reflection atomic and molecular spectroscopy in the scrape-off … · 2014. 12. 16. · atomic and...
TRANSCRIPT
Mem
ber
of th
e H
elm
holtz A
ssocia
tion
S. Brezinsek | Institut für Energie und Klimaforschung – Plasmaphysik | Forschungszentrum Jülich
S. Brezinsek, G. Sergienko, A. Pospiesczyk
M.F. Stamp, A. Meigs
Atomic and Molecular Spectroscopy in the
Scrape-Off Layer of High Temperature Fusion Plasmas
- Results from TEXTOR and JET -
IAEA Atomic, Molecular and Plasma-Material
Interaction Data for FS&T
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 2
Plasma-Surface Interaction Processes
Scrape-off layer Reflection
Confined plasma
Erosion
Deposition, mixing
and co-deposition of
fuel (retention)
Separatrix
Plasma-facing material
Processes depend on material mass, projectile mass, material mix and concentration, impact
energy (Ein), impact angle (a), surface roughness and temperature (Tsurf)
Here: focus on recycling, erosion and impurity fluxes in the SOL and edge layer
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 3
Plasma-Facing Materials
Low-Z: strong wall erosion (also at low Ein)
Sputtering Yields
High-Z: low sputtering / mainly by impurities
energetic threshold for each species
Steady-state divertor
conditions Transients
(ELMs)
detached attached divertor
… from all-C to Be/W mix ….
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 4
Particle-Flux Determination
e p
= * 1
4 n A A ij
Line emission
n A n n A ik k i
A e Exg e
*
£
å = < > s u
with B as branching ratio:
B = £ å A A ik ik k i
/
I h
n r n r dr tot A e Exg e
r
r
= < > ò B n
p s u
4
2
( ) ( )
Particle flux <=> number of ionisation events
d
dr
d n
dr n r n r
A A A
A e I e
G = = - < > ( )
( ) ( ) u
s u
G A A e I e
r
r
n r n r dr = < > ò ( ) ( ) s u
1
2
G B A tot
A e I e r
r
r
A e Exg e r
r
r
I
h
n r n r dr
n r n r dr
=
< >
< >
ò
ò 4
1
2
1
2 p
n
s u
s u
( ) ( )
( ) ( )
( )
( ) 1
Assumption of a fully ionising plasma & almost constant local plasma conditions
in the region of emission. Otherwise corrections factor or full rate coefficients.
G B X
A tot I
h =
4 p
n
I e < > s u
Exg < > s ue
= B tot I
h 4 p
S
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 5
Outline
§ Introduction
§ Hydrogen spectroscopy
§ D2 molecules in front of W PFCs
§ Tritium molecules in JET
§ Hydrocarbon spectroscopy
§ Molecular break-up chain
§ Effective sputtering yields
§ Beryllium spectroscopy
§ Effective sputtering yields
§ Chemical-assisted physical sputtering
§ Tungsten spectroscopy
§ In-situ W source calibration
§ Effective W sputtering yields
§ Summary
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 6
Fulcher-a Spectroscopy
§ Fulcher-a routinely used for vibrational population and plasma analysis [see talk by U. Fantz]
§ Impact of material on D2 population and release studied in TEXTOR (Te~30-100eV) and labs
TEXTOR
D2reference
spectrum
(Te~30eV)
(S. Brezinsek et al. JNM
PFR 2008)
Q(0-0)-branchQ(1-1)-branch
Q(2-2)-branch
Q(3-3)-branch
Q(4-4)-branch
Q(5-5)-branch
605 610 615 620600 625 630 635 640
0
1
2
3
4
5
6
600.0 602.0 604.0 606.00
4
6
2
JET-ILW
D2 spectrum
in outer divertor
(Te~30eV)
wavelength [nm]
Inte
nsit
y [
arb
. u
nit
s]
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 7
D2 Recycling in JET W Divertor
0 1 2 3 4 50
100
200
300
400
500
600
700
800
900
1000
1100
1200
D2 (d
3P)
Tro
t [K
]
vibrational quantum number
0 1 2 3 40.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
D2 (d
3P
-) line inegrated density (sum v=0-19)
(4.20±0.25) 1012
m-2
measurement
fit Tvib=6088K±(2548K/1408K)
popu
latio
n
vibrational quantum number
§ Contribution of reflected ions (neutralised at the PFC) is larger for W than for C PFCs
§ Increase in atom-to-molecule ratio of the recycled deuterium
§ Strong variation of surface temperature is changing the fuel content AND release species
§ Non-Boltzmann population in the vibrational ground state measured – different population
to previous JET-C measurements. Detailed analysis started.
