100% Noninductive Operation at High Beta Using Off-Axis ECCD by M. - - PowerPoint PPT Presentation

NATIONAL FUSION FACILITY

S A N D I E G O

DIII–D

100% Noninductive Operation at High Beta Using Off-Axis ECCD

by

• M. Murakami

in collaboration with November 2, 2004 Presented at 20th IAEA Fusion Energy Conference Vilamoura, Portugal

C.M. Greenfield,2 M.R. Wade,1 T.C. Luce,2, J.R. Ferron,2 H.E. St. John,2 M.A. Makowski,3 M.E. Austin,4 S.L. Allen,3 D.P. Brennan,5 K.H. Burrell,2 T.A. Casper,1 J.C. DeBoo,2 E.J. Doyle,6 A.M. Garofalo,7 P.Gohil,2 I.A. Gorelov,2 R.J. Groebner,2 J. Hobirk,8 A.W. Hyatt,2 R.J. Jayakumar,3 K. Kajiwara,5 C.E. Kessel,9 J.E. Kinsey,10 R.J. La Haye,2 J.Y. Kim,2 L.L. Lao,2 J. Lohr,2 J.E. Menard,9 C.C. Petty,2 T.W. Petrie,2 R.I. Pinsker,2 P.A. Politzer,2 R. Prater,2 T.L. Rhodes,6 A.C.C. Sips,8 G.M. Staebler,2 T.S. Taylor,2 G. Wang,6 W.P. West,2 L. Zeng,6 and the DIII–D Team

1Oak Ridge National Laboratoty, Oak Ridge, Tennessee, USA 2General Atomics, P.O. Box 85608, San Diego, California, USA 3Lawrence Livermore National Laboratory, Livermore, California, USA 4University of Texas at Austin, Austin, Austin, Texas, USA 5Oak Ridge Institute for Science Education, Oak Ridge, Tennessee, USA 6University of California at Los Angeles, Los Angeles, California, USA 7Columbia University, New York, New York, USA 8Max-Planck-Institut for Plasmaphysiks, Garching, Germany 9Princeton Plasma Physics Laboratory, Princeton, New Jersey, USA 10Lehigh University, Bethleham, Pennsylvania, USA

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Steady-state operation

— 100% noninductive fraction: fNI = INI/Ip — High Bootstrap current fraction: fBS = IBS/I P p

Maintaining sufficient fusion gain with reduced

engineering parameters

— Hgh T — High E High Normalized fusion performance: G = NH/q2

DIII-D AT experiments have demonstrated

performance required for ITER steady state scenario

DIII-D AT PROGRAM GOAL: SCIENTIFIC BASIS FOR STEADY STATE, HIGH PERFORMANCE OPERATION IN FUTURE TOKAMAKS

High βp, high q regime 0.0 0.1 0.2 0.3 0.4 0.5

Normalized fusion performance, G Bootstrap current fraction, fBS

0.0 0.2 0.4 0.6 0.8 Baseline regime Hybrid regime ITER glf23 simulation (fNI=1) ITER Q~5 steady state scenarios DIII-D AT target

• T. Luce: OV1-3
• G. Sips: IT/P3-36

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100% NONINDUCTIVELY DRIVEN PLASMAS OBTAINED WITH GOOD CURRENT DRIVE ALIGNMENT

fNI = 1 – fOH ; JOH = neoE| | neopol/t fOH = 0.5%, fNI = 99.5% T= 3.5%, N = 3.6, q95 = 5.4

JOH

EQUILIBRIUM MEASUREMENTS

0.0 0.2 0.4 0.6 0.8 1.0 –50 50 100 150 RADIUS, ρ Toroidal Current Density (A/cm )

2

120096.4160

Jtot

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CRITICAL ISSUES COVERED IN THIS TALK

• Self-consistent solutions for full noninductive, high performance operation

requires:

• 1. fNI = 100%
• 2. Good current drive alignment
• 3. Pressure profile evolution stable for ideal MHD and NTMs
• 4. Current profile stops evolving (E | | 0 everywhere)
• Predictive modeling:

— Validated by the experiment — Projects longer sustainment of 100% noninductive in DIII-D — Applied to the ITER steady-state scenario development

