The requirement of a plasma solution without large edge-localized modes (ELMs) for future fusion devices motivates the study of plasmas without Type I ELMs. The enhanced D– α (EDA) and quasi-continuous exhaust (QCE) scenarios are two such Type I ELM free plasmas, but their underlying physics principles are not fully understood. A database of EDA and QCE plasmas from ASDEX Upgrade was compiled and analyzed using the correlation electron cyclotron emission diagnostic in order to study differences between properties of the quasi-coherent mode (QCM) between these two regimes. Investigations into measured spectral properties of the QCM, radiated temperature fluctuations δ T rad / T rad , and radial correlation lengths L c showed no differences between the two regimes. Spectral properties using the cross-power spectral density, G xy were similar between regimes, with the values measured to be a central frequency, f QCM ≈ 20 − 50 kHz; spectral width, Δ f ≈ 5 − 40 kHz; δ T rad / T rad ≈ 4 − 6 % ; and L c ≈ 1 − 2 cm. Investigations into a quantity representing the relative bandwidth Δ f / f QCM revealed differences between EDA and QCE plasmas when plotted radially, suggesting some type of interaction between the QCM in QCE plasmas with the surrounding broadband turbulence that is not present in EDA phases. Additionally, investigations into various drive terms for hypothesized instability drivers for the QCM are performed showing no difference in the parameter spaces of collisionality and the ion temperature, electron temperature, or electron pressure scale lengths between each regime indicating that there is no observable difference between the drive behind the QCM in each regime.
Plasmonic nanocavities are ideally suited for optical sensing due to their unique ability to localize and focus light on the nanoscale. However, plasmonic nanocavities formed between metallic nanoparticles on a metal film are either hydrophobic or entirely filled with nonmetallic spacer layers, hindering molecular diffusion into the hotspot regions. In this study, we designed and fabricated a plasmonic structure of multitipped Au@Ag-Au particle in nanocuboids (PCs), integrated with a metal film to create open plasmonic nanocavities. By adjusting the pH of the growth solution to control the reduction rate and the etching rate of Au3+, we precisely regulated the selective growth of metallic nanoparticles on the surface of Au@Ag core-shell nanocuboids. This plasmonic nanocavity is spaced by metal nanoparticles and forms 5 nm cavities open to the surroundings, which results in significantly enhanced Raman performance compared to traditional plasmonic nanocavities. Finally, functionalization of this plasmonic nanocavity enabled ultrasensitive detection of Cr6+ Ions.
We present the process and results of neutronics-driven shielding design using metal and ceramic matrix metal hydride neutron shields within the context of compact, high-power tokamaks. In particular, hafnium hydrides were considered within a matrix of stainless steel or magnesium oxide and contrasted with established and novel fast neutron shielding materials. These shielding materials are found to substantially increase the lifetime of toroidal field magnets made of high-temperature superconductors by a factor of up to 14.5. Specifically, a stainless steel-20% HfH1.7 thermal shield and outer neutron shield, paired with an inner tungsten carbide (WC) shield and toroidal field magnet case and winding pack both doped with 40% HfH1.7 by volume, were found to achieve a 93.1% reduction in peak fast neutron flux to high-temperature superconductor tapes. Simultaneously, this configuration reduced the total mass (and cost) of the neutron shield, as well as the nuclear heating rate of the magnet coil, in comparison to monolithic shields of WC and boron carbide.
Confining individual luminescent molecules in nanoscale spaces and investigating the correlation mechanism between molecular structure and luminescent properties under external stimuli is an effective strategy for optimizing their luminescent performance. Herein, 2,2 '-biquinoline-4,4-dicarboxylic acid disodium salt (BCA) molecules with significant AIE characteristics were confined within the two-dimensional layers of Ni-MOF, forming a dye-embedded MOF (DE-Ni-MOF). A remarkable pressure-induced luminescence enhancement was observed when the confined BCA was released from high pressure to ambient conditions. In situ experimental and theoretical investigations under high pressure have revealed that the application of pressure compresses the lattice structure of DE-Ni-MOF, ultimately leading to the disruption of its layered framework. A binding interaction was established between the confined BCA molecules and the framework after pressure treatment, effectively restricting the vibrational and rotational motions of the BCA molecules. This binding was maintained to atmospheric pressure, and the pressure treatment significantly enhanced the luminescence of BCA.
