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

2 E. Delchambre Demoncheaux Culham (22/07/08) Euratom EXPERIMENTAL SET-UP

3 E. Delchambre Demoncheaux Culham (22/07/08) Euratom 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 D nm CD nm C nm wavelength Bandwidth 15 Å optical fibres validate filtered images CCD and spectrometer system both calibrated in situ with labsphere

4 E. Delchambre Demoncheaux Culham (22/07/08) Euratom JAI CCD camera (Dα fixed filter) VISIBLE IMAGING SYSTEM (2/2) fibre bundle DαDα 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

5 E. Delchambre Demoncheaux Culham (22/07/08) Euratom 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 D α emission 6 s 2) Warping technique allows to superimpose images taken on the same object with cameras with different angle of view. HR IR image

6 E. Delchambre Demoncheaux Culham (22/07/08) Euratom α TPL SOL α = 0 Contact 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

7 E. Delchambre Demoncheaux Culham (22/07/08) Euratom 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 s

8 E. Delchambre Demoncheaux Culham (22/07/08) Euratom GROWTH OF DEPOSITS C2 553 nm & IR 40 s 40 s

9 E. Delchambre Demoncheaux Culham (22/07/08) Euratom 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 7.9 s CD 8.9 s CD 9.9 s

10 E. Delchambre Demoncheaux Culham (22/07/08) Euratom DITS CD Emission Zone of deposits which. consistent with TEXTOR [P. Wienhold et al., Journal of Nuclear Materials, vol (2003) p (2003) @20s

11 E. Delchambre Demoncheaux Culham (22/07/08) Euratom disturbance from thermal photons ? No, but corelation with a local increase of T surf 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 Supra thermal electron generated by LH heating which circulate on the LCFS and might intercept deposits in the tangential area. Scaling in P LH /n for those electron experiment Intercepted surface by electron as a function of the heat flux decay length decay length

12 E. Delchambre Demoncheaux Culham (22/07/08) Euratom Max of CII emission on VD1 and VD3 VD1 VD2 VD3 VD4 CII emission – optical fibres views 2MW LH 1.2 MW LH

13 E. Delchambre Demoncheaux Culham (22/07/08) Euratom Highest D photon flux on deposits zone and an increase of 20 % Ha emission – optical fiber views 2MW LH 1.2 MW LH Modification of the recycling coefficient at the surface ? Modification of the release mechanism ? not straightforward need clarification. VD1 VD2 VD3 VD4

14 E. Delchambre Demoncheaux Culham (22/07/08) Euratom [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 VD2 VD3 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

15 E. Delchambre Demoncheaux Culham (22/07/08) Euratom CONCLUSIONS 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)/H α ~ 2 % BUT no comparison available with CII(426nm)/Dγ since issues with CII lines mentionned yesterday was highlited after DITS campaign Issue under investigation

16 E. Delchambre Demoncheaux Culham (22/07/08) Euratom ADDITIONAL SLIDES

17 E. Delchambre Demoncheaux Culham (22/07/08) Euratom RADIAL PROFILES Physical erosion seems dominent CII CD DγDγ

18 E. Delchambre Demoncheaux Culham (22/07/08) Euratom [S/XB] CII 426nm, CII 658nm (ADAS) CII 658 nm CII 426 nm