Abstract
Optical emission spectroscopy was conducted for measuring vibrational and rotational temperatures of atmospheric millimeter-wave discharge plasma. Measured spectra were fitted to the second positive system of nitrogen molecules with a theoretical scheme assuming Boltzmann distribution. The results showed that vibrational temperature was constant at about 6000 K and on the other hand, rotational temperature decreased from about 5500 K to 3000 K with the increase of peak intensity. The comparison between millimeter-wave absorption time and
required time for satisfying equilibrium in vibrational–translational modes, revealed that the non-equilibrium is attributed to ionization front propagation velocity. Finally, the structure of millimeter-wave supported detonation was proposed and the pressure and temperature behind a detonation wave is thought to depend on ionization front propagation velocity.
