ITPA Scrape Off Layer and Divertor Topical Group

Scope

The physics studied by the Scrape Off Layer (SOL) and Divertor Topical Group covers a wide range of issues. Starting at the first wall surface, issues include plasma-material interactions and their dependence on materials, and hydrogen isotope recycling and their storage in the first wall. A more engineering-like issue is the first wall geometry and material and how these affect operation. Moving into the divertor and SOL plasmas, the issues are related to transport (parallel and perpendicular to the magnetic field) of hydrogenic and impurity species. At the SOL/core interface this group shall address the relationship between core and edge confinement (e.g., H-modes and density limits) as well as the understanding of changes in core confinement on the edge and first wall (e.g., Edge Localized Modes) and the resultant heat loads.

Tasks

The Scrape Off Layer & Divertor Topical Group shall focus its tasks on the following topics:

• Participate in developing and validating divertor physics (including detachment, impurity transport and pumping) of ITER on the basis of experimental, theoretical, and modelling results
• Assist the ITER Organization in defining the goals and program for ITER operation, including diagnostic requirements
• Develop a quantitative understanding of heat loads on all plasma-facing components for steady state and transients, e.g., Edge Localized Modes (ELMs) and disruptions
• Understand the role of external actuators (e.g., radiofrequency heating and resonant magnetic perturbations) on the SOL and impurity sources as well  as the effect of the SOL on those actuators
• Characterize and understand the multiple hydrogenic retention paths and their dependences on material and operating scenario, while also addressing the effects of mixing materials on material properties (e.g., erosion rates and thermal conductivity) as well as tritium removal techniques
• Develop new diagnostics for a variety of processes such as dust, erosion, and hydrogenic retention
• Develop methods of conditioning for pre-operation as well as during operation