Implications of Li divertor and otherliquid-metal technologies

D.N. Ruzic and J.P. Allain

Department of Nuclear, Plasma and RadiologicalEngineering

University of Illinois, Urbana-Champaign

UFA Burning Plasma Science Workshop IIGeneral Atomics, San Diego, CA

May 1-3, 2001

Outline of Talk

hThe walls as the problemhThe walls as the solutionhCurrent efforts in plasma facing component

science and technologyhEnabling technologies for existing/future

fusion deviceshConclusionshAcknowledgements

Many of fusion’s problems involveplasma wall interactions

hCheaper electricity means higher powerdensity and therefore more power towalls.

hDisruptions (unplanned and planned)severely limit lifetime and thereforedesirability.

NC ARIES-RS Design Module

C.P.C. Wong, et al. “Toroidal reactor design as a function of aspect ratio”

SC ARIES-RS Design Module

C.P.C. Wong, et al. “Toroidal reactor design as a function of aspect ratio”

Lithium on surfaces could solve theseproblems and have other benefits

h Flowing liquid plasma-facing systems canrapidly remove heat.

hContinuous recovery of damaged surfacesexposed to large heat fluxes due to off-normalevents as well as disruptions.

h TFTR Li pellet and DOLLOP experiments

h Possible stabilization of MHD modes bysubstituting a moving conducting wall forplasma rotation

TFTR Results: Li conditioning

Li conditioning effect on nτeT

TFTR Results

D.K. Mansfield, PPPL, ALPS/APEX Albuquerque, NM 2000

TFTR DOLLOP Results

Disruptions set severe limits onITER-FEAT

hVDE (verticaldisplacement event60 MJ/m2 for 300mson first wall

hThermal quench 30MJ/m2 in 1 ms ondivertor

G. Federici, et al. J. Nucl. Mater. 290-293 (2001) 260.

Net erosion of ITER divertor

J. Brooks, D. Alman, G. Federici, D.N. Ruzic and D.G. WhyteJ. Nucl. Mater. 266-269 (1999) 58.

ELMs set power limit even for W

G. Janeschitz, et al., J. Nucl. Mater. 290-293 (2001) 1-11

Plasma Facing Component Science andTechnology Program

• Integrated concepts

• Lab-scale investigations

• Modeling efforts

• Near-term experiments

C.P.C. Wong, et al. “Exploration of Innovative Advanced Solid Wall Concepts” presented at:U.S. Fusion Chamber Technology Peer Review, UCLA, April 26, 2001

Flowing Li dropletdivertor

Flowing lithium droplet divertorcassette

R.F. Mattas, “ALPS – advanced limiter-divertor plasma-facing systems”” Fusion Engineering and Design 49-50 (2000) 127-134

CLiFF(Convective Liquid

Flow First-Wall)

N. Morley, et al. APEX Interim Report, UCLA-ENG-99-206, Nov 1999

Conceptual sector schematic ofCLiFF implementation in ARIES-RSreactor

CLiFF – Flow/Temperature Schematic

N. Morley, et al. APEX Interim Report, UCLA-ENG-99-206, Nov 1999

IIAX (Ion-surface InterAction eXperiment)

In-situ cleaving arm design and HVheaterhCleaving arm is

designed to removethin oxide layerformed on Li layer ofliquid tin-lithium orliquid lithium sample

hSurface compositionexperiments showthat Li segregates tothe liquid Sn-Lisurface1

A HV heater was installed insidea BN cup.

TC

QCM-DCU

Plasma cup

1. B. Bastasz J. Nuclear Mater. 290-293 (2001) 19.

Secondary ion fraction and deuterium-saturation studies of liquid metals in

IIAX at UIUC

102 103 1040.00

0.25

0.50

0.75

1.00

Sec

onda

ry io

n sp

utte

ring

frac

tion

(spu

tterin

g io

ns/ s

putte

red

atom

s)

Incident particle energy (eV)

Secondary Li ion fraction (non D-sat.) Secondary Li ion fraction (D-saturated)

h Saturation of solid and liquid (T/Tm ~ 1) tin-lithium with D atomsresults in no effect on the absolute sputtering yield of lithium.

h Ion fraction measurements show that 55-65% of sputtered atomsfrom D-saturated solid and liquid lithium are in an ionized state.

102 10310-2

10-1

100

Abs

olut

e S

putte

ring

Yie

ld o

f Li (

atom

s/io

n)

Incident particle energy (eV)

D-treated Liquid 0.8 Sn-Li non D-treated solid 0.8 Sn-Li D-treated solid 0.8 Sn-Li

IIAX experimental and modeling data onliquid lithium erosion

hD treatedlithium yieldsare well belowunity

hData taken at45 deg.Incidence and200 C surfacetemperature 101 102 103

10-2

10-1

100

Abs

olut

e S

putte

ring

Yie

ld (

a.u.

