Divertor physics and concept development on DIII-D and Doublet-III tokamaks

The pioneering research on the Doublet-III (DIII) tokamak and its upgrade the DIII-D has contributed significantly to understanding of the physics of divertor plasmas and the development of the modern poloidal divertor. The earliest experimental investigations of the "class of open divertors" were carried out on DIII and DIII-D tokamaks. Divertor advances on these devices include the discoveries of the "high-recycling regime" and divertor impurity enrichment via induced scrape-off-layer flow. Density control was achieved, and high-confinement modes were discovered with the aid of an innovative in-vessel cryopump. In this paper, we present a review of research and development on the DIII and DIII-D tokamaks that has contributed to the development of the modern poloidal divertor, emphasizing the aspects that are of importance to the next-generation tokamak devices.