Study of Plasma Impurity Composition in the Experiments with Carbon, Tungsten and Lithium Limiters on T-10

Resumo

This paper is devoted to the studies of the T-10 plasma impurity composition during experimental campaigns of 2014–2016, when a carbon limiter was replaced by a tungsten one and a movable lithium limiter was installed. In these experiments, the effective charge of the plasma was determined from the bremsstrahlung intensity and from CXRS measurements. The total concentration of tungsten ions in the column was estimated from the intensity of the radiation detected by AXUV. The source of light impurities (C, N, O, Li), as well as of tungsten atoms, was estimated from absolute measurements of line emission profiles. The experiment showed that the use of lithium as a limiter material can significantly reduce the flow of light impurities into the discharge and also reduce the dispersion of the W diaphragm. At the same time, the concentration of lithium nuclei in the column does not reach values measurable by CXRS diagnostics of the T-10 (0.3–0.5% of the plasma density).