AnalysisofsamplesexposedtoPilot–PSI Plasma P. Paris, A. Hakola, K. Bystrov, G. De Temmerman, M. Aints, I. Jõgi, M. Kiisk, J. Kozlova, M. Laan, J. Likonen, and A. Lissovski Outline Problemsofsingle-shot LIBS H&D detection Linear plasma machinePilot-PSI and testingmethods Results Conclusions Euratom-TEKESAnnualFusion Seminar; Tartu; 29-30 May 2012
Laser inducedbeakdownspectroscopy (LIBS) – a tool forin situ monitoringofplasma-firstwallinteraction Theelementaldepthprofiles are foundmeasuring LIBS spectraas a functionof laser shot number. Twomaindrawbacksofsingle-shot LIBS General: usually applied ensemble-averaged LIBS methods are not applicable Specific: becauseof a longrecoveringdistanceand lowconcentrationofsomeimportantspeciestheroleofnoiseisbig Development of ITER relevant techniquesfordepositedlayerremovalandtritiuminventorydiagnostics EFDA-CSU; ForschungszentrumJülich, EURATOM-FZJ;VTT, Euratom-Tekes; DIARC-Inc.; University of Tartu, Euratom-Tekes;ENEA, EURATOM-ENEA; DIFFER, EURATOM-FOM; AlfvénLaboratory, EURATOM-VR; Institute of Plasma Physics and Laser microfusion, EURATOM-IPPLM
Pilot-PSI (DIFFER): Ionenergy and intensityof plasma fluxes are thesameasin ITER DIARC Inc.: SampleswithITER-relevantmaterials W, DLC (carbon), Al (proxyofBe) 4 mm 3 mm Pilot-PSI, experimentalconditions Theplasma fluence on targets was (2-3.5)1020 m-2s-1. Electron temperature Te = (0.5–1.1) eV;fieldB = 0.4 T, temperatureTsurf< 7000C DLC coatingwasexposedtohydrogen plasma during80-120 swhileincaseof W/Al coatinghydrogen – neon plasma wasused and theexposuretimewas500-550 s. Post mortemanalysis Single-shotLIBS (NdYAG laser: l=1064 nm) spectra as a function of the laser shot number were recorded from about 10 different spots corresponding to differently modified areas . Elementaldepthprofileswerealsoobtainedby SIMS. Changes at the surface were alsostudied using SEM, X-ray microanalysis and X-ray diffraction techniques.
SEM Photoof DLC sampleafter 100 s exposer 5 mm Unexposedarea: C 99.5 % Depositionarea: C 91% W 8% G r N = G(1-r) 1 mm Exposedarea: C 18 % W 82%
DLC XRD analysis Laser craters
W/Al 1 2 3 W 85% 81% 88% 88% CRACKING Mo 8% Al 0.6% 1 2 W 75% 79% 89% 88% 3 Mo 9% W 60% 78% 88% 88% Mo 10% 40 mm Al 1% 1% SEM
Conclusion Applying earlier elaborated data processing procedures, a good qualitative matching between LIBS and SIMS profiles was achieved. The study showed that LIBS diagnostics gives reliable information about the plasma induced erosion/deposition processes and it could be used for in situ monitoring of fusion reactor walls. Near-termsteps Modification of the optical set-up for reliable spectral resolving of hydrogen and deuterium lines Obtaining experience with Be-containing samples (VTT, Romania) 3. Start ofin situ measurements at DIFFER Thankyouforyourattention!