of dissociation of nitrogen molecules.