pwi tf meeting, warsaw, k. krieger, 04/11/2009 report on task agreements of wp09-pwi-07 within sewg...

PWI TF Meeting, Warsaw, K. Krieger, 04/11/2009

Report on task agreements of WP09-PWI-07 within SEWG ITER Material Mix

K. Krieger,A. Hakola, Ch. Linsmeier, A. Litnovsky, Ch. Lungu, R. Mateus,

M. Rubel, K. Schmid


WP09-PWI-07-01Compound formation in binary mixing of Be, C and WInfluence of substrate temperature and dependencies on incoming flux composition.Reaction kinetics for Be-W and Be-C mixtures (e.g Be/W interdiffusion, Be sublimation from Be/W alloys).WP09-PWI-07-02Compound formation in ternary systems of Be, C, W and OFormation and properties of ternary system Be-C-W and influence of oxygen on the underlying processes.WP09-PWI-07-03Material intermixing and fuel retention behaviour under dynamic conditionsD retention properties of mixed materials as function of temperature, composition of mixed material and incident flux composition.

WP09-PWI-07-04Collect data on composition, fuel retention and chemical characterisation from mixed deposits in tokamaksAnalysis of Be-C and W-C deposits collected in tokamaks for comparison to laboratory experiments: composition, fuel retention properties.

WP09-PWI-07-05Modelling of material mixing for extrapolation to ITER conditionsIntegrated plasma-wall Monte Carlo transport modelling, kinetic MC simulation of material mixing; MD modelling of mixed layer properties and processes.

Overview

Basicphysicsstudies

Data fromfusiondevices

Modelling


WP09-PWI-07-01/IST/PS Responsible Scientist: R. MateusStudy of Be, W and C interdiffusion with microbeam and of carbideand Be/W alloy formation and W alloy sublimation.

WP09-PWI-07-01/MEdC/PS Responsible Scientist: Ch. LunguStudy of substrate temperature influence during film deposition information of the stable alloys: Be2C for the Be-C system and Be2W, Be12W, Be22W for Be-W system.

WP09-PWI-07-02/MEdC/PS Responsible Scientist: Ch. LunguStudy of ternary system formation Be-C-W using thermionic vacuum arcmethod; influence of oxygen on the process.

WP09-PWI-07-02/IPP/PS Responsible Scientist: Ch. LinsmeierAnalysis of ternary systems.

WP09-PWI-07-03/IPP/PS Responsible Scientist: K. SchmidAnalysis of Be-contaminated PISCES samples.

WP09-PWI-07-04/TEKES/PS Responsible Scientist: A. HakolaAnalysis of W-C mixed layers on AUG tiles, work on hot cells.

WP09-PWI-07-04/FZJ/PS Responsible Scientist: A. LitnovskyCharacterisation of mixed W/C layers formed in TEXTOR , analysis offuel retention in W/C mixed layers.

WP09-PWI-07-04/VR/PS Responsible Scientist: M. RubelStudies of material mixing on surfaces exposed to plasma.

Tasks with priority support


Be/C interdiffusion, compound formation and sublimation

• C deposition on polished Be samples– C films evaporated with an electron beam

using graphite as source– thickness of hundreds of μm

Current work

• Annealing of Be/C samples in the 100 – 600°C range

• Be/C interdiffusion, compound formation and sublimation• WP09-PWI-07-01/IST/PS task

• Rutherford Backscattering Spectrometry (RBS)• X-ray photoelectron spectroscopy (XPS)• WP09-PWI-07-01/IST/BS task

• Surface observation by Scanning Electron Microscopy (SEM)• (compound formation, surface sublimation ...)

100 150 200 250 300 350

50

100

150

200

C

O

Cou

nts

Channel

Be

RBS spectrum


Be alloy and compound formation

0 100 200 300 400 500 6000

20

40

60

80

100

com

posi

tion

Ar+ fluence (1016/cm2)

Be% C% O% W%~450nm total depth

0 100 200 300 400 500 600 7000

20

40

60

80

100

com

posi

tion


Be% C% O% ~500nm total depth

Be films deposited on C and W were:• poly-crystalline (proved by TEM–SAED)• sufficiently pure (proved by sputter–XPS)• oxidized surfaces (due to air exposure)• low oxygen content (small increase at

interface due to substrate contribution)

No significant differences in depth profiles were observed with respect to substrate temperature during deposition (possibly due to the short deposition time).

