Summary of IAEA Theory Papers on Energetic Particle Physics

Guoyong Fu

Statistics

• A total of 15 papers presented ;• 5 talks, 10 posters;• 4 papers on low frequency modes (GAM,BAAE);• 2 papers on nonlinear simulations of AE;• 2 papers on EP transport due to micro- turbulence;• 5 papers on EP-related physics in 3D geometry;• 1 paper on control of sawteeth by NBI.

TH/4-1 Chapman, I.T. “The Physics of Sawtooth Stabilisation in Tokamak Plasmas”

• The application of off-axis NBI can destabilise sawteeth which had previously been strongly stabilised by simultaneous on-axis heating. This is explained qualitatively through the role of passing energetic ions with a positive pressure gradient at the q=1 surface.

Weak Fast Particle Transport due to micro turbulence

TH/8-3 Angioni, C. Germany 20 Gyrokinetic Simulations of Impurity, He Ash and Alpha Particle Transport and Consequences

on ITER Transport Modelling

Weak Fast Particle Transport due to micro turbulence

TH/P3-14 Chen, L. “Gyrokinetic Simulation of Energetic Particle Turbulence and Transport”

4 papers on low frequency modes (GAM, BAAE)

• TH/P3-7 Zonca, F. “Kinetic Theory of Geodesic Acoustic Modes: Radial Structures and Nonlinear Excitations”

• TH/P3-11 Kolesnichenko, Y.I. ”Sub-GAM Modes in Stellarators and Tokamaks”

• TH/P3-15 Fu, G.Y. “Energetic Particle-induced Geodesic Acoustic Mode”

• TH/5-2 Gorelenkov, N.N. “Theory and Observations of Low Frequency Eigen-modes due to Alfvén Acoustic Coupling in Toroidal Fusion Plasma”

TH/P3-7 Zonca, F. “Kinetic Theory of Geodesic Acoustic Modes: Radial Structures and Nonlinear Excitations”

• Geodesic Acoustic Modes (GAM) are shown to constitute a continuous spectrum due to radial inhomogeneities.

• The existence of a singular layer causes GAM to mode convert to short-wavelength kinetic GAM (KGAM) via finite ion Larmor radii; analogous to kinetic Alfv´en waves (KAW). KGAM are shown to propagate radially outward; consistent with experimental observations and numerical simulation results.

• KGAM can be nonlinearly excited by drift-wave (DW) turbulence via 3-wave parametric interactions

TH/P3-11 Kolesnichenko, Y.I. ”Sub-GAM Modes in Stellarators and Tokamaks”

• Equations describing eigenmodes with the frequencies of the order of the geodesic acoustic frequency and the electron/ion diamagnetic frequency in toroidal plasmas are derived and analyzed.

• It is shown that there exist drift-sound eigenmodes and new drift-Alfven eigenmodes.

• It is shown experimentally that the modes rotating in different directions can be destabilized simultaneously, which agrees with theory predictions (W7AS).

TH/5-2 Gorelenkov, N.N. “Theory and Observations of Low Frequency Eigen-modes due to Alfvén Acoustic Coupling in

Toroidal Fusion Plasma”

TH/5-2 Gorelenkov, N.N. “Theory and Observations of Low Frequency Eigen-modes due to Alfvén Acoustic Coupling in

Toroidal Fusion Plasma”

• Due to large plasma beta in NSTX, characteristic frequency sweeping of RSAEs is suppressed.

• New low frequency modes (BAAE) are studied and observed in JET, NSTX and DIII-D. They exist in the BAAE gap with the frequency below GAM.

• Kinetic theory of BAAEs is formulated. It is shown that gap BAAEs are usually have smallest Landau damping in comparison with the sweeping up modes. If electron temperature exceeds thermal ion temperature BAAE dispersion is close to the MHD and has weak damping.

• Observed BAAE frequencies are low and within the experimental uncertainty agree with theory.

TH/P3-15 Fu, G.Y. “Energetic Particle-induced Geodesic Acoustic Mode”

• A new energetic particle-induced Geodesic Acoustic Mode (EGAM) is shown to exist. The mode frequency and mode structure are determined non-perturbatively by energetic particle kinetic effects.

The mode width is determined by the particle orbit width

/a=0.006 /a=0.016

2 papers on nonlinear simulations of AE

• TH/P3-9 Todo, Y., “Simulation Study of Interaction between Energetic Ions and Alfvén Eigenmodes in LHD”

• TH/5-1 Vlad, G. “Particle Simulation of Energetic Particle Driven Alfvén Modes”

TH/P3-9 Todo, Y., “Simulation Study of Interaction between Energetic Ions and Alfvén Eigenmodes in LHD”

• A numerical code that simulates the time evolution of energetic particles and AE mode amplitude and phase in a self-consistent way has been newly developed for three-dimensional equilibria such as LHD. In the simulation code, AE mode spatial profiles are assumed constant.

• Simulation with neutral-beam injection and collisions taken into account was carried out in the LHD equilibrium using the two TAE modes. It was demonstrated that Alfvén eigenmode bursts can be simulated with the new code.

TH/5-1 Vlad, G. “Particle Simulation of Energetic Particle Driven Alfvén Modes”

• Abstract: The results of hybrid MHD-particle simulations of the Alfv´en mode dynamics in a reversed-shear beam-heated DIII-D discharge are reported and compared with the experimental observations. Specific attention is devoted to the inclusion, in the numerical model, of nonlinear coupling between different toroidal mode numbers

5 papers on EP-related physics in 3D geometry.

• TH3-4 Spong, “Energetic Particle Physics Issues for 3-dimensional Toroidal Configurations”

• TH/P3-5 Biancalani, A. “Shear Alfvén Wave Continuous Spectrum in the Presence of aMagnetic Island”

• TH/P3-9 Todo, Y., “Simulation Study of Interaction between Energetic Ions and Alfvén Eigenmodes in LHD”

• TH/P3-11 Kolesnichenko, Y.I. “Sub-GAM Modes in Stellarators and Tokamaks”

• TH/P3-12 Yakovenko, Y.V. “Effect of the Toroidal Asymmetry on the Structure of TAE Modes in Stellarators”

Plasma Energetic Particle Simulation Center (PEPSC)

PEPSC team:

• PPPL: G.Y. Fu (PI), S. Ethier, N. N. Gorelenkov, R. Samtaney ;

Jianying Lang (12/01/08); J. Breslau, J. Chen (CEMM)

• IFS: H. L. Berk, B. N. Breizman, J. W. Van Dam; E. Chen (01/01/09)

• Univ. of Colorado: Y. Chen, S. E. Parker;

• ORNL: Scott A. Klasky

PEPSC Plan

• Upgrade M3D-K code: extension to 3D domain decomposition for particles; add source and sink.

• Build a new gyrokinetic/MHD hybrid code GKM (start from M3D-K) that uses gyrokinetic closure to include kinetic effects of thermal ions as well as energetic particles.

• Implement advanced numerical methods: nonlinear implicit method, high-order finite elements, and workflow method. Also, optimize code speed.

• Explore reduced models for comparison with GKM.

• Apply codes to experiments for code validation and physics understanding.

• Apply GKM to ITER for simulations of alpha particle-driven high-n TAEs.

Research Plan (2008-2009)

• Extend particle domain decomposition to 3D (scale to >1000 processors);

• Add source/sink (CU and PPPL);

• Formulate nonlinear GKM model (PPPL and IFS);

• Build GKM0 (initial GKM version);

• M3D-K simulations of beam-driven Alfven modes in NSTX.