Presented by

High-Performance Computing inMagnetic Fusion Energy Research

Donald B. Batchelor

RF Theory

Plasma Theory Group

Fusion Energy Division

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It is the

process that

powers the sun

and the stars

and that

produces the

elements.

Nuclear fusion is the process of buildingup heavier nuclei by combininglighter ones.

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The simplest fusion reaction—deuteriumand tritium.

About 1/2% of the mass isconverted to energy (E = mc2 ).

n

n

n n

n

n+

+

+

+

+

+

nn

n

En = 14 MeV

Deposited inheat exchangerscontaining lithium fortritium breeding.

E = 3.5 MeV

Deposited inplasma; providesself-heating.

Remember this guy?

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Nuclear thermos bottle

We can get net energy productionfrom a thermonuclear process.

• We heat a large number of particlesso the temperature is much hotter thanthe sun, ~100,000,000°F. PLASMA: electrons + ions

• Then we hold the fuel particles and energylong enough for many reactions to occur.

Lawson breakeven criteria:

• High enough temperature—T (~ 10 keV).

• High particle density—n.

• Long confinement time— .

ne E > 1020 m-3s

T

T

T

T

T

T

TT

TT

TD D

D

D

DD

D

D

D

D

= 1 breakeven> 20 energy-feasible

ignitionQ =

PfusionPheating

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We confine the hot plasma using strongmagnetic fields in the shape of a torus.

• Charged particles move primarily along magnetic fieldlines. Field lines form closed, nested toroidal surfaces.

• The most successfulmagnetic confinementdevices are tokamaks.

DIII-D Tokamak

Magnetic

axis

Minorradius

Magnetic

flux

surfaces

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Latest news: http://www.iter.org.

An international effort involving Japan, Europe, U.S., Russia, China, Korea, and India.

R0 = 6 m

ITER will take the next steps to explorethe physics of a “burning” fusion plasma.

• Fusion power ~500 MW.

• Iplasma = 15 MA, B0 = 5 TeslaT ~10 keV, E ~4 s.

• Large – 30 m tall, 20 ktons.

• Expensive ~10B+.

• Project staffing, administrative

organization, environmental

impact assessment.

• First burning plasmas ~2018.

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What are the big questionsin fusion research?• How do you heat the plasma to 100,000,000°F, and once you have done so,

how do you control it?

We use high-power electromagnetic waves or energetic beams of neutral atoms.Where do they go? How and where are they absorbed?

• How can we produce stable plasma configurations?

What happens if the plasma is unstable? Can we live with it? Or can we feedbackcontrol it?

• How do heat and particles leak out? How do you minimize the loss?

Transport is mostly from small-scale turbulence.

Why does the turbulence sometimes spontaneously disappear in regions of theplasma, greatly improving confinement?

• How can a fusion-grade plasma live in close proximity to a material vacuumvessel wall?

How can we handle the intense flux of power, neutrons, and charged particles onthe wall?

Supercomputing plays a critical role in answering such questions.

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Center for

Extended MHD

Modeling

Center for Simulation

of Wave-Plasma

Interactions

• AORSA

• TORIC

• CQL3D

• ORBITRF

• DELTO5D

We have SciDAC and other projects addressingseparate plasma phenomena and time scales.

• M3D code

• NIMROD

Gyrokinetic Particle

Simulation Center

• XGC code

• TEMPEST

Edge Simulation

Projects

• GTC code

• GYRO

RF accelerated

beam ions

Minor radius

Thermal

ions

Injectedbeam ions

Vpar

Vp

erp

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Objectives: Understand heating

of plasmas to ignition, detailed

plasma control through localized

heat, current, and flow drive.

Petascale problems in wave heating andplasma control—GSWPI/SWIM project.

• The peak flop rate achievedso far is 87.5 TF using 22,500processors with HighPerformance Lapack (HPL)and Goto BLAS.

• AORSA has been coupled tothe Fokker-Planck solverCQL3D to produce self-consistent plasma distributionfunctions. TORIC is nowbeing coupled to CQL3D.

500

200

100

50

20

100

50

20

10

5

2000 5000 104 2 104

350 350

ScaLAPACK flop rate (TF)

500 500 (89.5 TF) HPL+Goto BLAS

400 400 (69.2 TF) HPL

350 350 (64.6 TF) HPL

450 450 (47.2 TF) HPL

400 400 (62.6 TF) HPL

350 350 (38.0 TF) HPL

Wall clock time (min)W

all

clo

ck t

ime

(m

in)

Flo

p r

ate

(T

F)

2000 5000 104 2 104

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Objectives: To reliably simulate the sawtooth and other unstable behavior

in ITER in order to access the viability of different control techniques.

100,00010,000500No. processors

7.52.51Rel. proc. speed

150 TF5 TF100 GFActual speed

3 10141 10132 1011Space-time pts.

1,500501Relative volume

ITERLarge present-daytokamak (DIII-D)

TODAYSmall tokamak (CDX-U)

Petascale problems in extended MHD stabilityof fusion devices (M3D and NIMROD codes)—CPES/SWIM.

• M3D uses domain decomposition in thetoroidal direction for massive parallization,partially implicit time advance, and PETcfor sparse linear solves.

• NIMROD uses spectral in the toroidaldimension, semi-implicit time advance,and SuperLU for sparse linear solves. NIMROD simulation of sawtooth crash

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Contact

Donald B. Batchelor

RF TheoryPlasma Theory GroupFusion Energy Division(865) 574-1288batchelordb@ornl.gov

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