1 E. Delchambre Demoncheaux Culham (22/07/08) Euratom CARBON SOURCES IN TS LONG DISCHARHES

1E. Delchambre Demoncheaux Culham (22/07/08)

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CARBON SOURCES IN TS LONG DISCHARHES

CARBON SOURCES IN TS LONG DISCHARHES


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EXPERIMENTAL SET-UPEXPERIMENTAL SET-UP


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CCD

4 fibers linked to a Czerny-Turner spectrometre

JAI CCD camera (filters wheel)

Filters wheel(Dα, C2, C+, CD)

VISIBLE IMAGING SYSTEM (1/2)

Splitter cube

Materialisation of fibre views

erosion area

erosion area

D434.0 nm

CD 430.7 nm

38799C+ 426.7 nm

wavelength

Bandwidth 15 Å

optical fibres validate filtered images

CCD and spectrometer system both calibrated in situ with labsphere


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JAI CCD camera (Dα fixed filter)

VISIBLE IMAGING SYSTEM (2/2)

fibre bundle

38056Dα

High field side

Low field side

1) Upgrade of the diagnostic: system multi – cameras simultaneous C+, Dα, CD, better spatial resolution, higher frequency acquisition and programmable exposure.

1) Upgrade of processing tool WOLFF (developped by G. Dunand & V. Moncada)

TPL view of the new system


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WOLFF (Warping toOL For Fusion) is a quantitative imaging processing tool for IR and visible cameras.

1) Superimpose on the real geometry (images from same camera with/without no filter) validate CCD with fibres

IMAGING PROCESSING TOOL

Materialisation of fibre views

erosion area

erosion area

1

23

4

Dα emission

38803 @ 6 s

2) Warping technique allows to superimpose images taken on the same object with cameras with different angle of view.

HR IR image


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α

TPL

SOL

α = 0Contact point between the limiter and the LCFS

NET EROSION ZONE

DEPOSIT ZONE

SHADOWED AREA

poloidal cut of interaction plasma/limiter

EROSION DEPOSITION PATTERN

Contact point between the limiter and the LCFS

Magnetic configuration (plasma shape & ripple) determines the toroidal heat flux pattern therefore the erosion/deposition pattern


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C sources: erosion area + leading edge + gap . Growth of deposits

CII

Ha

CII & Ha Emission Evolution

CII

Ha

Beginning of DITS campaign (+ 183 shots) End of DITS campaign

39748 @ 40 s 39931 @ 40 s


EuratomGROWTH OF DEPOSITS C2 553 nm & IR

39774 @ 40 s 39930 @ 40 s


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Need to increase acquisition rate: 1 frame/s 15 frames /sec

Tangential zone: deposition/erosion zone (consistent with with TEXTOR results on the Alt-II limiter

Material migration: dust deposited on tile

CD 39836 @ 7.9 s

CD 39836 @ 8.9 s

CD 39836 @ 9.9 s


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39800

DITSCD Emission

Zone of deposits which. consistent with TEXTOR [P. Wienhold et al., Journal of Nuclear Materials, vol.313-316 (2003) p.311-320 (2003) ]

39760 @20s 39855 @20s 39862 @20s


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disturbance from thermal photons ? No, but corelation with a local increase of Tsurf

CD Emission ?

Correlation with LH heating Supra thermal electron ? CD emission ? Need to be spectrally

resolved fiber views now looking at this area

R. Mitteau, L. Colas, Note de travail, CH/NTT-2003.003

Supra thermal electron generated by LH heating which circulate on the LCFS and might intercept deposits in the tangential area. Scaling in PLH/n for those electron experiment

Intercepted surface by electron as a function of the heat flux decay length decay length


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CII (6578A)

2,00E+18

7,00E+18

1,20E+19

1,70E+19

2,20E+19

39750 39800 39850 39900 39950 40000 40050

chocs

bri

lla

nc

e (

ph

oto

ns

/m².

s)

VD1 VD2 VD3 VD4Max of CII emission on VD1 and VD3

VD1

VD2VD3

VD4

CII emission – optical fibres views

2MW LH1.2 MW LH


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Ha (6570 A)

2,00E+20

2,50E+20

3,00E+20

3,50E+20

4,00E+20

4,50E+20

5,00E+20

5,50E+20

6,00E+20

6,50E+20

7,00E+20

39750 39800 39850 39900 39950 40000 40050

chocs

Bri

llan

ce (

ph

oto

ns/

m².

s)

VD1

VD2

VD3

VD4

Highest D photon flux on deposits zone and an increase of 20 %

Ha emission – optical fiber views

2MW LH1.2 MW LH

Modification of the recycling coefficient at the surface ?Modification of the release mechanism ? not straightforward need clarification.

VD1

VD2VD3

VD4


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[S/XB] Hα = (15-20) * 2 (molecular contribution) = 30

[S/XB]CII (5678A) = 10

Total erosion yield of about ~ 2 % on net erosion area. No variation observed during the campaign

Erosion yield (Ha & CII 658 nm)

VD1

VD2VD3

VD4

Low signal. Long integration time Ychem = CD/Dg < 1 %

Difficult to conclude on chemical erosion contribution

[S/XB] Hγ = 1000

[D/XB] CD = 2.8*25 (Te~20-30eV) = 65


EuratomCONCLUSIONS

Carbon sources identified on erosion zone, leading edge and radial gap tiles.

Growth of deposits observed in CII, CD and Dα with highest Hα emission on deposits which increases during the campaign.

Strong radiative activity in tangential area observed with CD filtered during LH heating probably related to flaking of deposits in this region need spectrally resolved observation with new fibres views

Ytot deduced from CII(568nm)/Hα ~ 2 % BUT no comparison available with CII(426nm)/Dγ since issues with CII lines mentionned yesterday was highlited after DITS campaign Issue under investigation


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ADDITIONAL SLIDESADDITIONAL SLIDES


EuratomRADIAL PROFILES

Physical erosion seems dominent

CIICD

Dγ


Euratom[S/XB] CII426nm, CII658nm (ADAS)

CII 658 nm

CII 426 nm

Documents

1 E. Delchambre Demoncheaux Culham (22/07/08) Euratom CARBON SOURCES IN TS LONG DISCHARHES