ASIPP Overview of the first H mode and future plans of the ... · Y. R. Martin, T. Takizuka and...

ASIPP

Overview of the first H mode and future

plans of the superconducting tokamak

EASTG. S. Xu on behalf of the EAST team

and our international collaborators

Institute of Plasma Physics

Chinese Academy of Sciences

ITPA & TTF meeting April 2011 Santiago

ASIPP

EAST team and international collaborators

Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China : Jiangang Li, Baonian Wan, Yuanxi Wan, Xianzhu Gong, Bingjia

Xiao, Yuntao Song, Yu Wu, Jiafang Shan, Yanping Zhao, Liqun Hu, Yanfang Bi, Lei Cao, Jiafeng Chang, Yue Chen, Junling Cheng, Xu Deng,

Bojiang Ding, Siye Ding, Shijun Du, Yanmin Duan, Peng Fu, Jia Fu, Daming Gao, Ge Gao, Wei Gao, Xiang Gao, Shiying He, Yanlan Hu,

Liansheng Huang, Juan Huang, Zhensan Ji, Ming Jiang, Xiang Jie, Yinxian Jie, Jiahong Li, Yinyin Li, Shiyao Lin, Bili Ling, Fukun Liu, Saochen

Liu, Yong Liu, Peng Liu, Guangnan Luo, Zhengping Luo, Bo Lv, Dengkui Ma, Yuzhou Mao, Shengming Pan, Xuebing Peng, Jing Qian, Jinping

Qian, Chengming Qing, Pinjian Qing, Biao Shen, Linhai Sheng, Xiaoyang Sheng, Lan Shi, Yuejiang Shi, Xiaoyang Sun, Ang Ti, Xiaogang Wan,

Fudi Wang, Houying Wang, Huazhong Wang, Linsen Wang, Mao Wang, Shenming Wang, Xiaoming Wang, Yong Wang, Huiqian Wang, Keping

Wu, Hao Wu, Jiefeng Wu, Jinhua Wu, Junshuan Wu, Zhenwei Wu, Xiaoqi Xi, Weibing Xi, Chunyi Xie, Guosheng Xu, Huangdong Xu, Liuwei

Xu, Ping Xu, Tiejun Xu, Diye Xue, Ning Yan, Lei Yang, Zhongshi Yang, Chunyan Yuan, Qiping Yuan, Junyu Zhao, Qing Zhan, Ling Zhang,

Qiyong Zhang, Ruirui Zhang, Wei Zhang, Xiaodong Zhang, Xinjun Zhang, Fali Zhong, Guoqiang Zhong, Zhibo Zhou, Yanfei Zhu, Youhua Zhu,

Ping Zhu, Donghui Zhuang, Ming Zhuang

Donghua University, Shanghai, China : Jiarong Luo

South West Institute of Physics, Chengdu China : Qingwei Yang

Tsinghua University, Beijing, China : Zhe Gao

University of Science and Technology of China, Hefei, China : Adi Liu, Xiaoyuan Xu, Chanxuan Yu

General Atomic, San Diego, USA : Paul Anderson, Vincent Chan, Punit Gohil, Dave Humphreys, Al Hyatt, Lang L.Lao, Jim Leuer, Ali

Mahdavi, Gary Jackson ,Ben Penaflor, David Piglowski, Michael Schaffe , Mike Walker

Fusion Research Center, UT at Austin, USA : He Huang, Kenneth Gentle, Perry Philippe, William Rowan

Princeton Plasma Physics Laboratory, USA : R.Hawryluk, D.Mansfield, D.Mueller, M.Bitter, N.Fisch, K.W.Hill, D.M. Mastrovito, G.Fu ,

H.Qin , R.Wilson , L.Zakharov, M. Zarnstorff

Tri Alpha Energy, California, USA : Houyang Guo

Oak Ridge National Laboratory, USA : R. Maingi

National Institute for Fusion Sciences, Toki, Japan : H. Kasahara, R.Kumazawa, T.Mutoh , A. Naoko, H. Okada , K.Saito, Y. Shuichi , K.Toi,

T.Watari

Association Euratom-CEA, CEA Cadarache, France : A.Becoulet, B.Bremond, D. Douai,A.Ekedahl, T.Hoang, P.Huynh, Y.Peysson, K.Vueillie

Natiaon Fusion Research Institute, Korea Basic Science Institute, Daejeon, Korea : S.G.Lee, J.G.Bak

