Variation of axial temperature in thermal plasma jets

The excitation temperature of the plasma column in a spray torch can be determined using the atomic Boltzmann method, The spatially integrated intensities of emission lines resulting from Ar-I transitions in the wavelength region 400-451 nm have been measured. The central axis temperature of an inhomogeneous, axisymmetric, plasma column has been determined using a modified atomic Boltzmann technique without using the Abel inversion technique, The spectral measurements were made up to a distance of 20 mm from the nozzle exit point. The plasma torch was operated at power levels of 5 and 10 kW and the flow of argon was kept at 25 1/min, The average temperature of the plasma jet at the nozzle exit paint was estimated using an energy balance technique, The temperatures estimated using heat loss data and the centre line temperature differ significantly. A simple analytical expression was used to relate the average temperature and centre line temperature at the nozzle exit point. The temperature profile parameter n has also been calculated.