hagis code lynton appel … on behalf of simon pinches and the hagis users ccfe is the fusion...
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HAGIS Code
Lynton Appel
… on behalf of Simon Pinches and the HAGIS users
CCFE is the fusion research arm of the United Kingdom Atomic Energy Authority
EURATOM/CCFE Fusion Association, Culham Science Centre, Oxon, UK
The HAGIS code - ANU, Australia May 2010
HAGIS DescriptionHAGIS Description11
• 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
1SD Pinches, LC Appel et al., Comput. Phys. Commun. 111 131 (1998)
The HAGIS code - ANU, Australia May 2010
Boozer CoordinatesBoozer Coordinates
The HAGIS code - ANU, Australia May 2010
Evolution of Energetic ParticlesEvolution of Energetic Particles
The HAGIS code - ANU, Australia May 2010
Equations of MotionEquations of Motion
• Derived from total system Hamiltonian
The HAGIS code - ANU, Australia May 2010
Fast Particle OrbitsFast Particle Orbits
• ICRH ions in JET deep shear reversal
– On axis heating: = B0/E = 1
– E = 500 keV
R [m]
z [m
]
The HAGIS code - ANU, Australia May 2010
Calculation of AE EigenfunctionsCalculation of AE Eigenfunctions
The HAGIS code - ANU, Australia May 2010
Wave EvolutionWave Evolution
The HAGIS code - ANU, Australia May 2010
• Linear eigenstructure assumed invariant
• Introduce slowly varying amplitude and phase:
• Gives wave equations as:
• where
Additional mode damping rate, d
Wave EquationsWave Equations
The HAGIS code - ANU, Australia May 2010
Delta f MethodDelta f Method
- νeff δf
The HAGIS code - ANU, Australia May 2010
Quiet Start MethodQuiet Start Method
The HAGIS code - ANU, Australia May 2010
Conservation of ParticlesConservation of Particles
The HAGIS code - ANU, Australia May 2010
ApplicationsApplications
• AE linear growthrates and
nonlinear saturation amplitudes
• Determination of
– fast particle re-distribution
– Fast particle lossesd/
0=2.7%
Mode saturates at B/B~10-3np =
52,500
Wave-particle trappin
g
Fast ion redistributi
on
The HAGIS code - ANU, Australia May 2010
TAE Amplitude DeterminationTAE Amplitude Determination
• 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
8070 7264 6866
Time [ms]
140
120
100
Fre
qu
en
cy [
kHz]
MAST #5568
0 10050 150Time [Lt]
Fre
quen
cy [
0]
0.7
0.8
0.9
1.0
1.1
1.2
Chirping modes exhibit frequency sweeping, /0~
20%
The HAGIS code - ANU, Australia May 2010
Fast Ions in MASTFast 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 ModellingTransport Code Modelling
Sn TRANSPExperimentDifference
• 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 m2/s
The HAGIS code - ANU, Australia May 2010
Fast Particle SimulationsFast 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 ExperimentComparison 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 performanceHAGIS code performance
• HAGIS code parallelises very well– relatively low level of inter-processor communication traffic
0
1000
2000
3000
4000
5000
6000
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Number of processors, #
Ru
n t
ime
[s]
1/n scaling
Linux Cluster
Wall clock time to calculate TAE linear
growthrate in ITER