Theory Weekly Highlights for December 2017

December 22, 2017

Lang Lao attended and chaired the 9th ITER Integrated Modeling Expert Group (IMEG) Meeting at ITER Headquarters, Cadarache, France December 11-13, 2017. The IMEG consists of two representatives from each of the seven ITER partners. The main goal of the IMEG meeting is to review progress since the last meeting and advise ITER on its Integrated Modeling (IM) Program to develop an Integrated Modeling Analysis Suite (IMAS) and an infrastructure to support ITER plasma operation and research. The IMAS infrastructure consists of a workflow management system and a data model. Orso Meneghini also attended the IMEG Meeting as a domestic participant, and attended the Technical Meeting on IMAS Infrastructure December 4-5, 2017. For this year's meeting, IMEG was also asked to review the proposals for technical improvements to IMAS raised by ITER members at the IMAS Technical Infrastructure Meeting, and to make recommendations for improving alignment of the ITER IM Program with domestic activities to encourage increased engagement in IMAS.

December 15, 2017

Several members of the GA Theory Group: Gary Staebler, Phil Snyder, Federico Halpern, Brendan Lyons, and Chris Holland, attended the Second Community Workshop on U.S. Magnetic Fusion Research Strategic Directions Meeting in Austin TX this week.

December 08, 2017

An OMFIT module has been developed that predicts temperature, density and impurity density profiles from the magnetic axis to the separatrix. Reduction in the number of input parameters and assumptions in the simulations is achieved by using physics based models that are self-consistently coupled to one another. Previous coupled core-pedestal simulations were shown to be able to reproduce experimental profiles, but treated Z_eff as an input parameter (either estimated in predictive simulations, or taken from measurements in post-experiment analysis). The plasma effective ion charge (Z_eff) is an important parameter since it influences both core performance, through transport and line radiation, and pedestal transport and stability via its effect on the bootstrap current. To self-consistently account for the effects of impurities, the new core-pedestal workflow is iteratively coupled to the 1D impurity transport code STRAHL within the OMFIT framework. In this scheme NEO and TGLF provide the transport fluxes used to calculate the diffusion and pinch profiles used in STRAHL. Initial comparison of these simulations with a DIII-D observations shows that the self-consistent workflow is able to capture the profiles, including the impurity carbon density profile, with good accuracy.

December 01, 2017

A combined all-hands meeting of the Advanced Tokamak Modeling (AToM) and Edge Simulation Laboratory (ESL) projects was held at GA this week. AToM is a new 5-year SciDAC-4 project jointly funded by FES and ASCR with the goal of accelerating the state-of-the-art in integrated and whole-device modeling of tokamak plasmas and systems. AToM shares numerous team members with the ESL, which is an ongoing project aimed at kinetic Eulerian high performance computing (HPC) simulation of edge plasmas, as well as development of electromagnetic reduced models of the pedestal and boundary plasma. The meeting was attended by over 30 participants and included a code camp day in which members formed teams to tackle immediate software issues, brainstormed about early-term project deliverables, and discussed other topics of mutual interest.

These highlights are reports of research work in progress and are accordingly subject to change or modification