Xiaolong Zhang

We demonstrate the use of a genetic algorithm with binary amplitude modulation of light through turbid media. We apply this method to binary amplitude modulation with a digital micromirror device. We achieve the theoretical maximum enhancement of 64 with 384 segments, and an enhancement of 320 with 6144 segments.

Abstract In the last two years, three major technical improvements have been made on J-TEXT in supporting of the expanded operation regions and diagnostic capabilities. (1) The successful commission of the 105 GHz/500 kW/1 s electron cyclotron resonance heating (ECRH) system increasing the core electron temperature from 0.9 keV up to around 1.5 keV. (2) The poloidal divertor configuration with an X -point in the high-field side has been achieved. In particular, the 400 kW electron cyclotron wave has also been successfully injected into the diverted plasma. (3) A 256-channel electron cyclotron emission imaging diagnostic system and two sets of four-channel Doppler backscattering diagnostics have been successfully developed on J-TEXT, allowing detailed measurement of the electron temperature and density fluctuations for turbulence and MHD research. The locked mode (LM), especially the 2/1 LM, is one of the biggest threats to the plasma operation. Both the thresholds of 2/1 and 3/1 LM are observed to vary non-monotonically on electron density. The electrode biasing was applied successfully to unlock the LM from either a rotating or static resonant magnetic perturbation (RMP) field. In the presence of 2/1 LM, three kinds of standing wave (SW) structures have been observed to share a similar connection to the island structure, i.e. the nodes of the SWs locate around the O - or X -points of the 2/1 island. The control and mitigation of disruption is essential to the safe operation of ITER, and it has been systematically studied by applying a RMP field, massive gas injection (MGI) and shattered pellet injection on J-TEXT. When the RMP-induced 2/1 LM is larger than a critical width, the MGI shutdown process can be significantly influenced. If the phase difference between the O -point of LM and the MGI valve is +90° (or −90°), the penetration depth and the assimilation of impurities can be enhanced (or suppressed) during the pre-thermal quench (TQ) phase and result in a faster (or slower) TQ. A secondary MGI can also suppress the runaway electron (RE) generation, if the additional high-Z impurity gas arrives at the plasma edge before TQ. When the secondary MGI has been applied after the formation of the RE current plateau, the RE current can be dissipated, and the dissipation rate increases with the injected impurity quantity but saturates with a maximum of 28 MA s −1 . The non-local transport is experimentally observed in the ion transport channel. The electron thermal diffusivity significantly increases with the ECRH power. Theoretical work shows that significant intrinsic current can be driven by electromagnetic turbulence, and the robust formation mechanism of the E × B staircase is identified from the Hasegawa–Wakatani system.

With the advent of droplet-based triboelectric nanogenerators (D-TENGs), methods for converting raindrop kinetic energy to electrical energy have developed rapidly. However, current D-TENG designs suffer from slow solid–liquid interface separation speeds and susceptibility to liquid residues. These issues compromise the output performance of D-TENGs and limit their applications in high-power electrical appliances. To address this, this study presents a needle electrode droplet-based triboelectric nanogenerator (NED-TENG). The needle electrode functions as the top electrode, optimizing solid–liquid contacts and efficiently harvesting raindrop kinetic energy by leveraging the triboelectric and electrostatic induction mechanisms. This needle electrode is made from one end of a copper wire, with its other end directly connected to the energy harvester. This setup positions all of the wiring on the back of the substrate, accelerating liquid separation, mitigating residue formation, and simplifying device fabrication. Upon assembly of the device, several factors influencing the performance of the fabricated D-TENG and its action mechanisms are explored to improve its output efficiency. Experimental results reveal that the designed D-TENG only requires 6 s to saturate the surface charge of its polytetrafluoroethylene film, achieving a short-circuit current (ISC) of up to 4.76 mA and an output voltage (V0) of up to 563 V. Overall, this study offers a straightforward and effective approach for harvesting kinetic energy from rainwater.