Theory Weekly Highlights for November 2011

November 18, 2011

Phil Snyder presented an invited talk at the 53rd APS-DPP Meeting summarizing research in the EPED pedestal model development and validation against experiments. The predictive model combines non-local peeling-ballooning mode and near-local kinetic ballooning mode physics with no free parameters. The model has been successfully tested against existing machines over a wide range of parameters, including dedicated experiments as part of the DOE joint experiment-theory milestone. Tests so far suggest the model should be accurate to roughly 20% when used to predict pedestals for future devices such as ITER.

November 11, 2011

Phil Snyder and Nate Ferraro will present invited talks at the upcoming 53rd APS Meeting in Salt Lake City, Utah. The talk by Snyder, “The EPED Pedestal Model: Extensions, Experimental Tests, and Application to ELM-suppressed Regimes”, in the afternoon session on Monday Nov. 14, will present extensive tests of the EPED pedestal model against observations, and develop a new working model to explain aspects of ELM control by 3D fields. In his talk “Calculation of Linear Two-Fluid Plasma Response to Applied Non-Axisymmetric Fields”, scheduled in the afternoon of Tuesday, Nov. 15, Ferraro will show non-axisymmetric response calculations using the M3D-C1 code. These calculations demonstrate that perpendicular electron rotation is primarily responsible for the screening of core islands, and that strong rotation shear in the pedestal may increase the plasma response in the edge.

November 04, 2011

Calculations using the TGLF transport model predict that a higher pedestal pressure than the previous GLF23 prediction is required for ITER to reach its target fusion gain. The increase is about 25% and results from the finite aspect ratio and shaping effects that are included in TGLF. The TGLF Gyro-Landau-Fluid transport model has been successful in reproducing the observed density and temperature profiles in a wide variety of tokamak discharges from DIII-D, JET and TFTR. A key ingredient in the TGLF predictions of ITER is profile stiffness, S, defined as the ratio of the incremental energy diffusivity to the power balance energy diffusivity (See weekly highlights from December 17 2010 and March 25 2011). To date, we find S ~ 10 is typical in the plasma core and drops to less than three in the near edge region. The stiffness results for ITER are similar to those calculated for DIII-D ITER demonstration discharges. The results will be presented in an oral talk at the ITER session of the APS Meeting in Salt Lake City, Utah along with results from recent DIII-D stiffness experiments.

Lang Lao attended and chaired the third ITER Integrated Modeling Expert Group (IMEG) Meeting in Cadarache, Oct 25-27 to review progress in the ITER Integrated Modeling (IM) Infrastructure Conceptual Design and the near-term development of the IM infrastructure by the ITER IM Design Team.

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