Lithium experiments on HT-7 and EAST tokamak G. Z. Zuo, J. S. Hu, Z.S, J. G. Li, EAST team

ASIPP

Lithium experiments on HT-7 and Lithium experiments on HT-7 and EAST tokamakEAST tokamak

G. Z. Zuo, J. S. Hu, Z.S, J. G. Li, EAST teamInstitute of Plasma Physics, Chinese Academy of Sciences, China

D.K. Mansfield, L.E. Zakharov

Princeton Plasma Physics Laboratory, Princeton, USA

Jan. 23, 2010

ASIPPOutline

IntroductionIntroduction

Lithium limiter on HT-7 Lithium limiter on HT-7

Lithium coating on EASTLithium coating on EAST

Latest results on EASTLatest results on EAST

Further planFurther plan

ASIPPInner Structure of HT-7

Medium-sized superconducting tokamak;Medium-sized superconducting tokamak; Major radius 1.22 m;Major radius 1.22 m; Minor radius 0.27 m;Minor radius 0.27 m; Plasma volume ~1.75 m3;Plasma volume ~1.75 m3; First wall materials: First wall materials:

stainless steel;stainless steel; 18% covered by graphite tiles.18% covered by graphite tiles.

Poloidal limiter

Toroidal limiter

Belt limiter

Main limiterMain limiter toroidal limiter on the top and bottom toroidal limiter on the top and bottom

of HT-7 : R270mm, 1.2m2 of HT-7 : R270mm, 1.2m2 belt Limiter located at high field belt Limiter located at high field

sideside :R270mm, 0.54m2:R270mm, 0.54m2 total limiter area: 1.74m2total limiter area: 1.74m2

Other limiterOther limiter south and northsouth and north poloidal limiter: poloidal limiter:

R275~280mm, 0.06m2R275~280mm, 0.06m2 guard Limiter for protecting LHCD guard Limiter for protecting LHCD

antenna: R276~278mm, 0.077m2antenna: R276~278mm, 0.077m2 total area: 0.137m2total area: 0.137m2

ASIPPLithium limiter on HT-7

First lithium limiter experimentFirst lithium limiter experiment Free lithium surface;Free lithium surface; Lithium plate with plasma facingarea~377cm2;(130mm in Lithium plate with plasma facingarea~377cm2;(130mm in

width, 290mm in length). width, 290mm in length). The lithium is 3mm in thickness.The lithium is 3mm in thickness. SS dish has Mo protection at each side.SS dish has Mo protection at each side.Second lithium limiter experimentSecond lithium limiter experiment CPS configuration was used for confinement of lithium;CPS configuration was used for confinement of lithium; Other structure similar to the first lithium limiter.Other structure similar to the first lithium limiter.

Liquid Lithium was kept to 230degree during plasma Liquid Lithium was kept to 230degree during plasma dischargedischarge

ASIPPResults of lithium limiter with free surface on HT-7

H recycling measured by Hα intensity decreased by a factor of 4;H recycling measured by Hα intensity decreased by a factor of 4; The carbon and oxygen impurities measured by CIII and OV spectroscopy The carbon and oxygen impurities measured by CIII and OV spectroscopy

decreased;decreased; Loop voltage had a slight decline; the core electron temperature slightly Loop voltage had a slight decline; the core electron temperature slightly

increased;increased;

ASIPPPlasma confinement

Particle confinement time increased by a factor of 2; Particle confinement time increased by a factor of 2; and the energy confinement time increased from and the energy confinement time increased from 25.86ms to 30.04ms.25.86ms to 30.04ms.

ASIPPLithium limiter with CPS configuration on HT-7

Further reduction of H recycling;Further reduction of H recycling; Impurity radiation was further decreased;Impurity radiation was further decreased; Improvement of lithium confinement using CPS Improvement of lithium confinement using CPS

configuration by comparing lithium distribution after configuration by comparing lithium distribution after experiment.experiment.

