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Journal of Physics D: Applied Physics - latest papers
Latest articles for Journal of Physics D: Applied Physics
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Recent advances in the enhancement of interfacial properties in carbon fiber reinforced polymer composites with nanomaterials
Carbon fiber reinforced polymer composites (CFRPs) are widely used in aerospace, transportation, and defense industries due to their excellent properties such as lightweight, high specific strength and stiffness, superior thermal stability, and corrosion resistance. However, the smooth and chemically inert surface of carbon fiber (CF) results in poor interfacial adhesion between the fiber and matrix, thereby impacting the mechanical performance of CFRPs. To address this issue, nanomaterials have been introduced to the fiber surface, leveraging their exceptional mechanical properties and large specific surface area to enhance the interfacial properties of CFRPs. Compared to conventional modification methods like sizing, plasma treatment, and oxidation treatment, nanomaterials provide a superior approach by creating a robust transition layer at the interface. This layer can enhance mechanical interlocking, balance the modulus of the CF with that of the matrix, and effectively disperse interfacial stress, thus improving load transfer from the matrix to the fiber. This review examines recent advances in CF surface modification using nanomaterials and discusses the mechanisms behind interfacial enhancement. It also explores the potential future directions for research in this field, aiming to promote nanomaterial applications for advancing the use of higher-performance CFRPs from lab to industry.
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Investigation on horizontal asymmetries in plasma plume of a pulsed plasma thruster
This study investigates the horizontal asymmetry of plasma plumes in a pulsed plasma thruster (PPT), focusing on the distribution of electron density and magnetic field strength. Using a triple Langmuir probe, the electron density was measured, revealing a peak density on the right side that was up to 87 higher than the left side at representative points. Concurrently, magnetic field measurements using a magnetic probe revealed a non-uniform distribution, with the strongest disparities localized near the electrodes during current reversal, exhibiting a 59.11 higher magnetic field strength in these areas. These magnetic asymmetries were identified as the primary driver of the observed plume canting, influencing the Larmor radius of charged particles and inducing trajectory differences. The experiments demonstrated repeatability errors of 7.43 for Langmuir probe data and 34.79 for magnetic probe measurements, confirming the reliability of the results. The findings highlight that plume canting originates from non-uniform Lorentz forces caused by asymmetric magnetic fields near the electrodes. This phenomenon results in a preferential plasma flow direction, leading to risks of component contamination and reduced thruster efficiency. Additionally, plasma backflow was observed traveling at approximately 5 km s−1, occurring approximately 10 µs after the discharge and lasting for 4µs on both sides of the thruster, further contributing to potential contamination risks. These results underscore the importance of accounting for horizontal asymmetry in PPT designs and suggest that optimizing the magnetic field distribution could improve thruster performance.
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Four peak and high angle tilted insensitive surface plasmon resonance graphene absorber based on circular etching square window
This article introduces a new type of graphene-based perfect absorber that features tunability across four wave peaks and high sensitivity, consisting of Ag–SiO2–graphene. By controlling the Fermi level and relaxation time of graphene, the tunability of the absorber is achieved, and by changing the refractive index of SiO2, the selectivity of the resonant wavelength is realized. The results show that the absorber has an average absorption rate of 98.54% at four wavelengths: 2092.24 nm, 2180.67 nm, 2230.08 nm, and 2336.17 nm. The electric field distribution intensity is simulated to verify whether it meets the impedance matching theory, exploring the physical mechanism behind the high absorption rates at these four peaks. Different polarizations and inclined incidence angles are investigated to explore the absorber’s insensitivity to polarization, demonstrating excellent insensitivity within an inclination angle range from 0° to 65°. The sensitivities of the four peaks are 501.54 nm RIU−1, 565.76 nm RIU−1, 605.47 nm RIU−1, and 582.70 nm RIU−1, respectively. Finally, the practical application of the absorber in detecting aqueous solutions of 10%, 20%, 25% glucose solutions, and 30%, 50% sugar solutions is simulated, and the results show that the absorber has good sensing performance. This paper’s absorber features four-peak perfect absorption and excellent tilt insensitivity, good refractive index sensitivity, and holds great potential applications in detectors and optical communication systems.
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Are local-field and local-energy approximations appropriate for modeling nanosecond discharges?
A comprehensive solution of the electron kinetics in gas discharges, accounting for dependencies in space, velocity and time, is often unfeasible. Therefore, the electron behavior is frequently coupled to fluid models under one of two assumptions: the local-field approximation (LFA), which equates the electron kinetics to the steady-state calculation with the local and instantaneous value of the reduced electric field; or the local-energy approximation (LEA), in which the rate coefficients and the electron power distribution among different collisional channels depend on the local value of the mean electron energy. In this work, we focus on time-locality to assess the impact of the LFA and LEA assumptions on the calculation of the temporal evolution of the electron kinetics in nanosecond discharges. To do so, we consider an accurate Monte Carlo time-dependent formulation as golden standard. We study electron relaxation in different background gases (air, argon, and mixtures of both) at two pressures (10 and 100 Torr). The LEA generally provides more accurate results than the LFA, with increasing differences at lower pressures, where energy relaxation is slower. The greater accuracy of the LEA comes from the temporal effects introduced by the equation for the mean electron energy, which is absent in the LFA. Opting by the LFA in conditions of slow relaxation can lead to serious degradation of the model results, with errors on the production of excited species up to several tens of percent. Hence, in those scenarios, and when a kinetic approach is not possible, the LEA should be adopted instead of the LFA. The comparison is extended to a two-term time-dependent solver based on a quasi-stationary assumption for the first anisotropy. This method provides a good description of the electron kinetics, except at early times ( ns) at 10 Torr, where the quasi-stationary assumption becomes inaccurate.
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Generation and control of vortex waves using tunable metasurfaces
This paper proposes an actively tunable reflective metasurface containing solely addressable meta-atoms capable of continuous phase adjustment within the microwave frequency range. Each meta-atom’s response can be quickly and accurately adjusted by adjusting the external voltage applied to each meta-atom, thereby regulating the phase distribution of the unit structures on the metasurface. Successful generation with three modes of vortex beams (VBs). Additionally, focusing and non-diffracting VBs with limited beam radii are achieved by superposing the vortex phase profile with a focusing phase profile and a non-diffracting zeroth-order Bessel beam phase profile, respectively, by combining laboratory simulations and sample testing, demonstrating the metasurface’s high-precision phase control capability in the reflective state. The presented scheme facilitates the development of metasurface devices with more functionalities. It exhibits significant potential for microwave fields, like intelligent wireless communication, antennas, and radars.