Systematic investigation of the formation behavior of helium bubbles in tungsten

Miyamoto, M.; Mikami, Saki; Nagashima, Hisayuki; Iijima, N.; Nishijima, D.; Doerner, R.; Yoshida, N.; Watanabe, Hideo; Ueda, Y.; Sagara, A.

doi:10.1016/j.jnucmat.2014.10.098

Cited by 98 publications

(82 citation statements)

References 12 publications

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“…The resolution limit of SEM is about 10 nm. Figure 2 shows the SEM images of W specimens irradiated at He + fluxes of (a) 2.3×10 21 [14]. This could be attributed to the difference in the detection methods.…”

Section: Methodsmentioning

confidence: 99%

High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions

Liu

Hong

et al. 2016

Journal of Nuclear Materials

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A large-power inductively coupled plasma source was designed to perform the continuous helium ions (He +) irradiations of polycrystalline tungsten (W) under International Thermonuclear Experimental Reactor (ITER) relevant conditions. He + irradiations were performed at He + fluxes of 2.310 21-1.610 22 /m 2 s and He + energies of 12-220 eV. Surface damages and microstructures of irradiated W were observed by scanning electron microscopy. This study showed the growth of nano-fuzzes with their lengths of 1.3-2.0 m at He + energies of >70 eV or He + fluxes of >1.310 22 /m 2 s. Nanometer-sized defects or columnar microstructures were formed in W surface layer due to low-energy He + irradiations at an elevated temperature (>1300 K). The diffusion and coalescence of He atoms in W surface layers led to the growth and structures of nano-fuzzes. This study indicated that a reduction of He + energy below 12-30 eV may greatly decrease the surface damage of tungsten diverter in the fusion reactor.

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Section: Methodsmentioning

confidence: 99%

High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions

Liu

Hong

et al. 2016

Journal of Nuclear Materials

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“…This temperature is significantly below the lower threshold of the fuzz nanostructure formation, that is, ∼ 1000 K [7]. Although a large number of studies have been conducted on the fuzz nanostructure [7][8][9][10], little attention has been given to such low temperature ranges [11]. This motivates us to investigate helium exposure at relatively low temperature.…”

Section: Introductionmentioning

confidence: 99%

Surface morphology in tungsten and RAFM steel exposed to helium plasma in PSI-2

et al. 2017

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Impact of the helium plasma exposure on the surface modification in tungsten and RAFM (Reduced Activation Ferritic/Martensitic) steel have been investigated on the linear plasma device PSI-2 assuming the condition of DEMO first wall. In tungsten, a nanoscale undulating surface structure, which has a periodic arrangement, is formed under low temperature conditions below fuzz nanostructure formation threshold ∼ 1000 K. Interval and direction of the undulation shows dependence on the crystal orientation. A large variation in surface level up to 200 nm has been observed among grains at a fluence of 3 × 10 26 He/m 2 showing dependence of the surface erosion rate on the crystal orientation. The {100} plane in which the undulating surface structure is not formed shows the highest erosion rate. This significant erosion is due to the multistage sputtering through impurity. In RAFM steel, sponge-like nanostructure is developed and it grows with increasing helium fluence beyond 1 µm. In the sponge-like nanostructure, a composition change from the base material is observed in which the tungsten ratio increases while the iron ratio decreases showing differences in sputtering ratio depending on the atomic mass.

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“…Под воздействием гелиевой плазмы в экспериментах на линейных плазменных установках NAGDIS-II, PISCES и др. был обнаружен эффект роста на вольфрамовой поверхности пористых слоёв (так называемый fuzz) [100,[106][107][108][109][110][111][112][113][114]. Степень пористости и глубина слоя зависят от интенсивности потока ионов гелия на поверхность и флюенса (суммарного потока на поверхность) [93].…”

Section: формирование пористых слоёв в не-плазмеunclassified

Results of High Heat Flux Tungsten Divertor Target Tests Under Iter and Reactor Tokamak-Relevant Plasma Heat Loads (Review)

Budaev¹

2015

PAST-TF

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Тепловые нагрузки на вольфрамовые мишени дивертора в ИТЭР и токамаках реакторного масштаба в стационарной стадии DT-разряда будут достигать ~10 МВтм −2 , а при срывах плазмы и ЭЛМах импульсные кратковременные нагрузки будут увеличиваться до ~0,6-3,5 ГВтм −2. В обзоре изложены результаты исследований поведения вольфрама при таких плазменнотепловых нагрузках. Основное внимание уделяется описанию микроструктуры поверхности, рекристаллизации и морфологии трещин мишени. Наблюдаются плавление и растрескивание вольфрама, капельная эрозия, формирование неоднородных и пористых слоёв на поверхности материала. Обсуждается формирование вольфрамовой пыли субмикронного размера и влияние неоднородной вольфрамовой поверхности на взаимодействие плазма-стенка. Отмечается необходимость дополнительных испытаний и изучения стойкости вольфрама в условиях повышенных импульсных плазменных нагрузок на диверторные пластины ИТЭР, в том числе при срывах плазмы и ЭЛМах. Ключевые слова: материалы термоядерного реактора, вольфрам, плазменно-тепловые испытания, токамак, ИТЭР.

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Systematic investigation of the formation behavior of helium bubbles in tungsten

Cited by 98 publications

References 12 publications

High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions

High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions

Surface morphology in tungsten and RAFM steel exposed to helium plasma in PSI-2

Results of High Heat Flux Tungsten Divertor Target Tests Under Iter and Reactor Tokamak-Relevant Plasma Heat Loads (Review)

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