ASIPPOutline






ASIPPIntroduction of EAST

EASTEAST Non – circular advanced steady-state experimental device;Non – circular advanced steady-state experimental device; Plasma volume ~26mPlasma volume ~26m33;; Plasma facing areas~50~60mPlasma facing areas~50~60m22;; EAST had a major radius R=1.847 m, a minor radius a=0.483m, the EAST had a major radius R=1.847 m, a minor radius a=0.483m, the

position of moveable limiter R=2.33m, an elongation rate of 1.7-1.9position of moveable limiter R=2.33m, an elongation rate of 1.7-1.9 Doped graphite (GBST1308Doped graphite (GBST1308 ：： 1%B1%B ，， 2.5%Si2.5%Si ，， 7.5%Ti7.5%Ti ）） with with

100~200 micron SiC coating was served for the plasma facing 100~200 micron SiC coating was served for the plasma facing materials.materials.

EAST

ASIPPFirst Lithium coating on EAST by evaporation and ICRF

discharge in 2009

Lithium oven

Lithium coating using lithium Lithium coating using lithium evaporation at single position by evaporation at single position by means of ICRF plasma on EAST in means of ICRF plasma on EAST in 2009 2009 Only 2 grams of lithium injection;Only 2 grams of lithium injection; SXR radiation and total impurity radiation SXR radiation and total impurity radiation decreased;decreased;Higher and broader electron temperature Higher and broader electron temperature distribution;distribution;

ASIPPLithium coating on EAST

300 ℃475 ℃

ICRF lithium coatingICRF lithium coating

Evaporating lithium by oven to realize lithium Evaporating lithium by oven to realize lithium coating as a routine way in the second campaign in coating as a routine way in the second campaign in 20102010Total 67 times and use 982.4g lithiumTotal 67 times and use 982.4g lithium

Using two ovensUsing two ovens14.2 grams lithium/oven14.2 grams lithium/oven500~550 /outside of oven℃500~550 /outside of oven℃1~2Hr./coating1~2Hr./coating10~28.4g/coating;1-2 time /day(~100 shots)10~28.4g/coating;1-2 time /day(~100 shots)Inserted oven to more close to center of Inserted oven to more close to center of vacuum vesselvacuum vesselBy means of ICRF/GDC or only evaporationBy means of ICRF/GDC or only evaporation

oven

oven

Red zone during lithium coating

Red zone during lithium coating

ASIPPLi coating by dropper from PPPL

Real time coating by Li powder dropper:

• ~50 mg/s;~50 mg/s;• lithium injecting during lithium injecting during 550 550

discharges;discharges;• Using about Using about 38.9g lithium38.9g lithium powder powder

in second campaign in EASTin second campaign in EAST

dropper

Lithium powder

44 µm dia.

30 nm Li2CO3

99.9% Li

0.1% Li2CO3

0 2 4 6 8 10 12

Ou

tpu

t (m

g/s

)

0

20

40

60

80

100

120

Applied RMS Voltage

Li Powder• 50mg/s for EAST

• 3 x106 Li Spheres/s

• ~2 x D influx EAST

• 14 x Evaporator Rate

ASIPPResults of lithium coating on EAST by oven

Easy plasma recoverEasy plasma recoverAfter lithium coating, plasma recovers after ~1 shot; After lithium coating, plasma recovers after ~1 shot; After siliconization, about 5-10shots ;After siliconization, about 5-10shots ;Without wall coating, it needs more shots to recover.Without wall coating, it needs more shots to recover.

Realize 1MA plasma current ;Realize 1MA plasma current ;Lower H recycling;Lower H recycling;

Decrease H/H+D from about 45% before lithium coating toDecrease H/H+D from about 45% before lithium coating to below 10%(min ~7%) to lead to improve ICRF heat efficiency.below 10%(min ~7%) to lead to improve ICRF heat efficiency.

Reduce impurity radiation, Zeff~2 during plasmas;Reduce impurity radiation, Zeff~2 during plasmas;Suppress MHD activity;Suppress MHD activity;Improve plasma confinement;Improve plasma confinement;increase plasma stored energy;increase plasma stored energy;Reduce H-mode power threshold and get H-mode.Reduce H-mode power threshold and get H-mode.

ASIPPEffect of lithium coating on plasma

#29686 and 29688: before lithium coating#29689:the first shot after lithium coating

Via the lithium coatingVia the lithium coating the plasma can restore quickly and the plasma current the plasma can restore quickly and the plasma current can be easily controlled;can be easily controlled; also the disruption discharges significantly reduces.also the disruption discharges significantly reduces.

