Assessment of the DIVIMP 'Onion-Skin' Model in the JET Mark I Divertor

摘要

The DIVIMP-NIMBUS [1] 'Onion-Skin' model has been used to predict upstream plasmaparameters using as input measurements by Langmuir probes in the divertor target tiles. Measurements of density and temperature (both T_i and T_e ) across the SOL close to thestagnation point at the top of the torus have been made using a reciprocating probe carrying both Langmuir and retarding field analyser (RFA) heads. In addition, a lithium beam diagnostic has been used to measure radial distributions of density upstream. Ohmic, L-mode and H-modedischarges have been studied, and good agreement with code predictions in all cases has been found. The inclusion of convection has a small but helpful effect for T_i. The heat transportcoefficient, χ_⊥ (r), has been evaluated across the SOL, and is found to increase with increasing distance from the separatrix.