NATIONAL FUSION FACILITYS A N D I E G O

DIII–D248-04/MRW/jy

byM.R. Wade

for the DIII–D Team

November 3, 2004

Presented at 20th IAEA Fusion Energy Conference

Vilamoura, Portugal

Development, Physics Basis, andProjections of Hybrid Scenario

Operation in ITER on DIII–D

M.R. Wade,1 T.C. Luce,2 R.J. Jayakumar,3 P.A. Politzer,2 A.W. Hyatt,2 J.R. Ferron,2 C.M. Greenfield,2 E.H. Joffrin,4 M. Murakami,1 C.C. Petty,2

R. Prater,2 J.C. DeBoo,2 J. La Haye,2 P. Gohil,2 T.L. Rhodes,5 and A.C.C. Sips6

1Oak Ridge National Laboratory2General Atomics

3Lawrence Livermore National Laboratory4CEA Cadarache Euratom Association5University of California-Los Angeles

6Institut fur Plasmaphysik

0 2

ITERBaseline

(Qfus = 10)

4 6

Neutron Fluence Per Pulse (10–5 MW - year/m2)

Qfus = ∞

Qfus = 5

Materials Testing

8 10 120.0

0.2

0.4

0.6

0.8

1.0

1.2

P alph

a / P lo

ss

'HYBRID' REGIME: A NEW STANDARD IN STATIONARY TOKAMAK PERFORMANCE THAT OFFERS ENHANCED

RESEARCH OPPORTUNITIES IN ITER

263-04/MW/jy

● 'Hybrid' Regime was originally conceived to take advantage of improved performance and current drive capabilities to achieve long-pulse operation in ITER (at Qfus < 10)

● Over the past few years, DIII–D has demonstrated stationary operation with β ≥ 80% βno-wall and H89 > 2 over a wide range in q95 (2.8 < q95 < 5) and density (0.3 < neo/nGW < 0.75)

● Projections based on this data are uniformly positive and offer a wide range of operating options in ITER

— Qfus = ∞ (q95 = 3)

— Qfus = 10 for 3900 s (q95 = 4.4)

S A N D I E G O

DIII–DNATIONAL FUSION FACILITY

Burn

ing

Plas

ma

Phys

ics

Using FullTransformer Capability

Projections based on DIII–D data

RECENT EXPERIMENTS HAVE DEMONSTRATED TRULYSTATIONARY (> 9 τR), HIGH PERFORMANCE OPERATION

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

0.0

0.5

1.0

1.5 IP (MA)PNBI (MW/10)

βN

βT

H89

τR10 τE

H98y2

01234

01

2

0

5

10

15n = 1 B rmsn = 2 B rms

~~

Time (s)

0.0

2.5

5.0

(G)

⟨ne⟩ (1019 m–3)Zeff (ρ = 0.5)

Dα

0 2 4 6 8 10 12

Zeff =2.0

H98y2 =1.3

H89P =2.3

βT ≈4%

βN ≈2.7

NORMALIZED FUSION PERFORMANCE AND DURATION COMFORTABLY EXCEED THAT OF ITER BASELINE SCENARIO

263-04/MW/jy

G = βN

H89/q95 as measure of Pα/PLOSS

[Mikkelsen, Phys. Fluids B 1 333 (1989)]S A N D I E G O

DIII–DNATIONAL FUSION FACILITY

2

0.0

0.2

0.4

0.6

0.8

1.0G

0 2 4

q95 < 4q95 > 4

6 108

● Duration:● Fusion Performance:NτR = tdur/τR as measure of stationarity

NτR

ITER BaselineScenario Target

PERFORMANCE AT OR ABOVE ITER BASELINE DESIGN HAS BEEN ACHIEVED OVER A WIDE RANGE IN q95

263-04/MW/jy

● No Sawteeth

● βN ≈ βN

S A N D I E G O

DIII–DNATIONAL FUSION FACILITY

no-wall no-wall

● G ≈ GITER

● q95 = 3.2

● Small Sawteeth

● βN > 0.8 βN

● G ≈ 1.5 GITER

~

)

)

10 IP (MA) 10 IP (MA)

<PNB> (MW)

βNβN4 li

4 li

H89P H89P

G G

Time (s)

)

05

1015

113993 115863

0

2

4

0

2

4

0

2

4

0.0

0.5

1.0

ITER Baseline Scenario

ITER Baseline Scenario

ITER Baseline Scenario

ITER Baseline Scenario

ITER Baseline Scenario

ITER Baseline Scenario

05

1015

0

2

4

0.0

0.5

1.0

<PNB> (MW)

0 1 2 3 4 5 6Time (s)