Film preparation Be films of ≈500 nm thickness were deposited on C and W using TVA (thermionic vacuum arc discharge) method with substrates kept at different temperatures.


0 1000 2000 3000 4000 5000 6000 7000 80000

20

40

60

80

100Be/C 30 minutes annealing

Con

cent

ratio

n (a

t%)

Thickness (1015 at/cm2)

Be before O before C before Be after O after C after

0 1000 2000 3000 4000 5000 6000 7000 80000

20

40

60

80

100


Con

cent

ratio

n (a

t%)

thickness (1015 at/cm2)

Be/C 90 minutes annealing

Thermal treatment of Be films deposited on graphite at 350° C

• Be films of ≈500 nm deposited on graphite were annealed in high vacuum conditions on different time scales at 350°C.

• A mixture of Be2C, BeO and C develops at the film-substrate interface.• On increasing the annealing time, the thickness of this mixed material layer also increases.

0 1000 2000 3000 4000 5000 6000 7000 80000

20

40

60

80

100


Be/C 60 minutes annealing

Con

cent

ratio

n (a

t %)

Thickness (1015 at/cm2)

Thermal treatment of Be films deposited on tungsten is still ongoing. Higher temperatures are necessary for Be-W alloy formation (above 500°C)



E-Beam irradiation/annealing ofW film (100nm) + Be film (200nm) on graphite substrates

0 2000 4000 6000 8000 10000 120000

10

20

30

40

50

60

70

80

90

100

Co

nc (

at%

)

Depth (at/cm2*1015)

W C Be O

Before annealing After annealing at 900oCInterdiffusion of Be and CNo mixing with surface W layer


0 2000 4000 6000 8000 10000 120000

20

40

60

80

100

Depth (at/cm2*1015)

Co

nce

ntr

atio

n (

at%

)

W C Be O

Depth profiles derived from RBS analysis


0 100 200 300 400 500 600 700

1E11

1E12

1E13

1E14

1E15D

2 molecules

Des

orp

tio

n r

ate

(mo

lec

/ sec

)

substrate temperature (oC)

carbon substrate tungsten substrate

Deuterium retention

D implantation was performed with IPP Garching High Current Ion Source. D energy 600 eV D3+

(i.e. 200 eV / D) with normal incidence and target at room temperature. Fluence was 5×1022 D/m2.

No significant differences in retained deuterium amount were observed with respect to substrate material (C or W) and substrate temperature during deposition

TDS spectra of D2 molecules for Be films implanted with 200 eV D+ ions at room temperature:



Be anode assembly

Elemental mapping (EDS analysis) and concentration compositions of Be-C-W films

deposited on silicon substrates

Ternary system formation Be-C-W

C-W anode assembly


0.5 1.0 1.5 2.0 2.5 3.02

4

6

8

10

Oxi

gen

(At%

)

Deposition rate (nm/s)

Depositions performed at 3*10-6torr

0.5 1.0 1.5 2.0 2.5 3.02

4

6

8

10

Oxi

gen

(At%

)

Deposition rate (nm/s)

Depositions performed at 3*10-6torr

p=3*10-5torr

O-concentration dependency on deposition rate

0 2000 4000 6000 8000 10000 120000.0

0.2

0.4

0.6

0.8

1.0

Be W O C

Co

nc.

(re

l)

Depth (At/cm^2)

RBS Depth ProfileFilm composition and oxygen contamination during film preparation

Sample deposited at 350° C

0 20 40 60 80 100 120 140 160 180 200 220 240 260 2800.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Co

mp

osi

tion


Be O C W

Elemental depth profile

XPS analysis

0 50 100 150 200 2500.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

De

con

volu

tion

of

the

Be

1s

pe

ak


Be% met% alloy% oxide% carbide%

Beryllium structure versus depthBe2C formation attributed to ion bombardment. Oxygen found only at interface and at surface

Depth profiles show varying mixing fractions of Be, W and C.

