Low-pressure air micro-plasmajets with a length of 10mm were generated through a nozzle with a diameter of 0.7mm at the pressures of 31.3 and 5.3kPa. Spectroscopic measurements were conducted at the point of 0.5mm from the nozzle exit on the central axis. The N
2+ 1- and N
2 2+ bands were predominant in the wavelength region of 280 to 420nm and the band shape was almost independent of the pressure. From temperature determination by a spectral matching method, it was found that the plasmajets were in a thermal nonequilibrium state and that vibrational temperature was much higher than rotational one. The experimental intensity distribution was reconstructed by the equilibrium radiation theory, in good agreement except for the N
2 2+ bands with v′ ≥ 2 as in case of atmospheric air micro-plasmajet. For these bands, much better agreement was obtained by taking the effects of predissociation and non-Boltzmann rotational population distribution for N
2C
3Π
u state into consideration in the theory. Discussions were made about potential cause of high vibrational temperature and slight difference between experimental and theoretical band shapes of the N
2 2+ bands at the low-pressures.
抄録全体を表示