The absorption band in which near-unity or perfect absorption can be realized is still narrow in the current broadband metamaterial absorbers (BMAs). In this article, a broadband perfect metamaterial absorber (BPMA) based on surface plasmon resonance (SPR) is proposed for the visible and near-infrared range. The BPMA composed of a patterned Ti₃C₂T_x layer, SiO₂ layer and the ground gold layer can offer over 90% absorption across the wavelength range of 639–967 nm. It is worth noting that near-unity absorption can be achieved in the range 728–890 nm, which is out of reach by the currently reported BMA. The electric field distribution reveals that localized SPR generated by the Ti₃C₂T_x layer contributes to the broadband perfect absorption. Additionally, the BPMA is insensitive to incident and polarized angles at TE and TM modes. The calculated results based on interference theory agree well with the simulation results, thus supporting the design. This work may provide a potential approach to broadband perfect absorption in the visible and near-infrared region.

A single-layer, quartz-supported frequency selective surface (FSS) with a gear-shaped metallic array is proposed for 6G communication. Full-wave simulation, along with the method of equivalent circuit, is applied to investigate the transmission characteristics, while the distributions of surface current distribution, as well as electric field and magnetic fields, are studied to further interpret the transmission mechanism. The simulation indicates that the resonant frequency of 131 GHz with an attenuation of −40 dB can be obtained and the relative bandwidth approximates to 12%. The transmission response of the fabricated FSS prototype is measured using the free space measurement setup. The measured results show a good agreement with the simulated ones, which demonstrates the reliability of the design and fabrication. The proposed FSS with the advantages of simple structure, low cost, easy fabrication, and integration can be applied in enhancing the communication performance and anti-interference ability in the future 6G communication system.

Acceleration grid power supply (AGPS) is the energy provider of the negative neutral beam injection (NNBI) system. With the construction of the Comprehensive Research Facility for Fusion Technology (CRAFT), higher parameter requirements are proposed and a high-voltage power supply (HVPS) rated $-$ 200 $\sim$ $-$ 400 kV/28 A has been developed. This article introduces the design of each part of the AGPS in detail, such as the neutral-point-clamped (NPC) inverter, step-up transformer, and diode rectifier. The control system is also discussed and an optimized mathematical model from the duty cycle of the inverter to the dc output of the power supply (PS) is given. A scheme is put forward to solve the special grid breakdown (GB) condition of NNBI AGPS. The experimental results demonstrate that AGPS can meet the rated output requirements of the NNBI system and it can be quickly turned off to protect the AGPS in GB condition, which provides a related reference for the subsequent development of other HVPS for auxiliary heating of nuclear fusion.

A simple and compact terahertz frequency selective surface (FSS) with high selectivity is presented for cases of normal incidence. Guidelines for the design along with the operation mechanism are presented in detail from the view of an equivalent circuit. The design is implemented by mapping the lumped components of a microwave filter topology circuit with two transmission zeros to structures of the FSS; the mapping is realized by slotting a cross-shaped aperture in the grid. An intensive study on the equivalent circuit model predicts the existence of transmission zeros and poles. It can afford two transmission zeros and two transmission poles ranging from 350 GHz to 450 GHz with a band separation of 1.05 and 1.07, thereby exhibiting fast roll-off characteristics. The two transmission zeros can be controlled independently by simply changing the structure parameters of the unit cell. The proposed FSS is superior in terms of roll-off rate as well as the balance between selectivity and overall thickness. The measured results of the prototype are consistent with the simulation results, which validates the robustness of the design.