Radiating Divertor Behavior in Single- and Double-Null Plasmas in DIII-D

The ability to concentrate impurities in the divertor region to provide effective radiative divertor operation has been found on DIII-D to be sensitive to the divertor magnetic geometry and the grad-B drift direction. Argon impurities were injected into the private flux region of one divertor, while deuterium flow into the divertors was simultaneously enhanced by a combination of midplane gas puffing and divertor cryopumping. For DN plasmas it was difficult to balance the radiated power between divertors during argon injection; significant increases in radiated power and argon concentration were observed mostly in the divertor that was \textit{opposite} the grad-B drift direction. For SN plasmas, there was a higher divertor argon accumulation in the divertor when the grad-B drift direction was away from the dominant X-point, and so this setup may provide the best prospect of successfully coupling a radiating divertor approach to a high performance H-mode plasmas.