Correlation between plasma temperature and impurity flux in the limiter shadow of the Textor tokamak

Abstract
This paper presents a method of utilizing collector probe techniques to determine quantitatively parameters controlling the impurity production in fusion devices. Thus, a particle collection probe system was used to investigate the effects of a variation in the plasma core temperature on the flux of heavy impurities in the limiter shadow of the Textor tokamak. Time resolved impurity flux measurements were carried out in five hydrogen plasma discharges. The electron temperature at the plasma center was varied in the interval 0.66-0.95 keV during the flat top part of these discharges. The results of the measurements show that this temperature increase was accompanied by a factor 2-5 increase in the heavy impurity flux. A comparison with existing sputtering yield data was carried out. It showed that the results could be explained in terms of sputtering of the limiters by hydrogen ions, the energy of these ions and the corresponding sputtering yield were derived.

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