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.