Analysis of samples exposed to Pilot–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 Euratom-TEKES Annual Fusion Seminar; Tartu; May 2012 Outline 1.Problems of single-shot LIBS 2.H&D detection 3.Linear plasma machine Pilot-PSI and testing methods 4.Results 5.Conclusions

Laser induced beakdown spectroscopy (LIBS) – a tool for in situ monitoring of plasma-first wall interaction The elemental depth profiles are found measuring LIBS spectra as a function of laser shot number. Two main drawbacks of single-shot LIBS 1.General: usually applied ensemble-averaged LIBS methods are not applicable 2.Specific: because of a long recovering distance and low concentration of some important species the role of noise is big

Samples Diarc Inc: 3  m D-doped DLC coatings on W substrate

Pilot-PSI (DIFFER): Ion energy and intensity of plasma fluxes are the same as in ITER Pilot-PSI, experimental conditions The plasma fluence on targets was (2-3.5)  m -2 s -1. Electron temperature T e = (0.5–1.1) eV; field B = 0.4 T, temperature T surf < C DLC coating was exposed to hydrogen plasma during s while in case of W/Al coating hydrogen – neon plasma was used and the exposure time was s. DIARC Inc.: Samples with ITER-relevant materials W, DLC (carbon), Al (proxy of Be) 3  m4  m Post mortem analysis Single-shot LIBS (NdYAG laser: =1064 nm) spectra as a function of the laser shot number were recorded from about 10 different spots corresponding to differently modified areas. Elemental depth profiles were also obtained by SIMS. Changes at the surface were also studied using SEM, X-ray microanalysis and X-ray diffraction techniques.

Photo of DLC sample after 100 s exposer D eposition area: C 91% W 8% 1  m U nexposed area: C 99.5 % 5  m SEM E xposed area: C 18 % W 82% G r N = G  (1-r)

XRD analysisLaser cratersDLC

DLC, SIMS

W/Al W 85%81%88%88% Mo 8% Al 0.6% W 75%79%89%88% Mo 9% W 60%78%88%88% Mo 10% Al 1% 1% 40  m CRACKING 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-term steps 1.Modification of the optical set-up for reliable spectral resolving of hydrogen and deuterium lines 2.Obtaining experience with Be-containing samples (VTT, Romania) 3. Start of in situ measurements at DIFFER Thank you for your attention!