General scope of the meeting

1. 6th ITPA MHD Topical Group Meeting combined withW60 IEA Workshop on Burning PlasmasSession IIMHD 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")

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

3. But the essence of burning plasma physics is the coupling between different elements a’s Turbulence and transport Macro- stability Plasma /wall interaction a’s a’s Burning plasma a’s a’s Wave-particle interaction a’s 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?

4. MHD Stability and Fast Particle Confinement • Ripple effects • Low frequency MHD • fishbones, kBMs • 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

5. 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?

6. 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 kBMs 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 a-stabilised sawteeth) • Sawtooth stabilisation by NBI • Quantitative effect of sawteeth on a distribution • Fast ion motion with NTMs (Hamamatsu) • Robust control method for (2,1) mode (Strait) • ECCD for NTM control (Modulated or continuous) (Guenter)

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

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

9. MAST 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

10. AE wave-field na(r) initial final r/a r/a F.Zonca et al. 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

11. High frequency MHD and fast particlesNonlinear 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

12. High frequency MHD and fast particlesDiagnostic 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

13. High frequency MHD and fast particlesPossibilities 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-60U) • Otherwise open question

14. 6th ITPA MHD Topical Group Meeting combined with W60 IEA Workshop on Burning PlasmasSession II MHD Stability and Fast Particle Confinement