| Fusion will play an important role in solving energy problem which is in-fluencing the society development. It could produce energy on a large scale, using plentiful fuels, releasing no greenhouse gases, and leaving little radioactiv-ity waste. The retention and recycling of deuterium/tritium in Plasma Facing Material (PFM) are related to the fuel balance and operation safety of future fusion reactor, such as the International Thermonuclear Experimental Reactor (ITER). Therefore, it is of great importance to study the deposition and diffusion of deuterium/tritium in PFM. Most of experiments in this field are focused on the statical deuterium concentration, which means the deuterium implantation or plasma exposure are separated from the deuterium profiling. As a result, the deuterium concentration in implantation zone of target might be changed because the diffusion process occurs from the implantation termination to the analysis start. Thus, the real-time deuterium retention could not be studied properly by off-line methods.In this work, the D(d,p)T reaction analysis where low energy deuterium ions serve as both implanted species and analyzing ions has been suggested and a real-time method has been proposed to study the dynamical deuterium con-centration. The implantation of deuterium ions and the analyse of deuterium concentration have been completed with the low-energy high-intensity acceler-ator in the Research Center for Electron Photon Science. Tohoku University, Japan. In this experiment, the saturated dynamical deuterium concentration and related critical fluence have been obtained. The ratio of free deuterium to trapped deuterium has been gotten. Furthermore, the dependence of dynamical deuterium concentration in surface layer under balanced condition (shortened as dynamical balanced concentration, the same as following) on deuterium energy and target damage level have also been studied. In order to compare the dynami- cal balanced concentration to statical ones, the retained deuterium concentration has been measured by Elastic Recoil Detection Analysis (ERDA) in Center of Ion Beam Application (CIBA), National University of Singapore when the same samples were stored in room temperature for about one year. According to these experiments, the results have been given as following.(1). The saturated dynamical concentration nD/nSe in surface layer for Be is (20±2) at.%, and the related critical fluence is8×1018D/cm2, nD/nMo is (32±2) at.%at a fluence of about9.4×1017D/cm2, and nD/nw is (42±3) at.%at a fluence of about1.5×1018D/cm2.(2). Deuterium concentration have been decreased after storing for one year in room temperature, the retained deuterium concentrations of Mo and W target is only about10%of their dynamical balanced concentration except for Be target which has a maximum concentration of22at.%at the average range of20keV/D deuterium ions.(3). The dynamical balanced concentration does not depend on the deu-terium ions energy, but is related to the target damage level. These values reduce about (29±3)%for Be target,(23±1)%for Mo, and (11±1)%for W target after severe target damage induced by6-13keV/D deuterium irradiation. The possible reason could be that the surface recombination has been enhanced by the ion induced damage of surface layer.(4). The trapping centers where deuterium atoms are trapped do not in-crease linearly with the damage level increasing. The trapping center reaches saturation after a damage level less than2dpa for Mo and1dpa for W target.(5). Some unstable components, such as free deuterium atoms or D-metal complex, do exist in material during ion beam implantation. This parts are as high as90%in total dynamical balanced concentration for Mo and W target.The present work, i.e. the study of dynamical balanced concentration with real-time D(d,p)T nuclear reaction and ERDA method, is for the first time. |
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