Intense pulsed plasma jets with electron densities of in excess of 10(2)(1) m(-)(3) and temperatures of similar to 13 eV were used to dissociate CO2 under Martian pressure conditions at 1-5 Torr for in-situ oxygen production. Our method demonstrated 20-50 times greater temporal efficiency than an RF plasma, which achieved a 23 % conversion in similar to 450 s. This advantage stems from our method's reduced sensitivity to non-thermal back reactions and thermal recombination, as well as its notably short CO2 dissociation time of just 5 nanoseconds. A peak conversion rate of 33.29 % was reached at 1 Torr, with an O-2 produced mass of 5.5 mg per pulse at 5 Torr. Energy efficiency reached 7.2 % at a low specific energy input (SEI) of less than < 11 eV/molecule, surpassing RF and DC plasmas which feature 1.6 %, although all plasma systems exhibit reduced efficiency at low pressures due to high SEI from low molecular density. These findings highlight pulsed plasma jets as a promising, scalable solution for rapid oxygen generation on Mars, with optimization via larger chambers and possibly catalysts approach.
Research on the Tokamak & agrave; Configuration Variable addresses a wide range of key questions relevant to ITER and future fusion power plants. Over the past two years, highly productive experimental campaigns have led to major advances across several areas: the ITER baseline scenario; pedestal properties in low-collisionality, peeling-limited conditions; and the development of high- beta N, non-inductive regimes. Alternative high-confinement scenarios have likewise received significant attention, with remarkable progress in quasi-continuous exhaust operation, X-point radiator plasmas, and negative triangularity configurations. Substantial achievements were also made in the mitigation or benign termination of runaway electron beams, in elucidating fast-ion loss mechanisms, and in improving exhaust behaviour in both conventional and alternative divertor geometries. These experimental results have been strongly supported by advances in modelling and their direct application to the experiment, ranging from gyrokinetic simulations of core and pedestal turbulence to fluid-based studies of scrape-off layer and divertor physics in diverse geometries. Plasma control has taken on an increasingly important role, with model-based and data-driven approaches now closely intertwined with physics studies. This article provides a overview of these recent activities, together with a brief outlook on forthcoming upgrades and next steps.
This paper gives an overview of erosion and migration studies of tungsten (W) in the WEST tokamak during its Phase 1 (2016–2021) and Phase 2 (from 2022) experimental campaigns with a focus on plasma-facing components (PFCs) at the divertor. In Phase 1, gross erosion of PFCs is in line with observations from other major fusion devices and attributed to low- Z impurities in the plasma. In addition, a strong asymmetry is observed between the high- (inner) and low-field (outer) side divertor targets, in favour of the inner side. Net erosion at rates of <0.5 nm s ^−1 is measured around the strike points while the remaining areas are dominated by net deposition. The thickest deposited layers (up to 50 μ m) with the most complex structures result from a cumulated plasma exposure of ∼7 h. The overall erosion-deposition pattern is further influenced by the strong magnetic ripple of WEST, which can result in almost an order of magnitude difference between the maxima and minima of the ripple. In Phase 2, increasing plasma fluence leads to the deposits growing to hundreds of micrometres in thickness. At the same time, erosion proceeds at a constant rate and can reach values up to 30 µ m in ∼18 h of plasma time. In the main chamber, erosion is weaker than at the divertor but especially at low densities it can result in notable transport of W into the core. In addition, upon switching on the ICRF antennas, W sputtering on the close-by limiter structures can increase by a factor of more than 10. Modelling is able to catch many of the observed phenomena in Phase 1, with the exception of the inner–outer asymmetry and the formation of the thick deposits. In contrast, the patterns during the high-fluence operations in Phase 2 require more work to be reproduced.
ABSTRACT Surfaces play a central role in catalytic processes, and understanding the transformation of ruthenium metal into ruthenium oxide during annealing is essential for tailoring functional catalytic interfaces. In this study, we systematically investigate ≈22 nm thick Ru metal films deposited by atomic layer deposition (ALD) at 300°C, focusing on their chemical composition, structural evolution, and surface hydration behavior following post‐deposition annealing in air from 400 to 600°C. Lab‐based and synchrotron X‐ray photoelectron spectroscopy (XPS) reveal a gradual conversion from metallic Ru to fully oxidized Ru4+ with increasing annealing temperature, accompanied by a corresponding increase in lattice oxygen. X‐ray diffraction (XRD) shows amorphous Ru oxide phases at 400°C and 500°C that evolve into crystalline RuO2 at 600°C, while atomic force microscopy (AFM) indicates enhanced grain growth and surface roughening upon annealing. Ambient‐pressure XPS (AP‐XPS) under controlled H2O vapor environments (1–17 Torr) demonstrates that samples annealed at 400°C and 500°C exhibit initially high hydroxyl coverage that decreases with increasing water vapor pressure, concurrent with a rise in molecular H2O adsorption. In contrast, the crystalline RuO2 surface formed at 600°C maintains stable hydroxylation and supports increased water uptake. Overall, this work provides fundamental insight into Ru oxide–H2O interactions and establishes design principles for engineering oxide surfaces optimized for electrocatalytic applications.
A directly pumped Nd:LGSB laser with emission around 1.06 & micro;m is explored for the first time, to our knowledge. A maximum continuous wave output power of 3.05 W is measured at 4.22 W absorbed pump power for a Nd: LGSB c-cut medium pumped directly into 4F3/2 emitting level, placed in a plane-plane cavity. The laser was operated with high-0.80-slope efficiency, close to 0.83 quantum defect level. By comparing the laser performances for continuous wave diode pumping at 880 nm with conventional 807 nm, while keeping similar laser cavity conditions, increases of 15 % of slope and 14 % of optical-to-optical efficiencies were observed, at optimum 5 % transmission of the output coupler. In addition, temperature measurements during continuous wave direct pumping of Nd:LGSB crystal are presented, envisaging further laser power scaling. The enhanced infrared lasing performance offers motivation for future studies aiming boosted visible emission of Nd:LGSB bifunctional crystal under direct pumping condition.
