During the presentations and discussion is was recognized by all that:
- in high beta, and in presnece of Energetic Particles (EP) in AUG and JET there complex self-organisation taking place between EP driven modes (TAE, Fishbones), non EP driven modes (NTM, ST) and turbulent transport leading to Ti(0) oscillations in phase or out of phase of TAE/FB. See Ph Lauber's slides
- That presently we do not have models to capture such oscillations and interplay. With our reduced physics turbulent transport models (QuaLiKiz or TGLF) in integrated modelling frameworks (ASTRA, JETTO) we can sometimes match the measured Ti and sometimes undeestimate it. Some ad-hoc tricks based on the fraction of EP have been propsoed.
- To reproduce the non-linear interplay observed on multiple confinement times, only integration of turbulent transport EP MHD and MHD is needed in integrated modelling framework. No global electromagnetic gyrokinetic code will be able to run over multiple confinement anytime soon.
- The need is therefore to develop reduced models for the various physics at play. For example ATEP (ENR) as developed reduced models for EP driven MHD. In the model reduction the theoretical undertsanding of the interplay between turbulence and MHD has to addressed. Progresses are being made in various european labs w/o coordination. Hence the white paper.
- The impact of high beta large EP physics is crucial for JT60-SA scenario preparation (based on ITB as BEST by the way) as recalled by Jeronimo in his slides. At the momet we are simply blind.
- prediction of core Ti and density is even more crucial in burning plasmas since Pfus scales as Ti(0)^2 and n(0)^2 rougly. Clarisse showed a small change in TGLF settings allowing for KBM to be resolved and leading to a drop of Pfus by 500 MW for ITER 15 MA case.
- During the discussion, the overall need is acknowledged as well as its importance for JT60-SA, BEST, ITER, VNS, DEMO.
- The fact that it includes theory, very high fidelity modelling (global elmagnetic gyrokinetic), model reduction and validation is understood. The discussion on how to organize such an activity. Marco Wischmeier, in the context of budget reduction, is proposing a transersal activity. Philipp and Clarisse being more in favour of a multidisciplinary team targetting this key fusion topic.
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