26th IAEA FEC, 17-22 October 2016, Kyoto Japan
ASIPP

Overview of EAST Experiments on theDevelopment of High-Performance SteadyState Scenario

B.N. Wan on behalf of
EAST team & collaborators
Email: bnwan@ipp.ac.cn

Institute of Plasma Physics, Chinese Academy of Sciences1Collaborators
ASIPP

2

Scenario Developments on EAST
ASIPP
Step I
Improve heating efficiency anddevelop the SSO-relevant
fundamental physics and key
diagnostics;
Step II
Develop the SSO highperformance plasma scenariosand demonstrate (≥100s) longpulse H-mode plasmas;
Step III
Optimize the SSO plasma andextend the EAST operation
domain towards long-pulse, highbeta, high power, highperformance regime.
3Outline Introduction

ASIPPo Facility upgrade in support of steady-state long-pulse scenarios
 Exploration of Steady-State Plasma Operation with ITER-like Tungsten
Divertoro Scenario development with RF dominated heatingo Hot spot issues
 Progress of Key Physics Issues towards Steady-State Operation Regimeso LHCD at high density
o MCM physics at low collisionality
o RMP ELM controlo W & particle/power exhaust control
 Summary and Future Plans
4

Outline
ASIPP Introductiono Facility upgrade in support of steady-state long-pulse scenarios
 Exploration of Steady-State Plasma Operation with ITER-like TungstenDivertor
o Scenario development with RF dominated heatingo Hot spot issues
 Progress of Key Physics Issues towards Steady-State Operation Regimeso LHCD at high density
o MCM physics at low collisionality
o RMP ELM controlo W & particle/power exhaust control
 Summary and Future Plans
5

EAST SSO Capabilities
ASIPP
 LHCD 4+6 MW（2.45/4.6GHz）
 Fast Electron Source Edge Current Drive /Profile

ITER-like W/Cu divertor

 ICRH 6+6 MW （25-75MHz）
TZM/Cu FW
C/Cu FW-NBI

EAST In-Vessel@2016

 Ion and Electron Heating
 Central Current Drive NBI 4+4 MW （co/counter, 80kV）
 Sufficient power to probe β limit
 Variable rotation/ rot-shear

 ECRH 2(4) MW (140GHz)
 Dominant electron heating
 Steering mirror, jϕ tailoring Elevated capabilities in last two years allow

EAST to play a key role for developing
advanced SS scenarios Fully

non-inductive CD, high bootstrap
current fraction (fbs).
 Active control of ELM and stationary heatload on divertors

6

Diagnostics for key profiles
 Polarimeter Interferometer(POINT): ne, jϕ, q, Bp profiles

ASIPP

 Core & edge TS: Te, ne AXUV & Bolometer: radiation CXRS & XCS: Ti, rotation
 SXPHA & ECE: TePOINTchannels

 Reflectometry: pedestal ne He-BES: edge ne, Te Recip.-LPs: SOL ne, Te, flow
 Bremsstrahlung: Zeff
 FIDA: Vfast-particle
 High speed CCD
 IR camera: heat flux
 Div-LPs: div. particle/heat flux

 Using POINT measurement as constraint,accurate q profile were derived
 Powerful tools for developing scenarios

 Total: >70 diagnostics
7

OutlineASIPP
 Introductiono Facility upgrade in support of steady-state long-pulse scenarios
 Exploration of Steady-State Plasma Operation with ITER-like Tungsten
Divertoro Scenario development with RF dominated heatingo Hot spot issues
 Progress of Key Physics Issues towards Steady-State Operation Regimeso LHCD at high density
o MCM physics at low collisionality
o RMP ELM controlo W & Particle/Power exhaust control
 Summary and Future Plans
8

Fully non-inductive, high βP long-pulse Hmode operations

ASIPP

 The goal is to develop
fully non-inductivescenarios
 High LHCD with moderate fbs

 Recent EAST results
show that Zero loop voltage is achieved
at moderate density
 Extension for ITER andCFTER Optimization of PCD, ηCD andfbs

Vloop>0

Scatter plot of EAST βP versus lineaveraged density of low loop voltage
plasmas9Fully non-inductive plasmas with RF heating
 Demonstration ofnegative loop voltage HmodeASIPP βP~1.1; q95~6.3