JPN 87456-58
G. Sergienko et al.
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 8
JET-C T2 in Trace Tritium Experiment
§ Detailed studies of D2, H2, HD rovibrational population in TEXTOR, JET-C, AUG etc.
§ T2 injection in the main chamber and local observation of molecular emission
§ Injected amount of 2.5mg is recycled/pumped in JET-C. A fraction ends up in the divertor
PFCs (CFC) and can be detected as TD and T2 Fulcher-a emission
§ Tritium surface content down to 0.1% of recycling flux measurable via DT molecules
A. Pospieszczyk et al. J. Nucl. Mater. 2007
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 9
Outline
§ Introduction
§ Hydrogen spectroscopy
§ D2 molecules in front of W PFCs
§ Tritium molecules in JET
§ Hydrocarbon spectroscopy
§ Molecular break-up chain
§ Effective sputtering yields
§ Beryllium spectroscopy
§ Effective sputtering yields
§ Chemical-assisted physical sputtering
§ Tungsten spectroscopy
§ In-situ W calibration
§ Effective W sputtering yields
§ Summary S. Brezinsek et al. JNM 2007
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 10
Hydrocarbon Break-up
S. Brezinsek et al.
JNM 2007
TEXTOR hydrocarbon injection experiments:
§ CD, CD+, C2, D2, Db, Dg,!CI, CII, CII lines
§ Comparison with HYDKIN and ADAS
§ Production efficiency between 20 and 100%
§ Break-up chain & excited states
C2C2C 2
CHCD
CHCD
CII
CII
CII
CIICIII
HeI CII
CIIDg
Da(sat.)
Db
Da
CD Douglas-Herzberg+
CH+
CD+
CH+
CD+
C2 C2
[nm]
difference spectra
CD Gerö-band
inte
nsit
y
[arb
. u
nits
]
C Swan band2
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 11
Simple plasmas in TEXTOR (3.0-4.0 1018m-3 and 60-65eV at the LCFS)
Injection in the SOL, gas inlet 1.5cm -2cm behind the LCFS
Isotope experiment – surface influences minimised
Hydrocarbon Break-up Footprints: CD & C2
S. Brezinsek et al.
JNM 2007
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 12
Outline
§ Introduction
§ Hydrogen spectroscopy
§ Tritium molecules in JET
§ D2 molecules in front of W PFCs
§ Hydrocarbon spectroscopy
§ Molecular break-up chain
§ Effective sputtering yields
§ Beryllium spectroscopy
§ Effective sputtering yields
§ Chemical-assisted physical sputtering
§ Tungsten spectroscopy
§ In-situ W source calibration
§ Effective W sputtering yields
§ Summary Radius [m]
He
igh
t[m
]
#82626
at 11s
KS3 view
HFS LFS
a)2.0 2.5 3.0 3.5 4.0
2.0
1.0
0.0
-1.0
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 13
§ Determination of Be sputtering yields in limited configuration to verify data base
and ERO code used for ITER Be wall life-time predictions [D. Borodin PS2014].
§ Spectroscopy averages over observation spot (Tsurf, ion flux, geometry)
§ Dominant self-sputtering observed at high electron temperatures / impact energies
§ Energetic threshold at low impact energies
Effective Beryllium Sputtering Yields
S. Brezinsek et al.
Nucl. Fusion 2014
0.1
10
1
0 10 20 30 40
(eff.)
