Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 1

EU-PWI Task Force &

EFDA Plasma Edge Technology Programme

Alberto Loarte, Joachim Roth, Emmanuelle Tsitrone

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 2

Outline

1. Background to EFDA Plasma Edge Technology Programme and Integration with EU-PWI Task Force

2. Description of Existing Tasks & Status Details to be found in http://efdasql.ipp.mpg.de/efdatpp

3. Tasks Launched in 2006 Programme

4. Discussions of Priorities for 2007 Programme (new EFDA)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 3

Background

Need of fundamental Understanding of PWI Processes

Well defined Laboratory Experiments

Specific Modelling and Extrapolation to ITER

Contributions from Associations without voluntary Physics Programme

Financial Volume (2005): 1.3 M€(20% sub.) 5.1.a, 475 k€(40% sub.) 5.1b

(Financial Volume (2006): 3.4 M€(20% sub.) 5.1.a, 285 k€(40% sub.) 5.1b)

EU Task Force aims to better integrate Technology and Physics Aspects of the EFDA Plasma Edge Technology Programme

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 4

Integration with EU-PWI TF Topics (I)

Tasks in 2002/2003/2004/2005

1. Erosion behaviour

Chemical Erosion of C by D/Be, TW2-TPP-ERDEP (√) (EU-US)

Sputtering of W and Be, TW3-TPP-ERTUBE (√) SEWG

Chemical Erosion of C, TW4-TPP-ERCAR (√) SEWG

C/W/Be mixed-material formation, TW5-TPP-CARWBER (EU-US)

2. Material transport and re-deposition

Flake Formation from Deposits, TW2-TVM-CFC2 (√)

Scavenger Technique, TW3-TPP-SCAVOP (√) SEWG

CxHy Formation and Re-deposition in ITER Geometries TW4-TPP-TRIDEP (√)

Erosion/deposition metal wall + C divertor TW5-TPP-TILCAR (√)

Midplane and Divertor W macro-brush studies in ASDEX-Upgrade (√)

UT4-TUNAUG & UT5-MBWAUG

(√) Already reported at previous meetings (√) Reported this year

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 5

Integration with EU-PWI TF Topics (II)

3. Fuel recycling, retention and removal (2 SEWGs)

Optimisation of He-O Glow for C-H removal, TW5-TPP-HEGLO (√)

T removal by non-O2 oxidative methods, TW4-TPP-TRIREMA-B (√)

Characterisation of Oxidised PFCs, TW5-TPP-TILCAR (√)

4. Off-normal heat loads (SEWG)

Modelling of Disruptions and ELMs, TW3-TPP-DISELM (√)

Validation of ELM Damage Modelling, TW3-MATDAM (√) (EU-RF)

ELM-Disruption exposed Target Characterisation, TW4-TARCAR (√) (EU-RF)

W and CFC damage and plasma evolution in ITER, TW5-TPP-ITERTRAN (√)

Modelling of Be damage under Disruptions/ELMs, TW5-TPP-BEDAM (EU-RF)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 6

Integration with EU-PWI TF Topics (III)

5. Edge modelling, erosion and deposition modelling

Improvements to ERO Code and ITER Modelling, TW3-TPP-ERMOD (√)

MD Modelling of Erosion Processes, TW4-TPP-CARWMOD (√)

W Erosion and Edge Plasma Contamination in ITER, TW5-TPP-TUNMOD (√)

6. Edge and SOL physics

Improvements to B2-Eirene for ITER Modelling, TW3-TPP-NEUTMOD (√)

Modelling of n-n and n- effects in ITER divertor, TW5-TPP-ITERNEUT (√)

7. Task force relevant diagnostics

Speckle Interferometry for Erosion, TW0-T438/01 (√)

Laser Ablation Techniques for Film Deposition, TW3-TPP-ERDIAG (√)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 7

Description of Tasks and Status (I)

ERTUBE : Exposure of W macro-brush elements to plasmas & fuel retention in TEXTOR and FTU

