Study of stagnation enthalpy profiles in a plasma plume: comparison between computation and experiments

Calorimetric measurements have been carried out in air to measure the heat flux delivered by an impinging plasma jet on a substrate placed perpendicular to the jet axis. The total heat flux delivered to the substrate has been resolved spatially using both Gaussian and exponential profiles with the profile constants determined from inversion of experimental data. It has been observed that the exponential profile gives a slightly better match with the experimental results compared to a Gaussian profile, which is more commonly used to represent concentrated energy flux beams such as plasma, electron or laser beams. Simultaneously, the conservation equations of mass, momentum and energy for the same plasma plume have been numerically solved to compute the stagnation heat flux profiles with conduction, convection, diffusion and radiation as the basic transport processes. An isothermal homogeneous, cylindrical, plasma column approximation has been applied in a modified form to take into account the energy lost due to radiation. The results from the simulation are compared with the experimental results. The degree of validity of the simplifying assumptions made in the analysis and their contribution to the discrepancy between the theory and the experiment are discussed.