Association Euratom-RisøDTU, Denmark : V. Naulin, A.H. Nielsen, J. Juul Rasmussen

JET-EFDA, Culham Science Centre, UK : W. Fundamenski

ASIPP

Outline

I. Introduction of EAST

II. First H mode in the last campaign

H mode access

H mode performance

ELM characteristics

L-H transition

III. Future plans

IV.Summary

ASIPP

I. Introduction of EAST

Commenced operation in Sep. 2006

First H mode on 7 Nov. 2010, 23:16

Shot number 32525

ASIPP

Missions and achievements

EAST missions : 1MA, 20MW high-performance

steady-state operation (SSO).

1. Stationary H mode operation > 400 s

Achieved : 6.4 s H mode, HIPB98(y,2)~0.9

2. Long pulse divertor operation >1000 s

Achieved : 100 s L mode, Te0~1.2 keV

3. Plasma current up to 1.5 MA

Achieved : Ip = 1 MA, L mode

EAST parameters :

Major radius : R0 = 1.9 m

Minor radius : a = 0.5 m

Toroidal field : Bt = 3.5 T

Elongation : = 2

Triangularity : = 0.65

H mode

100 s

1 MA

ASIPP

II. First H mode : access


First H mode in 7 Nov. 2010, 23:16

Shot number 32525

ASIPP

Conditions for H mode access

Power : LHCD 2.45GHz, 1.3MW (2MW), ~14% transmission line loss

ICRF 20-70MHz, 1MW, effective coupling < 0.5 MW

Control : RTEFIT/Isoflux control, SN, DN, limiter (2 removable limiter)

PFC : doped graphite tiles (~9000) with a ~100 m SiC coating

bolted to Cu heat sink, 2MW/m2

Wall conditioning : lithium evaporation and lithium powder injection

Pumping : In-vessel cryopump, pumping speed ~75.6 m3/s for D2

Fueling : gas puffing at different locations for various gas (D2, CD4, Ar, N2 …)

D2 working gas

Diagnostics : >40, for all key profiles

LHCD launcher

ICRF antenna

Removable limiter

Tile and Cu heat sink

ASIPP

Overview of the H mode shots

485 H mode shots in total

89% : POhm + PLHW including the first H mode discharge

duration 3.6 s, limited by Ip flat top durations

11% : POhm + PLHW + PICRF

duration 6.4 s, limited by discharge durations

51% : DN or unbalanced DN

16% : LSN (BB towards lower X-point)

33% : during configuration switches from DN to LSN

0% : USN

80% : first L-H transition during Ip flat top

16% : first L-H transition during Ip ramp-up

4% : first L-H transition during Ip ramp-down

Parameters at L-H :

Bt = 1.4~2 T

Ip = 0.4~0.8 MA

ne = 1.9~3.41019m3

PLHW = 0.5~1.1 MW

PICRF < 0.5 MW

SA = 38~42 m2

= 1.64~1.94

low = 0.45~0.58

q95 = 2.7~5.0

ASIPP

Key actions leading to the H mode

1. Wall conditioning by lithium coating : to reduce recycling, suppress impurities

and radiation.

2. Outer gap optimization by isoflux control and antenna position adjustment : to

improve LHW & ICRF power coupling and minimize impurity generation by the

plasma-antenna interaction.

3. Local gas puffing near the LHW launcher : to improve LHW coupling (not

routinely applied).

4. Shape the plasma into a divertor configuration early during Ip ramp-up : to

reduce impurities and radiation.

5. Increase the gas puffing rate during Ip ramp-up : to suppress runaway electrons.

6. Gas fueling from either the HFS or the domes : higher fueling efficiency than LFS

gas fueling.

ASIPP

LHW Power ~ 1MW

~ 0.6 during the H phase

Wave accessibility is good Wave deposition profiles

N|| ~2.1, spectral width ~0.2 TRANSP-LSC code

Strongly off-axis

ASIPP

LHW power coupling problem

Reciprocating Langmuir probe measurements

at the outer midplane showed that the ne and Te

in the SOL were significantly reduced in the

ELM-free phase, resulting in increased LHW

reflection.

Time history in SOL SOL profilesMultiple L-H-L transitions : when the applied LHW

power was marginal to the threshold.

H-L back transitions : increased power loss by

radiation & LHW reflection during ELM-free phases.