0 1 2 3 4 5 6

● q95 = 4.4

FUSION PERFORMANCE MAXIMIZES AT LOW q95;G ª GITER AT q95 = 4.5

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

1

2

3

ITER BaselineSawteeth No Sawteeth

4

3.0 3.5 4.0 4.5 5.0 ITPA Joint Experiment0.5

1.0

1.5

2.0

2.5

3.0

bN

2

q95

ITER Baseline

G = bN H89/q95

ITER BaselineH98y2

H89

l All sustained for at least tR

2.5 3.0 3.5 4.0 4.5 5.0q_95

2.5 3.0 3.5 4.0 4.5 5.0q95

0.0

0.2

0.4

0.6

0.8

2.5

FUSION PERFORMANCE MAXIMIZES AT LOW q95;G ª GITER AT q95 = 4.5

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

1

2

3

ITER BaselineSawteeth No Sawteeth

4

ITPA Joint Experiment0.5

1.0

1.5

2.0

2.5

3.0

bN

2

q95

ITER Baseline

G = bN H89/q95

ITER BaselineH98y2

H89

2.5 3.0 3.5 4.0 4.5 5.0q_95

2.5 3.0 3.5 4.0 4.5 5.0q95

0.0

0.2

0.4

0.6

0.8

3.0 3.5 4.0 4.5 5.02.5

FUSION PERFORMANCE WEAKLY DEPENDENT ON PLASMA DENSITY

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

● All discharges are at stationary (> τR) β limit

ITERBaseline

ITER Baseline

H89

ITER Baseline

ITPA Joint Experiment

βN

{

H98y2 {

1

2

3

4

0.0 0.2 0.4 0.6 0.8 1.0ne /nGW

0.5

1.0

1.5

2.0

2.5

3.0

0.0 0.2 0.4 0.6 0.8 1.0ne/nGW

0.0

0.2

0.4

0.6

0.8

q95 = 3.2 q95 = 4.5

2G = βN H89/q95

FUSION PERFORMANCE WEAKLY DEPENDENT ON PLASMA DENSITY

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

● All discharges are at stationary (> τR) β limit

ITERBaseline

ITER Baseline

H89

ITER Baseline

ITPA Joint Experiment

βN

{

H98y2 {

1

2

3

4

0.0 0.2 0.4 0.6 0.8 1.0ne /nGW

0.5

1.0

1.5

2.0

2.5

3.0

1.0 1.5 2.0 2.5Central Ti/Te

0.0

0.2

0.4

0.6

0.8

q95 = 3.2 q95 = 4.5

2G = βN H89/q95

SAWTEETH BEHAVIOR DISTINGUISHES HYBRID REGIME FROM CONVENTIONAL REGIME

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

● With early heating, sawteeth do not appear

q = 4.5n = 1 B rms (G/2)~ ~

βN

0

1

2

3 Hybrid

1.00.0 2.0 3.0Time (s)

4.0 5.0

Early Heating

n = 2 B rms (G/2)

SAWTEETH BEHAVIOR DISTINGUISHES HYBRID REGIME FROM CONVENTIONAL REGIME

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

● With early heating, sawteeth do not appear

● Without early heating, m =2, n =1 NTM triggered by sawteeth at 20% lower βN

q = 4.5n = 1 B rms (G/2)~ ~

βN

0

1

2

3 Hybrid

0

1

2

3 Conventional

1.00.0 2.0 3.0Time (s)

4.0

2/1 NTMTriggered

5.0

No EarlyHeating

Early Heating

Sawteeth

n = 2 B rms (G/2)

SAWTEETH BEHAVIOR DISTINGUISHES HYBRID REGIME FROM CONVENTIONAL REGIME

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

● With early heating, sawteeth do not appear

● Without early heating, m =2, n =1 NTM triggered by sawteeth at 20% lower βN

● At slightly lower βN, 2/1 mode not destabilized

● After 3/2 mode grows, sawteeth diminish

q = 4.5n = 1 B rms (G/2)~ ~

βN

0

1

2

3 Hybrid

0

1

2

3 Conventional

1.00.0 2.0 3.0Time (s)

4.0

2/1 NTMTriggered

5.00

1

2

3 Conventional → Hybrid

No EarlyHeating

No EarlyHeating

Early Heating

n = 2 B rms (G/2)

Sawteeth

Sawteeth

STUDIES HAVE SHOWN 3/2 NTM AMPLITUDE IS KEY TO AVOIDANCE OF SAWTEETH

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

012345

No 3/2mode

With 3/2mode

Sawteethn = 1 B rms (G)

~n = 2 B rms (G)

~

012345

3.0 4.0 5.0Time (s)

6.0 7.0

STUDIES HAVE SHOWN 3/2 NTM AMPLITUDE IS KEY TO AVOIDANCE OF SAWTEETH

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

012345

No 3/2mode 1.15

q (0

)

