EXPERIMENTAL-STUDY OF A SUPERSONIC LOW-PRESSURE NITROGEN PLASMA-JET

A supersonic nitrogen are plasma jet expanded in a low-pressure test c hamber is studied. Radial measurements of temperatures and densities a re performed in the expanding region over various sections from the no zzle exit. Nitrogen is highly dissociated in the are chamber and the p lasma is far from equilibrium. Electron temperature and density, as we ll as gas velocity, are measured by means of parallel and crossed elec trostatic probes. Measurements of selected atomic and molecular line i ntensities are performed in the 250-850 Mn spectral range to obtain nu mber densities of various N-2, N-2(+) and N excited levels. The rotati onally resolved emission spectrum from the (0-0) band of the N-2(+) fi rst negative system (B-2 Sigma(u)(+) --> X(2) Sigma(g)(+)) is analyzed and compared to synthetic spectra to evaluate the rotational temperat ure within the flow field. The kinetic scheme of ionic recombination o f N+ and N-2(+) is examined. A recombination path of the N-2(C-3 Pi(u) ) electronic state via the N-2(C''5 Pi(u)) state is proposed for the N (D-2(0))+N(S-4(0)) nitrogen recombination.