PowerPointPrsentation

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• Report on European Task Force on Plasma Wall
  Interaction, period 2003-2005
• V. Philipps, J . Roth, A. Loarte
• on behalf of the EU- PWI TF members
• scientific case for the TF
• organisation and working structure
• selected PWI topics
• outlook

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scientific case for the TF
EU PWI Task Force
Plasma Wall Interaction First EU Task Force
(formed end of 2002)
V.Philipps, STAC,Spetmber 2005
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scientific case for the TF
EU PWI Task Force
- Motivation for the TF - Critical PWI topics
and - EU-PWI-TF work programme Follow directly
from the first wall material selection
700m2 Be first wall 100m2 Tungsten 50 m2
Graphite CFC
ITER
Present ITER material choice is the result of
long experiences in fusion research
V.Philipps, STAC,Spetmber 2005
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scientific case for the TF
EU PWI Task Force
Main rationale for this choice is to guarantee
access to a broad range of plasma scenarios and
to validate the predictions for Fusion power,
confinement, MHD stability, ELM behaviour, ITB
current drive, disruptions, Power particle
exhaust etc The demonstration of fusion power
production is a main goal of ITER and a major
step in fusion research In the past, selection
of first wall materials was determined by
optimisation of plasma performance and flexibility
V.Philipps, STAC,Spetmber 2005
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scientific case for the TF
EU PWI Task Force

• ITER will have
• much longer timescales and thus larger particle
  fluencies
• much larger power densities in transients
• energy input 1 ITER pulse about 0.5-1 JET years
• ion fluence 1 ITER pulse about 4 JET years
• stored energy ITER about 100 x JET
• ? wall lifetime (erosion, sublimation, melting
  )
• long term T-retention
• become critical ? focus of EU-TF

V.Philipps, STAC,Spetmber 2005
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Organisation work structure
EU PWI Task Force

• Contact Persons in associations.
• Definition of common experiments and data
  analysis
• Special working groups meetings (SEWG)
• General TF meetings (4)
• All reports and information on the PWI TF Web
  site
• http//www.efda-taskforce-pwi.org

Institution
Contact Person
CEA-
Cadarache
T.
Loarer, E.Tsitrone
CIEMAT
F.
Tabarés
CNR-
Milano
F.
Ghezzi
CRPP-
Lausanne
R. A.
Pitts
EFDA-CSU
Garching
A.
Peacok
ENEA-
Frascati
G.
Maddaluno
FOM
N. Lopes-
Cardozo
FZ-
Jülich
Ph.
Mertens
FZ-
Karlsruhe
I.
Landman
IPP-
Garching
A.
Kallenbach
IST-Lisbon

C. Silva
ITER-IT
G.
Federici
Jozef Stefan
Institute-Ljubljana
I.
Cadez
NRG-
Petten
J.G. van
der
Laan
ÖAW-EURATOM association
T.
Märk
Royal Institute of Technology
M.
Rubel
Stockholm-VR
TEKES
J.
Likonen
UKAEA
G.
Counsell
Slovenia and Poland newly integrated in TF work
Radomir Panek
IPP Prague
V.Philipps, STAC,Spetmber 2005
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Organisation work structure
EU PWI Task Force
Definition of common experiments and data
analysis

• 1
• Co-ordinated research in associations
• Fusion devices
• linear plasma machines
• lab experiments

• 2
• EFDA edge technology PSI programme
• specific tasks
• integration of work outside associatio.

3 Integrated wall experiments in fusion devices
V.Philipps, STAC,Spetmber 2005
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Organisation work structure
EU PWI Task Force
Work plan has been defined for each association
topic
association
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Organisation work structure
EU PWI Task Force

• Seven working areas defined
• Erosion behaviour and impurity location
  (SEWG) ?short report
• Material transport and re-deposition ? short
  report
• Fuel recycling, retention and removal (2 SEWG)
• Transient heat loads (SEWG) ? short report
• Edge erosion and deposition modelling
• Edge and SOL physics
• Task force relevant diagnostics
• TF duty summarise the knowledge, coordinate the
  research, initiate new work and aim for solutions

V.Philipps, STAC,Spetmber 2005
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Special working groups
EU PWI Task Force
Chemical erosion S. Brezinsek (FZJ) Gas balance
T. Loarer (CEA) Fuel removal G.
Counsell (UKAEA) Transient heat loads A. Loarte
(EFDA)
V.Philipps, STAC,Spetmber 2005
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1. Erosion behaviour location
EU PWI Task Force

• carbon chemical erosion (special working group,
  SEWG)
• work in JET, AUG, TEXTOR , PSI Berlin, Tore
  Supra, Pisces,
• effect of Be deposition on carbon and tungsten
  erosion and transport (EU-Pisces co-operation)
• work in Pisces and IPP Garching (lab)
• supporting tasks on chemical C-erosion,
  sputtering of W and Be
• Ciemat, Enea, IPP Garching, FZJ
• impurity production in the main chamber
• JET , AUG

