27th IAEA Fusion Energy Conference, Gujarat, India, Oct. 22-27, 2018

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Recent advances in EAST experiments in supportof steady-state operation for ITER and CFETRby

B. N. Wanon behalf of EAST team & collaborators

Institute of Plasma Physics, Chinese Academy of SciencesWe acknowledge contributions from domestic andinternational partners to EAST research program

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B.N. Wan/IAEA FEC/October 20182

Outline•

Introduction•Extension of steady-state operational regime with dominant
RF H&CD•

Physics studies to resolve scientific and technical issues forEAST steady state operation– LHW PI effect– ELM control– Particle/power exhaust control

•
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Summary and future Plan
B.N. Wan/IAEA FEC/October 2018

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CFETR and ITER aim SS or hours operation
CFETR SSO
CFETR HB
ITER SSO

Qpl

βN

fbs

H98Y2Ip(foh)nbar/nGR

q95_iter R/a~10>15>5

2.0
2>2.6

0.5 1.4
0.5 1.2
0.5 >1.31414(0.3)
90.57
0.85
0.85

5.5~6 7.2/2.2~3.3
5.5~6 7.2/2.2~3.3
56.2/2~3.1

fbs ~e1/2*bpµbN*q95 ; large ε is favorable for confinementG. Zhuang OV/3-2• Develop physics basis for steady-state operation (e, bp)• Extend integrated high performance results to true SSO
DIIID; A~2.6
EAST; A~4.2
J Qian, Nucl. Fusion 57 (2017)
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4

EAST demonstrated high βP long pulse H-mode
operation with high fbs for ITER and CFETR
EAST aims to find integrated solutions of tokamak steady-state operation•

Long pulse operation with metal wall•

Bootstrap current fraction fbs ~ 50%

World record long pulse steady-state H-mode
operation with tungsten divertor

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Extension of βP operational regime
with fbs~50% at CFETR relevant q95

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5

EAST capabilities facilitate to extend highperformance to true steady-state operation
ITER-like W/Cu divertor•– Fast Electron Source/Edge Current Drive /Profile•
TZM/Cu FW
C/Cu FW-NBI

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New 4.6GHz LHW W
guide limiter
Pin-Max~3.5MW

LHCD 4+6 MW（2.45/4.6GHz）ICRH 6+6 MW （25-75MHz）– Ion and Electron Heating Central Current Drive•ECRH 1+1(4) MW (140GHz）– Electron heating/Steering mirror, jϕ tailoring•

NBI 4+4 MW （co/counter, 80kV）•– Ion heating/Variable rotation/ rot-shear
Fueling（gas puffing, SMBI, pellet)•••

In-vessel cryopump
Wall conditioning
Active water cooling (PFC)

B.N. Wan/IAEA FEC/October 20186

Diagnostic systems in support of steady-state longpulse operation and physics study
Thomson Scattering•

Plasma operation– Magnetic measurement, visible/IR camera,
thermocouples, LP, pressure gauges, RGA•

Profile diagnostics– POINT, TS, ECE, XCS, ME-SXR, HCN,
Reflectometry, Recip.-LPs, He-BES, Li-BES,XCS, CXRS

•CXRS

Plasma impurities & radiation– filterscope, Vis Spec, EUV, XEUV, SX-PHA,Divertor W Spec, Vis Brems., CXRS, XCS,Bolometer, AXUV• Energetic particles:– FIDA, FILDs, ssNPA, neutron camera• Multi-scale fluctuations– Mirnov, soft X-ray, ECE/ECEI, POINT, BES,DBS, ECEI, GPI, CO2 laser
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B.N. Wan/IAEA FEC/October 20187

Outline•Introduction•Extension of steady-state operational regime with dominant
RF H&CD•Physics studies to resolve scientific and technical issues forEAST steady state operation– LHW PI effect– ELM control– Particle/power exhaust control•ASIPP

