1. Target nominal (TEKES)
Development of ITER Relevant Laser Techniques for Deposited Layer characterization and Tritium Inventory
A. Malaquias*a,b, V. Philippsc, A. Huberc, A. Hakolad, J. Likonend, J. Kolehmainene, S. Tervakangase, M. Aintsf, P. Parisf, M. Laanf, A. Lissovskif, S. Almavivag, L.Caneveg, F.Colaog, G. Maddalunoh, M. Kubkowskai, P. Gasiori, H.J. van der Meidenj, A.R. Lofj, P.A. Zeijlmans van Emmichovenj, P. Peterssonk, M. Rubelk, E. Fortunal, and Q. Xiaoc,m
aAssociação EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais 1, , Lisboa, Portugal, bEFDA-CSU, Culham Science Centre, Abingdon, OX14 3DB, UK, cInstitute for Energy Research - Plasma Physics, Forschungszentrum Jülich GmbH, Associat. EURATOM-FZJ, dVTT, Association Euratom-Tekes, P. O. Box 1000, VTT, Finland, eDIARC-Technology Inc., Kattilalaaksontie 1, Espoo, Finland, fInstitute of Physics, University of Tartu, Association Euratom-Tekes, Tahe 4, Tartu 51010, Estonia, gENEA, UTAPRAD-DIM, C.R. Frascati P.O.Box 65, Frascati, Roma, Italy, hAssociazione EURATOM-ENEA sulla Fusione, C. R. Frascati, P.O.Box 65, Frascati, Roma, Italy, iInstitute of Plasma Physics and Laser Microfusion, Association EURATOM/IPPLM, Warsaw, P.O. Box 49, Hery St. 23, Poland, jFOM Institute for Plasma Physics Rijnhuizen, Association, EURATOM-FOM, Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands, kAlfvén Laboratory, Royal Institute of Technology, Association EURATOM-VR, Stockholm, Sweden, lFaculty of Materials Science, Warsaw University of Technology, Association EURATOM-IPPLM, Warsaw, Poland, mSchool of Physics and Optical Electronic Technology, Dalian University of Technology, Dalian, , P R China
Laser Induced Breakdown Spectroscopy (LIBS) is being investigated in a cooperative research programme on devices such as TEXTOR, FTU, MAGNUM-PSI and in various lab-experiments. The work aims to define the optimum laser parameters, test ITER like optical layouts, validate methodologies and calibration procedures to provide the accuracy level of interest for ITER (20% relative and 50% absolute) on the determination of fuel content and deposited layer composition on plasma facing components.
Mix-layer targets – C+Al+W+D/W
DLC targets – C+D/W
TEKES/EST
D - ablated
H -
background signal
FZJ
Large H background
D is ablated
ENEA
@ 11 J/cm2
D and H are clearly detected in spite of its content being up to two orders of magnitude lower than the total elemental composition signal.
In the first pulse most of the D is released revealing that most of the D is co-deposited in the skin of the layer.
Mix layer - spectral lines showing the transition to the substrate.
A relatively initial strong W signal can be attributed to layer content and exposed bare W spots in the target after initial irradiation
Representation of cumulative ablation for all spectral lines.
It is clear to distinguish the ablation of the layer by the change in the slope of the lines.
Deuterium
IPPLM
D + H signal
@ 28 J/cm2
The signals show clear presence of layer elements (non-zero slope) when the substrate is reached due to the presence of un-removed layer material (optimization of laser pulse length and energy required to reduce un-removed layer to marginal values)
All experiments show clearly the ablation of the deposited C layer and the transition to the W substrate. The transition occurs around the same energy fluence for all different experiments (note some have different laser energy)
D is clearly detected as an ablation signal . H is a background signal existing in all experiments.
@ low energy fluence irradiation
@ high energy fluence irradiation
FINAL RESULTS
DETERMINATION OF LAYER COMPOSITION
Target nominal (TEKES)
NRA (VR)
NRA (FZJ)
LID-QMS (FOM)
LIBS
mix layer #1
W(5-10%):C(45-48%):Al(45-48%)
(D%)-not known
13:58:27
D (3.1%) = 5.22E+17 cm-2
10:32:58 
D (2.6%) = 8.25E+17 cm-2
D = 5.28E+17 cm-2
22.9:37.5:39.6
D (3%) = 8.7E+17
(D=1406 au)
DLC #1
D (1.7%) = 9.1E+17 cm-2
D (1.7%) = 4.3E+17 cm-2 -
D intensity
(D=3458 au)
Mix-layer targets – C+Al+W+D/W
DLC targets – C+D/W
Calibration Samples
Conclusions
LIBS performed in several laboratories on same targets showed exceptionally similar features regarding spectral lines evolution for energies 2-30J/cm2
Relative content of MIX and DLC layers was determined using LIBS (partial) calibration from bulk materials (MIX layer deviations of 60% for W, 37% for C and 31 % for Al and for DLC layer - 6% deviation on C content)
Mix layer morphology is affected by LIBS process masking the relative target composition explaining the deviations to the nominal values. Dedicated calibration with bulk samples and optimization of laser parameters are key to improve the quality of the measurements
D content was determined by a calibration free model within 30-50% of absolute value
D LIBS measurements between targets show agreement with off line methods (within 20%)
Calibration free
Acknowledgements: This work was supported by EURATOM and carried out within the framework of the European Fusion Development Agreement. The views and opinions expressed herein do not necessarily reflect those of the European Commission.