Introduction Prediction of ITER loads and T retention A. Loarte

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IntroductionPrediction of ITER loads and T
retentionA. Loarte
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Specification of ITER Loads

• Specification of ITER loads has been reviewed
  during ITER Design Review ? update to take into
  account present physics understanding
• Particle/Power Fluxes to wall during diverted
  operation
• Redefinition of divertor controlled ELM loads
• Update of ELM divertor and wall power fluxes
• Update of disruption and VDE thermal loads
• Update of disruption and VDE EM loads
• etc.
• Revised load specifications will be used to
  redesign details of ITER PFCs (main wall) ?
  Advice from ITPA required
• Uncertainties in load specifications is
  considerable ? judgment to specify reasonable
  and non-fluctuating values

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Evaluation of T retention
in ITER

• T retention is one of the key drivers for plasma
  facing materials choice in ITER ? PFM foreseen
  strategy based on present understanding of PWI
  in ITER
• Change of CFC to W divertor to minimise T
  retention
• Prediction of T retention in ITER is a complex
  and uncertain
• Uncertain plasma fluxes and conditions
• ITER-specific issues (high Tsurf/Gplasma,
  n-irradiation, etc.)
• Formation of mixed-materials
• etc.
• Determination of fuel retention for ITER on
  present understanding, on-going RD and Hydrogen
  phase results crucial to decide on best timing
  for change of divertor plasma materials in ITER
  programme

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QDT 10 steady plasma loads (I)

• All divertor tomakaks measure plasma particle
  fluxes (II B) to the main wall
• Extrapolated plasma flux to the main wall in
  ITER 1.0 - 5 .0 1023 s-1 (1-5 of Gdiv)

Lipschultz IAEA 2000
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QDT 10 steady
plasma loads (II)

• Plasma fluxes predominantly on outer side of
  first wall
• Corresponding maximum IIB power densities up to
  5 MWm-2 (Upper X- point) to 1 MWm-2 near outer
  midplane and 0.4 MWm-2 near inner midplane

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Tolerable ELM size
QSPA experiments on NB31 targets show
Tolerable ELM energy density 0.5 MJm-2 no
broadening 21 in/out asymmetry ? DWELM
1MJ fELM 20-40 Hz ? 8000-16000 ELMs/QDT10 shot
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Wall ELM loads
Wall ELM power/particle deposition starting to be
characterised/understood ? extrapolation to
ITER uncertain
Uncontrolled ELMs in ITER? DWELM 20
MJControlled ELMs in ITER ? DWELM 1.0 MJ
Model by W. Fundamenski and R. Pitts

• Uncontrolled ELMs ? DWELM,wall 2-4
  MJControlled ELMs ? DWELM,wall 0.05-0.1 MJ
• tELM,wall ½ tELM,divertor

• AIIELM lt Afil Nfil dpol dr 10 0.25 0.1
  0.25 m-2 (A. Kirk)
• Uncontrolled ELMs ? EIIELM gt 8-16 MJm-2
  (ltqII,ELMgt 8-32 MWm-2 )
• Ewall,ELM (4o) 0.6- 1.1 MJm-2
• Controlled ELMs ? EIIELM gt 0.2-0.4 MJm-2
  (ltqII,ELMgt 4-16 MWm-2 )
• Ewall,ELM (4o) 0.01-0.03 MJm-2