W & Mo macrobrush limiters have been exposed to TEXTOR plasmas in the far SOL (deposition studies) and at separatrix for power load studies

W macrobrush is

effective in preventing melt layer

loss caused by jthermX B

forces

D deposition inside brush correlated with C deposition with typical decay lengths of ~ 2 mm

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 8

Description of Tasks and Status (II)

ERTUBE : Exposure of W macro-brush elements to plasmas & fuel retention in TEXTOR and FTU

W macrobrush probes have been exposed to C-free plasmas in FTU limiter

Surface contamination by C during macrobrush manufacturing most

likely cause of larger than expected retention

D retention determined by outgassing and typically ~10-4 of the incident flux

(low but ~ 10 times larger than expected)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 9

Description of Tasks and Status (III)

TW4-UT4-TUNAUG & TW5-UT5-MBWAUG : Exposure of W macro-brush element in the SOL and divertor in AUG

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 10

Description of Tasks and Status (IV)

ERCAR : Characterisation of thermal response of Carbon PFCs exposed to plasmas and of CFC under repetitive laser loads

AUG samples have been characterised Samples from erosion dominated areas maintain unexposed properties Samples from deposition dominated areas covered by low conductivity layers

Exposure of NB31 to 1000 under threshold laser loads does not cause deterioration of thermal

properties nor observable surface damage

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 11

Description of Tasks and Status (V)

TILCAR : Characterisation of erosion/redeposition in divertor tokamaks

Marker coating on 3 divertor and 4 limiter tiles produced for AUG 2006

campaign(C- 2 m, W-3 m on Re interlayer)

Size of 13C deposition depends on substrate (12% on C, 6% on W)

12 % of injected 13C Divertor 11% of injected 13C Inner wall

Analysis of long term erosion/deposition in AUG carried out In 2004 13CH4 (1.4 1022) was puffed at outer midplane in 5 SN Type l ELMy H-modes in H

Measurements provide basis for understanding of erosion/deposition

balance in divertor tokamaks

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 12

Description of Tasks and Status (VI)

UT4-TUNAUG/UT5-TUNAUG : Development and testing of W coatings for AUGW coated (200 m) tiles installed at

ICRH protection limiter in 2004/2005

Thermal cycling and tests in ASDEX Upgrade still outstanding

Delay caused by wrong interlayer (Cr vs.Re) used in first coating series (Plansee)

Coatings delaminated (wrong C surface treatment) & W melted under power load but only minor restrictions

to plasma operations

New W coatings with high and low porosity developed (180-210 m) and screen-tested

in GLADIS facility to 23.5 MWm-2

0 2 4 6 81000

1500

2000

2500

16.2 MW/m²

6.5 MW/m²10.8 MW/m²

4.2 MW/m²

23.5 MW/m²

density 95% bulk W90% bulk W

pulse length (s)T

surf (

°C)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 13

Description of Tasks and Status (VII)

TRIDEP : CxHy formation and deposition in remote areas (PSI-2) Deposition experiments in Ar show larger rates than state-of-the-art ERO modelling CH emission shows unexpected local patterns at higher <ne> (influenced by Vbias) Experiments to quantify H erosion of C-H re-deposits carried out

CH emission ne = 2.0 1017 m-3

CH emission ne = 2.5 1018 m-3

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 14

Description of Tasks and Status (VIII)

HEGLO : Removal of hydrocarbons by He/O2 plasmas in TEXTOR and ASDEX Upgrade + TILCAR : Characterisation of TEXTOR He/O2 exposed components HeO GDC applied to TEXTOR C removal rate of 2.0 1019 C/s weakly dependent on He concentration (30-100%) Recovery : weekend D2 GDC + Boronisation ICRH HeO discharges Most C released after ICRH pulse, with 1:10 duty cycle similar rates to HeO GDC antenna pressure + pumping limits removal Recovery : overnight D2 GDC

