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JET PFC Analysis, TFFT and the ILW
JET
J P CoadEURATOM/UKAEA Culham Division, Abingdon, UK
Introduction to TFFT and interaction with JETSummary of programme of analysis of JET samples removed in 2004Plans for JET samples removed in 2007Update on progress on the JET ITER-like wall
JET FT
Tritium in Tokamak
Tritium processes & Waste management
Test Beds
Neutronic& safety
Plasma Facing ComponentsEngineering
AGHS
Activation models
T spreading
Shutdown dose rate calculation
Collection ofOperating experience
Dust conversion factor of dust
Fatigue testing W coatings
Glow improvements
Active IRthermography
JET Flakes
CharacterisationJET Tiles
Improvement of gas balance
JET WDSsystem
T removalFrom tiles
Micro gaschromatography
Materialtransport
Retention incastellation
Microanalysisof cross section
detritiation
Erosiondeposition
LIBS
Heating of tilesIn JET NB test bed
AES/XPS T & Be JET
tiles
Fibres &neutrons
JET FT2008
Tritium in Tokamak
Tritium processes & Waste management
Test Beds
Neutronic& safety
Plasma Facing ComponentsEngineering
Benchmarking of CAD to MCNP interface
Shutdown dose rate prediction:
In situ opticalDust
measurements
Advanced study for detritiation
of non-plasma facing metals
Be Tiles detritiation
Material transport
+ erosion
tungsten erosion in the JET divertor
Microanalysis of plasma deposited
layers
tritium profile in carbon-based plasma-
facing componentsLIBS
Installation and commissioning
of the plasmatron
collection of data(VV & BeHF)
characterisation of mirrors
Laser lock in
Inspection ofbolometer
Tasks on Fusion Technology 2006-2007 and 2008
Plasma Facing Components (10)
Test Beds
Tritium in Tokamak (2)
Tritium process and waste management (4)
Engineering (4)Neutronics and Safety (2)
22 new tasks have been launched during WP 2006-07
15 tasks on going from previous years and 22 tasks launched during the year 2006
12
Presently FT has 37 running tasks
For the FT WP-2007-08 16 new tasks have been approved
for a total budget of ~2.4 m€
More and more papers published and/or presented at conferences
Active IR Thermography in metal environment
Goal: get rid of reflected flux and measure real surface T
Heat pulse = perturbation of T0
2 measurements and ratio surface T°
(Material Emissivity constant!)
(CEA, Semerok, Gauthier)
LIBS to characterise divertor PFC
test of laser detritiation on JET tiles
Goal : test in BeHF + assessment of efficiency
(CEA, Semerok and UKAEA, Widdowson and Coad)
300 microns
Laser treated zone
CFC substrate
Cleaning JET tiles by Laser Ablation
• total removal of film• some damage of the substrate• sharp boundary at edge of treated zone
Detritiation : inside gap generator
Goal : clean & detritiate castellations
D=60 mm
d= 0.8 mm
Power: 130W, Pressure: 69mbar
However, pattern not explained
Retention in castellations
Goal: characterise the retention in Be limiter castellations
(VR, Rubel)
• Cold self-sustained volumetric plasmaVolume: 18 litres Target diameter: ~25cm Ion energies: 20 - 500 eVMagnetic field: 0.2T Pulse duration: steady stateFlux density target: ~ 1020-1021 ions/m2.s
• Designed for PWI studies • Installation for operation in glove box• A gas mixture with a certain D/T ratio can be created in a volume
by measuring the pressure and the mass flow of D/T coming from volumes containing D and T. Both loops have a separate control system.