 Upper single null t/τR~ 15

 Good Confinement:
H98y2~1.1
Ip=0.45MA/USN, Bt=2.5T, ne=3.0, PLH~2.6MW,
PICRF~1.0MW, PECRH~0.5MW
POINT measurement showed stationary current
profiles were maintained.
10

Core confinement and ELM effect
ASIPP。

Adding additional central
heating power i.e. ECR, iscritical for keeping highperformance{{ELM-free H-mode(6.06-8s)

High confinement (𝐻98 ~ 0.93)
Impurity accumulation and high core
radiation

Small-ELM Hmode (1.6-6.06s)

High confinement (𝐻98 ~ 1)
Lower impurity/radiation level
Suitable for long-pulse H-mode
operationMinute-scale H-mode discharges (>60s)!
ASIPP Pure RF heating:
PLHW, 2.45GHz=0.4
PLHW, 4.65GHz=2.1MW
PICRF=0.8MW,
PECRH=0.3MW;

 Good confinement with
H98(y2)~1.1;
 Good control of impurity
level- assisted by ELMs
and ECRH, and an edge
coherent mode; Divertor heat flux was
mostly controlled below
2.0 MW/m2
12
Divertor strike point splitting reduce heat flux

Minute-scale H-mode discharges (>60s)!
ASIPP
 Pure RF heating:
PLHW, 2.45GHz=0.4
PLHW, 4.65GHz=2.1MW
PICRF=0.8MW,
PECRH=0.3MW;

 Good confinement with
H98(y2)~1.1;
 Good control of impurity
level- assisted by ELMs
and ECRH, and an edge
coherent mode; Divertor heat flux was
mostly controlled below
2.0 MW/m2
13
Divertor strike point splitting reduce heat flux

Core confinement for RF heated long-pulse fully noninductive H-mode plasmas

ASIPP• Stationary peaked Te profile wastypically maintained in the series oflong pulse discharges on EAST
• Power balance analysis shows thesignificantly reduced ce in plasma
core• The core Te profile meets the ITB
criterion
 rTe*(max)=0.02>rITB*~0.014• The improved confinement wassustained very stably for tens ofseconds!
14G. Tresset, Nucl. Fusion, 42(2002)520

Hot spot issue and solutions
ASIPP
 Strong hot spots observed on theguard limiter of 4.6GHz LHCD
antenna: limiting power and pulse
length due to strong impurity influxand damage to the limiter Global parameter scan identified athreshold LHCD power was around2.5~3.0MW
 Possible mitigation from rotating
RMP was observed by tuning theparticle flux hitting on the guardlimiter New guard limiter design wasproposed with inclined surface tolessen direct particle deposition on
the surface
15

OutlineASIPP
 Introductiono Facility upgrade in support of steady-state long-pulse scenarios
 Exploration of Steady-State Plasma Operation with ITER-like Tungsten
Divertoro Scenario development with RF dominated heatingo Hot spot issues
 Progress of Key Physics Issues towards Steady-State Operation Regimeso LHCD at high density
o MCM physics at low collisionality
o RMP ELM controlo W & particle/power exhaust control
 Summary and Future Plans
16

Higher CD and rotation driving at 4.6GHz
ASIPP

HXR counts as a function of line averaged density
also shows higher current drive capability with
4.6GHz wave.
● Higher CD efficiency indicated by thelower loop voltage● Peaker current profile indicated by thelarger li●Better heating effect indicated by WMHD
and electron temperature.

Less parametric instability (PI) behavior with
4.6GHz wave
17

EX/P7-5;EX/P7-7

LHCD still effective at high density in Hmode

ASIPP

Even if at ne~4.5×1019m-3, part of current is still driven by LHW!
Simulation show that N|| upshift improves accessibility of LHW at high density
18EX/P7-5

Profile control with LH spectrum tuning
ASIPP

The best CD effect is obtained with N//peak=2.04
li in 49464 (N//peak=2.04) is the largest,indicating more current is driven in thecore region compared to other cases.