V.Philipps, STAC,Spetmber 2005
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2. Erosion behaviour location
EU PWI Task Force
Chemical C- erosion (Chairman S.
Brezinsek) Guiding question what will be the
chemical erosion of the ITER CFC target?
FZJ Erosion at test limiters in TEXTOR (high
fluxes) , D/XB calibration, ERO code
modelling IPP Synergistic erosion of Ho with
inert gases Erosion mitigation due to metal
doping Erosion and deposition in ASDEX
Upgrade Erosion and deposition in PIS-2 UKAEA
chemical erosion at JET CEA Chemical erosion
on neutraliser plate CIEMAT Influence of N2
on C-erosion/deposition collaboration through
ITPA JT60-U,DIIID Chemical erosion at divertor
plates PISCES-B Influence of Be seeding
V.Philipps, STAC,Spetmber 2005
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2. Erosion behaviour location
EU PWI Task Force

• In-situ calibration mass/optical spectroscopy
• Temperature normalisation to Tmax
• Ion energy normalisation to 30 eV

• Description of Y as function of
• Ion energy
• Surface temperature
• Ion flux
• ? Low yields under ITER divertor conditions
• Further decrease by Be deposition expected
• Still open questions
• e.g. redeposited layers, dependence on structure
  ..

V.Philipps, STAC,Spetmber 2005
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Introduction
2. Erosion behaviour location
EU PWI Task Force
EU-DOE collaboration at PISCES B,
UCSD Dependence of carbon chemical erosion on
deposited Be

• For steady state conditions Large (80) decrease
  of C-erosion for comparable small Be plasma
  (upstream) concentrations (0.15 )
• need further confirmation and modelling
• thermal stability of Be layers important issue
  for ITER

V.Philipps, STAC,Spetmber 2005
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2. Erosion behaviour location
EU PWI Task Force
Main publications Methane fuelling in the JET
MkIIGB divertor A. Huber, et al., Physica Scripta
T111 (2004) 101 Chemical Erosion Measurements by
Spectroscopy S. Brezinsek, et al., Physica
Scripta T111 (2004) 42 Molecular carbon sources
in JET S. Brezinsek, et al., accepted by J.
Nuclear Materials (2004) Modelling of carbon
transport in JET and implications for ITER A.
Kirschner, accepted by J. Nuclear Materials
(2004) Influence of Beryllium on the erosion of
Carbon K. Schmid, M. Baldwin, R. Doerner,
accepted by J. Nuclear Materials (2004) Flux
dependence of chemical erosion J. Roth, et al.,
Nucl. Fusion 44 (2004) L21-L25 Modelling of
tritium inventory in ITER J. Roth, et al.,
accepted by J. Nuclear Materials (2004)
V.Philipps, STAC,Spetmber 2005
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3. Material transport and re-deposition
EU PWI Task Force

• A main research topic of EU PSI TF
• global and local material transport ways
• (JET, AUG , TEXTOR, Tore Supra)
• quantitative erosion/deposition balances
• (JET, AUG, Tore Supra, TEXTOR)
• dedicated deposition studies
• (Quartz detectors, sticking monitors,
  temperature dependence (JET, AUG,TEXTOR,PSI
  Berlin )
• migration to gaps and hidden areas
• (JET, AUG, TEXTOR..)
• erosion /deposition in the main chamber

V.Philipps, STAC,Spetmber 2005
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3. Material transport and re-deposition
EU PWI Task Force
1. Fusion devices AUG JET TEXTOR
Tore Supra 2. Linear PSI devices PSI 2
Berlin PISCES B 3. Other associations
involved through post mortem surface and tile
analysis VR Stockholm Tekes CNR
Milano IFPILM Warsaw Jozef Stefan
Institute-Ljubljana
V.Philipps, STAC,Spetmber 2005
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3. Material transport and re-deposition
EU PWI Task Force
Significant progress in understanding material
migration
e.g. AUG
e.g. JET
Be deposition
Quartz monitor
C deposition
louvre

• carbon is transported stepwise
• final deposition pattern determined by
  different plasma configurations
• no significant long range transport of Be

• deposition decreases with temperature
• results from re-erosion by D-atoms

V.Philipps, STAC,Spetmber 2005
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Material transport and re-deposition
EU PWI Task Force

• Along wetted areas, C is effectively transported
  along surfaces by multi-step chemical erosion
• Effective C- transport can lead to significant
  deposition in gaps (depending on geometry )
• C deposition (in shadowed areas) is mainly by
  high sticking species, thus line of sight, a
  small part migrates longer distances
• Be does not show long range transport
• ? ITER C will be transported from the upper SOL
  down along the target, part trapped in gaps and
  part escape from the strike point region towards
  the dome
• Be (deposited from main chamber) will be also
  transported from the upper SOL to the strike
  point region but mostly not escape and remain
  there