Technique C removal rate

Oxygen venting2.5·1018 C/s for 0.3mbar, Twall=620K

Glow discharge conditioning

2-3·1019 C/s

ICRF conditioning1.8·1019 C/s for 1:10 duty cycle for pump out

Integral TEXTOR carbon redeposition rate 2.7·1020 C/s

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 15

Description of Tasks and Status (IX)

HEGLO : Removal of hydrocarbons by He/O2 plasmas in TEXTOR and ASDEX Upgrade + TILCAR : Characterisation of TEXTOR He/O2 exposed components

Laboratory prepared a:C-D layers and in-situ boronised layers (a:B-D-C layers) were exposed to HeO GDC (removal rate > 1014 C cm-2s-1 = 0.1 m/h) for a:C-D layers D removal rates from a:B-D-C layers are a factor of ~ 10 lower than from a:C-D layers

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 16

Description of Tasks and Status (X)

HEGLO : Removal of hydrocarbons by He/O2 plasmas in TEXTOR and ASDEX Upgrade + TILCAR : Characterisation of TEXTOR He/O2 exposed components HeO GDC on a:C-H layers & AUG layers : D removal from real films ~ 10 times lower than for lab films = 1013 C cm-2s-1 = 0.01 m/h. No removal of deposits in ~ 3 mm gaps Oxidation of W reversible by exposure to H Tests in AUG consistent with lab tests but arcing problems due to B layers on W (C removal rate of 6.0 1018 C/s)

0 20 40 600

1

2

3

4

5

6

7

oxyg

en c

over

age

(1016

cm

-2)

exposure time (min)

W coatings polished W

O2 ECR plasma, -200 V bias

H2 plasma

after before

HeO GDC laboratory tests with real AUG tiles HeO

GDC in AUG

showing arc

traces

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 17

Description of Tasks and Status (XI)

TRIREMA : O3 oxidation of hydrocarbon deposits in ITER-relevant conditions

Oxidation in ozone achieves rates within the ITER requirements (1 mh-1) and operating temperature (T < 250 oC) for fusion application graphites Rates of 0.5 mh-1 achieved for TEXTOR flakes Main problem is that oxidation rates of flakes and substrate are similar

~ 1 mh -1

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 18

Description of Tasks and Status (XII)

TRIREMB : Removal of fuel with alternative methods and comparison to O2

Oxidation by O2/ Nitric Oxide (NO) of Hard Films & TEXTOR flakes (H/D>>1) shows that NO oxidation is slower than O2 and does not produce H2 (260 oC @ 2 torr)

Isotope interchange on flakes from ASDEX Upgrade activated by H2O2 does not occurActivation of samples

with H2O2 + H/D interchangeCandidate reaction :

NO + H NOH + H NO + H2 Some

production of CO with NO but

no enhanced production of H2

H2O2 treated AUG flakes in H2 1 bar atmosphere show release of H2, DH and D2

at similar temperatures than in TDS

H2O

H2

D2DHO

D2O

HD

TDS

T(K

)

HD D2

H2

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 19

Description of Tasks and Status (XIII)

MATDAM : Validation of ELM Damage Modelling Experiments carried out in TRINITI plasma guns CFC and W targets exposed to 100 pulses at 0.5, 1.0, 1.5 MJ/m2 t = 500 s (two higher levels beyond melting of W and sublimation of C) Analysis of target damage on-going (completed for 0.5 & 1.0 MJ/m2) TARCAR

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 20

Description of Tasks and Status (XIV)

MATDAM : Validation of ELM Damage Modelling

CFC Damage is driven by preferential erosion of material above PAN fibres (fibre-matrix detachment) overheating an brittle destruction of material

W macrobrush damage threshold melting of castellations’ edges + layer displacement

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 21

Description of Tasks and Status (XV)

TARCAR : Characterisation of ELM-disruption damage modelling

Analysis of CFC & W targets exposed to 100 small ELM ITER-like pulses in TRINITI plasma guns CFC enhanced erosion of PAN fibres & fibre detachment already at 0.6 MJm-2 W macrobrush shows edge melting and significant surface cracking at 0.8 MJm-2)

