Results from the International Collaboration on Neoclassical Transport in Stellarators (ICNTS)

This contribution describes work carried out within the IEA Implementing Agreement for Cooperation in Development of the Stellarator Concept, with the ultimate goal of providing a comprehensive description of neoclassical transport processes in stellarator experiments. Such a description is mandatory for analyzing experimental results and carrying out predictive simulations as the performance of high-temperature stellarator discharges generally conforms to neoclassical expectations for confinement, bootstrap current and parallel electric conductivity. Within the ICNTS, a thorough benchmarking of the various numerical methods used to calculate mono-energetic neoclassical transport coefficients in the complex 3-D magnetic-field topologies of planned and existing stellarators has been performed. An overview of these results is presented here along with the theoretical and numerical tools required for practical application of these results. (author)