Ammonia formation and W coatings interaction with deuterium/nitrogen plasmas in the linear device GyM

Laguardia, L.; Caniello, R.; Cremona, A.; Dellasega, David; Dell’Era, F.; Ghezzi, F.; Gittini, G.; Granucci, G.; Mellera, V.; Minelli, D.; Pallotta, F.; Passoni, M.; Ricci, D.; Vassallo, E.

doi:10.1016/j.jnucmat.2014.12.087

Cited by 18 publications

(22 citation statements)

References 17 publications

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“…The exposure of W surfaces to N plasmas, N ion fluxes and N discharges in Tokamak leads to the retention of N either in the elemental form or as a nitride [24,25]. The properties of WN x coatings produced using Ar/N 2 mixture are similar to those obtained after exposure to N plasmas.…”

Section: Deposition and Characterization Of Wn X Coatingsmentioning

confidence: 73%

Retention of nanocrystalline WNx layers exposed to high-fluence deuterium plasmas

Vassallo¹,

Caniello²,

Angella

et al. 2015

Journal of Nuclear Materials

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Section: Deposition and Characterization Of Wn X Coatingsmentioning

confidence: 73%

Retention of nanocrystalline WNx layers exposed to high-fluence deuterium plasmas

Vassallo¹,

Caniello²,

Angella

et al. 2015

Journal of Nuclear Materials

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“…Differences in N relative concentrations along the depth, have been found for the samples [50]. The thickness of the layer in which N 2 is retained is about 6 nm.…”

Section: Nitrogen Seeding Experiments In Laboratory: Formation Of Nitrides and Ammonia By Plasma Wall Interaction In Gym Linear Devicementioning

confidence: 80%

“…The most probable loss channels are ion implantation into plasma-facing materials, co-deposition and NH 3 formation. These three mechanisms were investigated in laboratory experiments performed in linear device [46][47][48][49][50]. Linear devices have extensively contributed to understand the atomic and molecular processes led by N 2 injection, because of the good diagnostic accessibility and the capability of maintaining the plasma in steady-state regime for long time.…”

Section: Nitrogen Seeding Experiments In Laboratory: Formation Of Nitrides and Ammonia By Plasma Wall Interaction In Gym Linear Devicementioning

confidence: 99%

“…Reproduced from Ref. [50] and WN contributions survive up to 16.5 nm. When the negative bias potential was applied on the W substrate, the peaks due to the adsorbed species N, ND, ND 2 and ND 3 decreased with increasing negative bias potential.…”

Section: Nitrogen Seeding Experiments In Laboratory: Formation Of Nitrides and Ammonia By Plasma Wall Interaction In Gym Linear Devicementioning

confidence: 99%

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Theoretical and experimental aspects of non-equilibrium plasmas in different regimes: fundamentals and selected applications

et al. 2021

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This paper presents recent activities covering different plasma fields, from both theoretical and experimental point of views. An overview of the present interests of the scientific community is reported here. Starting from a brief description of the role of collisions in astrophysical plasmas, some fundamental aspects of gas discharges modelling, such as superelastic collisions and the basic concept of vibrational temperature, are discussed. Different plasma sources, as DBD and microwave discharges with their own specific applications, are reported. Edge plasmas in nuclear fusion reactors are investigated, focusing on the cooling mechanisms resulting from nitrogen puffing in the divertor region.

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“…A thorough review of the plasma-catalysis literature for NH 3 synthesis has been recently published . Several types of plasma discharges have been used for this purpose, e.g., dielectric barrier discharges (DBDs), − glow discharge, microwave, , and radiofrequency , plasmas, or linear plasma devices . Much research has been devoted to understanding the dissociation mechanisms of the N 2 molecule, − whose energy threshold of 9.8 eV contrasts to that of H 2 (4.5 eV). , The dominant dissociation mechanisms depend on the discharge conditions.…”

Section: Introductionmentioning

confidence: 99%

Plasma-Assisted Catalysis of Ammonia Using Tungsten at Low Pressures: A Parametric Study

Antunes

Steiner

Romero‐Muñiz

et al. 2021

ACS Appl. Energy Mater.

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The production of ammonia (NH 3 ) with lowpressure, radiofrequency plasmas is studied in this paper in a wide range of experimental conditions using tungsten as a catalyst. The relative position of the tungsten foil in the pyrex tube was observed to dramatically impact ammonia formation. By positioning the catalyst in the middle of the tube, the concentration of NH 3 peaked at 120 W with ≈20 mol %, while it decreased by more than a factor of 2 at 300 W. When the foil was placed close to the end of the tube, the production of NH 3 was rather stable beyond 120 W. These results provide clear evidence of the surface's role in the local enhancement of the NH 3 formation rates. In the plasma volume, at some distance from the foil, the decomposition of NH 3 is the major occurring process and the decomposition rate increases with the power primarily due to a higher electron density. The optimum production of NH 3 was found to be at 45 mol % N 2 and 120 W, and the position of the maximum was observed to slightly decrease to <40 mol % N 2 with an RF power of 60 W, highlighting that not only the material characteristics play a role but also the discharge conditions. The measured NH 3 decreased by increasing the pressure from 3 to 5 Pa, which is associated with a decrease in the electron temperature. The temperature of the discharge was found to have a negligible effect on NH 3 formation up to 673 K, demonstrating one of the key features of plasma catalysis in respect to thermal catalysis. The largest energy yield of 0.075 g-NH 3 kW h −1 was obtained with an equimolar mixture of N 2 −H 2 at 30 W and 3 Pa. Overall, our results show that the changes in the electron density, electron temperature, and gas composition allow a more effective tuning of the catalytic properties of tungsten than varying the bulk gas temperature.

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Ammonia formation and W coatings interaction with deuterium/nitrogen plasmas in the linear device GyM

Cited by 18 publications

References 17 publications

Retention of nanocrystalline WNx layers exposed to high-fluence deuterium plasmas

Retention of nanocrystalline WNx layers exposed to high-fluence deuterium plasmas

Theoretical and experimental aspects of non-equilibrium plasmas in different regimes: fundamentals and selected applications

Plasma-Assisted Catalysis of Ammonia Using Tungsten at Low Pressures: A Parametric Study

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