6 th ITPA MHD Topical Group Meeting combined

6 th ITPA MHD Topical Group Meeting combined with W 60 IEA Workshop on Burning Plasmas Session II MHD Stability and Fast Particle Confinement • General scope of the meeting – A major goal of this workshop on "Burning Plasma Physics and Simulations" is to provide a road map for burning plasma research – After the workshop we would like to have a short paper, outlining what our present knowledge is and where the gaps in our knowledge are ("where are we"), what we want to achieve ("where do we want to go"), and how we want to achieve this ("how do we get there")

Progress in key physics areas is leading to next step burning plasma experiment Turbulence and transport Macro- stability Burning plasma Wave-particle interaction Plasma /wall interaction

But the essence of burning plasma physics is the coupling between different elements Macro- stability a’s Wave-particle interaction a’s Burning plasma a’s Turbulence and transport a’s Plasma /wall interaction Can we progress on individual ‘building blocks’ and possible couplings in weakly self-heated plasmas, with fast particles produced by additional heating, before real BPX?

MHD Stability and Fast Particle Confinement • Ripple effects • Low frequency MHD – fishbones, k. BMs – Sawteeth and NTMs • Fast particle thermalisation • High frequency MHD (Alfvén) – – – Linear stability Nonlinear development (redistribution and losses) Nonperturbative modes (EPMs) Diagnostic use Possibilities for burn control

Ripple effects – Ripple losses in ITER? • Relatively well understood – Optimization of ferritic inserts in ITER to reduce ripple alpha losses in reversed shear configurations by more than one order of magnitude • Not an issue for ITER?

Low frequency MHD and fast particles • Interaction of fast ions with low frequency MHD – Fishbones: nonlinear modeling in qualitative agreement with experiments – Linear theory of k. BMs interchange modes well advanced • Neoclassical tearing modes – Questions being addressed • Mechanisms for seed island formation, mode coupling in NTM triggering • Island size after sawtooth crash (effect of -stabilised sawteeth) – Sawtooth stabilisation by NBI – Quantitative effect of sawteeth on distribution • Fast ion motion with NTMs (Hamamatsu) • Robust control method for (2, 1) mode (Strait) • ECCD for NTM control (Modulated or continuous) (Guenter)

Fast particle thermalisation • Is slowing down classical? – Large effort to develop methods to simulate fusion ’s in plasmas without significant fusion reactivity • fast and R fast ITER • vpart/v. A ITER • But slowing down time/ E >> ITER and *fast >> ITER • Trace T experiments -ray spectroscopy ( on Be) at T blip direct observation of collisional slowing down in the absence of instabilities Too low current V. G. Kiptily et al. , PRL 93, p. 115001 (2004) Current profile not apt to confine ’s • Interaction between drift turbulence and fast ions: an open question

At the core of burning plasma physics Effect of collective instabilities on self-heating thermalisation by collisions Tion If instabilities are excited resonantly by ’s and reach large amplitude tae tei Pa Tel losses pa redistribution / losses effect on fusion Q wall damage Collective instabilities

High frequency MHD and fast particles Linear stability • Most unstable fast ion driven modes in ITER scenarios? • Parameters that control mode stability? – Large amounts of data on instability thresholds, all n’s (anisotropic fast ion distribution) – Experimental techniques to launch and detect stable modes: large experimental databases of for low-n AEs, starting for intermediate/high n’s (Fasoli, Snipes) – Drive and damping mechanisms qualitatively understood – Quantitative predictions on damping to be improved, especially in regimes in which fluid and kinetic models give different results (Guenter, Gorelenkov) – Methods for systematic expt. -theory comparison when many modes coexist MAST

High frequency MHD and fast particles Nonperturbative modes (EPMs) – Effect of Energetic Particle Modes well above marginal stability on profile? • Ex. of simulation of a-AE interaction redistribution AE wave-field n (r) initial final F. Zonca et al. r/a

High frequency MHD and fast particles Nonlinear wave-particle interaction – Redistribution and losses • Limits to ITER operational scenarios? • Self-consistent fast particle profile in ITER? • Significant progress in qualitative understanding, particularly in weakly nonlinear regime, where even some quantitative aspects are reproduced • Limited experimental data on fast ion redistribution and losses (difficulty in achieving large amplitudes and in diagnosing radial distribution of fast ions) Todo, Gorelenkov, Takechi

High frequency MHD and fast particles Diagnostic use – Information from MHD spectroscopy? • Background plasma (e. g. Alfvén Cascades: qmin(t)) • Fast particle distribution – Potential for stand alone use and real time applications to be demonstrated

High frequency MHD and fast particles Possibilities for burn control – Burn control tools and methods? • Some building blocks based on control of fast particles and related modes (AEs + ICRH) are being tested (e. g. at JET) • Attempts at simulating burning plasmas using NBI to mimic heating (JT-60 U) • Otherwise open question

6 th ITPA MHD Topical Group Meeting combined with W 60 IEA Workshop on Burning Plasmas Session II MHD Stability and Fast Particle Confinement 14. 30 Introduction A Fasoli 14. 40 TAE and EAE damping in JET A Fasoli 14: 55 TAE damping rates compared with NOVA-K J Snipes 15. 15 Fast particle driven modes - a new gyrokinetic code with full orbits S Guenter 15. 35 Alfvén Eigenmode stability with beams and alpha-particle profile quasilinear relaxation in ITER N Gorelenkov 15. 55 Nonlinear evolution of Alfven eigenmodes in an ITER-like plasma Y Todo 16. 15 Coffee 16. 35 Fast particle confinement and TAEs in JT-60 U M Takechi 16. 55 CAEs on MAST L Appel 17. 15 Fast ion motion perturbed by NTM magnetic island K Hamamatsu 17. 35 ECCD feedback on NTMs on AUG S Guenter 17. 55 2/1 NTM stabilisation on DIII-D T Strait 18. 15 Discussion Led by A Fasoli 19: 30 Close