1.10

0.00 0.02 0.04

W3/2 (m)

0.06 0.08 0.10

1.05

1.00

0.95

Before ECCD

Co–ECCD

With 3/2mode

Co-ECCDsuppresses

3/2 mode

EC On

Sawteeth

Sawteeth

n = 1 B rms (G)~

n = 2 B rms (G)~

012345

012345

3.0 4.0 5.0Time (s)

6.0 7.0

STUDIES HAVE SHOWN 3/2 NTM AMPLITUDE IS KEY TO AVOIDANCE OF SAWTEETH

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

012345

No 3/2mode 1.15

q (0

)

1.10

0.00 0.02 0.04

W3/2 (m)

0.06 0.08 0.10

1.05

1.00

0.95

Counter–ECCD

Before ECCD

Co–ECCD

With 3/2mode

Co-ECCDsuppresses

3/2 mode

EC On

EC On

Ctr-ECCDenhances3/2 mode

Sawteeth

Sawteeth

n = 1 B rms (G)~

n = 2 B rms (G)~

012345

012345

3.0 4.0 5.0Time (s)

6.0 7.0012345

IMPROVED CONFINEMENT IS DUE TO GOOD TRANSPORTACROSS ENTIRE PROFILE

263-04/MW/jyS A N D I E G O

DIII–DNATIONAL FUSION FACILITY

● Leads to broad pressure profile which is favorable for high β limit

0.0 0.2 0.4 0.6 0.8 1.0 1.2Normalized Radius

0.0 0.2 0.4 0.6 0.8 1.0 1.201

2

3

45

(keV

)

0.0 0.2 0.4 0.6 0.8 1.0 1.2Normalized Radius

02

4

6

810

(keV

)

0.0 0.2 0.4 0.6 0.8 1.0Normalized Radius

ne

Te

Ti

0

1

2

3

410

8

6

(101

9 m–3

)

4

20

(m2 /s

)

χeffχiχe

IMPROVED TRANSPORT APPEARS TO BE DUE TO THE INTERACTION OF SEVERAL EFFECTS

263-04/MW/jy

● Improved transport is likely due to a combination of reduced turbulence drive (γmax) associated with Ti/Te > 1 and a favorable current profile and increased stabilization via ExB shear

● GLF23 indicates sensitivity to ExB shear

● Experiments in 2006 should help resolve this issue

— Is this due to small γmax or large ExB shear?

— Balanced NBI— Increased electron heating capability

S A N D I E G O

DIII–DNATIONAL FUSION FACILITY

0

2

4

6

8

10

12

0.0 0.2 0.4 0.6 0.8 1.0

DataGLF23 w/ γ

E

GLF23 w/o γE

DataGLF23 w/ γ

E

GLF23 w/o γE

T (k

eV) Ti

Te

Normalized Radius

#104276t=5.71 s

PROJECTIONS TO ITER ARE UNIFORMLYFAVORABLE AND SUGGESTS IGNITION IS POSSIBLE

263-04/MW/jy

— Use plasma shape, q95, and bN, and Hxx from experiment— 50/50 D-T mix, Zeff prescription from ITER, He ash treated self consistently— Use DIII–D ne, Te profiles, fix Te = Ti— Choose n/nGW = 0.85; tHe / tE = 5; CEJIMA = 0.6

Projections

Primary difference is b scaling:Petty, Fusion Sci. Tech. 43 1 (2003)

H89: b–0.5 H98y2: b–0.9 HDS03: b0

Plasma currentDurationScalingPfusionQfus

q95 = 4.5

10.3 MA3900 s

H894409.0

H98y24408.9

HDS03370•

q95 = 3.2

*

13.9 MA1900 s

H8978012.9

H98y274039

HDS03700•

S A N D I E G O

DIII–DNATIONAL FUSION FACILITY

Projection Methodology:

* *

*

S A N D I E G O

DIII–DNATIONAL FUSION FACILITY

● Stationary, high normalized performance operation has been demonstrated on DIII–D over a wide range in operating space.

q95 = 3.2: G = βNH89/q95 > 1.4 GITER for > 9 τR

q95 = 4.5: G ≈ GITER for > 4 τR

SUMMARY

263-04/jy

2

● Projections are uniformly favorable for ITER and suggest the possibility of very high fusion gain (possibly Qfus = ∞) operation as well as long pulse, Qfus > 5 operation in ITER

● Stability and confinement characteristics are similar to that of the conventional, ELMing H-mode case (ITER physics basis is still valid)

— Measurements indicate the importance of a small m=3/n=2 NTM in controlling the current profile to prevent or minimize sawteeth, thereby allowing high β, good confinement operation