Spatial characterization of emission intensities and temperatures of a high power nitrogen microwave-induced plasma

The spatial characterization of a high power nitrogen microwave-induced plasma (N-2-MIP), using an Okamoto cavity, was undertaken, The plasma operating conditions were fixed during all the experiments at a microwave frequency of 2.45 GHz, an incident power of 1.3 kW, a plasma gas flow rate of 11.01 min(-1), a carrier gas flow rate of 1.01 min(-1) and a sample uptake rate of 1.6 mi min(-1), A Ca solution was used to measure the emission intensity distribution for both Ca atom and ion lines in the N-2-MIP, and an Fe solution was used to determine the excitation temperature distribution of the N-2-MIP, which was obtained by using a Boltzmann plot under the assumption of LTE, In addition, rotational temperature measurements were carried out using the N-2(+) (0-0):B-2 Sigma(u)(+) --> X(2) Sigma(g)(+) band. Because the H-beta line (486.13 nm) could not be excited in the N-2-MIP, measurement of the electron number density was carried out by a method involving the Saha equation using both the emission intensity ratio (Ca II:Ca I) and the excitation temperature of the N-2-MIP, The degree of ionization of various elements in the N-2-MIP was also calculated. The spatial characteristics of the N-2-MIP were compared with those of the Ar-ICP.