Oxygen inclusion can be controlled trough deposition rate

Further morphology analysis and D implantation and retention studies ongoing

Ternary system formation Be-C-W


Information depth depends on kinetic energy of photoelectrons

Kinetic energy of photoelectrons depends on energy of the photons

By changing the excitation energy the information depth can be changed

Ternary system: C/BeO/W

XPS with synchrotron radiation


C 1s: After annealing at 875 K

Experiment•PVD of C on BeO on W•Annealing steps up to 1370 K•Recording of spectra with

6 different energies after each experimental step

Results•Observation: Tungsten

subcarbide formation near the C-BeO-interface (red circle)

•Explanation: •Diffusion of BeO into the

tungsten substrate•Tungsten and carbon get in

touch in the surface near region

Increasing surface sensitivityTernary system: C/BeO/W


Be and D area densities in the near surface region determined using NRA

Sample plasma exposure history:PISCES-B Targets (Pure D plasma)

Name Fluence

WITER1 ****

WITER2 1.2×1026 D ions/m-2



PISCES-B Witness plates (D+He mixed plasmas)

Name Temperature of Target

W WIT. PL. IPP 1 373 K



CU WIT. PL. 1 393 K

Be net deposition conditions

Be net erosion conditions

Be/D co-deposition studies in PISCES


Question:Amount of D left after 1273K TDS

Question:D/Be ratio in co-deposits

D amount scales with Be content In all cases significant D left

D/Be ratio 0.1 +/- 0.05 No significant variation within the

100K target temperature range

Be/D co-deposition studies in PISCES

W ITER 1 W ITER 2 W ITER 3 W ITER 4

1E17

1E18

1E19

1E14

1E15

1E16

1E17

1E18

Be

/ cm

2

Sample ID

Be deposition case has highest D level

Significant amounts remain afterTDS also in Be net erosion case

W WIT. PL. IPP1W WIT. PL. IPP2W WIT. PL. IPP3 CU WIT. PL.11E17

1E18

1E19373 K 459 K 410 K 393 K

1E16

1E17

1E18

Target temperature

Sample ID

D /

cm-2


SIMS used for surface analysis of retrieved ASDEX Upgrade samples: samples with a diameter of 17mm were cut from tiles 5-keV O2

+ primary ion beam used for sputtering positive secondary ions detected beam rastered across a 300×430-μm2 area contributions from walls of SIMS craters eliminated using a 10-% electronic gate

and a 1-mm optical gate sputtering rates: 0.37 nm/s for W coating, 1.5 nm/s for C (graphite) bulk

6A

4

6B

5

4B 9C

9B-1 9B-2

9A

10

1

2

3A

3Bs = 83 s = 196

1 29 35 20

1a 2a

9 36 19

Redeposited mixed material in AUG

Tile 6B


analyzed tiles had 0.2 and 0.5 mm thick W coatings on them.

redeposition results in a thin surface layer (thickness < 0.5 μm).

carbon (12C) and boron are the dominant elements deposited on W, deuterium is mostly retained in the deposited layer.

6A

4

6B

5

4B 9C

9B-1 9B-2

9A

10

1

2

3A

3BInner-divertor tile 6B Outer-divertor tile 3A

Depth (m)

0 1000 2000 3000 4000 5000 6000

Inte

nsi

ty (

s-1)

100

101

102

103

104

105 HDB12C13CCrW

Depth (m)

0 1000 2000 3000

Inte

nsi

ty (

s-1)

100

101

102

103

104

105 HDB12C13CCrW

Redeposited mixed material in AUG

depth profiles of baffle tiles from 2008 campaign


W balance in TEXTORMotivation: Test of W layer deposition during plasma operation.Fluorine long-term retention in plasma-facing components

Toroidal LimiterLocation of test limiter

Toroidal Limiterpoloidal

7 cm

toro

idal

11 c

m

Test Limiter after exposure

Surface analysis bySEM, EDX, EPMASIMS, NRA, RBS

Injection of WF6 during 7 NBI heated shots

3×1019 WF6 mol/shot = 2×1020 total

Shots without injection in between shots with WF6 injection

Hydrogen flux at injection (D+, r = 47.5) ≈ 4×18 /cm²s


W balance in TEXTOR

•Similar deposition profiles on tiles from different locations.•16 % of injected tungsten found by ion beam analysis. •No fluorine found on ALT-II (important result).•No evidence of compound formation on the plates.

