HAGIS Code Lynton Appel … on behalf of Simon Pinches and the HAGIS users EURATOM/CCFE Fusion Association, Culham Science Centre, Oxon, UK CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority HAGIS Description1 • Self-consistently models the nonlinear interaction between spectrum of linear eigenfunctions and fast particle distribution function – Weakly damped global Alfvén Eigenmodes (AE) could be driven unstable by fusion-born -particles • Straight field-line equilibrium – Boozer coordinates • Hamiltonian description of particle motion • Fast ion distribution function – • f method Evolution of waves – 1SD Wave eigenfunctions computed by CASTOR/MISHKA/CAS-3D and held invariant throughout system evolution Pinches, LC Appel et al., Comput. Phys. Commun. 111 131 (1998) The HAGIS code - ANU, Australia May 2010 Boozer Coordinates The HAGIS code - ANU, Australia May 2010 Evolution of Energetic Particles The HAGIS code - ANU, Australia May 2010 Equations of Motion • Derived from total system Hamiltonian The HAGIS code - ANU, Australia May 2010 Fast Particle Orbits • ICRH ions in JET deep shear reversal – On axis heating: = B0/E = 1 z [m] – E = 500 keV R [m] The HAGIS code - ANU, Australia May 2010 Calculation of AE Eigenfunctions The HAGIS code - ANU, Australia May 2010 Wave Evolution The HAGIS code - ANU, Australia May 2010 Wave Equations • Linear eigenstructure assumed invariant • Introduce slowly varying amplitude and phase: • Gives wave equations as: Additional mode damping rate, d • where The HAGIS code - ANU, Australia May 2010 Delta f Method - νeff δf The HAGIS code - ANU, Australia May 2010 Quiet Start Method The HAGIS code - ANU, Australia May 2010 Conservation of Particles The HAGIS code - ANU, Australia May 2010 Applications • AE linear growthrates and nonlinear saturation amplitudes Mode saturates at B/B~10-3 np = 52,500 • Determination of – fast particle re-distribution – Fast particle losses d/0=2.7% Fast ion redistribution Waveparticle trapping The HAGIS code - ANU, Australia May 2010 TAE Amplitude Determination • Frequency [kHz] • Frequency sweeping observed when damping rate ~ linear growth rate and holes/clumps form in particle phase space Modelling with HAGIS allows determination of experimental internal mode amplitudes from observed frequency sweeping Particle trapping frequency determined using HAGIS Chirping modes exhibit frequency sweeping, /0~ 20% MAST #5568 120 100 80 64 66 68 70 72 Time [ms] 1.2 Frequency [0] • 140 1.1 1.0 0.9 0.8 0.7 0 50 100 Time [Lt] The HAGIS code - ANU, Australia May 2010 150 Fast Ions in MAST • High performance MAST plasmas achieved with off-axis NBI – Off-axis NBI current drive used to tailor current profile • Fast ion distribution very different with on and off axis injection – Changes to current profile with offaxis beams studied in MAST The HAGIS code - ANU, Australia May 2010 Transport Code Modelling • Discrepancy in neutron rate coincident with observation of fast particle driven modes Sn TRANSP Experiment Difference – Fishbones • Can be explained by introducing an anomalous fast ion diffusion, D~0.5 m2/s The HAGIS code - ANU, Australia May 2010 Fast Particle Simulations • Fishbones simulated in HAGIS to study effect on fast ion population and calculate an effective fast ion diffusion The HAGIS code - ANU, Australia May 2010 Comparison with Experiment • Levels of anomalous fast ion diffusion found in simulations consistent with those required in transport codes to explain observations: – Neutron rate – Stored energy – Current profile The HAGIS code - ANU, Australia May 2010 HAGIS code performance 6000 1/n scaling 5000 Run time [s] Linux Cluster 4000 Wall clock time to calculate TAE linear growthrate in ITER 3000 2000 1000 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Number of processors, # • HAGIS code parallelises very well – relatively low level of inter-processor communication traffic The HAGIS code - ANU, Australia May 2010 14