Summary and future Plan
B.N. Wan/IAEA FEC/October 2018

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EAST long pulse steady-state H-mode operation withtungsten divertor• Integrated plasma control• Saturated W-Div. surface temperature (~10 sec)
• Good confinement (LHW+ICRF+ECH)– H98y2 ~ 1.1 with e-ITB• Small ELM
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B.N. Wan/IAEA FEC/October 2018

X. Z. Gong EX/3-1

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Recent experiments extended steady-state high bp
scenarios with fbs~45% using RF H&CD only•

Pure RF heating， Vloop~0.0– PLHW ~3.2MW,– PECRH ~ 1.0MW;•Good confinement– H98y2 ~ 1.2, βp ~ 1.9, βN ~ 1.5– fGr ~ 0.8, fBS ~ 45%•

Good control of impurity accumulation– Small ELMy, on-axis ECH•

Demonstrated steady-state operations
with similar q95 and good confinement
under ITER and CFETR relevant
condition– Metal wall, zero torque, e-heating

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B.N. Wan/IAEA FEC/October 2018

X. Z. Gong EX/3-1

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Achieved fbs over 50% using RF+NB H&CD•

RF+NB H&CD，– PLHW ~ 2.5MW,– PECH ~ 1.0MW;– PNB ~ 2.2MW•Plasma parameters– β p ~ 2.5, βN ~ 1.9– fBS ≥ 50%– q95 ~ 6.8•Density and beam voltage optimized
to reduce fast ion losses– fGr ~ 0.7， V beam ≤ 65kV

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Extension of operational regime towards steadystate operation for ITER and CFETR•βP versus line-averaged density of low
loop voltage plasmas– Vloop < 0.05V, q95 ~ 6.0 - 7.0•

2018

Extended operational regime– High density fGr~0.8– fBS ~ 45% pure RF– fBS ≥ 50% NB +RF•Good confinement– H98y2 ≤ 1.3– ITB inside r < 0.4ASIPP

B.N. Wan/IAEA FEC/October 201812

Development of high βN scenarios in the low q95regime•

High G (>0.3) plasmas obtainedwith q95 = 3.5 - 4.0 and βN ~2.0
– βN ~3 x li
– BT~1.5-1.8 T•

Double barrier structures (ITB+ETB)
observed in different q profiles– Montonic, central flat and weakly
reversed shear

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B.N. Wan/IAEA FEC/October 201813

Outline•Introduction•Extension of steady-state operational regime with dominant
RF H&CD•

Physics studies to resolve scientific and technical issues for
EAST steady state operation– LHW PI effect– ELM control– Particle/power exhaust control

•
ASIPP

Summary and future Plan
B.N. Wan/IAEA FEC/October 201814

Correlation between the parametric instability ofLH waves and modification in edge current profile•

Stronger PI was observed– With reduction in source frequency– With increase in plasma density•

Stronger PI with the increase ofplasma edge current-•

Control of PI is essential to accesshigher density regimes in a steadystate H-mode plasma.
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More LHW power dissipates in edge

Lithium coating and injection
LHW at higher frequency
B.N. Wan/IAEA FEC/October 2018

B. Ding et al NF 201815

Effect of PI induced spectral broadening on LH
current drive efficiency•

Spectral broadening has negative
effect on CD efficiency and LH power
absorption•ASIPP

Modeling result shows ion-soundquasi-mode-driven PI can redistributethe launched parallel refractive index(N//) spectrum

B. Ding et al NF 2018
B.N. Wan/IAEA FEC/October 201816

Extension of parameter space for the EAST grassy
ELM regime towards lower q95 and higher density
Parameter space for fELM > 500 Hz:• q95 ≥ 5.3• bp ≥ 1.1• nel/nGW ≥ 0.46, up to 1.1• bN up to 2
• H98y2 up to 1.4• fBS up to 70% (@300kA)
Overlap with CFETR 1GW scenario:
q95=5.5-7, bN~2, fBS~50%, nel/nGW~0.7
G.S. Xu EX/P2-4
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B.N. Wan/IAEA FEC/October 201817

