Influence of the oxygen feed position on the compositions and isotopic contents of reaction products in N$_{2}$ glow discharge

We have performed the nitrogen isotope separation by the plasma chemical reactions in N$_{2}$-O$_{2}$ glow discharge system and investigated the influence of the oxygen feed position on the compositions and isotopic contents of reaction products in N$_{2}$ glow discharge. This isotope separation method is due to the vibration-to-vibration energy exchange among the vibrational states of N$_{2}$ molecules. When the oxygen is fed into the N$_{2}$ glow discharge from the upstream of the discharge area, the nitrogen-15 enrichment is observed and the maximum nitrogen-15 separation factor of 1.6 is obtained in the NOx products while the ozone is the main component in the reaction products. On the other hand, when the oxygen is fed into the N$_{2}$ glow discharge from the downstream of the discharge area, the formation of ozone is negligible and NOx is the main component in the reaction products. However, when the oxygen is fed into the downstream of the discharge area, the nitrogen-15 isotope separation factor in NOx products is much smaller than that for the premixing case.