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PREDICTIVE SIMULATIONS INDICATE PREVIOUS ECCD DISCHARGE COULD BE EXTENDED TO 100% NONINDUCTIVE WITH INCREASED NBI POWER

Two transport models produce consistent results:

— Scaled experimental transport coefficients — Recalibrated GLF23

Normalized Radius, ρ 0.0 0.2 0.4 0.6 0.8 1.0 Jtotal JBS JECCD J

NBCD

1.5 t = 7.0 s 1.0 0.5

• 0.5

JOH

shot 111221 Modeling Non-Inductive Current Fractions 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2 3 4 5 6 Time (s) 7 Modeling P (t) inj 4 MW 10 20

fNI(t)

J (ρ)

[MW]

MA/m2

[ ]

P ECCDj

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WITH HIGHER NBI POWER, 100% NONINDUCTIVE CURRENT ACHIEVED, BUT NOT FULLY RELAXED

Achieved net fNI 100 % with N 3.5, 3.6% However, local Ohmic current is NOT zero

2.4 2.6 2.8 3.0 3.2 3.4 3.6

TIME (s)

0.0 0.2 0.4 0.6 0.8 1.0

• 1.0
• 0.5

0.0 0.5 1.0

Radius, ρ

MA/m2

TRANSP

NVLOOP JOH (ρ) @ t = 3.12 s

4 8 12 16

Pinj (MW) PEC fNI (TRANSP) fNI (NVLOOP) fBS

1.2 0.8 0.4 0.0 114741

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WITH HIGHER NBI POWER, 100% NONINDUCTIVE CURRENT ACHIEVED, BUT NOT FULLY RELAXED

2.4 2.6 2.8 3.0 3.2 3.4 3.6

Time (s)

0.0 0.2 0.4 0.6 0.8 1.0

Radius, ρ

MA/m2

TRANSP

NVLOOP JOH (ρ) at t = 3.12 s

|B|n=1 (G) n=3 n=2 Pinj (MW) PEC qmin q0

fNI (TRANSP) fNI (NVLOOP) fBS

4 8 12 16 1.0 1.5 2.0 2.5 10 20 1.2 0.8 0.4 0.0 –1.0 –0.5 0.0 0.5 1.0

Achieved net fNI 100 % with N 3.5, 3.6% However, local Ohmic current is NOT zero Neutral beam overdrive near the axis

decreases q0, resulting in NTMs

Confinement somewhat degraded (large PNB

demand) in these discharges

— Rotation velocity often slower — Flatter q profiles ... often more monotonic

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IMPROVED CONFINEMENT RESULTS IN REDUCED NEUTRAL BEAM CURRENT DRIVE NEAR THE AXIS

Confinement improvement in recent experiments is attributed to:

— Optimized non-axisymmetric field feedback — Slightly negative central shear

1.4 1.6 1.8 2.0 2.2 2.4 2.6 H89 20 30 40 50 60 70 80 90 J

NBCD(0) (A/cm ) 2

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WITH IMPROVED CONFINEMENT, fNI=100% ACHIEVED WITH GOOD CD ALIGNMENT

0.0 0.2 0.4 0.6 0.8 1.0 –50 50 100 150 RADIUS, ρ Flux Surface Averaged Toroidal Current Density (A/cm )

2

120096F05

〈J(ρ)〉

(NVLOOP)

Jtot JOH

Local toroidal current density (A/cm )

2 200 150 100 50 1.6 1.8 2.0 2.2

Midplane major radius, R (m)

2.4

Jφ(ρ)

MSE Array Tangential Radial Edge Analysis (EFIT)

fOH = 0.5%, fNI = 99.5%

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fOH = 0.5%, fNI = 99.5% Analysis shows: fBS=59% f NB=31% fEC= 8% fNI= 98% Challenge:

— Measurement: Local representation in EFIT, . . . — Analysis/modeling: Bootstrap model near axis and edge, . . .

These analyses indicate achievement of fNI 100%

WITH IMPROVED CONFINEMENT, fNI=100% ACHIEVED WITH GOOD CD ALIGNMENT

0.0 0.2 0.4 0.6 0.8 1.0 –50 50 100 150 RADIUS, ρ Flux Surface Averaged Toroidal Current Density (A/cm )

2

120096F05

〈J(ρ)〉

(TRANSP) (NVLOOP)

Jtot JEC Jboot JNB

JOH

JOH

Local toroidal current density (A/cm )

2 200 150 100 50 1.6 1.8 2.0 2.2

Midplane major radius, R (m)

2.4

〈J J 〉 (calc.) (calc.)

