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Comprehensive ITER Approach to Burn
L. P. Ku, S. Jardin, C. Kessel, D. McCunePrinceton Plasma Physics Laboratory
SWIM Project MeetingOct. 15-17, 2007
Oak Ridge National Laboratory
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A comprehensive simulation of an ITER discharge has been completed. Plasma states obtained are being used for testing various aspects of IPS.
• Using IPS/EPA we have carried out an ITER discharge simulation (a hybrid scenario) using NUBEAM and TORIC for the beam and RF calculations, respectively, via the alternate internal coupling method.
• We use this comprehensive ITER approach to burn to – test coupling to sophisticated source models in TRANSP– compare with previous calculations with analytic models– provide plasma states for IPS to run in re-play mode for
component development and testing, comparative studies for resolution requirement, and testing porting to new computer platforms of other components.
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Outline of Presentation
• Approach to ITER discharge simulation– EPA in IPS– EPA internal coupling to TRANSP (client-server)– TSC & EPA
• Physics models and results– discharge scenario– source and current drive models– summary of results
• Improvements, targets and plans
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In normal mode of operation the equilibrium and profile advance (EPA) component communicates with others via the plasma state and the controller.
Plasma State
Equilibrium &Profile
Advance Dist.Function
RF/BeamSource Electric
Fields &Others
MHD Stability
Controller
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However, there is an option in EPA which uses models in TRANSP to calculate the source and current drive in conjunction with the equilibrium and profile evolution.
Plasma State
EPA -- TSC
control
advance free-bndy
equilibriumadvance profiles
TRANSP
evolve sources
heating & currentsNB, RF, fusion products
control
equilibrium profiles
sources sourcesequilibrium profiles
Init, step, save, kill
ready, error
signal file passing
receive
request
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The engine driving EPA is the Tokamak Simulation Code TSC.
• TSC performs free-boundary self-consistent transport evolution in any part of a tokamak discharge.
• TSC models PF coils and 2-D passive structures with circuit equations. Arbitrary power supply models can be used.
• TSC runs with feedback control systems – radial position, vertical position, Ip, and shape– sensors and reconstructions– stored energy, current profile, etc.
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Using internal coupling to TRANSP initially facilitates the development of other components in ISP.
• TRANSP has several high fidelity source models– NB - NUBEAM (orbit following Monte Carlo)– ICRF - TORIC/SPRUCE (full wave), CURRAY (ray-tracing)– LH - LSC (ray-tracing 1D Fokker Planck)– EC - TORAY (ray-tracing, relativistic) -particles (orbit following Monte Carlo)
• TRANSP runs in “interpretive” mode for experimental analysis, but this same approach has been modified to run in “predictive” simulations by passing T(), n(), q(), and equilibrium geometry.
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The case study is a “hybrid” scenario
• Discharge scenario – off-axis beam and ICRF heating:– 3 s ≤ t ≤ 250 s
– pre-programmed: zeff, ne, Ip; flattop @ t~240 s
• ne20=0.924 @ t=240 s
• Zeff=1.2 (t<50 s), 1.8 (t<150 s) , 2.2 (t>150 s)• Ip=12 MA @ t=240 s
– total internal energy clamped at 450 MJ– particle confinement time=25 s– energy confinement
• t< 50 s Coppi/Tang profile consistent model• t 50 s relaxed GLF23 and neo-classical
Flux contours for the free-boundary equilibrium @250 s
B=5.3 T, R=6.2 m, a=2.0 m, =1.8, =0.45, p=0.74, q(0)=1.17, q(1)=4.30
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• Models for heating and current drive
– Neutral beams• off-axis (beam tangency 5.295 m), 1st beam on @ 10s,
with partial power and @ 50s with full power, 2nd beam on @ 110 s. Co, 1 MeV D, full power 16.5 MW.
• NUBEAM, sample size=1000.– ICRF
• 1 antenna, 20 MW, 52.5 MHz on @ 170 s, 3He minority (0.001), power level regulated by the total internal stored energy.
• TORIC, 31 poloidal modes, 128 radial, 64 angular grids– Alpha particles
• Monte Carlo fast ion slowing down, sample size=1000.
– Source integration time – 25 ms.
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Time Evolution of Power Balance
Beam 1+2
ICH+Beam
Total
Beam 1
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0.0 0.2 0.4 0.6 0.8 1.0
50000
100000
150000
0.0 0.2 0.4 0.6 0.8 1.0
50000
100000
150000
0.0 0.2 0.4 0.6 0.8 1.0
50000
100000
150000
0.0 0.2 0.4 0.6 0.8 1.0
100000
200000
300000
400000
500000
rho rho
t=150 s t=250 s<
J·B
>/<
B·B
> (
A/W
eber
)
<J·
B>
/<B
·B>
(A
/Web
er)
Ph
eat (
Wat
ts/m
3)
Ph
eat (
Wat
ts/m
3)
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Time Evolution of Central Temperatures
Decrease due to increased Zeff
1st beam (16.5 MW)
2nd beam (16.5 MW)
ICH (20 MW)
electron
Ion
1st beam (8 MW)
1st beam (5 MW)
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Time Evolution of Current Drives
Pre-programmed plasma current
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Te
Ti
Temperature, Density and q Profiles at t=250 s
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ne
ni
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Some simulation results during the first 50 s of an ITER discharge with beam turned on at t=10 s. Note the loss of power for t<15 s before the plasma is fully developed.
Requested power
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Requests of Improvement, Targets and Plans
• Simulation under full IPS control– Ease of use
• readily accessible to users (Kessel, Budney, and others)• having templates setup for machines (ITER, KSTAR, JET, NSTX, CMOD, DIII)
– Options for NBI and -particle slowing down• NUBEAM, Bounce-averaged FP (ACCOME?), ASTRA package
– Options for ICRF• TORIC, AORSA (full wave), GENRAY (ray-tracing)
– Options for LHCD• LSC/ACCOME, GENRAY (1D FP), GENRAY/CQL3D (2D FP)
– Options for EC• TORAY, GENRAY, GENRAY/CQL3D
– Routine use of stability codes• PEST, BALLON, DCON• NOVA-K
– Implement redistribution of fast ions• from sawtooth• from other MHD modes
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Improvements, Targets and Plans (cont.)
• EPA enhancement– Add prediction of plasma rotation profile
requires sources from all sources requires options for momentum transport
– Improve density prediction 3 hydrogen species and impurity pellet fueling model
– Include fast ion pressure in equilibrium evolution– Implement new GLF23 (TGLF23, available in Dec) and standardized
transport interface needs to be in parallel (10-100 processors)
– Implement options for edge pedestal model (including ELMs)– Porting and benchmarking on Jaguar– Implement interface with machine description files
• Application of IPS/EPA to additional ITER discharge simulations– ELMy H-mode
Q(0) ≤ 1, useful for testing sawtooth handling in IPS– Steady-State
High n, stability– Study sensitivity to resolution, calling frequency, etc.