CONTROLLED DETACHMENT AND PARTICLE-TRANSPORT IN THE DIVERTOR PLASMA IN TDEV

At high densities, the plasma detaches from the outboard divertor plat es in TdeV. The signatures are a reduction of the ion flux to the dive rtor plate, movement of the radiating zone from the plate toward the X -point, a pressure gradient between an ionization front and the target plate, and strong cross-field transport in the divertor. A toroidally -viewing TV imaging system allows us to observe local interactions bet ween the divertor plasma and the different divertor plates. As the pla sma detaches, the gas pressure in the divertor continues to rise, and there is evidence for molecular processes in the cold plasma near the divertor plates. Auxiliary heating increases the power and particle fl ow across the separatrix; our results suggest that detachment depends on the energy transported per particle. Simulations using the B2/EIREN E and DIVIMP codes give reasonable agreement with the measurements for the attached phase.