Measurements of Electron Temperature and Density Distribution on a V-Shaped Target of a Divertor Simulation Experimental Module in GAMMA 10/PDX

Abstract

Spatial distributions of electron temperature and density have been measured using Langmuir probes on a tungsten V-shaped target plate of a divertor simulation experimental module in GAMMA 10/PDX. In standard hot-ion plasmas, the electron temperature is about 30-50 eV, which is comparable to that in confined core plasmas. The electron density is on the order of 10¹⁶ m⁻³ but increases about 3 times owing to additional ion cyclotron range of frequency heating. In a direction along the target plate toward the corner, the electron temperature seems to slightly decrease toward the corner. In another direction perpendicular to this direction, the electron temperature profile seems to be roughly flat. The profile of electron density compensated for the expansion of magnetic flux tubes is similar to the core plasma, but the compensated density decreases near the corner. As the open angle of the target decreases, the compensated density decreases although the electron temperature does not change much. These density decreases may be due to increase in flow velocity caused by electric and pressure forces in the pre-sheath.