ASIPP

Improve LHW power coupling

To improve LHW coupling

the outer gap was optimized by isoflux plasma

boundary control and antenna position adjustment.

local gas puffing near the LHW launcher.

Reflection coefficient < 10%

ASIPP

Wall conditioning: Siliconization

30 min Siliconization + 35 min He-ICRF

15kW, 0.05 Pa, 1s on/1s off

using a gas mixture of SiD4:He = 1:9

Wall temperature ~ 70 ℃

This deposition technique suppressed

both O and C impurities but did little

to reduce either recycling or H/(D+H).

As a result no access to the H-mode

was achieved using wall conditioning

with silicon.

ASIPP

Wall conditioning: Li evaporation

oven

oven

lithium coated area

lithium coated area

300 ℃ 475 ℃

GDC or ICRF lithium coating

Li evaporation has been conducted 67 times.

Nearly 1 kg of Li has been injected into the

vessel through evaporation.

Before Li conditioning, bake-out of PFCs up

to 240 ℃ to reduce their hydrogenic loading.

Two ovens at outer midplane

10~30 g, evaporated at 500~550 ℃, 1~2 hours

Usually assisted by helium GDC or ICRF

discharge.

ASIPP

Wall conditioning: Li powder droplet

Real-time injection of fine lithium powder into the plasma edge : A collaboration with PPPL

D. K. Mansfield et al., Fusion Eng. Des. 85, 890 (2010)

Dropper ~50 mg/s

6.4 s H mode

~500 shots, ~30% of H-mode shots, 40g

ASIPP

Effects of lithium wall coating

The first H-mode plasma was achieved after

evaporation of 34 g of Li and 17 shots with Li powder

injection.

H/(D+H) ratio : ~50% ~7% in plasmas with

deuterium fueling, Li accumulated to > 50 g.

Isotope scaling : help to reduce the power threshold.

Improve ICRF heating efficiency.

ASIPP

II. First H mode : performance



Shot number 32525

ASIPP

LHCD 3.6 s stationary H mode

ne and Te pedestal formation

at the onset of the H mode.

Type-III ELMs with

frequencies up to 1 kHz.

~ 1ped

ASIPP

XUV profiles indicate pedestal formation

The formation of pedestal was further confirmed by a sharp rise in the XUV

(extreme ultra-violet) radiation at plasma edge.

ASIPP

X-point neutral density reduced by 4

~21017m3 ~51016m3

High recycling Low recycling

Visible CCD camera, at the same ne

ASIPP

H mode threshold power scaling 1:1

0.72 0.80 0.94

200.0488thresh e t AP n B S

loss aux Ohm rad diaP P P P dW dt

Threshold power of EAST LHCD H modes is aligned with predictions of the international

tokamak scaling

A threshold in density for H-mode access has been identified :

Didn't see density rollover

19 31.9 10en m

Y. R. Martin, T. Takizuka and ITPA CDBM H-mode Threshold

Database Working Group, J. Phys.: Conf. Ser. 123, 012033 (2008).

EAST

ASIPP

Power threshold comparisons

Similar power threshold for DN & LSN

LSNDN

Similar power threshold for Ip ramp up and flat top

Lower power threshold for Ip ramp down

Ip

ASIPP

LHCD H mode energy confinement

exp

E dia lossW P

89 0.85 0.2 0.5 0.1 0.5 1.5 0.3 0.50.048ITER P

E p tI B P n A R

98 ,2 0.93 0.15 0.69 0.41 0.19 1.97 0.58 0.780.145IPB y

E p tI B P n A R

HITER89-P 2 HIPB98(y2) 1.1

ASIPP

LHCD H mode HIPB98(y,2) is up to ~1

exp

E dia lossW P

Dwell time of L-H transition Triangularity dependence

Power dependence Density dependence

ASIPP

LHCD + ICRF 6.4 s H mode

LHCD was applied very early during Ip

ramp-up to assist target plasma build up,

enhance plasma temperature, so as to

improve ICRF heating efficiency.

The H mode duration was limited only by

presently attainable discharge durations.

It can be very easily extended to more

than 10 s when the LHW power is

upgraded in the next campaign.

ICRF at 27MHz in minority heating

dominated regime (~0.5 MW was

absorbed). Optimized coupling by

controlling density and the gap between

separatrix and antenna.

