ABSTRAKT

Entrainment of air molecules into spectrochemical ICPs, which are normally operated in the open air, may influence the plasma's behaviour, especially so at its edge. In this study, the air concentration and temperature just outside the plasma were measured by rotational Raman scattering. The electron density and temperature inside the plasma were determined by Thomson scattering. By using both techniques simultaneously and with spatial resolution, positioning errors are kept to a minimum. Just within the torch, but outside the plasma region, the gas temperature is well below 1000 К. and the air concentration is less than 10%. No region where both electrons and air were present in detectable amounts (10¹⁹ and 10²⁴ m^-3 respectively) was observed. This suggests that air entrainment does not play a significant role in the plasma dynamics of the ICP, perhaps with an exception at the outermost boundary.