Tota
l B
e s
pu
tteri
ng y
ield
Electron temperature (eV)
Be self
sputtering
JET
Pulse No:80319–23
80272, 74
ERO
max
min Experiment (i)low Tbase
high Tbase
limiter
plasmas divertor
plasmas
D. Borodin et al.
Physica Scripta
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 14
Chemical Assisted Physical Sputtering of
Be via BeDx
S.Brezinsek
Nucl. Fusion 2014
as function of the Be tile temperature
§ Comparison of BeD A-X band, BeI and
BeII provides dissociation path
§ Dominant BeD + e ->Be + D + e (75%)
over BeD + e-> BeD+ + 2e (25%)
§ With increase of Tsurf inreasing release
of D2 => less D in stored in Be!
§ Chemical-assisted physical sputtering
causes an increase of the net source
§ Lower binding energy of Be in the D
supersaturated Be surface likely
§ Physical sputtering process which releases
from near surface molecules: BeDx, x=1,2,3
§ Energetic threshold at low impact energies –
not like carbon chemistry!
§ Confirms Molecular Dynamics predictions [C.
Börkas] and PISCES results [D. Nishijima PPFC 2008]
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 15
Material Migration: Main Chamber
HFS LFS
SOL flows
Ions
CXN
Ions
CXN
Limiter configuration
§ At high Ein: Be sputtering yield (JET-ILW) is larger
than C sputtering yield (JET-C)
§ Moderate increase of total limiter source (25%)
with respect to C in JET-C
§ Campaign averaged erosion rate at centre tile:
Spectroscopy : 4.1x1018 Be/s gross erosion
Post-mortem analysis: 2.3x1018 Be/s net erosion
§ Majority of eroded Be remains in the main
chamber and is redistributed on limiter/wall
A: Widdowson Phys. Scr. 2013
S. Brezinsek IAEA2014,
ICFRM2013
I. Bykov PSI2014
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 16
Divertor configuration
§ Sputtering at recessed wall at low Te / impact
energies (Ein<10eV) and by CX neutrals
§ At low Ein: Be sputtering yield (JET-ILW) is lower
than total C sputtering yield (JET-C)
§ Factor 4-5 smaller primary source with ILW (Be in
JET-ILW vs. C in JET-C)
§ Absence of low energy erosion in the ILW case
(chemical erosion in case of C in JET-C!)
§ Majority of eroded Be transported in SOL towards
inner divertor.
S. Krat JNM 2014
S. Brezinsek PSI2014, IAEA2014
M. Mayer et al.
Global Material Migration in JET-ILW
Fair balance between Be eroded (21 g) in
main chamber and Be deposited (28 g) in
divertor after first year of ILW operation
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 17
Outline
outer
divertor
2D camera and
filter
WI at 400.9nm
inner
divertor
SOL
SOL
PFR
SOL
TEXTOR W limiter
JET W divertor
§ Introduction
§ Hydrogen spectroscopy
§ Tritium molecules in JET
§ D2 molecules in front of W PFCs
§ Hydrocarbon spectroscopy
§ Molecular break-up chain
§ Effective sputtering yields
§ Beryllium spectroscopy
§ Effective sputtering yields
§ Chemical-assisted physical sputtering
§ Tungsten spectroscopy
§ In-situ W source calibration
§ Effective W sputtering yields
§ Summary
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 18
WC
toroidalpoloidal
radial
80 mm120 mm
curvature: 70 mm
height: 37mm
§ Twin Limiter experiment with variation of impact energies of impinging impurities
§ Determination of the W sputtering yield and the impurity composition
§ Effective S/XB values from corresponding WF6 injections (into comparable plasmas)
TEXTOR Experiments:
W Sputtering and WF6 Injection
§ WF6 injection experiment with gas inlet and negligible limiter surface
§ Well-known amount of W injected / direct dissociation at about Te~0.1eV
§ Prompt re-deposition minimised / no impact from local deposition of W
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 19
TEXTOR: Comparison of W Atoms
from Sputtering and Injection
§ Is W from WF6 dissociation representative for W from sputtering?
