17 research outputs found
Investigation of radiofrequency plasma jets at low and atmospheric pressure by optical emission spectroscopy
No full textCharacterisation of a high-pressure direct-current magnetron discharge used for tungsten nanoparticle production
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Research in Romania on laser interaction with alcali atom isotopes to generate the unit of time: a progress report
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Hybrid Nanomaterial Architectures: Combining Layers of Carbon Nanowalls, Nanotubes, and Particles
No full textThermal balance of tungsten monocrystalline nanoparticles in high pressure magnetron discharges
No full textInternational audienceNanoparticles are produced in sputtering magnetron discharges operating with a tungsten cathode at 30 Pa argon pressure. Structure analyses show that they are of core-shell type. The core is a monocrystal mainly in the metastable beta-tungsten phase and the shell is made of tungsten oxide. The origin of the metastable phase is attributed to the presence of residual oxygen in the device. Since this phase transforms into the stable alpha-tungsten phase by annealing, a standard model on the thermal balance of nanoparticles was used to find the temperature that they can reach under the considered experimental conditions. It is shown that this temperature is significantly higher than the gas one but not high enough to transform the monocrystalline metastable beta-phase during the plasma process
Tungsten Molecular Species in Deuterium Plasmas in Contact with Sputtered W Surfaces
No full textWe show that in plasmas generated in deuterium in the presence of sputtered W surfaces, various molecular tungsten species are formed, whose chemical composition depends on the presence of gaseous impurities, namely, nitrogen, oxygen, and hydrogen. A magnetron discharge was used for plasma sustaining, and the species were investigated by mass spectrometry and optical emission spectroscopy. The identified tungsten-containing molecules are described by the chemical formula WOxNyDzHt, where x = 0–4, y = 0–3, z = 0–3, t = 0–5. Presumptively, even higher mass tungsten molecular species are present in plasma, which were not detected because of the limitation of the spectrometer measurement range to 300 amu. The presence of these molecules will likely impact the W particle balance and dust formation mechanisms in fusion plasmas
Tungsten nanoparticles with controlled shape and crystallinity obtained by magnetron sputtering and gas aggregation
No full textOES monitoring of sequential deposition of C/W layers by PECVD/magnetron sputtering techniques
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