Physics of the detached radiative divertor regime in DIII-D

This paper summarizes results from a two-dimensional ('2D) physics analysis of the transition to and stable operation of the partially detached divertor (PDD) regime induced by deuterium injection in DIII-D. The analysis [I] shows that PDD operation is characterized by a radiation zone near the X-point at T-c similar to 8-15 eV which reduces the energy flux into the divertor and thereby also reduces the target plate heat flux, an ionization zone below the X-point which provides a deuterium ion source to fuel parallel flow down the outer divertor leg, an ion-neutral interaction zone in the outer leg which removes momentum and energy from the flow and finally a volume recombination zone above the target plate which reduces the particle Bur to the low levels measured on the plates and thereby also contributes to reduction in target plate heat Bur.