ASIPPEffect of lithium coating on plasma

Circular plasmas Circular plasmas Divertor plasmas with double null Divertor plasmas with double null

By lithium coating, impurity By lithium coating, impurity and MHD activity (magnetic and MHD activity (magnetic probe measurement) was probe measurement) was effectively.effectively.

ASIPPImprovement of ICRF heating efficiency

H/H+D ~10%

Te increase ~200ev

Stored energy~10kJ

Siliconization: H/H+D above 25% Lithium coating : ~10%(min ~7%) to lead to improve ICRF heat efficiency.

ASIPPH-mode after lithium coating by oven

Ip/600kA/Nel~2./LHW~1MW/It~7000A;H-mode keeps about 200msH/(H+D)~7%

# 32924 CCD

ASIPPResults of lithium powder injection on EAST

Lithium powder injection is very effective in Lithium powder injection is very effective in suppressing MHDsuppressing MHD (spring (spring campaign in 2010 on EAST ).campaign in 2010 on EAST ).

ASIPPImprove plasma performance using lithium powder injection-H mode

#32525 :Before the shot , ~100g lithium coated by oven, powder injection from 1.9s to 2.9s, the confinement improves from about 4.8s;

#32537: IT ～ 6000A, IP ～ 600kA ， ne ～2.1*1019/m2 ， PLHCD~1MW, LSN from 3s;before the shots, about 30 shots lithium powder injection

Initial phase statistics about H mode:No.32525-33590:Total H-mode plasma: 141 shots (37.5 %) ; In H-mode plasmas, lithium powder injection:61 shots, 43.3 %.

ASIPP#32537 CCD

ASIPPBenefit for long plasma operation by Lithium injection

Plasma current(KA)

LiII emission

Ha emission

CIII emission

MHD signal

91s plasma discharge with 9 times lithium powder injection during a discharge

ASIPPBenefit for H mode discharge by lithium injection

Longest H mode shot when using 4 times lithium powder injection During a discharge in EAST

ASIPPOutline






ASIPP

Ip~0.6MA, Bt=1.9T, ΔWDIA>45KJ, PICRF=0.75MW, f=27MHz,PLHCD=1.0MW, f=2.45GHz

New milestone: H-mode Operation 6.4S ！

Ip

ne

PLHCD

Da/Ha

ECE

XUV

Sx-ray

Latest results on EAST— 6.4s H mode

PICRF

Ip

Beta P

WDIA

ASIPPLatest results on EAST—100s long pulse

ASIPPLatest results on EAST—1MA plasma

ASIPPL-H transition in

current ramping up and down phase

L-H transition in current ramping up phase

L-H transition in current ramping down

phase

ASIPP

LSNDN

ASIPPOutline






ASIPPFuture plan

Design new systems of lithium coating :– Another two new ovens evaporating systems—four systems for next campaign in

EAST– Design and upgrade lithium dropper.

Bench test for flowing liquid lithium limiter for HT-7– 2010-2011– Test whether liquid lithium can fluently flow by means of pump driving;– Some problems related with field and plasma can not resolve in preliminary

experiment Full metal walls with lithium limiter in HT-7

– 2011-2012– Remove all graphite limiter– Install Mo poloidal limiter– Modify the bottom to lithium limiter with a large area

Possibly after 2014 for EAST– 2014

– After all PFCs be modified from C to W

– Flowing liquid lithium divertor

ASIPPBench test

ASIPPHT-7 lithium limiter

1and 2:Poloidal Mo limiter

3:removable Mo limiter

4:high field Mo limiter

5and6: liquid lithium limiter

ASIPP

Thank you for your attention!

ASIPPLithium limiter with CPS configuration on HT-7

Improvement of lithium confinement using CPS Improvement of lithium confinement using CPS configuration .configuration .– In the case of lithium limiter with free surface, lithium spots were In the case of lithium limiter with free surface, lithium spots were

so big and dense;so big and dense;– When using CPS on the top of the lithium limiter, lithium spots When using CPS on the top of the lithium limiter, lithium spots

were small.were small.

Lithium spots deposited by using

free lithium surface

Lithium spots deposited by using lithium limiter CPS configuration

ASIPPOutline






Lithium experiments on HT-7 and EAST tokamak G. Z. Zuo, J. S. Hu, Z.S, J. G. Li, EAST team

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Transcript of Lithium experiments on HT-7 and EAST tokamak G. Z. Zuo, J. S. Hu, Z.S, J. G. Li, EAST team