Deuterium and helium retention in W with and without He-induced W ‘fuzz’ exposed to pulsed high-temperature deuterium plasma

Огородникова, О. В.; Klimov, K.S.; Poskakalov, A. G.; Kaziev, Andrey V.; Kharkov, M. M.; Ефимов, В. М.; Gasparyan, Yu. M.; Волков, Н. В.; Alimov, V.Kh.; Tokitani, M.

doi:10.1016/j.jnucmat.2018.12.023

Cited by 29 publications

(3 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…When ion irradiations and transient heat loadings were combined the cracking networks led to deeper mobility of ions into the material [21,37]. When pure W was exposed to simultaneous ion loading (D and He) and ELM-like heat loading the sample eroded more material via splashing and dust formation [5,19,38]. More erosion is most likely due to the D gas building up quickly sub surface and with a roughened surface more of the heat load is absorbed and can not easily be dissipated.…”

Section: Introductionmentioning

confidence: 99%

Synergistic effects of W–Ta alloys exposed to various ELM-like fusion events

Ray,

Tripathi,

Hassanein

2024

Nucl. Fusion

View full text Add to dashboard Cite

Recently tungsten alloys have shown capabilities in suppressing morphological changes when exposed to harsh fusion conditions. Morphological changes due to He+ and D+ ions at high temperatures (1000 - 2000 K) can lead to easier erosion and sputtering of W particles towards quenching the fusion plasma. This study investigated W-3Ta alloy as potential plasma facing materials (PFMs) exposed to different edge-localized mode (ELM)-like energies and ion loadings. Performance of W-3Ta has been tested as a function of ELM-like energies (0.6 - 1.5 GWm-2) and varying He+ and D+ ion concentrations (100% He+, 50% He+:50% D+,10% He+:90% D+ (similar ELM-like reactor condition), and 100% D+ ions). Early-stage fuzz formation and surface pores were observed during 100% He+ ion irradiation and mixed ion loadings but not observed during 100% D+ ion loadings. Pores decreased in quantity and increased in size with increasing transient heat loading. Grain boundaries acted as trapping sites of helium and deuterium atoms during dual beam ion irradiations, as observed through increased pore size along the grain boundary. Qualitative erosion estimates were measured using witness plates. Increased erosion was observed with increasing D+ ion concentration, which is attributed to D supersaturation in the near surface region affecting thermal and mechanical properties. More erosion was observed for W-3Ta samples compared to pure W, evident through large (>10 µm) cracks on the surface, and an increase in W metal XPS peaks under similar loading conditions. The slight enhancement in erosion is attributed to the slightly decreased thermal properties, ~10% thermal diffusivity drop, of W-3Ta at high temperatures. The damage threshold was impacted by ion loading, where distinct cracking was observed for 100% He+ at a lower heat loading. This matrix study using reactor-like loading supports the need for extensive studies on future W alloy PFMs before selecting one as an alternative.

show abstract

Section: Introductionmentioning

confidence: 99%

Synergistic effects of W–Ta alloys exposed to various ELM-like fusion events

Ray,

Tripathi,

Hassanein

2024

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

“…Также резко воз-растает скорость эрозии электродов [14,15], средний заряд ионов и температура плазмы снижаются по сравнению с обычным вольфрамом [16,17]. Автоэмиссионные свойства вольфрамового пуха широко исследованы, и получены значения усиления поля от 200 до 3000 [18,19].…”

Section: Introductionunclassified

Измерение длительности горения вакуумной дуги с W-fuzz катодом

Михайлов,

Музюкин,

Мамонтов

et al. 2023

MTD

View full text Add to dashboard Cite

В данной работе представлена экспериментальная методика определения времени горения вакуумной дуги в микросекундном диапазоне на вольфрамовых катодах с нано структурированной поверхностью. В качестве образцов использовались вольфрамовые пластины, подвергнутые воздействию гелиевой плазмы, в течении 4 часов. В результате бомбардировки поверхности вольфрама ионами гелия появляются наноструктуры, называемые вольфрамовым пухом (W fuzz). Они представляют собой тонкие вольфрамовые нити толщиной 10–50 нм. Средняя толщина W fuzz слоя составила 1 мкм. В работе использован триггерный метод поджига дуги. Для питания дуги использовался источник питания с напряжением 200 В и постоянным током от 0,1 до 0,7 А. Показано, что, как и для обычных металлических катодов, статистическое интегральное распределение времени горения дуги для катодов с fuzz слоем носит случайный характер, имеет экспоненциальную зависимость. Но время горения вакуумной дуги на W fuzz слое на порядок больше, чем для обычного вольфрама. На основе результатов эксперимента определено среднее время горения дуги, оно составило ~1 мкс для тока 0,17 А и ~40 мкс для тока 0,7 А.

show abstract

“…In addition, predictive modelling shows that the conditions of tungsten fuzz formation can also be achieved at the outboard divertor targets of ITER [18]. Studies related to tungsten fuzz effects such as optical reflectivity [19], thermal conductivity [20][21][22], fuel retention [23][24][25][26] and unipolar arcing [3,27,28] are commonly carried out by the fusion community. However, studies on hydrogen's reflective characteristics on tungsten fuzz are not well understood.…”

Section: Introductionmentioning

confidence: 99%

Modelling of hydrogen reflection on tungsten fuzzy surface in an erosive hydrogen plasma

et al. 2020

View full text Add to dashboard Cite

Modelling of the reflection of energetic hydrogen atoms from tungsten fuzz under hydrogen plasma exposure has been performed using the three-dimensional kinetic Monte Carlo program SURO-FUZZ. The simulation results show that the hydrogen reflection coefficient on a porous tungsten fuzzy surface is 50% lower in comparison with a smooth tungsten surface, which shows good agreement with the measurements. The time evolution of the tungsten fuzzy structure has been investigated under energetic hydrogen bombardment. A sustained removal of the porous tungsten fuzzy structure is obtained, which results in a reduced height of tungsten fuzz with exposure time and finally a smoothing of the tungsten fuzz. The erosion-induced degradation of the tungsten fuzzy structure leads to a high hydrogen reflection coefficient with exposure time. The simulated temporal evolution of the hydrogen reflection coefficient is in reasonable agreement with the experimental data. The simulation results show that the reflection coefficient of hydrogen atoms on fuzzy surfaces is decreased with increasing porosity. Parametric studies with varying porous structures have been performed to gain insights into hydrogen reflection characteristics on tungsten fuzzy surfaces.

show abstract

Deuterium and helium retention in W with and without He-induced W ‘fuzz’ exposed to pulsed high-temperature deuterium plasma

Cited by 29 publications

References 32 publications

Synergistic effects of W–Ta alloys exposed to various ELM-like fusion events

Synergistic effects of W–Ta alloys exposed to various ELM-like fusion events

Измерение длительности горения вакуумной дуги с W-fuzz катодом

Modelling of hydrogen reflection on tungsten fuzzy surface in an erosive hydrogen plasma

Contact Info

Product

Resources

About