Before exposure

Crack formationat edges of

bundles

PAN fibre erosion

~ 1.0 MJ/m2

Pla

sma

stre

am

Before exposure

~ 0.9 MJ/m2

Edge W melting+ displacement

Cracking of W surface

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 22

distance alonge target (cm)

Po

sitio

na

tth

ein

clin

ed

surf

ace

(cm

)

5 6 7 8 9 10 11 12 13-3.0x10-05

-2.0x10-05

-1.0x10-05

0.0x10+00

1.0x10-05

2.0x10-05

3.0x10-05

Q=0.6

GW/m2Q=

2.1GW/m2

Q=0.8

GW/m2

Q=1.1

GW/m2

Q=1.3

GW/m2

Q=1.5

GW/m2

Q=1.8

GW/m2

=0.5o

=1o

=1.5o

=2o

=2.5o

= 3o

Description of Tasks and Status (XVI)

ITERTRAN : Improved concepts for reduction of W and CFC damage + plasma evolution in ITER after ELMs

Optimisation of macrobrush geometry shows that minimum damage by melting and displacement is obtained with ~ 0.5 (gap shadowing effective area)

Modification of CFC structure to avoid PAN fibres parallel to surface decreases erosion damage (increases threshold energy for damage) by ~ 5 for 45o

Inclination angle of flat surface

Su

rfa

cero

ug

hn

ess

(cm

)

1 2 3 4

0.0x10+00

2.0x10-05

4.0x10-05

6.0x10-05

8.0x10-05

1.0x10-04

Q=2.1 MJ/m2, = 3o

Q=2.1 MJ/m2, = 5o

t = 0.5 ms

EELMmax= 0.5 MJm-2t = 0.1 ms

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 23

Description of Tasks and Status (XVII)

ITERTRAN : Improved concepts for reduction of W and CFC damage + plasma evolution in ITER after ELMs

Transient evolution of plasma discharge after ELMs in ITER refined : modelling ELMs by an increase of anomalous transport of factor ~ 10

Even for EELMmax < 1 MJm-2 t ~ 300 s significant carbon production and expansion

along the field with npedC ~ 5 1020 m-3 after 2 ms Prad modelling in progress

nC aftert ~ 500 snC aftert ~ 1.5 ms

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 24

Description of Tasks and Status (XVIII)

TUNMOD : W erosion and edge plasma contamination in ITER W concentrations remain under 2 10-5 for any coverage level by W in ITER and high

density operation (weakly influenced by seeding, Danomalous & parallel flows) W concentrations during the limiter phase can reach very large values > 1 % unless

Te,limiter < 50 eV without impurity seeding (W self-sputtering runaway)

Low ne,sep

High ne,sep

nAr/nee ~ 0.1 %

Zeff ~ 1.3

nW /nee ~ 1%

(no self-sputtering)

nW /ne ~ 10%

(with self-sputtering)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 25

Description of Tasks and Status (XIX)

ITERNEUT : Modelling of n-n and n- effects in ITER divertor Nonlinear effects (n-n & n-) and improved D2 kinetics introduced in B2-EIRENE Opacity increases plasma density but total divertor source remains constant (larger

recombination) different divertor dynamics but same divertor pressure Main impact on the ITER divertor caused by n-n and D2 + D+ collisions (larger PDT for

same peak divertor power load)

• Sionexcited > Sion

conventional

nD = 5 1020 m-3 R-target recycling

VR-volume recombination

I: ionization (total)

Iph: photo-induced ionization

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 26

New Tasks in 2006 (I)

1. Material erosion and transport

Erosion/Deposition in divertor tokamaks, TW6-TPP-CARTIL Material erosion and transport in ITER-like conditions, TW6-TPP-ERDEP Hydrocarbon sticking properties, TW6-TPP-CNDMSTICK

2. Fuel retention and removal

Fuel removal from macro-brush structures, TW6-TPP-GAPOX Fuel retention in mixed-materials, TW6-TPP-RETMIX Fuel retention in ITER metallic PFCs, TW6-TPP-RETMET