 GENRAY/CQL3D simulation suggest
different driven current profiles,
qualitatively consistent with theexperiments.
19EX/P7-5

New Stationary Small/No ELM H-Mode Regime atLow Collisionality

ASIPPn=1MCM

 A new stationary small/no ELM Hmode at low collisionality (𝝂𝒆∗ < 1)
 Good energy confinement, H98(y,2) ≳ 1.1,
 A low-n (mostly n=1 and sometimesn=2) electro-Magnetic Coherent Mode(MCM) at 30-60 kHz in the pedestal
region.

EX/10-2

 MCM frequency appears to be locatedin the TAE gap near the local trappedthermal-electron bounce frequency
 Frequency scales linearly with the local
Alfvén frequency, indicating thepossibility of trapped-electron-driven
TAE mode through bounce resonancewith trapped thermal electrons. 20

ELM pacing with LHCD modulation
ASIPP
120 Hz, 40% duty cycle LHCD-induced flattening of density
profile near the separatrix andpedestal density pump-out have been
observed.

 Vacuum-field modeling of LHCDinduced 3D magnetic topology change at
the plasma edge indicates that the flatdensity-profile region and its radialwidth expansion are largely consistent
with those of the LHCD-induced edge
stochastic magnetic field layer, which
may explain the observed density profilechange, similar to the effect of RMPs.21

 Density gradient is steepened near
the pedestal top, causing pedestalpressure-gradient increase that maybe responsible for the ELM
EX/10-2triggering.

ELM suppression with low n RMP
ASIPP

n=1 RMP Full ELM suppression was accessedusing low n RMP in low rotatingplasma with RF dominant heating inEAST
ELM suppression with n=1 RMP in 3MW LHCD + 1MW ICRF
slow-rotating RF heated plasmas
 n=1, 2 RMP［Sun Y. et al., Phys. Rev. Lett. 117, 115001 (2016)］  Ωφ ~ 022

EX/P7-4

Suppression over long pulse demonstrated!
ASIPP ELM suppression in longpulse (> 20s) operational
senario was realized withsmall effect on plasmaperformance (H98>1)

 Using n=1 RMP with
optimized spectrum
 Clear pump out effect on
W, which is helpful forsustain long pulse highperformance
EX/P7-4
EX/P7-1023

Nonlinear plasma response observed
ASIPP

Peak (linear)
Nonlinearobserved

n=1

 Linear plasma response determines the best spectrum for ELMsuppression.
 Nonlinear plasma response suggests that a critical level of magnetic
topological change taking into account plasma response plays a key rolein accessing final ELM suppression

24

EX/P7-4

W transport in RF-dominated ELMy H-mode
ASIPP
 ELM flushing effect is critical for impurity exhaust As a result, high Z impurity accumulation can be avoided by
ELM flushing and RF heating25

Control of 3D divertor footprint
Both LHW & RMP coils can induce edge topology change striated magnetic flux lobes  3D divertor footprints

The experimental and modeling results of different toroidal
locations show good agreement.
Simulations: EMC3-EIRENE (RMP), field line tracing taking intoaccount helical current filaments in the SOL (LHW).
Allowing further heat flux control using 3D footprint withregulated divertor conditions.

EX/P7-10; TH/P6-20

ASIPP

Active control of particle exhaustUSN, W-divertor, Bx∇B↓

ASIPP ELM particle flux favors outer
divertor in USN, while favoring
inner divertor in LSN.

 A reference for particle exhaust
during long-pulse H-mode
operation, together with cryopumps.
 Consistent with PS flow, as
measured by LFS/HFS
reciprocating Langmuir probes.
 Compatible with ICRF heating

LSN, C-divertor, Bx∇B↓

J. B. Liu et al., NF (2016)

Outline
ASIPP Introductiono Facility upgrade in support of steady-state long-pulse scenarios
 Exploration of Steady-State Plasma Operation with ITER-like Tungsten
Divertoro Scenario development with RF dominated heating;o Hot spot issues
 Progress of Key Physics Issues towards Steady-State Operation Regimeso LHCD at high density
o MCM physics at low collisionality
o RMP ELM controlo W & particle/power exhaust control
 Summary and Future Plans
28