Brief plasmatron facility description
Tominetti S. et al., Vuoto 26 (1997)
Plasma chamber
Gas, plasma, secondary ions and neutrals analyser
Gas inlet
CW
CW
CW
CW cooling water
TC
TC temperature control
I
I
I insulation
PM
PM
PM permanent magnets
T
T target
C CA
C cathode
A anode
UHV 1
UHV1 main pumping
UHV 3
UHV3 differential pumping
Sedano L. et al., Phys. Stat. Sol. 188 (2001)
1/81/5
1/2
1/11
3/13/23/43/4
3/8
4/24/44/94/10 6/1 6/4 6/9
7/17/37/57/77/88/18/48/78/88/108/11
6/3
1/81/5
1/2
1/11
3/13/23/43/4
3/8
4/24/44/94/10 6/1 6/4 6/9
7/17/37/57/77/88/18/48/78/88/108/11
6/3
1/81/5
1/2
1/11
3/13/23/43/4
3/8
4/24/44/94/10 6/1 6/4 6/9
7/17/37/57/77/88/18/48/78/88/108/11
6/3
Task Force E JET
JET MkII-SRP Divertor used 2001-2004
Key: 1/11 means tile 1, sample 11
Septum Replacement Plate (SRP)
Campaign included:• 4 weeks reversed field• trace tritium experiment• 13C-methane puffing on last day• operation with JET wall
temperature at 200°C
Inner Divertor Analysis
Depth (m)
0 10 20 30 40 50 60 70 80
Inte
nsit
y (s
-1)
100
101
102
103
104
105Be12C13CNi
SIMS profiles sample 3/8 exposed 1998-2004
Inner part (to right of line):•similar to film deposited 1998-2002•Outer part: (to left of line)• High Be + other metals (e.g. Ni) except close to surface• Little 13C at surface
JG
03
.67
6-1
c
Tile 1
Tile 3
Tile 4
Task Force E JET
• Film deposited 2001-2004 also has high Be/C ratio, although operations were at 200°C• He-fuelled campaign must be responsible for outer layer from 1999-2001• Film structure may be different allowing trapping of large amount of D
Tile 3: Deposition layer fills up the holes of the W layer
G3B
top
bottom
Micro-analysis cross sectionGoal: Composition of layers of 100µm thick via micro beam analysis of polished
cross sections. (% level of main constituents: C, D, O, Be and SS, spatial resolution of a few μm)
D2 mapping
(Tekes, Likonen and Emmoth, VR)
Tile 1-5, sputter cleaned
130 120 110 100
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
104 C
ount
s/s
Binding Energy (eV)
Be1s
310 300 290 280 270
0.0
0.1
0.2
0.3
0.4
0.5
104 C
ount
s/s
Binding Energy (eV)
C1s
550 540 530 520
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
104 C
ount
s/s
Binding Energy (eV)
O1s
890 880 870 860 850 840
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
104 C
ount
s/s
Binding Energy (eV)
Ni2p
Tile 1-5 before and after sputter cleaning
Before
After
Picture from previous divertor campaigns in JET as follows:• Erosion at outer divertor wall (tiles 7 and 8) [contrast to inner]• ~200 μm deposition on sloping part of tile 6 [same as inner]• No significant deposition in shadowed corner [contrast to inner]
New data from MkII-SRP campaign from• 13C puffing• IR measurements• Analysis of tiles• Deposition monitors, louvre clips from shadowed area
Erosion/deposition at the outer divertor
Task Force E
JET
JG
03
.67
6-1
c
Tile 8
Tile 7
Tile 6 Shadowed region
Deposition at outer divertor
Task Force E JET
JG
03
.67
6-1
c
Tile 8
Tile 7
Tile 6 Shadowed region
•4 weeks reversed field operation gave deposition at outer divertor (clear from the film effect in the infra-red camera)•During methane puffing local re-deposition observed
Deposition in outer shadow region [c.f. inner]:•Film on Deposition monitor slits ~20 μm [c.f. 90 μm]•Deposit inside monitor box 18 μm [c.f.35 μm], or 8.3 1019 atoms cm-2 [c.f. 25 1019 atoms cm-2]•Film on tile (SIMS) 8 μm [c.f. 80 μm]•Film on tile (section) 40 μm [c.f. 120 μm]•Louvre clips off-gas 0.49 MBq/day [c.f. 0.63 MBq/day]
G7B
12345678
0a1a
W Erosion
Outer divertor: SEM images
-1600 -1500 -14000.0
0.5
1.0
1.5
2.0
Initial RBS PIXE [a.u.]
