Plasma diagnostics using line intensity ratios

We discuss atomic concepts for electron temperature and density diagnostics of plasmas by use of line emission therefrom. The principle is related to competitive processes for the level population of atoms. Results of the measurement on the JIPP T-IIU tokamak are presented to demonstrate their usefulness for plasma research. The Te measure deduced from the line intensity ratio indicates underionization of oxygen in the plasma peripheral region, suggesting a presence of significant transport toward the higher temperature region. (author)