ASIPP

II. First H mode : ELM characteristics



Shot number 32525

ASIPP

ELM average heat load ~ 2MW/m2

IR CCD camera, 20 ms time resolution

Type III ELMs

ASIPP

In-out asymmetry in target heat load

LSN

Type III ELMs

LSN, dRsep = 1 cm

Inner > Outer

IR CCD data IR CCD data

DN

Type III ELMs

DN, dRsep = 0 cm

Outer > Inner

ASIPP

Energy loss by ELM W/W = 1~2%

1 ~ 2%div

ELM

dia

W

W

2kJdiv

ELMW

Target probes

LSN & DN

ASIPP

Type I like irregular isolated ELMs

Big ELMs caused energy

loss > 5% of stored energy

Target peak heat load >

3MW/m2

Deposited energy on

divertor plates > 3kJ

H mode was sustained by

0.3 MW as a result of the

hysteresis effect.

ASIPP

ELM control by Argon seeding

Argon gas was injected

from lower outer target at

a speed of 41020 particles/s

ELM frequency rises

ELM amplitude decreases

ELM duration decreases

Prad didn’t increase

Ploss increased

Wdia decreased

ASIPP

B

thodographs (Br B B )

The frequency of ELM

precursor decrease

from 130kHz to 60kHz

during 0.4ms

Type III ELM

2~ 1.5filj MA m

ELM precursor and current filament

Moveable, 3D pickup

coils & probes

In the SOL and edge

1cm < r < 10 cm

ASIPP

Negative D spikes near X-point

Inner target X-point

Ionization

region

High densityen 4

Not detached at the inner target

ASIPP

Mossy ELMs ~ 300 ms duration

XUV radiation

ASIPP

Alfven-like modes in ELM-free phase

Spectrum Phase

Alfven-like modes at frequency ~300kHz and ~30kHz

were sometimes detected by reciprocating mid-plane

probes during ELM-free phases.

Ddiv

ASIPP

II. First H mode : L-H transition



Shot number 32525

ASIPP

GAM disappear during H mode

Reciprocating probe data at the plasma

edge show GAM oscillation in L mode

but it disappeared in H mode.

ASIPP

Dithering just before L-H transition

D at inner target

Isat at outer target

Dithering was frequently observed just before L-H transition

or sometimes in L mode when ne>2, L-H precursor ?

ASIPP

III. Future plans



Shot number 32525

ASIPP

Plans for next 5 years

2011 2012 2013 2014 2015

Ip(MA) 1.0 1.0 1.0 1.5 1.5

LHCD(MW, CW)

2.45GHz 4.0 4.0 4.0 4.0 4.0

4.6GHz 6.0 6.0 6.0

ICRF(MW,CW)

20-75MHz 4.5 4.5 4.5 4.5 4.5

30-100MHz 1.5 4.5 4.5 4.5 4.5

NBI(80keV) 4.0 4.0 8.0

ECRH(140GHz, CW) 2.0 4.0 6.0 6.0

PFC Mo/C Mo/W/C Mo/W Mo/W W

Diagnostics 40 45 50 50 50

Duration(s) 100 200 300 400 500

t-Hmode(s) 30 60 100 200 400

With over 20MW CW power and > 50 diagnostics, EAST could play a key role

for long pulse advanced high performance plasma for ITER within next 5 years.

ASIPP

Liquid lithium limiter and divertor

2011, Liquid lithium limiter on HT-7

2014, Liquid lithium divertor on EAST

ASIPP

IV. Summary



Shot number 32525

ASIPP

Summary of the EAST first H mode

3.6 s stationary ELMy H mode with HIPB98(y,2) up to ~1 has been achieved

with only 1 MW of LHCD.

6.4 s stationary ELMy H mode has been achieved with 1 MW LHCD +

0.5 MW ICRF.

The threshold power for H-mode access follows the international

tokamak scaling and a threshold in density has been identified.

Strong effects due to lithium deposition and accumulation on the H-mode

access and performance have been observed. A likely contributing factor

is the lower edge recycling produced by lithium pumping as indicated by

a significant drop in the neutral density near the lower X-point.

More than 20 MW power and 50 diagnostics will be ready in next 3 years.

Steady-state H mode with 100 s duration will be achieve in next 3 years.

ASIPP

EAST is a open collaboration platform for

the world!

Welcome to join EAST experiments.

Thank you very much for your attention!

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