[en] Graphical abstract: - Highlights: • The plausible growth mechanism for the formation of CuO film with star-like structure is proposed for the first time. • In the process of electrodeposition, the electrodepisition voltage is the key factor to control the surface morphology of CuO films. • Cu₂O works as hard template to control the surface morphologies of CuO. • As-prepared CuO films whose photo-degradation rate of methylene blue can reach 95% own the best photocatalytic activity compared to CuO powder with nanoscale or general size. - Abstract: Monoclinic nanostructured CuO films with star-like morphology on indium tin oxide (ITO)-coated glass substrates were successfully synthesized by electrodeposition method in acidic solution with the pH of 5.7. The as-synthesized films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–vis. The influence of different electrodeposition parameters and annealing temperature on the growth of CuO films were investigated. The results showed that the nanostructured CuO film was well-crystallized and electrodeposition voltage is the main factor to control its morphology. Moreover, good photocatalytic activity was exhibited and photo-degradation rate to methylene blue can reach 95%. Its optical energy band gap is 3.3 eV. The plausible growth mechanism for the formation of CuO film with star-like structure is also proposed for the first time

[en] Stable-polarization VCSEL has gained an increasing attention in the field of target detection and laser medicine due to its compact size and relativity high beam quality. The VCSEL emitting stable-polarization uniform laser could, in particular, improve the accuracy of target detection. In this paper, a polarization control metal grating was processed on the top mirror of the VCSEL to inject carriers and select the polarization light. A diffractive optical element was processed on the substrate to shape the output beam. The design phase distribution of the DOE was based on G–S algorithm; as a result, an output power of 20 mW with a polarization ratio of 30:1 and a uniformity of 83.5% of the laser was obtained.

[en] The high speed CCD visible-light camera system has been installed to detect the dynamic characteristics of ELMs filaments on EAST tokamak. In order to convert the CCD video imaging coordinates into real space coordinates, the CCD system has calibrated using Tsai's two-stage calibration technique. A raised spike in the grayscale profile, drawn by selecting the grayscale value of the image in the vertical direction of the ELMs filament in the CCD image, represents an ELMs filament structure whose positional coordinates are determined by the apex of the spike. The Sobel edge detection operator was used to examine the edge profile of the filament to obtain the width of the filament. By analyzing the characteristics of the filament width of the ELMs, it is found that the width of ELMs filaments continuously decreases outward from the outermost magnetic surface. This indicates that the filaments continue to dissipate energy and particles as they propagate outward. The width of filaments of Type-I ELMs is greater than that of Type-III ELMs. (authors)

[en] Copper doped ZnO hierarchical nanostructures have been synthesized with a facile solution route at room temperature. Structural properties of the as-synthesized nanostructures have been studied X-ray diffraction, field emission scanning electron microscopy with energy dispersive. Meanwhile, light-absorption properties were studied with UV–Vis absorption spectroscopy. Photocatalytic performance of Cu-doped ZnO hierarchical nanostructures were evaluated by the light-driven degradation of methylene blue. The results indicated that Cu doping lead to the augment of average crystallite size of ZnO crystals. Moreover, morphological evolution of ZnO nanostructures was found with the addition of Cu ions. The photocatalytic test showed that there is an optimum Cu doping concentration which results in the enhancement of photocatalytic performance of Cu doped ZnO hierarchical nanostructures, compared with pristine ZnO. A novel and reasonable mechanism was proposed. It is believed that the enhanced photocatalytic performance of Cu doped ZnO hierarchical nanostructures can be attributed to the formation of acceptor level (Cu²⁺–Cu⁺) in the midgap of ZnO, which improved the utilization of light and separation efficiency of photogenerated electron hole pairs.

