DIII-D Contributions Toward the Scientific Basis for Sustained Burning Plasmas

C.M. Greenfield, (E. Schuster), et al. (Collaboration Paper)

IAEA Fusion Energy Conference

Daejon, Korea, 11-16 October 2010

Abstract

DIII-D is making significant contributions to a scientific basis for sustained burning plasma opera- tion. These include explorations of increasingly reactor relevant scenarios, studies of key issues for projecting performance, development of techniques for handling heat and particle efflux, and assessment of key issues for the ITER Research Plan. Steady-state scenarios are generated and maintained for a duration limited by hard- ware, using tailoring of the early evolution and precise targeting of external current drive. Joint DIII-D/JET 􏰀\rho* scans in the hybrid regime imply Bohm-like confinement scaling. Startup and shutdown techniques were devel- oped for the restrictive environment of future devices while retaining compatibility with advanced scenarios. Toward the goal of a fully predictive capability, the DIII-D program emphasizes validation of physics-based models, facilitated by a number of new and upgraded diagnostics. Specific areas include transport, rotation, energetic particles, and the H-mode pedestal, but this approach permeates the entire research program. Concerns for heat and particle efflux in future devices are addressed through studies of ELM control, disruption avoidance and mitigation, and hydrogenic retention in DIII-D’s carbon wall. DIII-D continues to respond to specific needs for ITER. Recent studies have compared H-mode access in several different ion species, identifying not only isotopic, but density, rotation, and geometrical dependencies that may guide access to H-mode during ITER’s non-activated early operation. DIII-D used an insertable module to simulate the magnetic perturbations intro- duced by one of ITER’s three Test Blanket Module sets, demonstrating that little impact on performance is seen at ITER equivalent levels of magnetic perturbation.