EC EC

Jφ(ρ)

MSE Array Tangential Radial Edge Analysis (EFIT)

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PRESSURE PROFILE EVOLUTION RESULTED IN n=1 FAST GROWING MODE WHICH TRIGGERED n=1 NTM

n=1 ideal instability caused by pressure peaking primarily due to

density peaking

Sustained n=1 NTM terminates high performance phase

• J. Ferron: EX/P-2-20

1 2 3 4 5 Pressure peaking facor, p(0)/〈p〉 2 4 6 βN

100 4091 4095 TIME (ms) (gauss)

|B| ~

Fit to modeling data for n=1 beta limit

n=1 Unstable t = 4.8 s t = 4.09 s t = 0.4 s 5 (h) 10 1 2 3 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4 120096 |B|n=1 (G) p(0)/〈p〉 ne(0)/〈ne〉 Time (s) 2.5 5.0 |B|n=2 (G) |B|n=3 (G) 2.5 5.0

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NEARLY FULL NONINDUCTIVE, STATIONARY DISCHARGE OBTAINED, LIMITED ONLY BY GYROTRON PULSE LENGTH

MSE signals stationary

J() stopped evolving

fNI~ 90% for 1 R (=1.8s ) T = 3.7%, N = 3.5, q95 = 5.1 G=NH/q2 = 0.3 with fBS=63% ECCD ECCD MSE Pitch Angle (deg.) TIME (s) MSE Channels 1 - 11 10 5 –5 –10 –15 2.5 3.0 3.5 4.0 4.5 5.0

4 gyrotrons → 3

118419

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GLF23/ONETWO CAN REPRODUCE EXPERIMENTAL PROFILES REASONABLY WELL, AND ALSO CAN PREDICT STEADY STATE PERFORMANCE IN TOKAMAKS

Good coupling between experiment and modeling

0.0 0.2 0.4 0.6 0.8 1.0 5 10 15

0.0 0.5 1.0 1.5 2.0

0.0 0.2 0.4 0.6 0.8 1.0

2 4 6 8 40 80 120 160

0.0 0.2 0.4 0.6 0.8 1.0

Te (ρ)

keV

Ti (ρ) Ωtor (ρ)

105 (rad/s) A/cm2

q (ρ) Jtot (ρ)

Radius, ρ Radius, ρ Radius, ρ Data (111221.03840) GLF23 (+560 ms)

(a) (b) (c)

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GLF23/ONETWO CAN REPRODUCE EXPERIMENTAL PROFILES REASONABLY WELL, AND ALSO CAN PREDICT STEADY STATE PERFORMANCE IN TOKAMAKS

Good coupling between experiment and modeling Numerical advance (global convergence technique) incorporated

into ONETWO allows prediction of steady state in one step (without time stepping calculation)

0.0 0.2 0.4 0.6 0.8 1.0 5 10 15

0.0 0.5 1.0 1.5 2.0

0.0 0.2 0.4 0.6 0.8 1.0

2 4 6 8 40 80 120 160

0.0 0.2 0.4 0.6 0.8 1.0

Te (ρ)

keV

Ti (ρ) Ωtor (ρ)

105 (rad/s) A/cm2

q (ρ) Jtot (ρ)

Radius, ρ Radius, ρ Radius, ρ Data (111221.03840) GLF23 (+560 ms) GLF23 (steady state)

(a) (b) (c)

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GLF23 MODELING INDICATES THAT STEADY STATE OPERATION IS POSSIBLE WITH VALUES CONSISTENT WITH STABILITY LIMITS

Modeling uses hardware improvements planned for DIII–D:

— Better control of J() and p() at high beta with more EC and FW power with long duration — Advanced plasma control system

0.0 0.2 0.4 0.6 0.8 1.0 r/a –50 50 100 150

〈J〉 (A/cm2)

