Studies of the influence of external hydrocarbon injection on local plasma conditions and resulting carbon transport

A one-dimensional fluid model, which calculates the modification of density and temperature along the magnetic field and the parallel electrical field in the presence of local impurity sources, has been implemented into the ERO code. The influence of impurity source strength on the local plasma parameters and resulting changes in impurity transport and deposition has been studied. Dedicated TEXTOR experiments of ¹³CH₄ injection through roof-like test limiters are modelled for comparison. Modelling with high injection rates (larger than about 4 × 10¹⁸ s^-1) results in too localized light emission pattern near to the injection hole, and therefore indicates an underestimation of the reduction of electron temperature in the model. Besides, the preliminary results indicate that possible modification of local plasma conditions cannot significantly reduce the modelled ¹³C deposition and therefore cannot explain the measured low ¹³C deposition efficiency.