Modification of W surfaces by exposure to hollow cathode plasmas

Stancu, C.; Stokker-Cheregi, F.; Moldovan, A.; Dinescu, M.; Grisolia, Christian; Dinescu, Gheorghe

doi:10.1007/s00339-017-1235-4

Cited by 5 publications

(6 citation statements)

References 15 publications

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“…The second one has been handpolished and exhibits a rms surface roughness in the range 100 − 200 nm (referred as sub-microscale surface in the following). The third tungsten substrate has been exposed to high temperatures (above 1000°C) by He plasma using radiofrequence (RF) hollow cathode discharge technique described by Stancu et al [2017] (referred as microscale surface in the following). The dimensions of the tungsten substrates are approximately 5 × 5 mm 2 .…”

Section: Methodsmentioning

confidence: 99%

Adhesion of tungsten particles on rough tungsten surfaces using Atomic Force Microscopy

Peillon

Autricque

Rédolfi

et al. 2019

Journal of Aerosol Science

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Adhesion forces between tungsten spherical microparticles and tungsten substrates with different roughnesses have been measured using the Atomic Force Microscopy (AFM) colloidal probe technique. Mean roughnesses of the tungsten substrates were measured by AFM and were ranked in three categories i.e. nanoscale, sub-microscale and microscale roughnesses. Experimental Hamaker constant of 37 ± 3.5 × 10 −20 J has been obtained using a spherical tungsten particle of 10.5 µm in radius and a tungsten substrate with nanoscale root-mean-square roughness of rms = 11.5 nm. It was shown that larger roughness of the order rms = 712 nm induces a two order of magnitude decrease on the adhesion of tungsten microparticles compared to a smooth tungsten surface with nanoscale roughness. Comparison with the van der Waals-based adhesion force model of Rabinovich which integrates the roughness of surfaces showed good agreement with experimental pull-off forces even when roughness of the substrate is close to the micrometer range. In such case, measurements have shown that dependency of adhesion force with particle size (in the micrometer range) has a secondary influence compared to the roughness of surfaces.

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Section: Methodsmentioning

confidence: 99%

Adhesion of tungsten particles on rough tungsten surfaces using Atomic Force Microscopy

Peillon

Autricque

Rédolfi

et al. 2019

Journal of Aerosol Science

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“…Additionally, taking the estimated gas temperature into account (approximately 0.05 eV), which is much smaller than the electron temperature, we can conclude that the plasma used for particle generation is cold and in a non-equilibrium state. The current studies are complementary to our previous work [28,30] wherein He and Ar plasmas were used in hollow-cathode geometry. Herein, the core of the experimental plasma system is represented by hollow-cathode geometry (and the corresponding method), which was especially used to constrain the plasma between tungsten plates.…”

Section: Introductionmentioning

confidence: 59%

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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“…The hollow cathode [47] (HC) setup (Figure 1a) uses a stainless-steel vacuum chamber (HydraCool, Kurt Lesker company, 30 cm diameter and 60 cm height) inside which are placed two parallel tungsten plates (3 cm × 1.5 cm × 0.3 cm), separated by 3 mm distance, which are electrically connected and serve as RF (13.56 MHz) electrodes. The electrical ground of the discharge is the chamber itself.…”

Section: Dedicated Experimental Setups For Plasma Generationmentioning

confidence: 99%

“…This is possible because the continuity in the characteristics of materials may extend on large range of parameter values. For example, in the case of tungsten, the exposure of surfaces to heating and He plasma showed the fuzz appearance, in conditions created in Tokamaks [44], Pilot PSI experiments [45], by simultaneously exposure to heat by laser and He plasma [46], but also in normal laboratory hollow cathode discharges [47]. Similarly, particle formation (droplets, debris, nanoparticles) is a common phenomenon in magnetron sputtering and plasma jets [48][49][50], in spite of the fact that plasma configurations are very different for Tokamak plasmas.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we study the interactions between plasma and tungsten surfaces in order to investigate the erosion/melting/vaporization phenomena, and as a direct consequence, the dust occurrence. Special generating systems were designed and used, namely a hollow cathode (HC) [47] and a microjet discharge (MD) [50]. The experiments were made with helium and argon gas, in order to investigate soft and hard damages of the exposed tungsten surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Material Erosion and Dust Formation during Tungsten Exposure to Hollow-Cathode and Microjet Discharges

et al. 2020

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Tungsten erosion and dust occurrence are phenomena of great interest for fusion technology. Herein, we report results concerning the material damage and dust formation in the presence of high temperature and large area or concentrated discharges in helium and argon. In order to generate adequate plasmas, we used tungsten electrodes in two experimental discharge systems, namely a hollow discharge and a microjet discharge. In both exposure cases, we noticed surface modification, which was assigned to sputtering, melting, and vaporization processes, and a significant dust presence. We report the formation on electrode surfaces of tungsten fuzz, nano-cones, nanofibers, and cauliflower- and faced-like particles, depending on the discharge and gas type. Dust with various morphologies and sizes was collected and analyzed with respect to the morphology, size distribution, and chemical composition. We noticed, with respect to erosion and particle formation, common behaviors of W in both laboratory and fusion facilities experiments.

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Modification of W surfaces by exposure to hollow cathode plasmas

Cited by 5 publications

References 15 publications

Adhesion of tungsten particles on rough tungsten surfaces using Atomic Force Microscopy

Adhesion of tungsten particles on rough tungsten surfaces using Atomic Force Microscopy

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

Material Erosion and Dust Formation during Tungsten Exposure to Hollow-Cathode and Microjet Discharges

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