V.Philipps, STAC,Spetmber 2005
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4. Transient heat loads
EU PWI Task Force
Special working group Chairman Alberto
Loarte IPP Garching G. Pautasso, A. Herrmann,
T. Eich JET V. Riccardo, J. Paley, P.
Andrew UKAEA G. Counsell FZJ K.H.
Finken FTU G. Maddaluno ITER G. Federici
V.Philipps, STAC,Spetmber 2005
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4. Transient heat loads
EU PWI Task Force

• Characteristics of transient heat loads has a
  major impact on target design and materials
• Present specifications for disruptions in ITER
• W th.que. Wth 350 MJ
• Energy quench time 1 ms
• power deposition ?Pdisr 3 ?Ps.s. , toroidally
  uniform

V.Philipps, STAC,Spetmber 2005
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Transient heat loads
4. Transient heat loads
EU PWI Task Force
Recent results from JET and AUG
JET
Riccardo
AUG
Pautasso
Before the thermal, quench the plasma has lost a
large part of its energy Typical Wt.q. /Wmax
0.25 0.12 for JET 0.40 0.22 for ASDEX
Upgrade
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4. Transient heat loads
Larger broadening seen in most experiments AUG,
MAST, JET ITER assumptions too pessimistic.

• Best assumptions presently
• Wt.q. (0.25 0.12) Wth
• tt.q. (2.3 1.8) ms
• ?Pdisr (7.5 2.5) ?Ps.s.

For the average disruption load a factor of 100-
200 more disruptions are tolerable compared to
the ITER reference assumptions
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Wall material experiments
EU PWI Task Force

• PSI tokamak experiences are mainly with graphite
  walls
• no or little experiences on
• T retention with the ITER like material choice
• Operation performance with metallic walls
• Plasma behaviour with high Z first walls
• Melt layer behaviour
• More integrated fusion experiments with non
  graphite, metallic wall materials are needed
• ? ASDEX-U tungsten first wall experiment
• JET ITER like Be / W / C wall experiment

V.Philipps, STAC,Spetmber 2005
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Wall material experiments
EU PWI Task Force
JET with Be wall and all Tungsten divertor

• Objectives
• Demonstrate low T retention
• Study effect of Be on W erosion
• Study ELMs and disruptions on wall divertor,
  melt layer behaviour
• Develop control / mitigation techniques for
  ELMs and disruptions
• Test de-tritiation techniques
• Operate tokamak without C - radiation

Demonstrate operation of ITER scenarios at high
current and heating power with Be/W wall choice
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Wall material experiments
EU PWI Task Force

• Objectives
• Similar to an all W divertor but including carbon
  chemistry
• Effect of Be deposition on carbon release and
  transport
• Study of Be/C(W) layers, their thermal
  stability, T-retention
• demonstrate that an ITER-like material selection
  has sufficiently low fuel retention to meet ITER
  requirements.

Full Be wall with ITER like Carbon/tungsten
divertor
Demonstrate operation of ITER scenarios at high
current and heating power with Be/C/ W wall choice
STRATEGY Prepare both options, decide options
depending on requirements
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Wall material experiments
EU PWI Task Force
AUG stepwise implementation of a full tungsten
FW

• Objectives
• Erosion, deposition migration in a W/C
  environment
• Behaviour under transient heat loads
• Hydrogen retention behaviour
• Impurity seeding to replace intrinsic C
  radiation
• Development of W diagnostics

Compatibility of W first wall with all relevant
operation scenarios
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• Strategies for ITER aiming for a maximum
  flexibility (1)
• Divertor prepare a CFC and a full tungsten
  divertor in parallel
• Decide the ITER divertor for the Tritium phase
  depending on
• transient power losses
• ELM disruption control
• melt layer behaviour
• fuel retention
• in the H-phase
• ? need adequate diagnostic to detect fuel
  retention and material deposition rates in the H-
  phase

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• Strategies for ITER aiming for a maximum
  flexibility (2)
• First wall material choice strong effort needed
  on
• characteristics of first wall PSI (steady state,
  ELMS..
• fuel retention removal with the present ITER
  materials choice
• (JET ITER like wall experiment)
• plasma behaviour with high Z walls
• (AUG FW W experiment)
• ? Keep the possibility to change the first wall
  

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Work of the EU PSI TF should continue
Effectivity can be improved PSI-EFDA technology
programme should be kept/ enlarged, effective way
to keep work together Benefit from different
expertises in EU- associations can be more
optimised (e.g. for diagnostics, post mortem
surface analysis, engineering, etc..) Stronger
EFDA financial support for execution of
TF-work-programme (e.g. meetings, defining
mobility..) General PSI programme of the
associations should concentrate on commonly
defined important experiments in EU fusion devices