Перегляд за Автор "Sadowski, M. J."
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Документ Erosion properties of tungsten and WTa5 alloy exposed to repetitive QSPA plasma loads below melting threshold(Kharkiv Institute of Physics and Technology, 2018) Makhlai, V. A.; Herashchenko, S. S.; Aksenov, N. N.; Byrka, O. V.; Garkusha, I. E.; Malykhin, S. V.; Surovitskiy, S. V.; Kulik, N. V.; Staltsov, V. V.; Lebedev, S. I.; Shevchuk, P. B.; Wirtz, M.; Sadowski, M. J.The damage of deformed double forged pure tungsten (W) and tungsten alloyed with 5 wt.% tantalum (WTa5) have been studied in experimental simulations of ITER-like transient events (surface heat load of 0.45 MJ/m² and the pulse duration of 0.25 ms) with quasi-stationary plasma accelerator QSPA Kh-50. The plasma exposures were performed for targets maintained at room temperature and preheated at 200 or 300°C. The large and fine cracks appeared in result of plasma impacts. The high number of repetitive plasma loads below the melting threshold led to the clear degradation of thermo-mechanical properties of the affected surface layers on tungsten. Comparative analysis of the cracks propagation to the bulk is presented for both W and WTa5 samples.Документ Erosion properties of tungsten and WTa5 alloy exposed to repetitive QSPA plasma loads below melting threshold(Національний науковий центр "Харківський фізико-технічний інститут", 2018) Makhlai, V. A.; Aksenov, N. N.; Byrka, O. V.; Garkusha, I. E.; Herashchenko, S. S.; Malykhin, S. V.; Surovitskiy, S. V.; Wirtz, M.; Sadowski, M. J.Документ Materials surface damage and modification under high power plasma exposures(2018) Garkusha, I. E.; Makhlaj, V. A.; Byrka, O. V.; Taran, V. S.; Voitsenya, V.; Malykhin, S. V.; Herashchenko, S. S.; Surovitskiy, S. V.; Nowakowska-Langier, K.; Sadowski, M. J.; Skladnik-Sadowska, E.; Terentyev, D.Influence of powerful plasma impacts on several materials used for the construction of energy systems, i.e. different grades of steels as well as tungsten coatings, has been discussed. Irradiations of these materials with hydrogen and helium plasma streams have been performed in several high-current-pulse and quasi-stationary plasma accelerators which provided the variation of a power load upon the exposed surface as well as changes of the particle flux in wide ranges: the energy flux density in the range of 1-25 MJ/m2, particle flux - up to 1026-1029 ion/m2s, the plasma stream velocity - up to about 500 km/s, and the pulse duration in the range of 1-250 μs. A response of the investigated materials to extreme plasma loads, which are relevant to transient events in fusion reactors, is briefly discussed. It is demonstrated that a broad combination of mechanisms of powerful plasma interactions with various materials includes not only a surface damage caused by different erosion mechanisms, but under certain conditions it may also result in a significant improvement of material properties in the nearsurface surface layer of several tens μm in thickness. Some improvement of the structure and substructure of such a layer may be caused by the high-speed quenching, the shock wave formation and material alloying with plasma- and coating-species. The creation of unique surface structures and a considerable improvement of physical and mechanical properties of different materials can be achieved by the pulsed plasma alloying, i.e. pre-deposited coating modifications and mixing caused by the impacting plasma streams.