[en] Highlights: • Three carbon nanosheets (CNSs) with similar pore sizes but different pore structures were synthesized. • Supercapacitors were assembled with the CNSs with stacking, double-layer, or flower-like pore structures. • Rate performances and self-discharge rates of the supercapacitors followed the same order of double-layer>flower-like>stacking CNSs. • The self-discharge was jointly controlled by diffusion-controlled and ohmic leakage processes. -- Abstract: Self-discharge is an important factor to be considered for practical applications of supercapacitors (SCs). While the transport of electrolyte ions largely determines the rate performance of SCs, it also affects their self-discharge rate. In this work, three carbon materials, namely stacking carbon nanosheets (S-CNSs), double-layer carbon nanosheets (DL-CNSs), and flower-like carbon nanosheets (FL-CNSs), with similar pore sizes but different pore structures were synthesized. Due to the different pore structures and correspondingly different ion transport resistances, the rate performances increased from S-CNS, FL-CNS, to DL-CNS SCs. On the other hand, the self-discharge rates increased following the same order – the open circuit voltage dropped from 2.0 to 0.99, 0.74, and 0.53 V after 24 h for S-CNS, FL-CNS, and DL-CNS SCs, respectively. Analysis of the self-discharge processes indicates a combined diffusion-controlled and ohmic leakage self-discharge mechanism and a larger diffusion constant was found for DL-CNS than that of FL-CNS and S-CNS SCs, consistent with their order of self-discharge rates. The results of this work suggest that although fast ion transport is beneficial to the rate performance of SCs, it may also lead to fast self-discharge and limit the duration of energy storage.

[en] Graphical abstract: FESEM image of the CdS obtained by 0.01 mol Cd(NO_3)_2·4H_2O, 0.03 mol thiourea and 0.5 g SDBS at 160 °C for 24 h. - Highlights: • The role of SDBS is to assemble CdS crystals together to form flower-like structures. • Both reaction time and temperature affect the morphology of flower-like structures. • The growth mechanism of flower-like structures is reasonable, clear and concise. • Its optical energy band gap is 2.50 eV, and it has absorption in visible region. • PL result of flower-like structures shows the max emission wavelength is 508.6 nm. - Abstract: In this article, the flower-like CdS have been prepared by hydrothermal method with thiourea as sulfur source and SDBS as surfactant. The effects of different experimental conditions on the morphology of CdS have been investigated. The performances of CdS have been analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), room temperature photoluminescence (PL) and UV–vis. The result of XRD indicates that CdS we prepared are highly crystallized, which are of hexagonal phase. The FE-SEM results indicate that the main role of SDBS is to make the CdS crystals assemble together to form the flower-like structures, and the reaction time affects the morphology of CdS, and the suitable reaction temperature is 160 °C. Its optical energy band gap is observed at 2.50 eV. The fluorescence spectrum shows that the flower-like CdS have a broad absorption peak and the max emission wavelength is 508.6 nm. The growth mechanism for the formation of CdS with flower-like structures is also described

[en] The phenomenon of multifaceted asymmetric radiation from the edge (MARFE) is investigated with impurity gas puff from the upper divertor on the Experimental Advanced Superconducting Tokamak (EAST). A typical process in which dense radiation region in the vicinity of the X point (X-point MARFE) further evolves into MARFE on the high field side (wall MARFE) after the plasma makes a transition from H-mode to L-mode confinement is observed in discharges with the impurity gas seeding. The electron density distribution and evolution in the divertor volume are measured by means of spectroscopy. It is observed in the experiments that the final position of MARFE is related to the ion ∇ B drift direction. After the phase difference of n = 1 resonant magnetic perturbation (RMP) change from 90° to 270°, MARFE begins to appear on the high field side, which may be caused by the density pump-out induced by RMP. At the same heating power, the density threshold for MARFE formation is somewhat higher in the Ne seeding discharge than in the Ar seeding discharge. This may be attributed to the fact that the divertor radiation fraction, P _rad,div/P _rad,main, in the Ne seeding discharge is lower than that in the Ar seeding discharge. In addition, MARFE is successfully suppressed by total radiated energy feedback control in radiative divertor experiments. Therefore, radiation feedback control may play a vital role in avoiding major disruption induced by impurity radiation in radiative divertor experiments. (paper)

