Nonsteady-state gas-discharge processes in plasmatron for combustion sustaining and hydrocarbon decomposition

This paper deals with the investigation of nonsteady-state discharge regimes in the plasmatron as applied to air-hydrocarbon mixtures. The electrode system is based on the design of a classical high-current arc plasmatron. Compared with a thermal plasmatron mode, the averaged discharge current in the described device has been decreased to about 0.2 A. Then, the discharge regime can be interpreted as a kind of glow discharge with the random transitions from glow to sparks. Two types of transitions have been observed: completed and noncompleted transitions. Completed transition is accompanied by the appearance of a high-conductivity spark channel, and for noncompleted transition, a low-conductivity diffuse channel arises. The discharge features have been investigated for plasmatrons with a long-length and with a short-length anode nozzle. The principal features of the nonsteady-state discharge behavior are the same for both designs. However, for the long nozzle, the discharge phenomena mainly proceed inside the anode cavity and for the short nozzle outside the cavity. Use of different designs of the plasmatron anode cavity offers to extend an area of plasmatron applications.