ISOCONTOUR MAPS OF ELECTRON-TEMPERATURE, ELECTRON NUMBER DENSITY AND GAS KINETIC TEMPERATURE IN THE AR INDUCTIVELY COUPLED PLASMA OBTAINED BY LASER-LIGHT THOMSON AND RAYLEIGH-SCATTERING

Isocontour maps of electron temperature (T(e)), electron number density (n(e)), and gas-kinetic temperture (T(g)) in an argon inductively-coupled plasma (ICP), have been constructed for five rf power settings and in the presence and absence of an aqueous aerosol, based on the simultaneous measurement of spatially resolved Thomson and Rayleigh scattering. Each map was assembled from 21 observation heights and 31 radial positions, the location of each point being controlled by a computer-driven three-axis translation stage. The maps demonstrate how T(e), n(e) and T(g) all increase throughout the plasma as rf power is raised, with the electron number density increasing most rapidly. At greater rf power levels (1.75 kW), the introduction of an aqueous aerosol into the central channel was found to increase n(e) over the entire plasma. In contrast, at lower applied power (0.75 kW), n(e) is depressed throughout the discharge upon the introduction of water aerosol. At intermediate rf powers (1.0, 1.25 and 1.5 kW), aerosol introduction raises n(e) only in the regions near the hot torus, while educing n(e) at all other spatial positions, particularly lower in the central channel. Aerosol introduction was found also to thermalize the plasma at all rf power settings by increasing T(g) in the higher regions and decreasing T(e) lower in the central channel. In general, T(e) is substantially higher than T(g) in the lower regions of the discharge, but the two approach each other in the upper zones.