Am
ou
nt
of
W
[10
19 a
t./c
m2]
Position [z-coordinate, mm] 50 µm
• Inhomogeneous erosion• Full erosion of W in some places
(IPP, Majer)
13C-methane puffing experiment in 2004
Task Force E JET
•31 similar pulses on last day of operation•ELMy H-mode discharges:- BT 1.2T, IP 1.2 MA, ~7.5 MW additional heating•Total of 4.3 1023
molecules 13C-methane puffed in outer divertor from 48 locations
Approximate line of W-stripe is shown as white dashes
JETTask Force E
Field line plot showing strike points and SOL region for the 13C-puffing experiment
•Occasional sweeps of strike-point position for Langmuir probe data•Collector probe on reciprocating probe in SOL at top of machine
JG
03
.67
6-1
c
Task Force E JET
Tile 1
Tile 3
Tile 4
Tile 8
Tile 7
Tile6
Amounts of 13C measured on divertor tiles by SIMS and IBA
Note: Measurements on one poloidal line have been extrapolated, assuming toroidal symmetry
Tile Number 13C amount
1 2.7% 3 0.5% 4 3.8% SRP ? 6 2.5% 7 10.9%* 8 6.1% Total 26.5%
* based on average of two poloidal scans
SRP
Local deposition of 13C on G3B
19-23(max) x1018 atoms/cm2
13-18.9 x1018 atoms/cm2
10-12.9 x1018 atoms/cm2
7-9.9 x1018 atoms/cm2
1-6.9 x1018 atoms/cm2
Total number deposited 13C in this area is ~215 x1018 atoms
Tungsten stripe
13C injection
20mm
Cores cut for SIMS analysis
Modelling of the 13C puffing for the inner divertor
Method• EDGE2D follows injected 13C atom trajectories with NIMBUS• EDGE2D ELM model of Kallenbach used (modified for smaller ELMs)• effects of sputtered carbon and re-erosion not included• impurity transport coefficients in private flux region chosen 10x SOL value• SOL flows in main chamber created by external force, classical drifts important in private flux region
3 paths dominate the 13C migration • most of carbon re-deposited on the outer target • a few % migrates via the main chamber SOL to the inner target (as also seen on a reciprocating probe at the top of the machine), and accounts also for the deposition on the inner baffle• a few % migrates via the private flux region by action of ExB drift to vicinity of inner strike point
Task Force E JET
SIMS
IBA
poloidal distance around the divertor (mm)
0 500 1000 1500 2000
13C
dep
osite
d / c
m2 /
13C
inje
cted
10-8
10-7
10-6
10-5
10-4
10-3final fit
J Strachan modelling for 13C experiment
Conclusions from 2004 samples
• Deposition at the inner divertor is not sensitive to wall temperature• Significant erosion of W-markers has been observed at the outer divertor, of interest to the ITER-like Wall Project at JET. • Infra-red temperature measurements clearly show when thin films are forming at the outer divertor• Some deposition occurred in shadowed region at outer corner in 2001-4, but the balance between erosion and deposition in this region requires further exploration• 13C-methane was puffed at the outer divertor in 2004, and preliminary modelling shows reasonable agreement with deposition at inner divertor
Task Force E JET
10μm
7μm
72μm
44cm3
67cm3
99cm3
105cm3
233cm3 17cm3
464cm3
26μm
10μm
38μm
33μm
41μm
19cm3
24cm3
60g on louvre
18μm 300μm 32μm
Tile analysis programmefor tiles removed in the 2007 shutdown
Objectives:•Distribution of 13C injected in April 2007 at outer mid-plane•Erosion of W-coatings in critical areas for ILW•Erosion/deposition behaviour to compare with QMB data•Results of rotating collector experiment (inc. Be evaporation)•Mirror tests for ITER•C-redeposition at load-bearing tile
Cross-section of JET 2005-7
JET-HD divertor 2005-
Quartz Micro-balance at the inner divertor
tile 1
tile 3
tile 4
QMB-system
quartzcrystal
carrier rib tile 1
tile 3
tile 4
QMB-system
quartzcrystal
carrier rib
JET ITER-Like Wall
• Update on materials, timescales
• Development of W coatings on CFC
• Be coatings on inconel
• Be markers
View inside JET 2005-7
Beryllium Coatings on Cast Inconel (I)
• Evaporated 8 m Be coating on inner wall Inconel cladding• Estimated maximum load in JET: 0.5 MW/m2 in 20 s corresponding to 10 MJ/m2
Steps in the material qualification process:• Optimisation of the deposition process (Nucl. Fuel Plant, Romania).• Pre-characterisation of layers: purity, structure, uniformity.• High Heat Flux testing (Forschungszentrum Jülich).• Characterisation after testing.
