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Information × Registration Number 0217U006495, 0115U004256 , R & D reports Title Critical issues of plasma-surface interaction in international fusion reactor ITER popup.stage_title Head Garkusha Igor Evgenevich, Доктор фізико-математичних наук Registration Date 06-09-2017 Organization National Science Center "Kharkiv Institute of Physics and Technology popup.description2 The damage of pure bulk tungsten (W) have been studied in experimental simulations of ITER-like transient events with relevant surface heat load below and above the tungsten melting threshold (0.6 MJ/m2 and the pulse duration of 0.25 ms) with quasi-stationary plasma accelerator QSPA Kh-50. The surface morphology is affected mostly by melting and re-solidification of a surface layer. The large and fine cracks appeared in result of plasma impacts. In dependence on the heat load value, dynamics of the erosion products is essentially different for the droplets and dust particles emitted from the target surface. Heat loads which accompanied by pronounced melting of tungsten cause an intense ejection of liquid droplets and also solid dust particles. Large 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. Ejection and re-deposition of the eroded material were observed also. Degradation of optical properties was studied for pure tungsten and tungsten alloys bombarded by ions of argon and deuterium plasma. Specimens from pure tungsten (PW) the reflectance at normal incidence do not degrade significantly, at least after sputtering the layer of ~4 ?m in thickness. The most part of their surface is continuing to be smooth till the end of sputtering procedures. The relationship of specular and diffuse parts of reflected light is stabilized after sputtering layer thickness reached ~1 ?m and does not change with following sputtering. The relief on WP specimens is a typical step structure with the height of steps reaching 1.4-1.6 ?m, in an excellent agreement with the step difference (up to 1.8 ?m) measured by laser prophilometry for recrystallized W specimen The reflectance of mirror specimens made from doped tungsten at normal incidence is decreasing faster with the increase of the sputtering time. The roughness developed due to sputtering for most of doped samples is characterized by a rather chaotic relief with an exclusion for the samples with 2% of Y addition. A quite big difference was found for sputtering rate: up to ~20%, with the most resistant – the tungsten specimens doped with 1% of yttrium (W-1Y). Two methods of radio-frequency wall conditioning have been investigated experimentally in the Uragan-2M device. The first one is based on a pulsed discharge at low magnetic fields. The discharge is initiated by the frame antenna and sustained by two antennas: the frame and the crankshaft ones. The last one is a version of a strap antenna. The discharge parameters are measured using optical, microwave and probe diagnostics. Theyare within the range suitable for wall conditioning discharges. Analysis of regular pulsed in Uragan-2M indicated that the time needed for such a wall conditioning is about 100 hours. The radio-frequency wall conditioning without magnetic field is performed in continuous regime at the frequency 130 MHz and launched power about 3 kW. The discharge can exist in high gas pressure 0.1 – 0.01 Torr, is located near the antenna and does not spread around the torus. Its parameters are measured using the Langmuir probe. The effect of wall conditioning is judged by the amount of substances accumulated at the cryogenic vacuum trap. This amount appears by the order of magnitude higher than without the discharge which indicates obviously the wall conditioning. Hydrogen, nitrogen and their mixtures had been tried as working gases. The wall conditioning in the mixture 50%/ 50% is selected as the best.. Product Description popup.authors І.Є. Гаркуша І.І.Без’язичний І.В. Рижков І.М. Панкратов І.О. Місірук І.У. Гур?єв А. Ю. Єськов А.А. Тюпа А.Г. Резнiченко А.М. Міняєв А.Н.Шаповал В. І.Бирка В.Є. Моісеєнко В.Б. Коровін В.В. Стальцов В.В. Чеботарьов В.В. Чечкін В.В. Яковлєва В.Г. Котенко В.М. Панасюк В.М.Листопад В.О. Махлай В.О.Басаргін В.П.Єрьомін В.С. Войценя В.С. Таран В.Ю. Красюк Г.Г. Лесняков Г.К. Марченко Д.І. Барон Е.Д. Крамский К.К. Трерьяк Л.І.Григор’єва Л.Л. Карпухін Л.М. Миронова М.Є. Мазніченко М.Б. Древаль М.В.Кулик М.Г. Шеденко М.М. Козуля М.М. Махов Н.Є.Селезньова Н.М. Агаркова О.В. Євсюков О.В. Бирка О.В. Лозін О.В.Погожев О.В.Скорина О.М. Бойко О.О. Блудов О.О. Скорик П. Б. Шевчук Р.І.Журкіна Р.О. Павличенко С.М. Мазніченко Т.О. Панаско Ф.І. Ожерельев Ю.К. Миронов Ю.М. Кучумов Ю.С.Кулик Ю.Ф. Коженков popup.nrat_date 2020-04-02 Close