Modelling of ¹³CH₄ injection and local carbon deposition at the outer divertor of ASDEX Upgrade

Numerical modelling of ¹³CH₄ injection into the outer divertor plasma of the full tungsten, vertical target of ASDEX Upgrade is presented. The SOLPS5.0 code package is used to calculate a realistic scrape-off layer plasma background corresponding to L-mode discharges in the attached divertor plasma regime. The ERO code is then used for detailed modelling of the hydrocarbon break-up, re-deposition and re-erosion processes. The deposition patterns observed at two different poloidal locations are shown to strongly reflect the cross-field gradients in divertor plasma density and temperature, as well as the local plasma collisionality. Experimental results with forward and reversed B_T, accompanied by numerical modelling, also point towards a significant poloidal hydrocarbon E×B drift in the divertor region.