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- Sunn Pedersen, Thomas, et al.
(författare)
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Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4, s. 042022-042022
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Tidskriftsartikel (refereegranskat)abstract
- We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases.
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- Wen, Xiaoyu, et al.
(författare)
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Materials Compatibility in Rechargeable Aluminum Batteries : Chemical and Electrochemical Properties between Vanadium Pentoxide and Chloroaluminate Ionic Liquids
- 2019
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Ingår i: Chemistry of Materials. - : AMER CHEMICAL SOC. - 0897-4756 .- 1520-5002. ; 31:18, s. 7238-7247
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Tidskriftsartikel (refereegranskat)abstract
- To demonstrate the importance of electrode/electrolyte stability in rechargeable aluminum (Al) batteries, we investigate the chemical compatibility between vanadium pentoxide (V2O5), a proposed positive electrode material for Al batteries, and the common chloroaluminate ionic liquid electrolytes. We reveal that V2O5 reacts with both the Lewis acidic (Al2Cl7-) and the Lewis neutral species (AlCl4-) within the electrolyte. The reaction products are identified using a combination of electrochemical analyses, Raman spectroscopy, liquid-state and solid-state nuclear magnetic resonance (NMR) spectroscopy, and density functional theory (DFT) calculations. The results establish that V2O5 chemically reacts with Al2Cl7- to form vanadium oxychloride (VOCl3) and amorphous aluminum oxide. V2O5 also chemically reacts with AlCl4- to produce dioxovanadium chloride (VO2Cl) and a new species of metavanadate anion coordinated with aluminum chloride (AlCl3VO3-). These products furthermore exhibit electrochemical redox activity between V5+ and V2+ oxidation states. Our results have significant implications when interpreting the electrochemical properties and mechanisms of rechargeable Al-V2O5 batteries.
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