Prsentation PowerPoint

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Visible imaging and DED resonance analysis
F. Dubois1), E. Dufour1), M. Lehnen2), P.
Monier-Garbet1), A. Pospieszczyk2),
G. Sergienko2), G. Telesca3), B.
Unterberg2), G. VanOost3) 1)
Association Euratom-CEA sur la fusion Contrôlée,
DSM/DRFC/SIPP, Centre dÉtudes
de Cadarache, 13108 Saint-Paul-lez-Durance,
France. 2) Institut für
Plasmaphysik, Forschungszentrum Jülich,
EURATOM Association, TEC, Jülich,
Germany. 3) Department of Applied
Physics, University of Gent, 9000 Gent, Belgium.
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Outline

• DED resonance in the 12/4 configuration
• What do we expect in terms of particle
  screening?
• Experimental results on Textor analysis of
  visible imaging diagnostic

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Resonance in the 12/4 configuration
Resonance is obtained for the plasma equilibrium
for which, in magnetic coordinates (q, j) ?
maximum deviation of the magnetic
field lines in front of the divertor ?maximum
effect on the plasma edge parameters
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The width of the edge region for which sgt1 is
3cm
Ip450kA qedge2.6

• comparable to
• the e-folding length of the perturbation

Chirikov parameter
acoil
? near field effects might be dominant
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Resonance is a local extremum of s
Equilibrium
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What do we expect in terms of particle screening?
? atomic physics lengths have to be compared to
width of the perturbed region
1.5 eV ? 4cm 20 eV ? 15cm
Deuterium ne2e18 m-3 Te
15eV

• Ionization length (?i) gt width of the perturbed
  region
• the perturbed region is transparent to D neutrals
  
• only a small effect on D screening may be expected

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• DED resonance in the 12/4 configuration
• What do we expect in terms of particle
  screening?
• Experimental results on Textor analysis of
  visible imaging diagnostic

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Experimental scenario Ip scan
12/4 configuration
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As expected, small pump out effect is observed as
DED is turned on
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Diagnostics CCD cameras
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IDED13kA, q scan
Da recycling is modulated by the DED coils
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The period of the modulation is controlled by
qedge
q3.4 (350kA), no DED
IDED13.0kA q4.0 (300kA) q3.0 (400kA) q2.6
(450kA)
p
Poloidal extension of the DED coils
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IDED13kA, q scan
DED controls the inner wall C sources
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CIII emission gives an indication of the Te map
(possible laminar effects)
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Conclusion

• ? Calculation of the Chirikov parameter indicate
  that
• the perturbed region is narrow (lt liD , the
  perturbed region is expected to be marginally
  transparent to neutrals)
• near field effects might be dominant

• ? Actually, observations show
• small D pump out effect
• DED controlled Da modulated emission
• possible laminar effects are indicated by CIII
  emission

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Da brightness
p
Poloidal extension of the DED coils