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In-situ studies in the IPP Dual Beam Experiment : Interaction and transport of hydrogen isotopes in tungsten

par Caroline CHAMPENOIS - publié le

séminaire du laboratoire
jeudi 16 novembre à 14:00,

W. Jacob

Max-Planck-Institut für Plasmaphysik, 85748 Garching, Germany

abstract : by J. Bauer, T. Schwarz-Selinger, K. Schmid, M. Balden, A. Manhard, U. von Toussaint and W. Jacob

The talk will present the experimental possibilities of the IPP Dual Beam Experiment which allows, e.g., simultaneous implantation of keV D (or H) ion beams and detection of the implanted D by high energy (MeV) ion beams. Over the last few years this experiment has been used for in-situ studies of different aspects of the interaction of H isotopes with polycrystalline W. For this purpose the experimental possibilities of existing set-up have been extended to enable implantation at temperatures as low as 150 K and to allow TDS analysis after implantation.

D implantation of D3+ ions with 9 keV – corresponding to 3 keV per D – at 150 K results at low fluences in 100 % retention of the implanted D amounts. The saturation of the retained D amount sets in for fluences higher than about 6×1021 D/m2. The D saturation concentrations within the ion penetration range are surprisingly high (more than 40 at.%).

Under these implantation conditions, the W surfaces show strong, grain-dependent blistering. The talk will also show the influence of near-surface blisters on D transport into depth and results for isotope exchange experiments at low temperatures. In particular the results of the isotope exchange experiments can easily be explained on basis of the fill-level model for H retention in traps with multiple occupancy.

contact : Thierry Angot