The JET 2019-2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major Neutral Beam Injection (NBI) upgrade providing record power in 2019-2020, and tested the technical & procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle physics in the coming D-T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed Shattered Pellet Injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design & operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D-T benefited from the highest D-D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER.
Copper oxide thin films were prepared by reactive rf magnetron sputtering of a pure copper target in an oxygen‐argon atmosphere. The phases of the deposited films strongly depend on the oxygen content in the sputtering gas. X‐ray diffraction studies show that by controlling the oxygen partial pressure single phase Cu2O and CuO can be obtained. The resistivity of the Cu2O film in the present study is 43 Ω cm. The optical constants were evaluated from transmission and reflection measurements.
Alpha particles with energies on the order of megaelectronvolts will be the main source of plasma heating in future magnetic confinement fusion reactors. Instead of heating fuel ions, most of the energy of alpha particles is transferred to electrons in the plasma. Furthermore, alpha particles can also excite Alfvénic instabilities, which were previously considered to be detrimental to the performance of the fusion device. Here we report improved thermal ion confinement in the presence of megaelectronvolts ions and strong fast ion-driven Alfvénic instabilities in recent experiments on the Joint European Torus. Detailed transport analysis of these experiments reveals turbulence suppression through a complex multi-scale mechanism that generates large-scale zonal flows. This holds promise for more economical operation of fusion reactors with dominant alpha particle heating and ultimately cheaper fusion electricity.
A helical model was previously proposed for sodium (NaDC) and rubidium (RbDC) deoxycholate micellar aggregates in aqueous solutions. SAXS, NMR, ESR, and CD measurements verified the helical model. Here we report an EXAFS study by the spherical wave formalism on the coordination of the Rb+ ions in the crystal, macromolecular fiber, and micellar aqueous solution of RbDC together with measurements carried out on rubidium oxalate (crystal and aqueous solution). The results show that the Rb+ ions of the micellar aggregates have the same (or very similar) peculiar coordination as that inside the helices of the crystal and macromolecular fiber. Moreover, their coordination remarkably differs from that observed in the aqueous solutions of rubidium oxalate, where the situation would be similar to that of a classical micelle. Thus, the helical model is unquestionably confirmed.
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