Variation of axial and radial temperature in an expanded thermal plasma jet

The distribution of temperature in an expanded thermal plasma jet is investigated by modified Langmuir probes. The validation of classical probe theory in the entire experimental chamber pressure range of 10-100 mbar is thoroughly established before the measurements. The average temperature of the plasma jet at the nozzle exit was also measured by calorimetric estimation of total heat loss from the plasma upstream of that point. A correlation is made using simple analytical expression in between the average temperature measured from the heat loss data and the centerline temperature at the nozzle exit measured by Langmuir probe. The profile parameter n for the radial distribution of temperature in a plasma jet is calculated for different operating current and gas flow rates.