Diagnostical measurements of spectroscopic characteristics in a helium ICP using an enhanced vortex flow torch

Helium inductively coupled plasma using an enhanced vortex flow torch for the analysis of aqueous samples was developed. The present study reports the spectroscopic measurements of electron number densities, helium excitation temperatures and OH rotational temperatures in the helium ICP. Significant increases in electron number densities but decreases in rotational temperatures were observed, upon increased introduction of carrier gas. The experimental results suggest that the local thermodynamic equilibrium (LTE) is not consistent, and the effects of aqueous sample introduction on the plasma parameters are greater than in the case of conventional argon ICP. Moreover, the doughnut like profile of electron number densities and plasma temperatures reported for argon ICP were not observed in the helium ICP. The helium excitation temperature, OH rotational temperature and electron number density are 4100 K, 2200 K and 0.75 × 1014 cm-3, respectively at 900 W of RF input power.