Study of Nonequilibrium High-Speed Plasma Flows with a Large Amount of Oxygen Atom

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(1) Nonequilibrium plasma generator which operates for air, nitrogen or oxygen gas was made for trial. Plasma torch has Cu anode and Hf cathode. The Hf cathode was effective for reducing the damage of the electrode. Preliminary experiments indicate that the core of plasma flows is about 2-6 cm long, and its temperature ranges 4000-9000K, depending on test-chamber pressure. From the results, it was found that the present apparatus was useful for the study of an interaction of material with nonequilibrium plasmas.(2) Strong air shock waves propagating in a shock tube were investigated numerically, detailed nonequilibrium reactive and radiative processes being included. Gas dynamic behaviors were calculated for shock Mach number above M=20. At M>30, unique radiative property with two peaks in radiative intensity distribution was found, one of which was due to nonequilibrium physico-chemical process and the other due to equilibrium one.(3) Low-density stagnation-flows in a strong N_2 shock … More layer were studied numerically to examine the effect of physical parameters such as nonequilibrium chemical reaction rates, cross section for vibrational relaxation, and so on. These parameters were found to have large effect on flow properties in the shock layer, but have very minor effect on the convective heat transfer rate to a stagnation point.(4) Nonequilibrium dissociation reaction rates and effective dissociation energy for O_2, N_2, NO and C_2 were calculated based upon the concept of "effective bond energy". Simple mathematical expressions for the effective dissociation energy are presented.(5) The Moire-Schlieren method was applied to supersonic free jets to visualize and investigate their structure. Using mathematical transformation method developed by the authors, jet structures from 3D nozzles were clarified.(6) Nonequilibrium radiation from air plasma was preliminarily investigated by means of the Maecker-type plasma generator. It was found that the plasma temperature was about 6000-10000K, and that N_2 molecular bands predominated for relatively low-temperature region and radiations associated with N and O did for high-temperature zone. Less