SummaryASIPP
 Stationary RF-heated long-pulse H-mode operations (>60s!)(>60s !)
were achieved on EAST with progress in the relevant physics
in support of SSO on tungsten divertor
Extension of the SSO towards high βP regime (up to 1.8);
Discovery of a new stationary small ELMy H-mode (H98(y,2)≳1.1,ue,ped*<1) regime, which exhibited a low-n MCM at the pedestal.
Achievement of low-n (1, 2) RMP ELM suppression in the RF
dominant slow-rotating long-pulse H-mode plasma; Observation of
the first evidence of a nonlinear transition from mitigation tosuppression of the ELMs by using RMPs;
Extension of the current drive in high-density domain (up to4.5×1019m-3) with 4.6 GHz and 2.45GHz LHCD systems together;Regulating heat deposition distribution and reducing transient peakheat fluxes on the divertor and PFCs by applying 3D magnetic
perturbations at the plasma boundary.
29

Future Plans
ASIPP

Step I

Step II

Step III• Improve heating
efficiency anddevelop the SSOrelevant
fundamental
physics and key
diagnostics;• Develop the SSO
highperformance
plasma scenariosand demonstrate(≥100s) longpulse H-mode
plasmas;• Optimize theSSO plasma andextend the EAST
operational
domain towards
long-pulse, highβ, high power,highperformance
regime.

30

List of EAST Contributions
ASIPP OV/2-2 B.N. Wan: Overview of EAST Experiments on the Development of High-Performance Steady-State Scenario EX/4-3 A.M. Garofalo: Development of High Poloidal β Steady-State Scenario with ITER-Like W Divertor onEAST
 EX/10-2 G.S. Xu: ELM Pace-Making and Long-Pulse ELM-Stable H-Mode Operation with LHCD in EAST EX/P7-2 X. Gao: Key Issues towards Long Pulse High Operation on EAST Tokamak EX/P7-4 Y. Sun: ELM Suppression Using Resonant Magnetic Perturbation in EAST EX/P7-5 B. J. Ding: Recent Experimental and Modelling Advances in the Understanding of Lower Hybrid Current
Drive in ITER-Relevant Regimes
 EX/P7-7 B. Lyu: Experimental Study of Radio-Frequency Driven Spontaneous Rotation for High-Performance
Plasmas on EAST EX/P7-8 X.J. Zhang: Heating and Confinements by the Waves in the Ion Cyclotron Range of Frequencies on EAST EX/P7-10 L. Wang: Evidence and Modelling of 3D Divertor Footprint Induced by Lower Hybrid Waves on EAST
with Tungsten Divertor Operations
 EX/P7-12 X.D. Zhang: Fishtail Divertor: A New Divertor Concept on EAST for Active Control of Heat Load onDivertor Plate EX/P7-15 G. Li: Predictions of the Baseline Operation Scenario in Chinese Fusion Engineering Test Reactor
 EX/P7-16 W. X. Ding: Current Transport and Density Fluctuations at L-H Transition on EAST
 TH/P6-19 T. Y. Xia: Divertor Heat Flux Simulations in ELMy H-Mode Discharges of EAST and Other Tokamaks
 TH/P6-20 J. Huang: EMC3-EIRENE Simulations for the Impact of External Magnetic Perturbations on EASTEdge Plasma
 FIP/1-1 P. Fu: Recent Progress of ITER Package in ASIPP
 FIP/P4-21 Z. Song: Research and Development Progress of the ITER PF Converter System
 MPT/1-2Ra G.-N. Luo: Overview on Decade Development of Plasma-Facing Components at ASIPP

Welcome to the poster session for further discussions!
31

ASIPP

Thank you !

ASIPP

Backup slides

33

EAST Experiment Shows New L-H Transition Mechanism
ASIPP
Shift accelerates
at the transition,accompanied byturbulence
suppression.

Eddy tilt increase
as approaching theL-H transition.

First direct observation of L-H
transition mediated by turbulence
kr spectral shift and eddy tilting.

Reciprocating
Langmuirprobe array

34

G.S. Xu, PRL 116, 095002 (2016)Low n=1 intrinsic error field measured in EASTASIPPResonant

Non-Resonant

Compass scan [Wang H.H et al, Nucl. Fusion 56, 066011(2016) ] The measured n=1 intrinsic error field is of the order B2/1/B0 ~10-5.
 The amplitude depends on the RMP configuration used, which agrees
with linear plasma response modeling by MARS-F.
 Non-Resonant: Resonant:B2/1/B0 ~0.6x10-5 (better coupling)

B /B ~4.4x10-535