Important operating parameters, temperature characteristics and radical production in an air plasma flow generated by a low-power pulsed arc discharge were experimentally clarified for lean combustion enhancement and surface treatment. Furthermore, the time-dependent thermofluid field downstream from the torch was also clarified numerically and the downstream temperature well agreed with experimental data. Finally, the time evolution of production and decay of the chemical species in air plasma were clarified numerically under a high electric field. (C) 2008 Elsevier Ltd. All rights reserved.