)

Incident particle energy (eV)

Li+ on liquid Li (IIAX data) VFTRIM-3D, Li on liquid phase Li He+ on liquid Li (IIAX data) VFTRIM-3D, He on liquid phase Li D+ on liquid Li (IIAX data) VFTRIM-3D, D on liquid phase Li

J.P. Allain, M.R. Hendricks and D.N. Ruzic, J. Nucl. Mater. 290-293 (2001) 180

Effect of deuterium surface treatmenton lithium erosion

102 10310-2

10-1

100

Abs

olut

e Li

spu

tterin

g Y

ield

(Li

par

ticle

s/ io

n)

Incident particle energy (eV)

He+ on non D-sat Li He+ on D-sat Li He+ on D-sat Li (neutrals only)

J.P. Allain and D.N. Ruzic, Nucl Fusion, submitted 2000

FLIRE concept

FLIRE (Flowing Liquid Surface IllinoisRetention Experiment)

hFLIRE will providefundamental data onthe retention andpumping of He, H,and other gases inflowing liquidsurfaces.

PMI Experimental efforts in ALPS

B. Bastasz, et al. SNLL

PISCES – glowing lithium

R. Doerner, et. al., J. Nucl. Mater. 290-293 (2001) 166.

DiMES

R

BT

0 2 4 6

1015

1014

1013

time (s)

1

10

Te(eV)

ne(cm-3)

Private-fluxPlasma Incident on

Lithium / DiMES

h Lithium is sputtered in private flux (PF) plasma

by charge-exchange neutrals

h Neutral lithium resonance line (670 nm, Ehν~2

eV) is easily excited by Te~1 eV PF plasma.

h Lithium is quickly ionized in very cold, dense

PF plasma!

Private fluxplasma at DiMES

ionization potential (eV)

2S 2P 2D

0

1.8

5.4

3.4 460 nm

671 nm

Li I Energy LevelDiagram

Li I Light from DiMESduring PF exposure

D.G. Whyte, et. al., UCSD and General Atomics

Lithium provides a unique opportunity to study erosion and

transport in the private flux region due to its ease of erosion &

excitation.

A * T H E R M A L - S ( T h e r m o d y n a m i c s / H e a t

T r a n s f e r / M H D / R a d i a t i o n T r a n s p o r t )

L i q u i d - L a y e r S p l a s h / B r i t t l e D e s t r u c t i o n

S P L A S H S U P E R A T O M

P h D ( P h o t o n D e p o s i t i o n )

( A t o m i c P h y s i c s )

D R D e p ( D e b r i s D e p o s i t i o n )

S i m u l a t i o n P a c k a g e f o r H i g h E n e r g y

I n t e r a c t i o n w i t h G e n e r a l

H e t e r o g e n e o u s T a r g e t S y s t e m s

I T M C ( M o n t e C a r l o / E n e r g y D e p o s i t i o n )

T R I C S ( T r i t i u m D i f f u s i o n )

H E I G H T S P a c k a g e

S O L A S ( S c r a p e - O f f L a y e r )

T R A P ( D i f f u s i o n i n

P o r o u s S t r u c t u r e )

P H I L T ( P u l s e d

H y d r o d y n a m i c s )

S W H I F T ( S h o c k W a v e H y d r o d y n a m i c s )

A. Hassanein and I. Konkashbaev, J. Nucl. Mater. 273 (3) (1999) 326.

Plasma-liquid surface interaction Modeling(cont.)

T. Rognlien and M. Rensink,LLNL

Plasma-liquid surface interaction Modeling(cont.)

Electron temperature in outer scrape-off layer forthe UEDGE plasma solution with low-recycleliquid lithium divertor

Gross and instantaneous (before liquid flow)net erosion rates from WBC code

J. Brooks, et al. J. Nucl. Mater. 290-293 (2001) 185

NSTX: application of flowing liquid metal(i.e. ALIST)

B. Nelson and P. FogertyAPEX Task I

Conclusions

h Plasma interactions with the surfaces limit thedesirability of fusion power

h Advances in fusion science and performanceoften follow new surface-related discoveries

h Wall concepts involving Li show great potentialto solve many known problems

h ALPS and APEX programs are actively engagedin pursuing these solutions

h Planned burning plasma devices shouldconsider including these – they may just bewhat makes it work.

Acknowledgements

hDOE ALPS Program (Advanced Limiter/Divertor Plasma-facing Surfaces)

hRichard Mattas

hArgonne National Lab

hUFA for the invitation to speak