3. Transient heat loads and control

Experiments on W & CFC under-threshold damage, TW6-TPP-REPELM Modelling of PFC damage and plasma evolution in ITER, TW6-TPP-DAMTRAN Analysis of Be-coated/Be-clad PFCs exposed to plasma guns, TW6-TPP-ANABE Coating by Be of W/CFC PFCs, TW6-TPP-BECOAT

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 27

4. PWI and ITER modelling

Modelling of mixed-materials formation, TW6-TPP-BETUNCMOD Modelling of erosion/redeposition balance in ITER, TW6-TPP-ERITERA-B 3-D modelling of SOL transport in ITER, TW6-TPP-SOLITER Modelling of ITER far SOL plasma (for ICRF coupling), TW6-TPHI-ICFCOUPL

5. Dust production and removal

Evaluation of dust generation mechanisms in tokamaks, TW6-TPP-DUSTGEN

6. Task force relevant diagnostics

Tests of dust measurement techniques in tokamaks, TW6-TPP-DUSTMEAS

New Tasks in 2006 (II)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 28

Money matters : History and Facts

Budget allocated for TPP area of EFDA Technology programme roughly constant since 2003

Real allocated budget increases with time (by a factor of 3-4 in 2006 !!!)

Increase of requested/allocated budget reflects interest of EFDA management on PWI issues + the good work of EU-PWI Task Force!!

2003 2004 2005 20060

500

1000

1500

2000

2500

3000

3500

Oficial Budget Real Budget

Year

Art

icle

5.1

.a (

kEu

ros

@ 2

0%

su

bsi

dy)

EFDA Plasma Edge Technology Programme Budget

0

100

200

300

400

500

600 Article

5.1

.b (kE

uro

s @ 4

0%

sub

sidy)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 29

Some ideas for 2007

Mixed Materials Studies development of techniques for T

removal from mixed materials

In-situ & spatially resolved diagnostic for erosion/redeposition

measurements

Diagnostics for in-situ T retention measurement

Techniques for dust removal in tokamaks

More ideas ?

EFDA-PISCES-B collaboration

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 30

EFDA-PISCES-B collaboration

EFDA-PISCES-B collaboration research topics in 2007 Studies of CD4 seeding in Be containing plasmas impacting on a C and

W target in steady state and under pulsed loads Studies of Be layers on W targets under steady and pulsed loads Studies of He/Ne/Ar interaction with C and W targets with Be-seeded plasmas Studies of redeposition in the witness plate (D content, changes in reflectivity of mirrors ?, etc.) during these experiments

EFDA will provide long term (~ 1 year) scientist to participate in experiments (mission expenses covered by Euratom mobility) :

Young dynamic and enthusiastic experimental physicist (post-doc) Knowledge of surface analysis and/or spectroscopic techniques To become Be worker (non-smoker & no beard) CV to be sent to A. Loarte by 31-12-2006 Selection by 30-1-2007 Start date in PISCES-B by spring 2007 (one month test period possible)

Alberto Loarte EU Plasma-Wall Interaction Task Force Meeting – Jozef Stefan Institute 13-15 – 11 – 2006 31

Conclusions

EFDA TPP Technology Programme is well integrated with EU-PWI Research Programme and producing ITER-relevant results

As recognised by EFDA and ITER management

Two major EFDA Collaborations with US (PISCES-B) and RF (TRINITI) on-going New large collaboration approved with RF (Kurchatov +TRINITI) on

Be damage under ITER transient loads EU staff to collaborate in-situ in the experiments (Euratom Mobility) + EU industry to provide targets (+ Be coated targets by MEdC) + destructive analysis of targets to be done in EU labs

Many Associations involved : CEA, CIEMAT, ENEA-Frascati, ENEA-

CNR Milano, FOM, FZJ, FZK, IPP, IPP.CR, IST, MEdC, MHST,

ÖAW, TEKES and VR