HHF testing in JUDITH to determine the layer durability limits:
1. Screening test by stepwise increase of power density: 0.4 – 3 MW/m2.
2. Cyclic test: 50 consecutive loads of 1.0MW/m2 for 10 s.
Message: No damage to layers exposed to the energy load of 19.8 MJ/m2.
200
700
5 m5 m
Original surface Tested: 1.8 MW/m2, 11 sTest: 1.8 MW/m2, 11 s
Beryllium Coatings on Cast Inconel (II)
SUMMARY OF RESULTS:• High uniformity and purity of coatings (oxygen only in a thin surface layer).• Layers survive power loads of 2.55 MW/m2 in 6.2 s (18.1 MJ/m2)• Melting of beryllium observed above 3 MW/m2.• No damage by 50 thermal cycles of 1 MW/m2 for 10 s each (10 MJ/m2 pulses).
0
200
400
600
800
1000
1200
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0
delta T, 3.3 ~ 3.6 mmdelta T, >4.0 mm
6.2 s, delta T
Energy density [MJ/m2]
extrapolation, ~11 s pulseon 3.5 mm Inconel case~ 11 s pulses,
thickness 3.3 ~ 3.6 mm
6.2 s pulse, thickness 4 mm
~ 11 s pulses, thickness > 4.0 mm
Surface Temperature versus Energy Density
Tem
per
atu
re
[oC
]
Conclusion: The layers meet operational requirements for JET-ILW.
PISCES
PC-Be data scaled () to Eckstein’s value
10-3
10-2
10-1
0 50 100 150
PC-Be (20060817)GA-Be (20060802)ROM-Be (20060802)
Eckstein (D+-->Be)
YB
e
Ei [eV]
20
06
08
02
&2
00
60
81
7
(10-3) = 7.7x102
Erosion of Beryllium Coatings on Cast Inconel:Exposure of Be to Deuterium Plasma in PISCES (UCSD)
D.Nishijima, J.Hanna, R.Doerner
GA & Romanian Be coatings show increased YBe’s at higher Eion compared to Poly Crystalline(PC)-Be.
Development of Beryllium Marker Tiles (I)AIM: The assessment of beryllium erosion from the main chamber wall (limiters)
Beryllium Tile (3 cm)
Nickel interlayer (2-3 m)
Be layer (7-9 m)
30 m
m
28 mm
Be coupon with marker coating.
For HHF testcoupons are with a
hole for a thermocouple.
Steps in the R & D process
• Production of optimised layers by Thermionic Vacuum Arc method
• High Heat Flux testing
• Broad characterisation of layers before and after testing.
Main Result of HHF test:
Layers withstand without damage 4.5 MW m-2 for 10 s.
Beryllium Marker Tiles (II)
Depth (m)
0 2 4 6 8 10 12 14
Inte
nsi
ty (
s-1)
100
101
102
103
104
105 BeCAlSiCaFeNi
Be test coupon with marker layers
Topography of Be coating
Depth (m)
0 2 4 6 8 10 12 14
Inte
nsi
ty (
s-1)
100
101
102
103
104
105 BeCAlSiCaFeNi
SIMS depth profiles
After HHF test
Fresh
Remaining Work: Produce and Install Tiles in JET
Inner Wall Structure with Location of Marker Tiles
Conclusions
• Analysis of tiles removed in 2004 shutdown almost complete
• Analysis has started on a new poloidal selection of tiles removed in 2007
• Preparations are in hand for the ILW installation in 2009-2010, including solid Be and W tiles, Be coatings on inconel, and marker tiles.
Recommended