§ No difference in line shape of different WI and WII lines
§ Line ratios of WI lines with same lower level comparable in sputtered and injected W
§ WII lines measured and quantified in WF6 injections
S. Brezinsek Phy. Scripta 2011
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 20
Inverse Photon Efficiencies for WI
§ Multimachine fit of effective S/XB values for 400.9 nm applied for quantification of W fluxes
§ Contrast to AUG data which uses constant 20 (but works only in the range od 5-15 eV)
§ JET outer divertor hotter and has larger ELM energy drops (higher Te)
Different methods:
§ Weight loss
§ Spectroscopy
§ WF6 injection
§ W(CO)6 injection
S. Brezinsek ITPA 2012 steady-state ELMs
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 21
Effectice S/XB for Different WI Lines
Modelling:
ADAS/Mons data
(O‘Mullane/
Palmeri et al.)
Experiment:
TEXTOR data
(Brezinsek/Laengner)
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 22
JET: Effective Tungsten Sputtering Yields
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
0 20 40 60 80 100
Te [eV]
GG
Wio
n/
ASDEX Upgrade
JET, density steps
JET, density ramp
TEXTOR
5.7% C4+
4.0% C4+
2.0% C4+
1.0% C4+
0.5% Be4+
0.5% Be2+
R. Dux JNM 2009
G.v. Rooij JNM 2013
§ General W sputtering well described by Be ions / slight shift in energetic threshold
§ Plasma cooling by N2/Ar seeding till Ein drops below threshold [AUG R.Neu JNM 2011/Giroud
2014]
Increasing N
Competition between higher impurity flux
and local cooling in seeded discharges
G. v. Rooij,
JNM 2013
Increasing N
Plasma cooling leads to reduction of the W
source down to physical sputtering threshold
Plasma cooling
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 23
JET: ELM-induced Tungsten Sputtering
§ H-mode plasmas have energetic transients (ELMs) which hit the target at impact
energies of 1keV or above
§ Residual W in seeded plasmas determined by ELMs (Be+D+N impact) [Guillemaut
PPCF]
N2 seeded
discharge
S. Brezinsek et al.
PSI 2014
§ Prediction of residual W source in ITER in H-mode plasmas
ASDEX: Dux et al.,
J Nucl Mat 2009
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 24
S. Brezinsek et al.
Chemical Assisted Physical Sputtering of W ?
WD A-X transition
Q branch
Garvey et al.
J. Phys. Chem. 1988
TEXTOR:
§ Molecular emission solely in W sputtering
experiment and not with WF6 injection
§ Molecular emission identified in high spectral
resolution as WD molecules
§ Surface reaction responsible for WD:
Chemical assisted physical sputtering
§ fast D impacts on D saturated W surface
and releases WD
§ C, O impacts on D saturated W surface
and releases WD
JET:
§ WD identified,
but poor
resolution
inte
nsity [
arb
. units]
l [A]
JPN 85326
S. Brezinsek | Institut für Energie und Klimaforschung - Plasmaphysik | Forschungszentrum Jülich 16.12. 2014 No 25
Summary
§ D2 d-a transition: Recycling flux
=> understood and good set of data (EIRENE)
=> impact of surface confitions / material needs to be investigated
§ BeD A-X band : Chemical-assisted physical sputtering / recombination
=> empiric set of S/XB values
=> more work required
§ WD A-X band : Swift chemical sputtering
=> just identified => no S/XBs
=> more work required
§ ND A-X band : Volume or surface reaction
=> identified => S/XBs?
=> more work required
§ CN, N2, N2+, CD, C2 in minor quantities. Hydrocarbons well documented.
§ Atomic and molecular species in the scrape-off layer of tokamaks
observed
§ Focus on species related to ITER materials, fuelling and seeded species