Pedestal profiles of grassy ELM regime characterizedby a wide pedestal and low pedestal density gradient•Characterized by– Relatively wide pedestal– Low pedestal density
gradient– Low pedestal bootstrap
current density– High ne,sep/ne,ped (up to 0.6)

•Good compatibility with– Low rotation– High bootstrap current fraction– High density– Fully non-inductive operation– Radiative divertor– Strong tungsten impurity exhaust
capability

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G.S. Xu EX/P2-4

B.N. Wan/IAEA FEC/October 201818

ErxB shear has a great impact on the ELM size
• Experimental modulation co- andctr-Ip NB;• Smaller ELM size observed at ctrNBI- stored energy and density profiles
keep the same (same collisionality)• Toroidal rotation (or 𝑬𝒓 ×𝑩 shear )plays an important role inmodifying the ELM
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D.F. Kong EX/P2-1

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Achievement of ELM suppression using n=2 RMP
in a wide low q95 window•Achieved ELM suppression instandard type-I ELMy H-modewith low q95 (~3.7) window•Robust ELM suppression in awide q95 window 3.2-4.2 with n = 2
RMP achieved

n=2 RMP on

BT ~ 1.6T, βN~1.5, Ne0~ 3x1019m-3, ν*e,ped~0.5
PNBI ~ 2MW, PLHCD ~ 1MW, ΩΦ0 ~ 50krad/s
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B.N. Wan/IAEA FEC/October 2018

Y. W. Sun EX/7-220

ELM suppression achieved using a rotating n=2 +static n=3 RMP field•

ELM suppression using rotating
n=2 superimposed on a static n=3
RMPs achieved in EAST•

control of 3D pattern of theparticle flux on the divertor– Footprint of particle flux is periodicallychanging during n=2 RMP rotation– consistent with modeling by TOP2D
with plasma response by MARS-F

Observed
particle flux

Modeled 1-ρminLCS
Divertor plate

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B.N. Wan/IAEA FEC/October 2018

Y. W. Sun EX/7-221

Demonstration of radiative divertor without confinement
degradation with feedback control on Jsat or Prad
Target Jsat feedback

Radiation power Prad feedback

Neon

L. Wang EX/P2-8
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Tet is sustained at ~ 10 eV
Promising diveror solution for
long-pulse H-mode operation
B.N. Wan/IAEA FEC/October 2018

G.S. Xu EX/P2-422

ECRH is essential to alleviate accumulation ofhigh-Z Impurities in long pulse operation•

Discharges are often terminated due totungsten accumulation•High-Z impurity control– ECRH power deposition at ρ<0.1

•

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Radial profiles clearly indicate thereduction of tungsten ions in plasma coreregime (ρ<0.2)

B.N. Wan/IAEA FEC/October 2018

L. Zhang EX/P2-3

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RMP applied for eliminating impurity accumulation•High-Z impurity concentration canbe significantly decreased with anZ-dependence– Stronger effect on higher-Z impurities•

RMP induced change significantlyin transport, leading to a flattened
impurity profiles.
– Increase in diffusion– Larger outward pinch velocity

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3D helical mode favorable to maintain advanced
high 𝛃𝐩 operation in weak magnetic shear•

Long-lived mode was observed in high 𝛃𝐩
plasma with 𝒒𝒎𝒊𝒏 ≳𝟏 (low magnetic shear) via
flux pumping mechanism•

No large sawtooth crash in the core andno NTM•

This mode helps avoiding high-Z
impurity accumulation

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𝜷𝒑 = 𝟏. 𝟖3-D nonlinear simulation by M3D
B.N. Wan/IAEA FEC/October 2018

L Xu EX/P2-1425

New method of discharge cleanings under strong
magnetic field
27.12MHzHWP@1TFirst successful operation of Helical Wave Plasma(HWP) and Direct-Current Glow Discharge Cleaning(GDC) in tokamaks under strong magnetic field!

