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
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.
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
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 (Flowing Liquid Surface IllinoisRetention Experiment)
hFLIRE will providefundamental data onthe retention andpumping of He, H,and other gases inflowing liquidsurfaces.
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 )
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
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.