analysis of samples exposed to pilot–psi plasma
DESCRIPTION
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. Outline Problems of single-shot LIBS H&D detection - PowerPoint PPT PresentationTRANSCRIPT
Analysis of samples exposed to Pilot–PSI
PlasmaP. 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; 29-30 May 2012
Outline1. Problems of single-shot LIBS2. H&D detection3. Linear plasma machine Pilot-PSI and testing methods4. Results5. 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 LIBS1. 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
Development of ITER relevant techniques for deposited layer removal and tritium inventory diagnostics EFDA-CSU; Forschungszentrum Jülich, EURATOM-FZJ; VTT, Euratom-Tekes; DIARC-Inc.; University of Tartu, Euratom-Tekes; ENEA, EURATOM-ENEA; DIFFER, EURATOM-FOM; Alfvén Laboratory, EURATOM-VR; Institute of Plasma Physics and Laser microfusion, EURATOM-IPPLM
Samples Diarc Inc: 3 mm 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 conditionsThe plasma fluence on targets was (2-3.5)1020 m-2s-1. Electron temperature Te = (0.5–1.1) eV; field B = 0.4 T, temperature Tsurf < 7000C DLC coating was exposed to hydrogen plasma during 80-120 s while in case of W/Al coating hydrogen – neon plasma was used and the exposure time was 500-550 s.
DIARC Inc.:Samples with ITER-relevant materialsW, DLC (carbon), Al (proxy of Be)
3 mm4 mm
Post mortem analysisSingle-shot LIBS (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 . 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
Deposition area:C 91%W 8%
1 mm
Unexposed area:C 99.5 %
5 mm
SEM
Exposed area:C 18 %W 82%
G
r
N = G(1-r)
XRD analysis Laser cratersDLC
DLC, SIMS
W/Al
12
3
1 2 3W 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 mm
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!