Transcript HAGIS code
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 Description
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• • • • • 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 – Wave eigenfunctions computed by CASTOR/MISHKA/CAS-3D and held invariant throughout system evolution 1 SD 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: =
B
0 /
E
= 1 –
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: • where Additional mode damping rate, d
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Delta f Method
ν eff δf
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Quiet Start Method
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Conservation of Particles
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Applications
• AE linear growthrates and nonlinear saturation amplitudes • Determination of – fast particle re-distribution – Fast particle losses n p = 52,500 Mode saturates at B/B~10 -3 d / 0 =2.7% Wave particle trapping
The HAGIS code ANU, Australia May 2010
Fast ion redistribution
TAE Amplitude Determination
• • • 140 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 1.2
120 100 80 64 MAST #5568 66 68 Time [ms] Chirping modes exhibit frequency sweeping, / 0 ~ 20% 70 72 1.1
1.0
0.9
0.8
0.7
0
The HAGIS code -
50 Time [ L t] 100
ANU, Australia May 2010
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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 off axis 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 – Fishbones • Can be explained by introducing an anomalous fast ion diffusion, D~0.5 m 2 /s S n TRANSP Experiment Difference
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
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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
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HAGIS code performance
6000 5000 4000 1/n scaling Linux Cluster 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 14
The HAGIS code ANU, Australia May 2010
Wall clock time to calculate TAE linear growthrate in ITER