GDC
5A×4@2T

p DC-GDC @ 2T is more efficient for retention removalp Uniform plasmas & high current density (0.4 A/m2)
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Collaboration withSuzhou University

B.N. Wan/IAEA FEC/October 201826

Outline•Introduction•Extension of steady-state operational regime with dominant
RF H&CD•

Physics studies to resolve scientific and technical issues for
EAST steady state operation– LHW PI effect– ELM control– Particle/power exhaust control

•
ASIPP

Summary and future Plan
B.N. Wan/IAEA FEC/October 201827

EAST new W lower divertor upgrade scheduled in 2019
for radiative divertor feedback control and X-divertor•Simple flat targets toreduce installation error
and thus leading edges•

Closed outer divertor andopen inner divertor forbalanced detachment•

A water-cooled internal coilfor X-divertor operation•

SMBI for impurity seeding
feedback control

ASIPP~10 MW/m2
B.N. Wan/IAEA FEC/October 201828

Summary•

Significant progress has been made in steady state long pulse operation– 101.2 s H-mode with H98y2>1.0 achieved with pure RF powers and W-divertor– Extended pure-RF scenarios with bp ≤2, fBS≤40-50%, fGr~0.6-0.8 at q95~6.0-7.0 relevant
to CFETR, demonstrated for longest 20s– High performance SSO scenarios have been developed for further long pulse operation•

Physics research has been conducted to resolve scientific and technicalissues for EAST long pulse operation, delivering steady state operation in
ITER and CFETR– LHW PI effect, ELM suppression , radiative divertor, high Z impurity control etc.

•ASIPP≥400s Long pulse & high performance operation are planned with moregyrotrons (2019-2020) and upgrade in lower divertor (2019)
B.N. Wan/IAEA FEC/October 201829

Contribution to 27th IAEA FEC from EAST team andcollaborators[Overview & operation]•OV/2-2
B. N. Wan•
EX/3-1X. Z. Gong•
EX/3-2
G. Calabro•
EX/P2-26 D. Moreau•
EX/P2-16 A. Ekedahl•EX/P5-1 Z. X. Liu•
EX/P6-21 J. Barr•
[ELM&RMPs]•EX/7-2
Y. W. Sun•
EX/P2-4 G. S. Xu[PSI&Divertor]•MPT/2-2migration•
TH/P1-5•
EX/P2-8•
EX/P2-3•
FIP/3-5Ra

EAST overview
Integrated operation
ELM-absent H-mode
Model-Predictive control
RF heated H-mode
I-modeLow-disruptivity rampdowns
RMP control
Grassy ELM regime

R. DingHigh-Z material erosion &F. Schluck
L. Wang
L. Zhang
R. Maingi

PSI 3D modeling
PSI control for H mode
Tungsten control
Li limiter and conditioning[Transport & turbulence]•EX/P2-12 P. J. Sun
Microturbulence & MHD modes•
EX/P2-2
Y. Yu
Anisotropic turbulence•
TH/P4-2
T. Y. Xia
Particle & heat fluxes•
TH/P6-2
S. Y. Ding Gyrokinetic Simulations on H-mode•
TH/P6-1
G. Q. Li
integrated modelling of transport•
TH/P7-21 X. Q. Xu
Boundary turbulent transport[MHD&EP]•TH/1-1
W. Shen•
EX/P2-15 J. Huang•
EX/P2-14 L. Q. Xu•
TH/P5-14 X. Q. Wu[CFETR]•OV/3-2•
TH/P5-16•
FIP/P7-27•
TH/P7-3G. Zhuang
R. HanH. L. Chen
M. Y. Ye

[Machine learning]•EX/P6-20 R. Granetz

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B.N. Wan/IAEA FEC/October 2018

EP instability & redistribution
EP studies
Kink mode study
Magnetic Coherent Mode
CFETR Design
RWM Stabilization
Vertical Displacement
Impurity Radiation
Distruption warning30

Thank you !