Jtot JOH JBS JNB JRF PEC = 4.5 MW PNB = 6.8 MW PFW = 3.5 MW Ip = 1.19 MA BT = 1.86 T

β = 4.1% βN = 3.8

200 LESS NBCD FWH and CD for q0 control and better ηECCD ECCD at

ρ = 0.6

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MODELING APPLIED TO ITER AT SCENARIO PREDICTS fNI = 100% FEASIBLE WITH Q > 7

Fusion Gain Noninductive, Bootstrap Current Fraction Normalized Fusion Performance Edge Temperature [T(ρ=0.90)] (keV)

Q

0.0 0.2 0.4 0.6 0.8 1.0 1.2 2 4 6 8 10 12 5.5 6.0 6.5 7.0 7.5 8.0

fbs

bs

fNI

NI

ITER Day-1: BT = 5.3 T, Ip = 9 MA q95 = 4.5, ne = 1.04 nGW PNB = 33 MW, PIC = 20 MW PEC ≤ 8 MW GLF23/ONETWO

βNH/q2

• Stiff transport model Core performance related to edge Edge temperature scan
• ped=1.2 % for Tped =7 keV appears to be below max(ped) for peering-ballooning mode
• It emphasizes importance of understanding the edge pedestal in AT plasmas
• More detail will be discussed by W. Houlberg [IT/P3-33

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CONCLUSIONS

100% noninductively driven plasmas with good CD alignment at

T 3.6% and N 3.5 for up to one current relaxation time

With good coupling between experiment and modeling, progress

has been made in several important areas:

— Current drive alignment — Current profile stationary over one current relaxation time — Challenge: Control of current and pressure profile evolution to avoid MHD instabilities to further extend high performance phase

Future plans include:

— Better control of J() and p() at high beta with more EC and FW power with long duration — Advanced plasma control system

The scientific basis being developed on DIII–D is leading to

increased confidence in establishing steady-state scenarios for ITER and beyond

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WITH IMPROVED CONFINEMENT, fNI=100% ACHIEVED WITH GOOD CD ALIGNMENT

fOH = 0.5%, fNI = 99.5% Analysis shows: f BS=59% f NB=31%

fEC= 8% f NI= 98%

Challenge:

—Measurement: Local representation in EFIT, . . . —Analysis/modeling: Bootstrap model near axis and edge, . . .

0.0 0.2 0.4 0.6 0.8 1.0 –50 50 100 150 RADIUS, ρ Flux Surface Averaged Toroidal Current Density (A/cm )

2

120096F05

〈J(ρ)〉

(TRANSP) (NVLOOP)

Jtot JEC Jboot JNB

JOH

JOH

Local toroidal current density (A/cm )

2 200 150 100 50 1.6 1.8 2.0 2.2

Midplane major radius, R (m)

2.4

〈J J 〉 (calc.) (calc.)

EC EC

Jφ(ρ)

MSE Array Tangential Radial Edge Analysis (EFIT)

0.0 0.2 0.4 0.6 0.8 1.0 –50 50 100 150 RADIUS, ρ

120096Q07

SIMULATION

Flux Surface Averaged Toroidal Current Density (A/cm )

〈J(ρ)〉

Jtot JEC Jboot JNB JOH

Simulation

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GLF23/ONETWO MODELING FOR ITER STEADY STATE SCENARIO

The pedestal values of ne=6e19, T=7keV give ped=1.3%which is not

particularly a high value

This value corresponds to maximum stable (Pearing-ballooning mode) ped for

ped/a=0.04, and our ped/a is assumed to be larger than that.

0.0 0.2 0.4 0.6 0.8 1.0 2 4 6 10 20 0.0 0.2 0.4 0.6 0.8 1.0

• 20

20 40 60 80 100 0.4 0.8 1.2 0.2 0.6 1.0

n (10 m )

20 -3

Ωtor (105 rad/s)

Te, Ti (keV)

Radius, ρ

Ωtor (ρ)

Radius, ρ

J (ρ)

total bootstrap (NCLASS) Ohmic FWCD ECCD

J (A/cm2)

Ti (ρ) Te (ρ) ne(ρ)

(steady state) Safety factore

GLF23/ONETWO T(ρ=0.9) = 7.2 keV

N-NBCD

s2m01

q(ρ) nD, nT(ρ)

(a) (c) (b) (d) (initial)