Injected 2×1020 100 %Local deposition:

Injection plate0.02×1020 1 %

Local deposition:

Back plate (integrated)0.134×1020 7 %

ALT-II (integrated) 0.16×1020 8 %0,00

0,50

1,00

1,50

2,00

2,50

0 5 10 15

Poloidal direction [cm]

W c

on

ten

t [

E15

/cm

2]

ALT-II 1/19

ALT-II 5/19

Toroidal limiter tile

Dep

ositi

on z

one

Eros

ion

zone

W distribution along the tiles

NiCr Fe

Fe

Ni Mo MoClMoNi

Mo Cl Ni

Fe

Cl

Ni

MoCr FeSi

CrOCr

C

1 2 3 4 5 6 7 8 9

keVFull Scale 681 cts Cursor: 0.093 (9 cts)

1

C, Cr, Ni, Fe, Mo, Sibut no W detected with EDS and EPMA

Surface after WF6 puffing experiment


Summary

Properties of mixed materials of ITER PFMs (Be, C, W) and formation ofcompounds studied under controlled conditions to establish data base onfundamental processes.Depending on temperature carbides and metallic alloys may form.Data on interdiffusion of respective species still incomplete.

Strong influence of deposited (foreign/mixed) material layers on D retention D codeposition with Be quantified

Further effort required to integrate fundamental results withplasma device data

Integrated plasma-wall modelling


Baseline Support Summary Table TA: WP09-PWI-07

*)Completed, Partially done, Not done

Task id.Associations involved

Manpower (PPY)

Status*)Short description with milestones/deliverables

WP09-PWI-07-05/CEA/BS CEA 1.25 Quantum modeling of Be/W alloy formation and reactivity

WP09-PWI-07-03/FOM/BS FOM 0.40

Material intermixing at ITER relevant fluxes in Pilot-PSI: Study of dynamic processes with C and Al (to mimic Be) on W targets.

MD Modelling of W-C-D mixed layers with HCPARCAS

WP09-PWI-07-04/FZJ/BS FZJ 0.40Characterisation of mixed W/C layers formed in TEXTOR, analysis of fuel retention in W/C mixed layers

WP09-PWI-07-05/FZJ/BS FZJ 0.50ERO code simulation of mixed layer formation, application to PISCES- B Be- seeding experiments

WP09-PWI-07-02/IPP/BS IPP 1.00 Analysis of ternary systems

WP09-PWI-07-03/IPP/BS IPP 0.20 Analysis of mixed material samples from PISCES

WP09-PWI-07-04/IPP/BS IPP 0.20Data collection of chemical compositions of mixed deposits

WP09-PWI-07-05/IPP/BS IPP 0.40MD calculations and potential development in collaboration with TEKES

WP09-PWI-07-04/IPPLM/BS IPPLM 1.25Laser ablation spectroscopy of samples from TEXTOR and AUG samples


Baseline Support Summary Table TA: WP09-PWI-07

*)Completed, Partially done, Not done

Task id. Associations involved

Manpower (PPY)

Status*) Short description with milestones/deliverables

WP09-PWI-07-01/IST/BS IST 0.10 Study of Be, W and C interdiffusion, carbide and alloy formation

WP09-PWI-07-01/MEdC/BS MEdC 0.50 Study of substrate temperature influence during film deposition in formation of stable compounds. Study of reaction kinetics for Be-C and Be-W using thermal desorption (TDS).

WP09-PWI-07-02/MEdC/BS MEdC 0.50 Study of the ternary system Be-C-W and the influence of oxygen on the system using thermionic vacuum arc method.

WP09-PWI-07-04/TEKES/BS TEKES 0.05 Analysis of W-C mixed layers on AUG tiles

WP09-PWI-07-05/TEKES/BS TEKES 1.20 MD simuation of mixed material properties and corresponding PSI processes. Coupling MD material simulation with ERO.

WP09-PWI-07-04/VR/BS VR 0.20 Studies of material mixing on surfaces exposed to plasma.

pwi tf meeting, warsaw, k. krieger, 04/11/2009 report on task agreements of wp09-pwi-07 within sewg...

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