Effect of initial exposure temperature on the deuterium retention and surface blistering in tungsten

Wang, Ting; Ren, Mengchong; Zhu, Xiu-Li; Ma, Xiaolei; Yuan, Yue; Cheng, Long; Lü, Guang-Hong

doi:10.1016/j.nme.2022.101245

Cited by 4 publications

(4 citation statements)

References 41 publications

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“…A comprehensive description of the TMAP code can be found in [36]. TMAP has been extensively employed for simulating HI diffusion and desorption [24,26,37,38]. In light of the rapid D release from the surface, the boundary condition prescribes a zero D concentration on the surface [37,39].…”

Section: Post-exposure Analysismentioning

confidence: 99%

“…These defects comprise inherent defects within the material as well as those induced by plasma exposure and thermal shocks occurring during fusion reactions. Extensive studies [24][25][26] indicate that D plasma exposure induces the formation of blisters, accompanying a substantial presence of dislocation-type defects [27]. Liu et al [24] proposed that blisters dominate D retention when blistering is severe.…”

Section: Introductionmentioning

confidence: 99%

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Deuterium retention in cyclic transient heat loaded tungsten with increasing cycle numbers

Ren,

Yuan,

Feng

et al. 2024

Nucl. Fusion

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Surface damage and microscopic defect evolution of tungsten (W) armor under transient heat loads are key factors for fuel retention in fusion reactors. In this work, experiments were conducted to investigate the effects of cyclic thermal shocks on deuterium (D) retention and surface blistering in W. Thermal shock experiments were conducted on recrystallized W using an electron beam with a power density of 0.15 GW m-2 across 100-1500 cycles, followed by D plasma exposure with high-fluence (~ 1 × 1026 D m-2). The results demonstrate that samples subjected to 500 and 1500 cycles exhibit a significant presence of sub-grains within 90 μm. Notably, the inhibition of blistering induced by thermal shock leads to a substantial reduction in D retention (5.45 × 1019 D m-2) at lower cycle numbers (100 cycles) compared to the reference sample (2.35 × 1020 D m-2) which was only exposed to D plasma. When cycle numbers increase to 500 and 1500, D retention reaches 1.98 × 1020 D m-2 and 4.56 × 1020 D m-2, respectively. Based on the Tritium Migration Analysis Program, we propose that total D retention is a consequence of the competition between defects reduced by thermal shock-induced suppression of blistering and defects generated by plastic deformation induced by thermal stress. D retention initially decreases with the increase in cycle numbers, followed by a subsequent rise, with the inflection point slightly higher than 500 cycles. Additionally, due to the extensive scope of thermal stress, an escalated exposure period will result in substantial D captured by heat-induced defects, consequently intensifying the D retention. Whether there exists an upper limit to D retention induced by the increasing thermal shock cycles necessitates further experimental analysis. Nonetheless, it is evident that thermal shock significantly contributes to D retention within a profoundly deep bulk region under high cycles.

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Section: Post-exposure Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deuterium retention in cyclic transient heat loaded tungsten with increasing cycle numbers

Ren,

Yuan,

Feng

et al. 2024

Nucl. Fusion

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“…Figure 2d-f show the occurrence of blisters more predominant in the margin zones. Deuterium, like hydrogen, can diffuse inside the bulk matrix [34][35][36], but less compared with hydrogen [13]. In addition, being in the same experimental conditions as in the case of hydrogen plasma, the deuterium diffused inside the tungsten plate, remaining trapped inside it, but not far away from the plate surface (because of low diffusivity compared with hydrogen).…”

Section: Tungsten Surfaces Exposed To H 2 and D 2 Plasmamentioning

confidence: 99%

Low-Temperature H2/D2 Plasma–W Material Interaction and W Dust Production for Fusion-Related Studies

et al. 2023

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In this paper, results concerning hydrogen and deuterium plasma (RF, 13.56 MHz) interactions with tungsten surfaces, were reported. We used the Hollow-Cathode (HC) configuration for plasma–tungsten surface interaction experiments, along with the collection of tungsten dust, at different distances. Further on, the plasma-exposed tungsten surfaces and the collected dust were morphologically analyzed by contact profilometry, scanning electron microscopy, and energy dispersive spectroscopy measurements, along with chemical investigations by the X-ray photoelectron spectroscopy technique. The results showed that exposing the tungsten surfaces to the hydrogen plasma induces surface erosion phenomena along with the formation of dust and interconnected W structures. Herein, the mean ejected material volume was ~1.1 × 105 µm3. Deuterium plasma facilitated the formation of blisters at the surface level. For this case, the mean ejected material volume was ~3.3 × 104 µm3. For both plasma types, tungsten dust within nano- and micrometer sizes could be collected. The current study offers a perspective of lab-scaled plasma systems, which are capable of producing tungsten fusion-like surfaces and dust.

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“…For the international thermonuclear experimental reactor (ITER), the estimated maximum tritium (T) inventory is 700 g with an all-metal Be/W first wall [3], and the limit for the inventory of releasable T in the vacuum vessel is 350/700 g [4], determined by safety considerations. Additionally, fuel retention also affects the thermomechanical properties of the plasma-facing material, resulting in blisters, cracks, and flaking, ultimately deteriorating plasma performance [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Deuterium recycling and wall retention characteristics during boron powder injection in EAST

Zuo,

Wang,

Sun

et al. 2023

Mater. Res. Express

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Boron (B), as a low-Z material, is widely employed for wall conditioning to enhance plasma performance in fusion devices. In the Experimental Advanced Superconducting Tokamak, a series of experiments involving real-time B powder injection has been conducted to investigate fuel particle behavior. It was observed that fuel particle recycling decreased with an increase in the amount of B powder injected, resulting in an increase in short-term fuel retention. The fuel recycling decreased by up to 80%, as indicated by divertor neutral pressure and Dα line emission. Furthermore, each B atom exhibited a trapping capacity of 0.3 D particles during B powder injection at a typical flow rate. The real-time B injection had no wall hysteresis effect on D retention, implying that cumulative B injection and deposited film did not affect long-term D retention. The possible mechanism for D retention is the formation of B-C-O-D compounds and co-deposition between B and D particles during discharges. This investigation would be valuable for evaluating T retention when B is used as wall conditioning material in future fusion reactor devices.

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Effect of initial exposure temperature on the deuterium retention and surface blistering in tungsten

Cited by 4 publications

References 41 publications

Deuterium retention in cyclic transient heat loaded tungsten with increasing cycle numbers

Deuterium retention in cyclic transient heat loaded tungsten with increasing cycle numbers

Low-Temperature H2/D2 Plasma–W Material Interaction and W Dust Production for Fusion-Related Studies

Deuterium recycling and wall retention characteristics during boron powder injection in EAST

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