Spatial distribution of gas temperature in an air plasma jet of direct current glow microdischarge

The spatial distribution of gas temperature in air plasma jet of dc glow microdischarge has been determined. The temperature field was measured by a thermocouple probe and compared to schlieren images. The jet can be separated in the radial direction into three characteristic regions with clearly pronounced boundaries. The central region represents a narrow hot zone corresponding to the visible plasma plume, in which the gas temperature varies from 50 to 200$^{\circ}$C depending on the air flow rate and distance from the anode. This zone is surrounded by a warm “coat” of $\sim$1-cm diameter and a temperature within 30–50$^{\circ}$C. The outer region represented ambient air at room temperature. The zone of temperatures above 50$^{\circ}$C did not extend to a distance above 3 cm from the output nozzle of the discharge cell.