[en] Toroidal field and q ₉₅ scalings of error field penetration are investigated with n = 1 resonant magnetic perturbation coil in EAST. The toroidal field scalings of error field penetration thresholds under fixed q ₉₅ are about $b_{r21}/B_T\propto <!--\; ???\; -->B_T^{-<!--\; ???\; -->1.0}$ in both ohmically and lower hybrid wave heated plasmas, where b _r21 is the vacuum error field at the q = 2/1 rational surface and B _T is the toroidal field. These scalings indicate a favorable tolerance on error field in ITER. To make clear the underlying physics on toroidal field scaling, the theoretical analysis is given. By subtituting penetration related scaling parameters into the theory, the obtained theoretical scalings are consistent with the experimental observations using the vacuum penetration thresholds. To further investigate penetration threshold in larger operation region, the q ₉₅ scaling on penetration threshold with $b_{r21}\propto <!--\; ???\; -->q_{95}^{1.66}$ has also been observed. The rational surface radius r _s and magnetic shear s, which are crucial to q ₉₅ scaling, are included in the theoretical analysis. The theoretical analysis is also consistent with the experimental scalings using the vacuum penetration thresholds. Moreover, the obtained theoretical scalings are easy to compare with experimental scalings. These theoretical analyses will stimulate the extrapolation of error field tolerance towards future reactors. (paper)

[en] The density scaling of n = 1 error field penetration is investigated under radio-frequency (RF)-dominant heated L-mode discharges in the EAST tokamak. It is found that the density scaling of the threshold field strength for error field penetration in lower-hybrid current drive (LHCD) plasmas is about $b_{\text{r}}\propto <!--\; ???\; -->n_{\text{e}}^{0.4}$, where b _r represents the error field amplitude. The results show a weaker density dependence compared to that observed in the previous ohmic heated discharges (Wang et al 2018 Nucl. Fusion 58 056024). For a better understanding of the density scaling, it is compared with field penetration theories, and it is found that it lies in the Waelbroeck regime. The observed scaling is consistent with that evaluated with the magnetohydrodynamic (MHD) theory on error field penetration, for which all the physical parameters are determined experimentally. Due to the density dependence of LHCD heating efficiency, the stronger negative correlation between density and temperature results in a weaker density scaling in these LHCD plasmas. Using realistic parameters under LHCD and ohmic heating as input, respectively, the numerical results based on a reduced MHD model reproduce well the scaling from the error field penetration theory and the observations. Besides, the density scaling in various tokamak operational regimes is also numerically investigated. This provides an excellent validation of MHD theory on error field penetration in the RF-dominant heated L-mode discharges. (paper)

[en] Experiments have been carried out at the EAST tokamak to study ITER-relevant scenario integration issues, related to edge localized mode (ELM) control in H-mode plasmas by the application of three-dimensional (3D) resonant magnetic perturbations (RMPs), which have a large impact on the execution of the ITER research plan. The EAST experiments have successfully demonstrated ELM suppression at normalized torque inputs similar to ITER. The application of RMP fields with high toroidal mode number (n = 4) reduces the impact of ELM control on energy and particle confinement compared to those use lower n (n = 1, 2) RMPs. Injection of successive pellets is found to be effective in increasing the plasma density in ELM-suppressed H-modes and reducing the divertor power without triggering large ELMs at EAST. Access to high recycling and radiative divertor conditions while maintaining ELM suppression has been demonstrated in EAST by the use of gas fuelling and neon impurity seeding. Both approaches have been found to be effective in reducing power fluxes to the divertor strike points in near-separatrix lobes for both n = 2 and n = 4 RMPs. However, reduction of power fluxes in off-separatrix lobes is only effective for n = 4 RMP application, which is consistent with magnetic topology modelling (including plasma response) results showing a shallow penetration into the confined plasma region of field lines connected to these lobes compared to n = 2. The EAST results support the use of high n 3D fields for ELM suppression in ITER high Q _DT scenarios since they provide optimum integration features regarding energy and particle confinement, pellet fuelling, radiative divertor operation while eliminating ELM transient power loads and being compatible with low torque input. (paper)